Vitamins & Supplements · Supplement formula
Proprietary Blends Explained: What Must and Must Not Be Disclosed
Proprietary blend · also called Proprietary formula, proprietary blend label, mezcla patentada
A proprietary blend is a group of ingredients listed under one name with one total weight on a US supplement label. The ingredient names must be shown, in order of weight, but not the amount of each. No trial has tested a blend against its own ingredients, and hidden amounts cannot be checked against limits or medicines. Some product types sold as blends have been found to hold hidden drugs.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Proprietary Blends Explained: What Must and Must Not Be Disclosed
A proprietary blend is a group of ingredients under one name with one total weight. The ingredients are named and ordered by weight, but individual amounts can stay hidden. That is allowed, and it limits what a buyer can check. No trial has tested a blend against its parts.
What a proprietary blend is
On a US supplement label, a proprietary blend is shown under the name 'Proprietary Blend' or a descriptive or made-up name. The label gives one total weight for the whole blend and lists the ingredients inside it, in descending order of weight.
A 2023 paper says the 1994 supplement law lets companies list non-nutrient ingredients this way to protect their formulas. The blend's weight and ingredient names must be shown, but not the amount of each one.
What is usually inside, and who buys it
Blends turn up in sports, energy, weight-loss, sleep, immune, brain and mushroom products. In pre-workout powders the usual ingredients are caffeine, creatine, beta-alanine, citrulline, tyrosine and taurine. In energy drinks and shots they are caffeine, B-vitamins and taurine. Many are sold in powders, capsules, gummies and drinks.
In a survey of 100 top pre-workout products, 8.1 of 18.4 ingredients per product, or 44.3% of all ingredients, sat inside a blend with no amount shown. In 75 energy drinks and shots, 15 products hid amounts this way.
Reading the label terms
'Order by weight' tells you which ingredient there is most of, not how much. A 600 mg blend of five ingredients could be mostly one ingredient with traces of the rest, or five similar parts, and the label would look the same.
Vitamins and minerals that have a Daily Value must be listed on their own lines with amounts, even if the product also has a blend. The '% Daily Value' is the share of the official daily reference a serving gives. Ingredients with no Daily Value are marked 'Daily Value Not Established' and can sit inside the blend. A serving is the largest amount the label recommends for one occasion, or one unit if none is stated, and the maker decides it.
What the research shows
No trial of a blend as a product type was found. The best-studied blend products are pre-workout powders, where a 2018 review found possible gains in endurance, mood and lean mass but could not compare formulas because amounts are hidden.
Lab checks found wrong labels in many weight-loss and sports products, and FDA warnings show hidden drugs in some product types. These findings are about product types, not about the blend format itself.
At a glance
Traditional uses history, not proof
- A modern label term, not a traditional remedy
- Used in pre-workout, energy, weight-loss, sleep, immune and brain products
Studied for research
- Comparing blend products and checking amounts, moderate certainty that hidden amounts block it
- Whether a blend works because its ingredients were studied, insufficient evidence
- Multi-ingredient pre-workout products, low certainty
- Label accuracy, low certainty (mismatches are common in samples tested)
- Hidden drugs in some product types, moderate certainty that it happens
- Third-party testing seals, insufficient evidence
Main compounds
- Caffeine
- Creatine
- Beta-alanine
- Citrulline
- Taurine
- B-vitamins
Common forms
- Powders
- Capsules and tablets
- Gummies
- Drinks and shots
Research links: 2023 perspective: proprietary blends in dietary supplements · 2018 review: multi-ingredient pre-workout supplements · 2019 survey: ingredient profiles of 100 pre-workout supplements · 2024 lab check: label accuracy of 44 weight-loss supplements · 2018 analysis: unapproved drugs in supplements named in FDA warnings · FDA: Questions and Answers on Dietary Supplements · FDA: Dietary Supplement Labeling Guide, Chapter IV · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Proprietary blend (dietary supplement label term)
- Common names
- Proprietary blend (English); Proprietary formula (English); Mezcla patentada (Spanish); Mezcla propia (Spanish)
- Family or group
- Supplement label format. A group of 'other dietary ingredients' (those without a Daily Value) shown under one name with one total weight.
- Look-alikes and adulterants
- Note: Shows every ingredient and its amount; hidden amounts are the difference.; Name: Fully disclosed formula; Note: Vitamins and minerals with a Daily Value are listed on their own lines with amounts, even inside a blend product.; Name: Multivitamin; Note: A product type, often with blends; has its own page.; Name: Pre-workout supplement; Note: A product type that FDA warnings often name for hidden drugs; has its own page.; Name: Weight-loss and fat-burner blend
- Sustainability and conservation
- Not assessed.
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
Traditional use shows how it was used. It does not show that it works or is safe today.
What is inside, and how it may work
What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.
Main compounds
| Compound | Family | Where it is concentrated | Activity studied | Level of evidence |
|---|---|---|---|---|
| Ingredients inside a blend (varies by product) | Not one substance | Hidden by design: only the blend's total weight is shown. In a survey of 100 pre-workout products, 8.1 of 18.4 ingredients per product sat in a blend. | Depends on the ingredients. Examples seen in blend products in the sources: caffeine, beta-alanine, citrulline, tyrosine, taurine and creatine (pre-workout); caffeine, B-vitamins and taurine (energy products). 6 7 | Label survey |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Not applicable (label format) | Not applicable | A blend has no mechanism of its own. Any effect would come from its ingredients and their amounts, which the label hides. The 2018 pre-workout review describes a possible combined effect but does not show it. 5 | Hypothesis |
Isolated compounds versus whole extracts
A blend is neither a whole food nor a single isolated ingredient. It is a mix of ingredients whose shares are not printed. Foods bring their nutrients in known, natural amounts; a blend does not tell you its amounts.
Nutritional composition
Vitamins and minerals that have a Daily Value must be listed separately with their own amounts (FDA labeling guide). Ingredients without a Daily Value, such as phosphatidylserine (FDA's own example), can be placed in a blend with no individual amount.
2 moderate certainty3 low certainty2 not enough evidence
What was looked at
The 7 benefits and uses checked for Proprietary Blends Explained: What Must and Must Not Be Disclosed, each with how strong the evidence is. Tap one to open it.
