Nutritional supplements are now a common feature of both sport and everyday life. Creatine, protein, vitamins, minerals, amino acids and pre-workout blends can be found on the shelves of shops and pharmacies, as well as online. But is it enough simply to go by what’s written on the label when choosing them?
In most cases, the label is the first place we should look for information on ingredients, dosage and the manufacturer. The problem arises when the actual contents of the product do not match those declared, the product contains an undeclared substance, or it is marketed in a way that gives the consumer the impression of a safe dietary supplement, even though it contains pharmacologically active substances.
This does not mean that we should automatically question every protein or multivitamin. However, research and the experience of regulatory and anti-doping organisations show that, particularly with certain products aimed at drastically boosting performance, building muscle or rapid weight loss, it is worth examining the ingredients much more closely.
What is a food supplement and how is it regulated?
A dietary supplement is not a medicine. In the European Union, it is classified as a foodstuff and its purpose is to supplement the normal diet. European legislation defines food supplements as concentrated sources of nutrients or other substances with a nutritional or physiological effect, which are sold in measured doses – for example, as capsules, tablets, powders or liquid preparations.
EU rules also regulate, for example, the vitamins and minerals that may be used in food supplements, their permitted sources and labelling requirements. The aim is to protect consumers from health risks and misleading information.
However, the situation is not the same in every country around the world.
The original article focused extensively on the US Dietary Supplement Health and Education Act (DSHEA) of 1994. Whilst this remains relevant to the topic, it must be interpreted correctly.
In the US, the FDA does not generally approve dietary supplements in the same way as medicines before they are placed on the market. The manufacturer or distributor bears primary responsibility for the safety of the product and the accuracy of its labelling. The FDA subsequently monitors the market, inspects manufacturers, evaluates reports of adverse effects and may take action against products that are dangerous or incorrectly labelled.
It is precisely this distinction between a dietary supplement and a medicine that is important. The fact that something is sold in a capsule or in a container resembling standard sports nutrition does not automatically mean that it is a standard supplement with a well-researched composition.
When the label does not match the actual contents
The biggest problem is not the existence of dietary supplements as such. The risk arises primarily with products where the composition is incorrectly declared, incomplete or deliberately altered to make the product appear more effective.
A very good example is products sold online as SARMs.
A study published in the journal JAMA analysed 44 such products. Only 23 of them – 52 per cent – actually contained one or more substances from the SARM group. In 39 per cent of the products, a different, unauthorised substance was found, and four products contained no active ingredient at all. Only in 18 out of 44 products did the amount of active ingredient match the information on the label.
However, it is important to interpret these figures correctly. The researchers did not test a random sample of all vitamins, proteins or sports nutrition products on the market. They examined a specific high-risk category of products sold online as SARMs. The results cannot therefore be automatically extrapolated to the entire dietary supplements market.
They do, however, illustrate why manufacturer transparency is essential when it comes to experimental and performance-enhancing substances. We have covered this group of substances, how they work and the available research in more detail in the article SARMs: what they are, how they work and what the research says.
Prohormones and designer steroids: when the line between a supplement and a pharmacological substance becomes blurred
A similar problem has arisen in the past with prohormones and so-called designer steroids.
Prohormones are substances that can act as precursors to other hormonally active compounds within the body. They came to the attention of the sporting public more prominently in the 1990s, alongside substances such as DHEA and androstenedione.
Later, however, products began to appear on the market which, although presented as ‘prohormones’ or legal alternatives to steroids, may in fact have contained pharmacologically active steroid compounds.
Researchers in the UK analysed 24 products suspected of containing anabolic steroids. Steroids were found in 23 of them, with 16 products containing different steroids to those stated on the packaging. It should be emphasised here that this was a specifically selected sample of suspicious products, not a representative cross-section of all dietary supplements on the market.
It is therefore advisable to exercise greater caution, particularly with products advertised using terms such as ‘legal steroid’, ‘extreme muscle’, ‘prohormone’ or similar claims.
However, the issue of prohormones is much broader. We discuss their mechanism of action, effects and potential health risks in more detail in a separate article Prohormones and Designer Steroids: Effects, Risks and What the Research Says.
