Dietary supplements in Portugal: Risks and expert warnings

Summary

Portugal's supplement boom raises safety concerns among health experts

Nutritionist Conceição Calhau highlights the differences between dietary supplements and calls for greater public awareness on the subject. "Not everything labeled as a supplement is the same," warns Calhau, a nutritionist and professor of nutritional biochemistry at NOVA Medical School. She argues that the first step when considering supplements is understanding their distinctions. "We should invest in disseminating information about supplements. Ultimately, this is a health issue," she emphasizes. To do so, it is essential to grasp how the dietary supplement industry operates. What rules must they follow to be sold? Which authority regulates and oversees them? And how can consumers know if they are safe and effective?

Sales Rules and Oversight

Dietary supplements are not classified as medicines, meaning they are not regulated by Infarmed (Portugal's National Authority of Medicines and Health Products). Instead, oversight falls to the Directorate-General for Food and Veterinary Affairs (DGAV), which defines them as "foodstuffs intended to supplement the normal diet, serving as concentrated sources of nutrients or other substances with a nutritional or physiological effect. They are marketed in measured doses and designed to be taken in small, precise quantities," as stated on the agency's website.

Before a supplement can be sold in Portugal—whether in supermarkets, pharmacies, health food stores, or online—its manufacturer must notify the DGAV of its market placement. This involves submitting an email with product details, including a copy of the packaging (or label if packaging is unavailable) and administrative and technical information. The DGAV does not issue formal authorization for market release; instead, an automated receipt confirmation is often mistakenly interpreted as approval or validation of the labeling.

"Oversight is carried out by ASAE (the Food and Economic Safety Authority) and the DGAV. During inspections or market controls, they sometimes identify non-compliant supplements—whether due to incorrect labeling or discrepancies between the listed and actual nutrient content," explains Gonçalo Cravidão, an agronomist and country manager for Pharma Nord.

In other European countries, he notes, "controls and oversight are stricter. If an illegal substance is detected in one member state, an alert is issued across the EU, prompting inspections or the removal of such products from the market."

What Do the Labels Say?

A supplement's label must list its ingredients and nutritional information—just like any food product—along with the specific quantity and recommended daily dose of the micronutrient(s) it contains. It must also state that supplements are not a substitute for a varied and balanced diet. Yet many consumers purchase supplements without fully understanding whether the product meets their actual needs.

"The supplement industry has increasingly mirrored the pharmaceutical sector, with companies presenting scientific dossiers to healthcare professionals. But this represents only a niche market. When we talk about dietary supplements in general, we're often referring to products sold in supermarkets or online," Calhau explains. In such cases, she stresses, "two critical questions arise: Does the label accurately reflect the contents and stated doses? And are there undeclared ingredients in the formula that could pose toxicity risks?"

Professor Conceição Calhau warns that people should not self-prescribe supplements but instead consult a healthcare professional for proper guidance. "Patients often tell me they take omega-3, and I always ask, 'What exactly is that?' Omega-3 is a family of fatty acids—so which one are you taking? Alpha-linolenic acid, EPA, DHA? And in what ratio? Most don't know," she explains. "People hear about omega-3 and buy it at the supermarket or online, but that approach is flawed. It might work by chance, or it might be completely unsuitable."

Countless dietary supplement brands are on the market, yet quality standards for their sale are identical whether in supermarkets or pharmacies. According to Portugal's Directorate-General for Food and Veterinary Affairs (DGAV), the fact that some supplements are sold exclusively in pharmacies "has nothing to do with quality but rather reflects marketing strategies that exploit consumer trust in qualified professionals and personalized advice."

Marta Silveira, a pharmacist, notes a growing trend of people purchasing supplements. "At the pharmacy counter, customers usually ask for multivitamins, and more specifically, magnesium or vitamin D," she says, adding that without proper guidance, many remain unaware of potential contraindications. "Three years ago, I worked in a mall pharmacy, and we frequently saw customers who had allergic reactions or adverse effects from supplements. In supermarkets, there's no counseling—people just buy whatever they want."

How to Know What to Take?

Gonçalo Cravidão outlines key criteria for assessing a supplement's safety and efficacy. First, check if it is packaged in a blister pack, as "a capsule in blister packaging better preserves its properties, vitamins, and minerals." Second, research the manufacturer—either through a healthcare professional or reliable online sources—to verify scientific backing and ensure the label accurately reflects the contents.

Calhau reiterates that supplementation often requires clinical justification: "It should be prescribed by a clinician, paired with a balanced diet, and tailored to the individual's specific needs."

For Silveira, health literacy is equally critical. "Fortunately, more healthcare professionals are giving talks or hosting podcasts about supplements, which is vital given the misinformation out there. You can never have too much health literacy," she argues.