- Comparing blend products and checking amountsModerate certainty
- Does a blend work because its ingredients were studied?Not enough evidence
- Multi-ingredient pre-workout products (many use blends)Low certainty
- Do labels match what is in the product?Low certainty
- Hidden drugs in some supplement typesModerate certainty
- Third-party testing and quality rulesNot enough evidence
- What energy drink and shot labels showLow certainty
Lab markers tracked in the studies
Share of listed ingredients inside blendsLabel accuracy in lab checks
What is Proprietary Blends Explained: What Must and Must Not Be Disclosed good for?
What research found on the main questions about blends, and how strong it is. A blend is a label format, so there is no single health benefit; these are findings about the format and the products that use it.
Benefits, one by one
Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.
Comparing blend products and checking amounts
Moderate certaintyResearchers who looked at blends say hidden amounts get in the way. A 2023 paper says the label cannot be used to work out how much of an ingredient someone takes or to set doses in trials. A 2018 review said comparing pre-workout formulas is often impossible for the same reason. A survey of 100 top pre-workout products found nearly half of all listed ingredients sat inside blends with no amount shown.
5 studiesNot applicable. The studies describe labels, not a taken amount.
Studies, doses and limits
What the trials found
No trial was needed for this question. It rests on a 2023 J Nutr perspective, a 2018 review of pre-workout products, a 2019 survey of 100 top-selling pre-workout products (18.4 ingredients per product on average, 8.1 of them inside a blend, 44.3% of all ingredients in blends) and a 2022 survey of 75 energy drinks and shots (15 with blends that hide amounts).
Results
Consistent across these sources: hidden amounts make intake, dose and comparison impossible to work out from the label alone.
Effect sizes as reported
Pre-workout survey: 44.3% of ingredients in blends. Energy products: 15 of 75 with blends. No outcome numbers, because this is about labels.
Why this rating
Moderate for this narrow point because three independent kinds of source agree. Not higher because one is a perspective paper, one a brief review, and the surveys cover only two product types.
Who was studied
Products on the US market, mainly sports and energy products.
Limits
Label surveys can only count what is printed. They do not show what is in the bottle.
Why researchers looked
If amounts are hidden, a buyer cannot compare a product with a trial, with another product or with an official limit. Researchers asked how often this happens and what it costs.
Traditional use
A proprietary blend is a label format, not an ingredient. Companies list a group of ingredients under one name with one total weight. This is not a traditional remedy.
Proposed mechanism Label rules
Not a biological effect. The limit is in the label: the blend's total weight is shown, but not each ingredient's share.
A proposed mechanism does not show that the effect happens in people.
If an amount is hidden it cannot be compared with an official upper limit. See the Safety tab.
Does a blend work because its ingredients were studied?
Not enough evidenceNo source read shows this. A blend lists ingredients that may each have been studied alone, but the amounts in the blend are not shown, so they cannot be matched to the amounts used in trials. A trial of the single ingredient does not show that a blend containing it works.
3 studiesNot applicable.
Studies, doses and limits
What the trials found
A 2023 perspective says label information cannot give the dose of a blend ingredient for a clinical trial. The 2019 pre-workout survey compared listed amounts with amounts shown to work and found the average beta-alanine amount was below the amount shown to work. No trial was found that tested a proprietary blend against its ingredients taken separately.
Results
Not shown. Absence of evidence in the sources read; this is not proof that blends never work.
Why this rating
Insufficient because no study answers the question, and the amounts needed to test it are hidden by the label format.
Limits
Only PubMed abstracts and two regulator pages were read. A trial of a specific branded blend may exist that was not found.
Why researchers looked
Makers often point to studies of single ingredients. The question is whether those studies carry over to a mixed product with hidden amounts.
Traditional use
A proprietary blend is a label format, not an ingredient. Companies list a group of ingredients under one name with one total weight. This is not a traditional remedy.
Proposed mechanism Hypothesis
Not established. Some pre-workout makers suggest ingredients work together; the 2018 review describes this as a theory, not a result.
A proposed mechanism does not show that the effect happens in people.
A long ingredient list does not show a useful amount of each ingredient is present.
Multi-ingredient pre-workout products (many use blends)
Low certaintyPre-workout powders are the best-studied kind of blend product. A 2018 review found taking them just before exercise may help muscle endurance and mood, with mixed results for strength and power. Used with weight training, they appeared to add lean mass. The review could not compare formulas, because blends hide amounts, and most safety studies were under eight weeks.
2 studiesFormulas differ. Amounts studied are not given in the abstract.
Studies, doses and limits
What the trials found
One 2018 narrative review summarised trials of multi-ingredient pre-workout products. The abstract gives no study count. It says acute use may improve muscular endurance and mood, results for force and power are mixed, and longer use with a periodised resistance programme appeared to increase lean mass. Effects on long-term strength, endurance and aerobic performance were unclear.
Results
Possible small gains in endurance, mood and lean mass for some formulas. These cannot be credited to blends as such, because the studies tested different formulas.
Effect sizes as reported
Not given in the abstract.
Why this rating
Low because the review is brief and narrative, formulas differ and cannot be compared, results on force and power are mixed, and the abstract gives no study count or effect sizes.
Form and dose studied
Formulas differ. Amounts studied are not given in the abstract.
Who was studied
Active adults in sports studies.
Limits
Industry funding of the trials was not checked. The review does not split blend products from products that show every amount.
Why researchers looked
Pre-workout products mix caffeine, creatine, beta-alanine, amino acids and similar ingredients, and sellers claim the mix works better than single ingredients.
Traditional use
A proprietary blend is a label format, not an ingredient. Companies list a group of ingredients under one name with one total weight. This is not a traditional remedy.
Proposed mechanism Hypothesis
Not established. The review describes a possible combined effect of the ingredients but does not show it.
A proposed mechanism does not show that the effect happens in people.
Most safety studies lasted under eight weeks. Some products may contain banned substances. See the Safety tab.
Do labels match what is in the product?
Low certaintyLab checks found many labels do not match. A review of 16 studies of sports supplements found labelled amounts differed from actual amounts. In a lab check of 44 weight-loss products bought near US military bases, 82% had inaccurate labels, 61% listed an ingredient that was not found, and 36% held a hidden ingredient. These are narrow samples and cannot be read as the whole market.
2 studiesNot applicable.
Studies, doses and limits
What the trials found
A 2021 narrative review of 16 studies (sports products: protein powders, pre-workout mixes, creatine and vitamin or mineral drinks). A 2024 case series of 44 weight-loss products analysed by liquid chromatography-mass spectrometry. Neither source says which products used proprietary blends.
Results
Label problems were common in the products tested, and worst in the weight-loss case series.
