Dietary supplement vs medicine: what is the difference and how to avoid being deceived

On the pharmacy shelf, side by side, stands a magnesium preparation in a green capsule labeled 'Magnesium Forte' and a magnesium supplement in an identical capsule. They look the same, cost similarly, and the difference between them is fundamental – one binds the manufacturer to clinical research, safety, and responsibility requirements, while the other only requires a notification. How to distinguish a supplement from a medicine? What information must be on the label? What cannot a supplement claim according to EU law and what does it mean in practice for your health?

KEY INFORMATION
• A dietary supplement is registered as a food product (GIS notification), while a medicine is registered as a medicinal product (URPL registration with clinical trial requirements).
• Regulation (EC) No. 1924/2006 prohibits supplements from claiming properties of treating or preventing diseases – only statements approved by EFSA are permissible.
• According to GIS data, over 30,000 dietary supplement notifications have been registered in Poland – an industry worth about 5 billion PLN annually (PMR Research, 2024).
• GMP certification and independent laboratory tests (Certificate of Analysis) are the minimum safety criteria when choosing a supplement.

Legal definition – a supplement is food, a medicine is a medicinal product

In Poland and the EU, a dietary supplement is classified as a food product under Directive 2002/46/EC and the Act of August 25, 2006, on food safety and nutrition. The supplement manufacturer submits a notification to the Chief Sanitary Inspectorate (GIS) – the office checks whether the composition is permitted but does not assess the product's effectiveness. This is a completely different standard than for medicines.

A medicine is a medicinal product as defined by the Pharmaceutical Law (Journal of Laws 2021, item 1977). Registration is carried out by the Office for Registration of Medicinal Products, Medical Devices and Biocidal Products (URPL) or the European EMA (under the centralized procedure). The manufacturer must provide results of preclinical and clinical trials (phases I-III) confirming efficacy and safety. The issued Summary of Product Characteristics (SmPC) specifies indications, dosage, contraindications, and interactions. This entire process costs billions and takes years – which is why medicines are significantly more expensive than supplements with the same composition.

Our Observations: The paradox of the market: an omega-3 supplement in capsules and the prescription drug Omacor (reimbursed) contain the same active ingredient (EPA+DHA). The drug costs several dozen PLN per month, while the supplement costs a few. The difference? The drug has proven efficacy, precise indications, and is subject to pharmacovigilance. The supplement may be of the same quality or significantly worse – there is no obligation for verification. For serious clinical indications (high triglycerides after a heart attack), choose the drug. For general prevention – a good supplement with certification is sufficient.

GIS registration vs URPL – what it means in practice

When a supplement manufacturer submits a product to GIS, the office checks: whether the product meets the definition of a supplement (is not a medicine), whether the ingredients are on the permitted list, and whether the label meets formal requirements. GIS does not assess whether the supplement works. It does not check clinical trials. It does not verify whether the declared content of ingredients corresponds to what is in the capsule. This responsibility falls on the manufacturer and – in case of disputes – on the control authorities (GIS, PIORiN) after the product is placed on the market.

Effect: tens of thousands of supplements with similar claims on the label but very different actual quality are available on the market. Studies Cooperman (ConsumerLab, 2020) showed that in an analysis of 40% of herbal supplements from the United States, discrepancies were found between the declared and actual content of active ingredients, contamination, or lack of standardization. In Poland, the scale of the problem is exacerbated by the lack of mandatory composition testing after market entry.

What must be on a supplement label – law vs reality

Regulation (EC) No. 1169/2011 and the Food Safety Act specify what must be included on a dietary supplement label. Mandatory elements: designation 'dietary supplement', names of active ingredient categories, recommended daily servings (amount), warnings ('do not exceed the recommended serving' and 'do not use as a substitute for a balanced diet, varied nutrition'), information 'keep out of reach of children'. Optional but important for consumers: percentage coverage of daily requirements (NRV – nutrient reference values) for vitamins and minerals, certificates (GMP, ISO, independent laboratory).

What it does not have to include: registration number. This is a significant difference from medicines, which have a marketing authorization number. A supplement may not have any identification number visible on the label, making verification in the GIS register difficult. When purchasing online from outside the EU, the risk of buying a supplement non-compliant with EU regulations is significantly higher – lack of notification in GIS means no regulatory oversight in Poland.

Health and nutrition claims – what a supplement can say

Regulation (EC) No. 1924/2006 on nutrition and health claims regulates what claims a supplement manufacturer can use in marketing. EFSA (European Food Safety Authority) has published approved health claims for hundreds of ingredients – examples of permissible claims: 'vitamin C contributes to the normal functioning of the immune system', 'magnesium contributes to the reduction of tiredness and fatigue', 'omega-3 DHA contributes to the maintenance of normal vision'.

