Dietary supplements. How they differ from medicines – and when they help rather than harm

You hesitate between swallowing a capsule and simply rethinking what is on your plate. In a recent episode of the Radio Wrocław programme “Różne punkty słyszenia”, dr hab. inż. Zuzanna Goluch, prof. UEW explains in clear terms how dietary supplements differ from medicines, when they can support health and when they may become a real risk. Her perspective – anchored in research and everyday teaching practice – cuts through marketing noise and returns to evidence. 

The discussion brought together several professional perspectives: 
Professor Zuzanna Goluch – Department of Food Technology and Nutrition, Wroclaw University of Economics and Business; 
Dr Magdalena Elżbieta Hurkacz– Department of Clinical Pharmacology, Faculty of Pharmacy, Wroclaw Medical University; 
Aleksandra Gąbka, MSc – clinical dietitian and psychodietitian (Wrocław); 
Łukasz Skowron, MSc – pharmacist, pharmacy manager, deputy disciplinary ombudsman for professional liability. 

What does the law call a “dietary supplement”? 

Polish food law defines a dietary supplement as a foodstuff intended to supplement the normal diet. It is a concentrated source of vitamins, minerals or other substances with a nutritional or other physiological effect, marketed in dose form (for example capsules, tablets, sachets or drops). 

For consumers, one conclusion is crucial: a supplement is not a medicine. It is not designed to treat diseases and must not be communicated as if it were a drug. 

The legal distinction translates directly into practice. Medicines are medicinal products: they require clinical trials, marketing authorisation and fall under pharmaceutical law. Supplements fall under food law. They are notified to the sanitary inspection authority; their efficacy is not assessed in the same way as medicines. This asymmetry explains both the scale of the supplement market and the need for critical reading of labels – including reference intake value. 

First food and diagnostics – only then a supplement 

Across the programme, one sequence of action emerges consistently – the approach which prof. Zuzanna Goluch emphasises in her research and teaching: 

• We start with the plate: correcting our diet on the basis of conventional food and sound nutrition education. 
• We then move to diagnostics: blood and urine tests, a detailed dietary interview, medical or dietetic consultation. 
• Only at the end, if at all, do we introduce a supplement – preferably single-ingredient, prescribed for a defined period and followed by repeat diagnostics to verify whether the deficiency has in fact been corrected. 

This “clinical order” brings clarity to the current chaos around “magic capsules” and restores food to its primary role. 

Concrete examples from practice illustrate this logic. Some of the guests admitted to taking vitamin D₃, but only after testing serum levels, in line with recommendations and under control of follow‑up tests. The popular principle “I’ll take it because everyone takes it” is replaced with: first evidence of deficiency, then targeted intervention. 

“Supplementation should only be periodic – based on diagnostic tests and properly monitored.” 

This sentence by prof. Goluch captures the core of the debate. Trust in a product grows when it is backed by robust research and transparent quality assurance – not just by advertising. 

When can a supplement be harmful? 

From a pharmacological perspective, one of the most important warnings concerns interactions. Calcium or magnesium ions can reduce the absorption of selected antibiotics. This is a reminder that a supplement, just like a medicine, may cause adverse effects and interact with other substances. 

The programme also recalled clinical situations associated with popular herbal preparations. The conclusion is straightforward: self‑medication without diagnostics increases the risk of error, while the package leaflet for a supplement often does not provide sufficient, nuanced warning for specific patient groups. 

Prof. Goluch directs attention to another dimension that is frequently overlooked: technological additives (the so‑called “E numbers”) in capsules and tablets. These substances form shells, serve as fillers or glazing agents. A shorter ingredient list – clean label – means a lower burden on the body. This is particularly relevant for vulnerable groups: children with immature detoxification mechanisms and older adults with multimorbidity and polypharmacy. 

A practical example: two vitamin D₃ products of the same declared strength (1000 IU) from different manufacturers. One has three ingredients, the other eleven. Choosing the first one is not pedantry – it is a tangible difference for the liver and kidneys. 

At the same time, the declared “50% RI” for a nutrient does not automatically translate into 50% of the body’s actual needs being covered. Absorption depends not only on the dose, but also on the overall dietary pattern, health status and concomitant medications. 

Marketing pressure versus professional advice 

The final warning concerns marketing – from influencers to aggressive sales of “miracle preparations” addressed to older adults. A valuable consultation with a pharmacist or dietitian begins with a simple question: “Do you really need this product?” Sometimes the best recommendation is not a capsule at all, but a return to basics: more diversity on the plate, more vegetables and fruit, less monotony. 

The message of the programme is both simple and demanding. A supplement does not treat disease and does not replace diet. Its place is at the very end of the pathway – after nutrition education, diagnostics and consultation. In this sequence, it may genuinely help instead of doing harm. 

At the Wroclaw University of Economics and Business we treat social responsibility as more than a slogan. It is a standard of competence that we aim to embed in our students – and, through them, in the wider socio‑economic environment. 

https://www.radiowroclaw.pl/articles/view/155005/Rozne-punkty-slyszenia-Suplementy-diety-Czym-roznia-sie-od-lekow-Kiedy-pomagaja-a-kiedy-szkodza  

badania.uew.pl/en – we invest in competent voices when noise drowns out common sense. 

Author: Barbara Grzelczak