Effect sizes as reported
Weight-loss products: 82% inaccurate labels (36 of 44), 61% listed-but-missing ingredient (27), 36% hidden ingredient (16). The 2021 review gave no overall percentage.
Why this rating
Low for how common this is in general: one review limited to sports products and one case series of 44 products from one setting. The finding that mismatches exist is well documented; how often is not.
Who was studied
Athletes and service members as buyers; products from the US market.
Limits
Samples were not random. Products from other categories, such as multivitamins, were not covered in the sources read.
Why researchers looked
If a label is wrong, the amounts printed on it, and any hidden-amount blend, cannot be trusted for dose or safety.
Traditional use
A proprietary blend is a label format, not an ingredient. Companies list a group of ingredients under one name with one total weight. This is not a traditional remedy.
Proposed mechanism Laboratory analysis
Not a biological effect. Causes named in the sources are errors in labelling, leaving out substances that are present, and wrong amounts.
A proposed mechanism does not show that the effect happens in people.
A wrong label can mean a hidden stimulant or too much or too little of an ingredient. See the Safety tab.
Third-party testing and quality rules
Not enough evidenceA 2019 expert statement says no regulator reviews supplements for quality before they are sold, and that testing programs differ in what they test. A 2025 laboratory review lists third-party testing as one tool among several against adulteration. None of the 44 weight-loss products in the 2024 lab check carried a third-party seal. No study read measured whether a seal makes a product safer or more accurate.
4 studiesNot applicable.
Studies, doses and limits
What the trials found
A 2019 consensus statement by experts from sport and military programmes on essential features of certification programmes. A 2025 laboratory review of tools against adulteration (good manufacturing practice testing, certification programmes, supplier agreements, third-party testing). The 2024 weight-loss lab check found no seal on any of 44 products.
Results
Description and opinion only. No measurement of results from certification.
Why this rating
Insufficient because the sources are expert opinion and descriptions, and none measured whether certified products are safer or more accurate.
Who was studied
Athletes, military service members and general buyers.
Limits
The 2019 statement is written for athlete and military settings and the 2025 review comes from supplement laboratory work; author affiliations were not read. Only abstracts were read.
Why researchers looked
Because FDA does not test products before sale, buyers look to outside testing seals. Researchers asked what those programs do.
Traditional use
A proprietary blend is a label format, not an ingredient. Companies list a group of ingredients under one name with one total weight. This is not a traditional remedy.
Proposed mechanism Expert statement
Not applicable. Third-party programs test samples for identity, strength and banned or harmful substances; what each tests differs.
A proposed mechanism does not show that the effect happens in people.
A seal, where present, tests samples; it does not show that a blend works.
What energy drink and shot labels show
Low certaintyA 2022 survey of the 75 top-selling energy drinks and shots found about 18 ingredients per product. Every product had caffeine. Many gave B-vitamin amounts far above the Daily Value, and 15 hid amounts inside blends. This describes labels, not health results.
1 studiesNot applicable.
Studies, doses and limits
What the trials found
One 2022 label survey of 55 energy drinks and 20 energy shots as of September 2021. Caffeine averaged about 174 mg; vitamin B12 averaged about 5,245% of the Daily Value; taurine was present in 37.3% with no amount shown.
Results
Descriptive. B vitamins with a Daily Value must be shown with their amounts, so those can be added up across products. Taurine and other ingredients without a Daily Value can be hidden in blends.
Effect sizes as reported
15 of 75 products had blends with undisclosed amounts.
Why this rating
Low because this is one survey of top sellers at one date, from labels alone, with no lab testing.
Who was studied
Buyers of energy products in the US.
Limits
Nothing was lab tested; most drinks in the survey are not sold as supplements.
Why researchers looked
To describe what these popular products contain so buyers, clinicians and researchers have a standard picture.
Traditional use
A proprietary blend is a label format, not an ingredient. Companies list a group of ingredients under one name with one total weight. This is not a traditional remedy.
Proposed mechanism Label survey
Not applicable. A survey of printed labels.
A proposed mechanism does not show that the effect happens in people.
A 2015 emergency-visit study linked weight-loss and energy products to most supplement-related fast heart rate and chest pain. See the Safety tab.
Connections to the rest of health
How Proprietary Blends Explained: What Must and Must Not Be Disclosed connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.
Explore every connection: goals, body systems, organs, symptoms, genes
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Preventive Wellness | Moderate certainty | Comparing blend products and checking amounts: Researchers who looked at blends say hidden amounts get in the way. A 2023 paper says the label cannot be used to work out how much of an ingredient someone takes or to set doses in trials. A 2018 review said comparing pre-workout formulas is often impossible for the same reason. A survey of 100 top pre-workout products found nearly half of all listed ingredients sat inside blends with no amount shown. | 10 5 6 7 13 | |
| Preventive Wellness | Not enough evidence | Does a blend work because its ingredients were studied?: No source read shows this. A blend lists ingredients that may each have been studied alone, but the amounts in the blend are not shown, so they cannot be matched to the amounts used in trials. A trial of the single ingredient does not show that a blend containing it works. | 10 6 5 | |
| Sports Performance | Low certainty | Multi-ingredient pre-workout products (many use blends): Pre-workout powders are the best-studied kind of blend product. A 2018 review found taking them just before exercise may help muscle endurance and mood, with mixed results for strength and power. Used with weight training, they appeared to add lean mass. The review could not compare formulas, because blends hide amounts, and most safety studies were under eight weeks. | 5 6 | |
| Peak Performance | Low certainty | Multi-ingredient pre-workout products (many use blends): Pre-workout powders are the best-studied kind of blend product. A 2018 review found taking them just before exercise may help muscle endurance and mood, with mixed results for strength and power. Used with weight training, they appeared to add lean mass. The review could not compare formulas, because blends hide amounts, and most safety studies were under eight weeks. | 5 6 | |
| Preventive Wellness | Low certainty | Do labels match what is in the product?: Lab checks found many labels do not match. A review of 16 studies of sports supplements found labelled amounts differed from actual amounts. In a lab check of 44 weight-loss products bought near US military bases, 82% had inaccurate labels, 61% listed an ingredient that was not found, and 36% held a hidden ingredient. These are narrow samples and cannot be read as the whole market. | 9 1 | |
| Preventive Wellness | Moderate certainty | Hidden drugs in some supplement types: FDA warned about 776 supplements with undeclared drugs between 2007 and 2016. About 45% were sold for sexual enhancement, 41% for weight loss and 12% for muscle building. The authors say the drugs can cause serious harm through misuse, overuse or interaction with other medicines. This is a quality risk in those product types, not a benefit. | 11 15 12 | |