Even the label ‘natural’ is no guarantee of safety
The marketing of dietary supplements often relies heavily on terms such as ‘natural’, ‘herbal’ or ‘plant-based’. However, such labelling does not, in itself, indicate that a product is safe.
Even natural substances can have significant physiological effects, interfere with the action of medicines, or be unsuitable for certain groups of people. Furthermore, the name of a plant extract on the label does not guarantee that the product does not contain other substances.
An interesting historical example is the stimulants DMAA and DMBA.
DMAA, also known as 1,3-dimethylamylamine, has been found in products intended to enhance sporting performance and aid weight loss, and was sometimes presented as a substance derived from plant sources. The FDA now states that it does not consider DMAA to be a legal ingredient in dietary supplements and also warns of potential cardiovascular risks.
A similar situation arose with the substance DMBA, which appeared in some products as another stimulant. The FDA states that it has no evidence to demonstrate its lawful use as a dietary ingredient prior to the introduction of the relevant regulatory rules.
These cases are a good reason not to judge the safety of a substance solely on the basis of whether its name sounds ‘natural’.
Beware of pre-workout stimulants with unclear compositions
Pre-workout supplements are among the most popular sports nutrition products. However, the category itself is not automatically problematic.
Commonly used substances such as caffeine, citrulline, beta-alanine and creatine have a completely different profile to experimental stimulants of unclear origin. If you’re interested in how pre-workout supplements work, when to take them and what to bear in mind when combining individual ingredients, we’ve covered this topic in more detail in the article Pre-workout supplements: usage, timing and safe combinations.
The specific composition of the product and the quantities of individual substances are therefore crucial.
A warning sign might be, for example:
an insufficient amount of active ingredients,
an unclear ‘proprietary blend’ without further explanation,
exaggerated marketing claims,
ingredients listed only under trade names or alternative names,
no traceable manufacturer,
a product without batch number or origin identification,
a combination of several potent stimulants without clearly stated doses.
With stimulant products, it is also true that more does not necessarily mean better. Combining multiple sources of stimulants can increase the risk of heart palpitations, insomnia, nervousness or other adverse effects. You can find out more about the individual ingredients used in pre-workout supplements – from caffeine and BCAAs to arginine and magnesium – in the article Pre-workout supplements: BCAAs, arginine, magnesium, caffeine and more.
The problem isn’t limited to muscle-building products
Incorrect or incomplete ingredient lists have also been found in completely different product categories in the past.
In a study published in the journal *Thyroid*, researchers analysed ten over-the-counter products marketed to support thyroid function. Nine contained detectable levels of the hormone T3 and five contained T4. In some products, the amounts were high enough to be of clinical significance.
Nor can this result be interpreted to mean that most common dietary supplements contain hormones. This was a small study of a specific group of products. However, it highlights another important principle: the more pronounced the pharmacological effect a product claims to have, the more important it is to verify exactly what it contains.
Caution is particularly advised with products making claims such as:
extremely rapid fat burning,
dramatic increase in testosterone,
steroid-like muscle growth,
an instant boost to metabolism,
extreme bursts of energy or focus.
Big promises aren’t automatically proof of a scam, but they should be a reason to look at the product in more detail.
Scientific research and effectiveness
How to choose a high-quality dietary supplement?
Dietary supplements can have their place in a balanced diet and sports nutrition. The best approach, therefore, is not to avoid them automatically, but to choose them based on need and quality, not on the loudest marketing claims.
1. Check the full list of ingredients
It is not enough to know that the product contains a ‘pre-workout complex’ or a ‘testosterone blend’.
Look at the specific ingredients and their quantities. The more transparent the label, the easier it is to assess what you’re actually taking.
2. Verify the manufacturer and the product’s origin
A traceable manufacturer, contact details, clear product labelling and batch identification are essential.
Anonymous products from unknown online shops, products without a clearly identified manufacturer, or products whose origin cannot be verified warrant extra caution.
3. Distinguish between marketing claims and evidence
Terms such as ‘scientifically developed’, ‘clinical strength’, ‘pharmaceutical grade’ or ‘100% natural’ may sound convincing, but they do not in themselves prove anything.
What matters more is what ingredients the product contains, in what quantities, and what evidence exists for their effectiveness.