Any claims suggesting treatment or prevention of specific diseases are prohibited: 'cures arthritis', 'reduces the risk of heart attack', 'fights cancer'. Such claims automatically turn a supplement into an illegal medicinal product without registration, which is subject to sanctions by URPL and GIS. In practice, manufacturers use linguistic tricks: instead of 'cures depression' – 'supports good mood' (permissible if the ingredient has an approved claim). The line is subtle. For consumers: any definitive clinical claims on a supplement's packaging (e.g., 'clinical studies confirm reduction of joint pain') without reference to specific studies should raise skepticism.

How to assess the quality of a supplement – certifications and red flags

In the absence of a requirement for proof of efficacy, the quality of a supplement depends solely on the manufacturer and what they voluntarily submit for verification. GMP (Good Manufacturing Practice) certification of the manufacturing facility guarantees that production processes meet minimum standards of cleanliness, traceability of raw materials, and composition control. This is the minimum. ISO 22000 or 9001 certifications for quality management processes provide additional assurance. Certificate of Analysis (CoA) – results of analysis of a specific batch of the product from an independent laboratory, confirming the content of active ingredients, absence of microbiological contamination, and heavy metals. The manufacturer should provide the CoA upon request or on the product page.

Red flags when choosing a supplement: lack of the EU manufacturer’s address on the packaging, absence of a CoA or GMP certificate, unavailability of the manufacturer at the provided contact, price drastically lower than known manufacturers with the same declarations (may suggest underdosed active ingredient or a cheaper chemical form), therapeutic claims exceeding health statements approved by EFSA (especially "clinical studies confirm treatment" without citing specific works). For sports supplements: Informed Sport and Cologne List are certifications verifying the absence of substances banned by WADA – an absolute necessity in active sports competition and anti-doping controls. supplements for athletes without doping

GMP, standardization, and bioavailability – what really matters

A supplement may pass through GIS and enter the market legally, but be practically useless or even harmful due to poor bioavailability or contamination. Several technical issues are of great practical importance here. Standardization of herbal extract guarantees that each capsule contains the same percentage of active ingredient – e.g., "ashwagandha extract standardized to 5% withanolides". Without standardization, the composition may vary between batches by as much as 10 times. The chemical form of minerals: magnesium sulfate is cheap and poorly absorbed (may cause diarrhea), citrate and glycinate are absorbed 4–5 times better. The chelate form (amino acid chelate) is even better bioavailable. A manufacturer hiding the chemical form under the name "magnesium compounds" should raise suspicions.

Bioactivity of coenzymes and vitamins: folate vs folic acid. Folic acid requires enzymatic conversion to the active 5-MTHF by the MTHFR enzyme. As much as 40–60% of the population has a partial or complete mutation of the MTHFR gene, which reduces the ability to convert. For these individuals, a supplement with L-MTHF folate (methyl tetrahydrofolate) is significantly better than cheap folic acid. Similarly, coenzyme Q10: ubiquinol (the reduced form) is several times more bioavailable than ubiquinone (the oxidized form, cheaper to produce). These are specific, significant differences – and the manufacturer is only required to state the form on the label if they use it as a marketing differentiator; it is not a legal requirement.

When to choose a supplement and when a medication – a practical rule

Supplements make sense for: preventing deficiencies (vitamin D3 in winter, B12 in veganism, magnesium in a diet low in vegetables), supporting health as part of a lifestyle, supplementing the diet of specific groups (pregnant women: folic acid and DHA, athletes: creatine, electrolytes), when the effect is well proven and you know your own status (you’ve checked with a test). The key word here is "supporting" – a supplement does not replace medication, a doctor, or lifestyle changes.

Medication is the right choice for: a diagnosed disease requiring treatment, a condition requiring a specific therapeutic effect with proven efficacy (iron deficiency with anemia – treatment with iron i.v. or iron succinate, not a supplement; infection – antibiotic, not a probiotic), interactions with other medications (only a specialist decides on supplementation in this case), an urgent or acute condition. Attempting to treat an active disease with a supplement instead of medication can delay proper treatment with serious health consequences. This substitution is particularly dangerous in cases of heart disease, diabetes, cancer, and infections – where every week of treatment delay has clinical significance.