| Preventive Wellness | Not enough evidence | Third-party testing and quality rules: A 2019 expert statement says no regulator reviews supplements for quality before they are sold, and that testing programs differ in what they test. A 2025 laboratory review lists third-party testing as one tool among several against adulteration. None of the 44 weight-loss products in the 2024 lab check carried a third-party seal. No study read measured whether a seal makes a product safer or more accurate. | 2 8 1 14 | |
| Energy Boost | Low certainty | What energy drink and shot labels show: A 2022 survey of the 75 top-selling energy drinks and shots found about 18 ingredients per product. Every product had caffeine. Many gave B-vitamin amounts far above the Daily Value, and 15 hid amounts inside blends. This describes labels, not health results. | 7 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Whole Body | Biological association | Moderate certainty | Studied for: Comparing blend products and checking amounts Studied for: Does a blend work because its ingredients were studied? | 10 5 6 7 13 9 1 11 15 12 2 8 14 |
| Musculoskeletal System | Biological association | Low certainty | Studied for: Multi-ingredient pre-workout products (many use blends) | 5 6 |
| Nutrition | Biological association | Low certainty | Studied for: What energy drink and shot labels show | 7 |
E. Health conditions
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Medication side effects | Documented concern | Undeclared drugs in some supplements can cause harm alone or with other medicines. Preparation or compound: Hidden drug ingredients |
11 15 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Share of listed ingredients inside blends | Biological association | Moderate certainty | Measured in trials: high in pre-workout products. A lab change is not the same as a health benefit. | 6 7 |
| Label accuracy in lab checks | Biological association | Low certainty | Measured in trials: mismatch common in samples tested. A lab change is not the same as a health benefit. | 1 9 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Ingredients inside a blend (varies by product) | Biological association | Label survey | Depends on the ingredients. Examples seen in blend products in the sources: caffeine, beta-alanine, citrulline, tyrosine, taurine and creatine (pre-workout); caffeine, B-vitamins and taurine (energy products). | 6 7 |
Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).
Evidence at a glance: what the research found for 7 outcomes
Each outcome below is one thing researchers measured. Certainty is how far the evidence can be trusted, not how well it works. The full studies are on the next tab.
The evidence
The research centre for Proprietary Blends Explained: What Must and Must Not Be Disclosed. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).
How we rate evidence
High certainty
Several well-run trials or reviews agree; further research is unlikely to change the picture much.
Moderate certainty
Good trials point the same way, but some doubt remains.
Low certainty
Small, short or inconsistent trials. The finding could change with better research.
Very low certainty
Very little or very weak human data. Treat as a possibility only.
Mixed findings
Trials or reviews disagree with each other.
Not enough evidence
Not enough human research to say either way.
Evidence against
Good research found no benefit, or found harm.
We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our earlier page on proprietary blends, then re-checked each PubMed study by reading its abstract, and re-read the FDA and NCCIH pages cited. Only abstracts were read for papers. The NIH Office of Dietary Supplements site blocked access and is marked unverified.
Study library: every study we checked 15
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Crawford 2024 Label Accuracy and Quality of Select Weight-Loss Dietary Supplements Sold on or near US Military Bases. Nutrients · PMID 39770990 · DOI |
Case series lab analysis product samples |
44 44 weight-loss supplements bought at stores on or near 12 US military installations, March 2023 to January 2024 |
Weight-loss dietary supplements |
36 products (82%) had inaccurate labels. 27 (61%) listed ingredients that were not detected. 16 (36%) contained hidden ingredients. 40 (91%) scored 'no-go' on the Operation Supplement Safety scorecard. None carried a third-party certification seal. Several products contained multiple stimulants, so their safety was unknown. 82% inaccurate labels; 61% listed-but-missing ingredient; 36% hidden ingredient (Not applicable) Methods, limits and fundingOutcomes: Label accuracy by liquid chromatography-mass spectrometry; hidden and prohibited ingredients; third-party seal Limitations: 44 products from one setting, chosen not at random. It does not tell how common these problems are across the whole market, and it covers one product type. Funding and conflicts: Not stated in the abstract. The abstract names Operation Supplement Safety, a US Department of Defense effort, as working on access to certified products. Read: abstract |
| Eichner 2019 Essential Features of Third-Party Certification Programs for Dietary Supplements: A Consensus Statement. Curr Sports Med Rep · PMID 31082891 · DOI |
Consensus statement |
Expert authors writing for athletes and military service members | Third-party certification programs for supplements |
The authors state that no regulatory authority conducts or requires a quality review before supplements are sold, and that FDA has no premarket safety review role. Several companies offer testing and quality review programs, each with different testing parts. It is hard for buyers to judge whether a given program lowers risk enough. The paper sets out best practices. Not applicable (expert consensus) (Not applicable) Methods, limits and fundingOutcomes: Best practice for third-party testing programs Limitations: Expert opinion written for athlete and military settings, not a measurement of how well certification works. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Gardener 2025 Heavy metals and phthalate contamination in prenatal vitamins and folic acid supplements. Environ Res · PMID 40020868 · DOI |
Laboratory analysis product samples |
184 156 commercial prenatal vitamins, 19 folate or folic acid supplements and 9 prescription prenatal supplements |
Multi-ingredient prenatal vitamins (not blends) |
Lead was above the lab's quantification limit in 83% of the commercial prenatal vitamins, and 15% were above the California Proposition 65 limit of 0.5 microgram of lead per daily serving. Cadmium was found in 73%. Higher calcium and iron amounts, and caplet, capsule or tablet forms, went with more contamination. Folate and folic acid supplements had less. Lead found in 83%; 15% above 0.5 microgram per serving (Not applicable) Methods, limits and fundingOutcomes: Lead, cadmium and phthalates measured per daily serving Limitations: A lab survey of one product type (prenatal vitamins), not of proprietary blends. Brands were not named in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Geller 2015 Emergency Department Visits for Adverse Events Related to Dietary Supplements. N Engl J Med · PMID 26465986 · DOI |
Surveillance study |
3667 Cases from 63 US emergency departments, 2004 to 2013 |
Dietary supplements of all kinds |
An estimated 23,005 emergency visits and 2,154 hospital stays a year in the US were linked to supplement adverse events. Weight-loss or energy products caused 71.8% of supplement-related palpitations, chest pain or fast heart rate, and 58.0% of those involved people aged 20 to 34. Unsupervised children were 21.2% of visits. Among adults 65 and older, choking or trouble swallowing pills caused 37.6% of visits, and micronutrients were involved in most of those. About 23,000 visits a year (95% CI 18,611 to 27,398) (18,611 to 27,398) Methods, limits and fundingOutcomes: Emergency visits and hospital stays linked to supplements Limitations: The study covers supplements as a whole and does not say which products were blends. Products were reported by patients, so ingredient lists were not always confirmed. Funding and conflicts: US government funded (listed in the PubMed record). Read: abstract |
| Harty 2018 Multi-ingredient pre-workout supplements, safety implications, and performance outcomes: a brief review. J Int Soc Sports Nutr · PMID 30089501 · DOI |