4. Look for independent testing
Laboratory analyses and testing of specific batches can enhance a product’s credibility.
However, a certification logo alone is not an absolute guarantee. Even independent testing cannot completely eliminate the risk – but it can reduce it.
5. Take particular care if you have health issues
If you are taking medication, have been diagnosed with a medical condition, are pregnant or are breastfeeding, it is advisable to consult your doctor or pharmacist about the suitability of a particular supplement.
A dietary supplement may contain a substance that is safe on its own but unsuitable when combined with a particular medicine or medical condition.
Athletes must also be aware of the risk of doping
For a competitive athlete, choosing the wrong dietary supplement can have another consequence – a positive doping test.
The problem can arise in several ways:
the product contains an undeclared banned substance,
contamination occurs during production,
the actual amount of the ingredient does not match the label,
the banned substance is listed under an alternative or ambiguous name.
At the same time, anti-doping rules operate on the principle of strict liability – an athlete is liable for any substances found in their body, even if they entered it via a dietary supplement.
For professional and competitive athletes, it therefore makes sense to prioritise products that have undergone independent testing of specific batches, to keep proof of purchase, and to check the current anti-doping rules.
Rather than copying a long list of prohibited substances into this article, it is better to check the current Prohibited List of Substances and Methods, as it is updated on an ongoing basis.
Does this mean that nutritional supplements cannot be trusted?
No.
Protein powder, creatine monohydrate, vitamin D or magnesium cannot automatically be placed on the same level as an anonymous product promising the effects of steroids or an experimental stimulant ordered from an unknown foreign website.
It is precisely this distinction that is crucial when it comes to the safety of dietary supplements.
The risk depends on the specific product, its composition, manufacturer, origin and category.
The problem is not the existence of supplementation itself. The problem arises when a consumer does not know what they are taking – or when the product’s marketing gives the impression that it is a standard dietary supplement, even though its contents and effects are entirely different.
What should we take away from this?
When choosing dietary supplements, there’s no need to panic, but you shouldn’t blindly trust the front of the packaging either.
Ask yourself:
What exactly does the product contain? Are the quantities of each ingredient listed? Do I know the manufacturer and the product’s origin? Do the marketing claims match what we know about the individual ingredients? Has the product been independently tested? And do I actually need this supplement at all?
The more extreme the results a product promises, the more thoroughly it deserves to be scrutinised.
A high-quality dietary supplement should not be shrouded in secrecy. Transparent ingredients, clear dosage instructions and a traceable origin are far more valuable than bombastic claims about ‘revolutionary’ effects.
Sources
European Commission. Food supplements. Available at: https://food.ec.europa.eu/food-safety/labelling-and-nutrition/food-supplements_en
U.S. Food and Drug Administration. Questions and Answers on Dietary Supplements. Available at: https://www.fda.gov/food/information-consumers-using-dietary-supplements/questions-and-answers-dietary-supplements
Van Wagoner RM, Eichner A, Bhasin S, Deuster PA, Eichner D. Chemical Composition and Labelling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet. JAMA. 2017;318(20):2004–2010. Available at: https://pubmed.ncbi.nlm.nih.gov/29183075/
Abbate V, Kicman AT, Evans-Brown M, et al. Anabolic steroids detected in bodybuilding dietary supplements – a significant risk to public health. Drug Testing and Analysis. 2015;7(7):609–618. Available at: https://pubmed.ncbi.nlm.nih.gov/25284752/
Kang GY, Parks JR, Fileta B, et al. Thyroxine and triiodothyronine content in commercially available thyroid health supplements. Thyroid. 2013;23(10):1233–1237. Available at: https://pubmed.ncbi.nlm.nih.gov/23758055/
U.S. Food and Drug Administration. DMAA in Products Marketed as Dietary Supplements. Available at: https://www.fda.gov/food/information-select-dietary-supplement-ingredients-and-other-substances/dmaa-products-marketed-dietary-supplements
U.S. Food and Drug Administration. DMBA in Dietary Supplements. Available at: https://www.fda.gov/food/information-select-dietary-supplement-ingredients-and-other-substances/dmba-dietary-supplements
Slovak Anti-Doping Agency. Dietary supplements. Available at: https://www.antidoping.sk/vyzivove-doplnky/