It is worth mentioning the gray area: herbal medicines (e.g., standardized valerian extracts as OTC medications, horse chestnut preparations as phlebological medications) have the status of a drug with clinical studies and can be prescribed by a doctor or recommended by a pharmacist. Do not confuse them with supplements with the same herbal composition – a herbal medicine meets the requirements of the SmPC, has proven standardization and safety.

Interactions of supplements with medications – a gap in the law

The drug manufacturer is required to describe interactions in the SmPC. The supplement manufacturer is not. This means that you will not find warnings about interactions with medications on the supplement packaging, even when they are clinically significant: St. John's Wort (Hypericum perforatum) induces CYP3A4 and CYP2C9, lowering the concentration of immunosuppressive drugs (cyclosporine), antiretrovirals, anticoagulants (warfarin), contraceptive pills. Milk thistle inhibits CYP3A4 and CYP2D6. Grapefruit (not a supplement, but an analogous example) blocks intestinal CYP3A4, raising the concentration of statins and calcium channel blockers.

Patients using prescription medications should check for interactions before starting any new supplement. Tools for this: Medscape Drug Interaction Checker (free online), NIH Office of Dietary Supplements database (in English), or consultation with a pharmacist – in Poland, pharmacists have the competence and obligation to advise on drug-supplement interactions. This is precisely why the supplement label is an insufficient source of safety information in polytherapy. supplements and safety interactions

Besides St. John's Wort, warfarin (an anticoagulant) interacts with vitamin K (reducing its effect), coenzyme Q10 (may weaken), and even with large doses of vitamin E. Omega-3 fatty acids at doses above 3 g may enhance the effects of anticoagulants and NSAIDs. Vitamin C at doses above 2 g increases iron absorption from supplements, which is dangerous in hemochromatosis. The list of known interactions is long – and the unknown ones potentially longer, as supplements are rarely included in clinical drug studies. Always inform your doctor about the supplements you are taking, treating them equally with over-the-counter medications.

The role of the pharmacist and doctor in choosing supplements

Polish pharmacies sell both OTC medications and dietary supplements – often on the same shelves, which can be misleading. The pharmacist is legally obliged to provide reliable information about products and interactions, but the time spent in the pharmacy is short. A useful rule: if you take more than 2 prescription medications or have a chronic illness, ask the pharmacist for a medication review – a service available in specialized pharmacies, requiring an appointment.

The attending physician should be aware of all the supplements you are taking. The Slone Survey found that over 72% of patients taking supplements do not inform their doctor about it – and as many as 16% of doctors do not actively ask about supplements during the interview. This communication gap leads to unidentified interactions. A simple rule: treat a supplement like a medication when filling out the medication list for your doctor or anesthesiologist before surgery. Many supplements (ginseng, garlic, omega-3, vitamin E) affect blood clotting and must be discontinued before planned surgical procedures.

Frequently Asked Questions

Below are answers to the most common questions about the differences between a supplement and a medication.

What is the difference between a dietary supplement and a medication?

A medication is registered by URPL after verifying clinical studies of efficacy and safety. A dietary supplement is notified to GIS as a food product – without the obligation of proof of efficacy. A medication has an SmPC with indications, dosing, and interactions. A supplement can only declare health claims approved by EFSA.

What should be on the supplement label?

Mandatory: designation „dietary supplement”, ingredients with dosages, recommended daily portion, warning „do not exceed the recommended portion” and „do not use as a substitute for a balanced diet”. For vitamins and minerals – percentage NRV (reference values). The GIS registration number does not need to be visible on the label.

How to check if a supplement is safe?

Minimum criteria: GMP or ISO certificate of the manufacturing facility, Certificate of Analysis (CoA) from independent batch tests, EU manufacturer address on the label, ability to contact the manufacturer. For athletes: Informed Sport or Cologne List certification guaranteeing the absence of doping substances.

Can a supplement claim to cure?

No. Regulation EC 1924/2006 prohibits supplements from claiming properties of treating, preventing, or curing diseases. Only approved health claims by EFSA are permissible, e.g. „contributes to the proper functioning of the immune system”. Medical claims turn a supplement into an illegal drug without registration.

What is an OTC medication and what is a supplement?

An OTC medication (over-the-counter) is a fully-fledged medicinal product registered by URPL with proven efficacy. A supplement is a food product notified to GIS – without proof of efficacy. They may contain identical ingredients, but a medication is subject to pharmacovigilance and has precise clinical indications in the SmPC.

This article is for informational and educational purposes and does not replace consultation with a doctor. If you are pregnant, breastfeeding, taking medications, or have chronic conditions, consult the use of supplements or herbs with a specialist.

Author: Michał Waluk · Published: 2026-05-04 · Updated: 2026-05-04