Narrative review |
Active adults in studies of multi-ingredient pre-workout products (number of studies not given in the abstract) | Multi-ingredient pre-workout supplements |
Direct comparison between formulas, or between a formula and a single ingredient, is often impossible because many use proprietary blends that hide amounts. Even so, acute pre-exercise use may help muscular endurance and mood, with mixed results for force and power. With resistance training, longer use appeared to add lean mass. Most safety studies lasted under eight weeks. Some formulas may contain banned substances, on purpose or by contamination. Not applicable (narrative summary) (Not applicable) Methods, limits and fundingOutcomes: Muscular endurance, mood, force and power, body composition, safety Limitations: A brief narrative review of one product category. It does not separate blend products from products that show every amount. Study number and quality were not given in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Jagim 2019 Common Ingredient Profiles of Multi-Ingredient Pre-Workout Supplements. Nutrients · PMID 30678328 · DOI |
Product label survey product labels |
100 The 100 top-selling pre-workout products found on retail sites |
Multi-ingredient pre-workout supplements |
Products listed on average 18.4 ingredients, of which 8.1 sat inside a proprietary blend with no amount shown. Nearly half (44.3%) of all ingredients were in blends with undisclosed amounts. Where an amount was shown, the average beta-alanine amount was below the amount shown to work, and caffeine was near the low end of an effective amount for a 70 kg person. Mean 18.4 ingredients per product; 8.1 in blends; 44.3% of all ingredients in blends (Not applicable) Methods, limits and fundingOutcomes: Number of ingredients, share inside proprietary blends, listed amounts compared with amounts shown to work in studies Limitations: Label survey only; no product was tested in a lab. Averages come from products that did list an amount. One product category. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Jagim 2022 Prevalence and Amounts of Common Ingredients Found in Energy Drinks and Shots. Nutrients · PMID 35057494 · DOI |
Product label survey product labels |
75 The 75 top-selling US energy drinks (55) and energy shots (20), as of September 2021 |
Energy drinks and shots |
Products listed on average 18.2 ingredients; 15 of the 75 contained proprietary blends with undisclosed ingredient amounts. All had caffeine (about 174 mg on average). Many B-vitamin amounts were well above the Daily Value (vitamin B12 averaged about 5,245% of the Daily Value). Taurine was in 37.3% of products with its amount undisclosed. 15 of 75 products had blends with hidden amounts; B12 average 5,244.5% Daily Value (Not applicable) Methods, limits and fundingOutcomes: Ingredient counts, blends with undisclosed amounts, caffeine and B-vitamin amounts Limitations: Label survey of top sellers on 2021 retail sites; nothing was lab tested. Drinks are not sold as supplements in most cases (energy shots are). Funding and conflicts: Not stated in the abstract. Read: abstract |
| Ma 2025 Dietary Supplement Adulteration: Laboratory Approaches to Risk Mitigation. J Nat Prod · PMID 40700739 · DOI |
Narrative review |
Not applicable (industry laboratory review) | Quality control and testing of supplements |
Adulteration is described as a continuing problem, with supply-chain problems raising the risk. US makers must follow good manufacturing practice, including quality testing for identity, purity, strength, composition and contaminant limits. Tools to reduce adulteration risk include certification or verification programmes, quality agreements with suppliers and third-party testing. Not applicable (narrative summary) (Not applicable) Methods, limits and fundingOutcomes: Tools that reduce the risk of adulteration Limitations: A review of laboratory tools; it describes them, not how well they work. Author affiliations were not read. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Martinez-Sanz 2021 Fraud in nutritional supplements for athletes: a narrative review. Nutr Hosp · PMID 33966444 · DOI |
Narrative review |
16 studies of nutritional supplements sold to athletes | Sports supplements (protein powders, pre-workout mixes, creatine, vitamin and mineral drinks) |
Labelled amounts differed from the actual amounts. This was found in protein powders, pre-workout mixtures, creatine and drinks with vitamins and minerals, among others. Errors from leaving out substances that were present, or from wrong amounts, were described as high. The authors call for better supplement legislation. Not applicable (narrative summary) (Not applicable) Methods, limits and fundingOutcomes: Match between label and actual content Limitations: A narrative review of 16 studies; only sports products. The abstract gives no overall percentage. Published in Spanish with an English abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Saldanha 2023 Perspectives on the Use of Proprietary Blends in Dietary Supplements. J Nutr · PMID 37004873 · DOI |
Narrative review |
Not applicable (discussion paper on US supplement labels) | Proprietary blends on dietary supplement labels |
The 1994 Dietary Supplement Health and Education Act lets companies list non-nutrient dietary ingredients as a proprietary blend to protect their formulas. The blend's weight and the names of its ingredients must be shown, but not the amount of each. So the label alone cannot be used to work out intake or to set doses in clinical trials. Not applicable (no pooled number) (Not applicable) Methods, limits and fundingOutcomes: Why blends are used and what they mean for researchers and consumers Limitations: A perspective paper, not a measurement study. Only the abstract was read. Funding and conflicts: PubMed lists NIH extramural research support; no product funding is stated in the abstract. Read: abstract |
| Tucker 2018 Unapproved Pharmaceutical Ingredients Included in Dietary Supplements Associated With US Food and Drug Administration Warnings. JAMA Netw Open · PMID 30646238 · DOI |
Regulatory database analysis product records |
776 776 adulterated supplements named in FDA warnings from 2007 through 2016, from 146 companies |
Supplements with undeclared drugs |
Most products were sold for sexual enhancement (353; 45.5%), weight loss (317; 40.9%) or muscle building (92; 11.9%). 157 (20.2%) held more than one unapproved ingredient. The most common hidden drugs were sildenafil (sexual enhancement), sibutramine (weight loss) and synthetic steroids or steroid-like drugs (muscle building). Of 28 products named in two or three warnings, 19 had new hidden drugs in the later warning. The authors say these drugs can cause serious harm through misuse, overuse or interaction with other medicines. 776 products; 45.5% / 40.9% / 11.9% by category (Not applicable) Methods, limits and fundingOutcomes: Types of products and hidden drugs found Limitations: Counts products FDA chose to warn about, so it shows what was found, not how common hidden drugs are in all supplements. It does not say whether the products used proprietary blends. Funding and conflicts: Not stated in the abstract. Read: abstract |
| s-fda-directory FDA: Information on Select Dietary Supplement Ingredients and Other Substances (ingredient directory; read 2026-10-26) · Source |
Regulator page n/a |
Methods, limits and fundingRead: page text | ||
| s-fda-label-guide FDA: Dietary Supplement Labeling Guide, Chapter IV Nutrition Labeling (April 2005, nonbinding; read 2026-10-26) · Source |
Regulator page n/a |
Methods, limits and fundingRead: page text | ||
| s-fda-qa FDA: Questions and Answers on Dietary Supplements (content current as of 27 Aug 2026; read 2026-10-26) · Source |
Regulator page n/a |
Methods, limits and fundingRead: page text | ||
| s-nccih-wisely NCCIH: Using Dietary Supplements Wisely (page shows last updated January 2019; read 2026-10-26) · Source |
Health agency page n/a |
Methods, limits and fundingRead: page text |
What we do not know yet
- No trial tested a proprietary blend against its ingredients taken separately.
