What are supplements?

What is a supplement (food supplement)?

Article 4 of the Communiqué defines a food supplement as a product prepared as concentrates or extracts, alone or in mixtures, of nutrients or of plants, plant- and animal-derived substances, bioactive substances and similar substances with nutritional or physiological effects, in forms such as capsules, tablets, lozenges, single-use powder sachets, liquid ampoules and dropper bottles, with a defined daily intake dose. ^[1] The text of the Communiqué states that the regulation was prepared in parallel with EU Directive 2002/46/EC. ^[1] The Ministry of Health’s TÜBER (Türkiye Dietary Guidelines) 2022 notes that the names “nutrient support,” “nutraceutical,” “food supplement” and “dietary supplement” are also used for the same concept. ^[4]

According to the Communiqué, these products can be placed on the market only under the name “food supplement” and are offered to the final consumer only in ready packaged form. ^[1] The Communiqué prohibits the production and marketing of food supplements for infants and young children under 2 years of age. ^[1]

How is the same concept defined in the EU and the US?

According to Article 2 of EU Directive 2002/46/EC, food supplements are foodstuffs intended to supplement the normal diet, that are concentrated sources of nutrients or other substances with a nutritional or physiological effect, alone or in combination, and that are marketed in dose forms such as capsules, lozenges, tablets and pills. ^[2]

In the US, under the Dietary Supplement Health and Education Act (DSHEA) of 1994, a “dietary supplement” is a product taken by mouth that contains a “dietary ingredient” and is intended to supplement the diet; according to the FDA, this term covers vitamins and minerals, herbs and botanicals, amino acids, substances present in the food supply such as enzymes and live microorganisms (“probiotics”), and concentrates, metabolites, constituents, extracts or combinations of these. ^[3] The three definitions are similar in outline; the difference lies in the control model at market entry (below).

What types of supplements are there?

The Communiqué and TÜBER group the substances that may be used in food supplements into three groups: vitamins and minerals (in the Communiqué’s annexes, with their forms and daily upper limits), botanicals (according to the Ministry’s “Plant List”; plants, herbs, fungi, algae and their extracts) and “other substances” apart from these (according to the Ministry’s “Restricted Substances List”; substances with minimum and/or maximum limits or bans). ^[4] In practice, these groups are seen as the families below; each family needs a separate evidence assessment.

The table is a mapping provided for the reader’s convenience; the place of a substance in the Ministry’s lists is determined by the substance’s own entry.

What is the difference between supplements, medicines, ordinary food and sports foods?

Classification can vary by substance and country: melatonin is sold as a supplement in the US but has the status of a licensed medicine in Türkiye; details are in the Melatonin guide. For the whole of the legislation in Türkiye, the guide Supplement regulation in Türkiye can be consulted.

What does Ministry approval mean and not mean?

The Ministry of Agriculture and Forestry states that food supplements must obtain approval. ^[6] Approval is product-based: according to the Ministry’s “commonly misunderstood” note, it is not true that if one product of a company is approved, all its products are approved; each product is approved separately and must appear on the list. ^[5]

The approval process is defined in the implementation instruction: the application is made to the provincial directorate; the file contains documents such as the product’s composition, a specification document and the daily intake dose; if the documents are complete and correct, the provincial directorate enters the product into the Food Safety Information System (GGBS) and issues the approval number. ^[8] The same instruction states that, because health claims fall under TİTCK’s authority, no assessment of them should be made when evaluating an approval application, and that the food business operator placing the product on the market is responsible for the health claim used; the sample approval letter annexed to the instruction also expressly states that the food supplement approval issued by the Ministry does not cover health claims. ^[8] According to the Ministry’s Güvenilir Gıda page, food supplements cannot be placed on the market with claims such as weight loss, increasing sexual performance, height growth, enhancing intelligence, quitting smoking or relieving attention deficit. ^[6] The Ministry announces that approved products are published in the Food Safety Information System and that products not on the list are not considered approved. ^[5]

The conclusion from this chain is that an approval number shows that a product can be legally offered on the market in Türkiye; it does not separately show that the product works, that it is good for a disease or that it is safe at a given amount. The question of efficacy is addressed through clinical trials, as in every supplement guide on this site. The US has a different model: under DSHEA, the FDA has no authority to approve supplements before they are marketed; the company is responsible for ensuring that the supplement it produces or distributes is not adulterated or misbranded; the FDA requires prior notification for new dietary ingredients and can act on problem products after they reach the market. ^[3]

Permitted health claims for supplements are subject to TİTCK’s 2023 regulation: a health claim cannot be vague, false or misleading; it cannot be used in a way that encourages excessive consumption of a product; claims that refer to testimonials or institutional endorsement are not allowed. ^[7]

How many people use supplements?

TÜBER 2022 reports that vitamins and minerals are the most used food supplements in Türkiye and that, according to the Türkiye Nutrition and Health Survey (TBSA) 2017, 9.9% of individuals aged 15 and over (men 6.3%, women 13.4%) use nutritional supplements. ^[4] For the US, the USPSTF 2022 recommendation statement, citing NHANES data, reports that 52% of US adults used at least one supplement and 31% used a multivitamin-mineral supplement in the past 30 days. ^[9] The two rates are based on different definitions and time frames (use of nutritional supplements in TBSA, at least one supplement in the past 30 days in NHANES) and are therefore not suitable for direct comparison between countries.

What do the evidence grades on this site mean for supplements?

In the guides on this site, each result row carries a grade: A means strong, B moderate, C weak and D insufficient evidence; E is for “no benefit shown” results. The system is explained on the levels of evidence page and the methodology page. A single randomized trial lowers the ceiling of the grade to C; a single trial of a multi-ingredient formula is also counted as a single trial. The grade relates not to a product’s sales status but to what studies show for a specific outcome in a specific group of people. For this reason the same supplement can receive A in one area and E in another (for example, creatine has a high grade in short-duration high-intensity exercise and E in endurance).

Vitamin and mineral guides

Other supplement guides

The summary in each row reflects the result of the relevant guide; the full evidence, study designs and limitations are on the relevant pages.

Where next after this guide?

Who may need a supplement is in Do you need supplements?, how to read a label is in How to read a label, and risks and interactions are in Are supplements safe?; drug interactions are also covered in Drug interactions, and timing in When to take supplements. This guide does not recommend a personal product or dose.