- No lab survey of label accuracy or heavy metals was found for blends as a category, or for multivitamins.
- No study measured whether third-party certification makes products safer or more accurate.
- NIH Office of Dietary Supplements pages could not be read, so no official upper limits are quoted.
- The text of 21 CFR 101.36 could not be fetched; FDA's guide to it was read.
- Rules outside the US were not read.
How new research is added
New studies are found by a saved PubMed search and placed in a review queue before the page changes.
Lab markers
What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".
Other 2
Share of listed ingredients inside blends
High in pre-workout products in trials
The share of ingredients on a label that sit inside a proprietary blend, so no amount is printed for them.
Moderate certaintyResults and what it means
Why it was measured
To see how often a buyer cannot tell how much of an ingredient is in a product.
Statistical vs. clinical meaning
Shows how common hidden amounts are in two sports and energy product types. It does not cover multivitamins or other types.
Safety implication
Hidden amounts cannot be checked against limits or medicines.
| Study | Result | People | Product |
|---|---|---|---|
| 6 | 8.1 of 18.4 ingredients per product, 44.3% of all ingredients, were in blends with undisclosed amounts | 100 top-selling pre-workout products | Not applicable (label survey) |
| 7 | 15 of 75 products had blends with undisclosed amounts | 75 top-selling energy drinks and shots | Not applicable (label survey) |
Label accuracy in lab checks
Mismatch common in samples tested in trials
Whether the ingredients and amounts printed on a label match what a laboratory finds.
Low certaintyResults and what it means
Why it was measured
To see whether label amounts can be trusted.
Statistical vs. clinical meaning
Shows mismatches occur; does not give a market-wide rate.
Safety implication
Wrong labels weaken any check of dose, interaction or banned substances.
| Study | Result | People | Product |
|---|---|---|---|
| 1 | 82% of labels inaccurate; 61% listed an ingredient not detected; 36% had hidden ingredients | 44 weight-loss supplements | Not applicable (lab analysis) |
| 9 | Labelled amounts differed from actual amounts across several sports product types | 16 studies | Not applicable (review of lab studies) |
Safety
What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.
Main points to know 4
- Some products hide drugs that are not on the label. FDA warned about 776 supplements with undeclared drugs between 2007 and 2016. About 45% were sold for sexual enhancement, 41% for weight loss and 12% for muscle building. The authors say these drugs can cause serious harm through misuse, overuse or interaction with other medicines. NCCIH says products promoted for weight loss, sexual enhancement and bodybuilding may contain prescription drugs not allowed in supplements, or other unlisted ingredients. A hidden drug is a different problem from a hidden amount, but a long blend makes both harder to spot. Ask a pharmacist before using these product types. Regulatory record and agency statement 11 15
- Labels can be wrong, not just incomplete. In a lab check of 44 weight-loss supplements bought on or near US military bases, 82% had inaccurate labels, 61% listed an ingredient that was not found, and 36% contained a hidden ingredient. A review of 16 studies of sports supplements also found labelled amounts differing from actual amounts. These are narrow samples, so they show it happens, not how often across all products. Laboratory analysis and narrative review 1 9
- A hidden amount cannot be checked against a limit or a medicine. The blend's total weight and ingredient names are shown, but not each ingredient's amount, so intake cannot be worked out from the label. Nothing in the law limits how much of an ingredient a serving may hold; the maker decides, and FDA does not approve it. If you take prescription medicines, bring the full label to a pharmacist and ask the maker for the amounts. Perspective paper and regulator statement 10 14
- Weight-loss and energy products are tied to most supplement-related heart-rhythm emergencies. A US study of emergency departments estimated about 23,000 supplement-related visits a year. Weight-loss or energy products caused 71.8% of the palpitations, chest pain or fast heart rate cases, and 58.0% of those involved people aged 20 to 34. The study covers supplements of all kinds, not blends as such. National surveillance study 4
Side effects 4
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Palpitations, chest pain or fast heart rate with weight-loss or energy products Whether the products used proprietary blends was not stated in the abstract. | 71.8% of supplement-related cases of these symptoms in US emergency departments, 2004 to 2013 | Can be serious Not stated in the abstract | National surveillance study 4 |
| Choking or trouble swallowing pills Applies to supplements of all kinds, including large multi-ingredient capsules. | 37.6% of emergency visits among adults 65 and older; micronutrients were involved in most of them | Can be serious Not stated in the abstract | National surveillance study 4 |
| Harm from undeclared drugs (for example sildenafil, sibutramine, steroid-like drugs) The authors describe potential for serious adverse effects through misuse, overuse or interaction; no outcome counts are in the abstract. | 776 warned products from 2007 to 2016; how often per product bought is not known | Can be serious Not stated | Regulatory record 11 |
| Few problems in short pre-workout studies The 2018 review calls multi-ingredient pre-workout products relatively safe, but most safety studies lasted under eight weeks, so long-term safety is unknown. | Not given | Not applicable Not applicable | Narrative review 5 |
Liver
No liver injury data specific to proprietary blends were found in the sources read. Liver safety depends on the individual ingredients, which a hidden amount makes hard to judge. A liver-safety reference (LiverTox) was not opened.
How often. No frequency was found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Proprietary Blends Explained: What Must and Must Not Be Disclosed supports liver health.
Medicines and supplements 5
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Prescription medicines (general) prescription | Depends on the ingredients, which a hidden-amount blend does not fully show. | NCCIH says supplements may interact with medicines. Because amounts inside a blend are hidden, an interaction check against a medicine cannot be completed from the label alone. | Agency statement and reasoning from the label rules Low certainty 15 10 | Bring the full label to a pharmacist or doctor and ask the maker for amounts. |
| Medicines, through hidden drug ingredients prescription | Undeclared drugs act like the medicine they are, and could add to or clash with a prescribed one. | The 2018 FDA-warning analysis says the hidden drugs can cause serious harm through interaction with other medicines, health conditions or other drugs in the same product. | Regulatory record (authors' statement) Low certainty 11 | If you take prescription medicines, ask a pharmacist before using products sold for weight loss, sexual enhancement or muscle building. |
| Other supplements (same nutrient in several products) supplement | Amounts add up across products. Ingredients with a Daily Value must show their own amounts, so those can be totalled. Hidden-amount ingredients cannot. | In a survey of 75 energy products, many gave B-vitamin amounts well above the Daily Value (vitamin B12 averaged about 5,245% of it). | Label survey and regulator guide Low certainty 7 13 | List every product you take for a pharmacist so the totals can be checked. |
| Surgery and anaesthesia procedure | Not specific to blends. | NCCIH says supplements may pose risks if you are going to have surgery. | Agency statement Low certainty 15 | Tell the surgical team about every supplement, including blends. |
| Anti-doping rules (athletes) other | Some pre-workout formulas may contain banned substances, on purpose or by contamination. | The 2018 review suggests athletes check the ingredients of a formula before use; a hidden-amount blend makes that harder. | Narrative review Low certainty 5 2 | Athletes who are tested should ask their sport body or a pharmacist. |
Who should check first 6
| Situation | Advice | Evidence |
|---|---|---|
| Pregnancy and breastfeeding | NCCIH says many supplements have not been tested in pregnant women or nursing mothers. A blend with hidden amounts cannot be checked against pregnancy limits. Ask a doctor or midwife first. A 2025 lab survey of prenatal vitamins (a different product type) found lead in 83% of commercial products. | Agency statement and laboratory analysis 15 3 |
| Children | NCCIH says many supplements have not been tested in children. Unsupervised children were 21.2% of supplement-related emergency visits in a US study. Keep all supplements out of reach and ask a doctor before giving any. | Agency statement and surveillance study 15 4 |
| Taking prescription medicines | Ask a pharmacist to review the full label before use, especially for weight-loss, sexual-enhancement, energy or muscle-building products. | Agency statement 15 11 |
| Heart rhythm problems, high blood pressure or stimulant sensitivity | Weight-loss and energy products were tied to most supplement-related palpitations and chest pain in one US study, and a case series found several products with multiple stimulants. Ask a doctor first. | Surveillance study and lab case series 4 1 |
| Kidney or liver disease | No blend-specific kidney or liver data were found in the sources read. Ask a doctor, because hidden amounts mean the load on these organs cannot be judged from the label. | Absence of evidence |
| Planned surgery | Tell the surgical team about every supplement, as NCCIH advises. | Agency statement 15 |
Overdose, product quality and regulators
Summary. A proprietary blend is a label format, not one substance, so it has no single toxicity profile. Risk depends on each ingredient and its hidden amount. No poisoning or overdose reports specific to blends were found in the sources read.
Animal. Not reviewed.
High dose or long term signals. Most pre-workout safety studies lasted under eight weeks, so long-term safety is unknown.
Overdose response. Not found.
Genotoxicity. Not researched.
Quality depends on the maker and the ingredients. Lab checks found label mismatches and hidden ingredients in some product types. No survey of heavy metals in blends as a category was found; one lab survey of prenatal vitamins (a different multi-ingredient product) is shown as an example.
Label accuracy in weight-loss products. 82% of 44 products had inaccurate labels; 36% held a hidden ingredient; none carried a third-party seal. 1
Label accuracy in sports products. Labelled amounts differed from actual amounts in protein powders, pre-workout mixtures, creatine and vitamin or mineral drinks (16 studies). 9
Lead and cadmium in a multi-ingredient product type. Prenatal vitamins (not blends): lead above the lab's quantification limit in 83% of 156 commercial products; 15% above 0.5 microgram per daily serving, the California Proposition 65 limit; cadmium in 73%. 3
What manufacturing rules require. US makers must follow good manufacturing practice meant to keep identity, purity, quality, strength and composition consistent. FDA does not test supplements before sale. 14 8
| Body | Action | Date |
|---|---|---|
| US Food and Drug Administration (FDA): Questions and Answers on Dietary Supplements (United States) | States that FDA does not approve dietary supplements before sale; that no law limits the serving size or the amount of an ingredient in a serving, so this is the maker's decision; that FDA does not test supplements before sale and mainly acts after they reach the market; that for more detail than the label gives, consumers can contact the manufacturer; and that consumers should talk to a doctor, pharmacist or other health professional before using a supplement. source | 2026-08-27 |
| US FDA: Dietary Supplement Labeling Guide, Chapter IV (United States) | Describes how a proprietary blend must be shown (21 CFR 101.36): named 'Proprietary Blend' or a descriptive or fanciful name, the total weight of the other dietary ingredients on the same line, and the ingredients indented in descending order by weight. Dietary ingredients that have Daily Values must be listed separately with their own weights. Ingredients without a Daily Value are marked 'Daily Value Not Established'. source | 2005-04 |
| NCCIH (US National Center for Complementary and Integrative Health): Using Dietary Supplements Wisely (United States) | Says supplements may interact with medicines or pose risks in some medical conditions or before surgery; many have not been tested in pregnant women, nursing mothers or children; some products promoted for weight loss, sexual enhancement and bodybuilding may contain prescription drugs not allowed in supplements or other unlisted ingredients; and FDA says it cannot test all products for harmful hidden ingredients. source | 2019-01 |
| US FDA: Information on Select Dietary Supplement Ingredients and Other Substances (directory) (United States) | A directory of FDA actions and communications on specific ingredients, including safety communications and warning letters. It states that FDA does not approve dietary supplements for safety and effectiveness. source |
When to get medical help
- Chest pain, a racing or irregular heartbeat, fainting, or trouble breathing after taking a weight-loss, energy or pre-workout product: call emergency services.
- Swelling of the face, lips or tongue, hives or wheezing after any supplement: call emergency services.
- A child has swallowed a supplement or several: call poison control or emergency services at once.
- Choking or a pill stuck in the throat: get emergency help.
- If you have side effects, stop the product and contact your doctor, as NCCIH advises. In the US, serious problems can be reported through the HHS Safety Reporting Portal.
Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.
General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.
Frequently asked questions
What does 'proprietary blend' mean on a supplement label?
Do vitamins and minerals have to be listed separately from a blend?
According to FDA's labeling guide, dietary ingredients that have Daily Values must be listed separately with their own weights. Only ingredients without a Daily Value can sit inside a blend.
Is a proprietary blend illegal or unsafe?
Does the order of ingredients tell me how much of each there is?
No. The order shows which ingredient has the largest weight and which the smallest, not how much of any of them.
Can I find the amounts if the label does not show them?
FDA says that for more detail than the label gives, you can contact the manufacturer. A reply is not guaranteed.
Do blends work because each ingredient was studied?
Do pre-workout blends work?
A 2018 review found possible gains in muscle endurance and mood, mixed results for strength and power, and possible lean-mass gains with training. It could not compare formulas, and most safety studies were under eight weeks.
Are supplement labels accurate?
Can a supplement contain drugs that are not on the label?
Does a third-party seal make a blend safe?
Does FDA approve or test supplements before sale?
Who should ask a doctor or pharmacist before using a blend?
Anyone who is pregnant or breastfeeding, giving a supplement to a child, taking prescription medicines, or planning surgery. NCCIH says many supplements have not been tested in pregnant women, nursing mothers or children.
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Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-26
- Last substantive update
- 2026-10-26
- How we research
- We started from our earlier page on proprietary blends, then re-checked each PubMed study by reading its abstract, and re-read the FDA and NCCIH pages cited. Only abstracts were read for papers. The NIH Office of Dietary Supplements site blocked access and is marked unverified.
- How we rate evidence
- See "How we rate evidence" in the Evidence tab.
- Independence
- No product is promoted on this page. No affiliate links are shown. Funding was not stated in most abstracts read.
Sources 15
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Crawford C, Lindsey AT, Avula B, Katragunta K, Khan IA, Deuster PA. Label Accuracy and Quality of Select Weight-Loss Dietary Supplements Sold on or near US Military Bases.. Nutrients. 2024. PMID 39770990. DOI 10.3390/nu16244369. (abstract)
- Eichner AK, Coyles J, Fedoruk M, Maxey TD, Lenaghan RA, Novitzky J, Lindsey AT, Deuster PA. Essential Features of Third-Party Certification Programs for Dietary Supplements: A Consensus Statement.. Curr Sports Med Rep. 2019. PMID 31082891. DOI 10.1249/JSR.0000000000000595. (abstract)
- Gardener H, Bowen J, Callan SP. Heavy metals and phthalate contamination in prenatal vitamins and folic acid supplements.. Environ Res. 2025. PMID 40020868. DOI 10.1016/j.envres.2025.121255. (abstract)
- Geller AI, Shehab N, Weidle NJ, Lovegrove MC, Wolpert BJ, Timbo BB, Mozersky RP, Budnitz DS. Emergency Department Visits for Adverse Events Related to Dietary Supplements.. N Engl J Med. 2015. PMID 26465986. DOI 10.1056/NEJMsa1504267. (abstract)
- Harty PS, Zabriskie HA, Erickson JL, Molling PE, Kerksick CM, Jagim AR. Multi-ingredient pre-workout supplements, safety implications, and performance outcomes: a brief review.. J Int Soc Sports Nutr. 2018. PMID 30089501. DOI 10.1186/s12970-018-0247-6. (abstract)
- Jagim AR, Harty PS, Camic CL. Common Ingredient Profiles of Multi-Ingredient Pre-Workout Supplements.. Nutrients. 2019. PMID 30678328. DOI 10.3390/nu11020254. (abstract)
- Jagim AR, Harty PS, Barakat AR, Erickson JL, Carvalho V, Khurelbaatar C, Camic CL, Kerksick CM. Prevalence and Amounts of Common Ingredients Found in Energy Drinks and Shots.. Nutrients. 2022. PMID 35057494. DOI 10.3390/nu14020314. (abstract)
- Ma C, Monagas M, Bronstein L, Cadwallader A, Goldman V. Dietary Supplement Adulteration: Laboratory Approaches to Risk Mitigation.. J Nat Prod. 2025. PMID 40700739. DOI 10.1021/acs.jnatprod.5c00456. (abstract)
- Martinez-Sanz JM, Mata F, Sala Ripoll M, Puya Braza JM, Martinez Segura A, Sanchez Oliver AJ, Cortell Tormo JM. Fraud in nutritional supplements for athletes: a narrative review.. Nutr Hosp. 2021. PMID 33966444. DOI 10.20960/nh.03413. (abstract)
- Saldanha LG, Dwyer JT, Hardy CJ, MacKay DJ. Perspectives on the Use of Proprietary Blends in Dietary Supplements.. J Nutr. 2023. PMID 37004873. DOI 10.1016/j.tjnut.2023.03.035. (abstract)
- Tucker J, Fischer T, Upjohn L, Mazzera D, Kumar M. Unapproved Pharmaceutical Ingredients Included in Dietary Supplements Associated With US Food and Drug Administration Warnings.. JAMA Netw Open. 2018. PMID 30646238. DOI 10.1001/jamanetworkopen.2018.3337. (abstract)
- . FDA: Information on Select Dietary Supplement Ingredients and Other Substances (ingredient directory; read 2026-10-26). . . (page text)
- . FDA: Dietary Supplement Labeling Guide, Chapter IV Nutrition Labeling (April 2005, nonbinding; read 2026-10-26). . . (page text)
- . FDA: Questions and Answers on Dietary Supplements (content current as of 27 Aug 2026; read 2026-10-26). . . (page text)
- . NCCIH: Using Dietary Supplements Wisely (page shows last updated January 2019; read 2026-10-26). . . (page text)
Where to buy
Check the label first. Whatever you buy, look for these:
- The amount of the active ingredient per serving, not just the front-label claim
- A third-party testing mark (USP, NSF or ConsumerLab)
- Other ingredients and allergens
- Ask a pharmacist about interactions with your medicines
Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.
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