What are dietary supplements?

Various definitions for dietary supplements exist worldwide. In the UK, the definition developed by the Proprietary Association of Great Britain (PAGB), British Herbal Manufacturers’ Association (BHMA) and the Health Food Manufacturers’ Association (HFMA) is that they are:
Foods in unit dosage form, e.g. tablets, capsules and elixirs, taken to supplement the diet. Most are products containing nutrients normally present in foods which are used by the body to develop cells,bone, muscle etc, to replace co-enzymes depleted by infection and illness, and generally to maintain good health.

In addition to vitamins and minerals, this definition also covers ingredients such as garlic, fish oils,evening primrose oil and ginseng, which can be taken to supplement dietary intake or for their suggested health benefits. For the purposes of the European Union (EU) Directive on food supplements the term ‘food supplements’ means:

Foodstuffs the purpose of which is to supplement the normal diet and which are concentrated sources of nutrients or other substances with a nutritional or physiological effect, alone or in combination, marketed in dose form, namely forms such as capsules, pastilles, tablets, pills and other similar forms, sachets of powder, ampoules of liquids, drop dispensing bottles, and other similar forms of liquids and powders designed to be taken in measured small unit quantities.

In the USA, the Dietary Supplement Health Education Act (DSHEA) 1994 defines a dietary supplement as:

A product (other than tobacco) that is intended to supplement the diet which bears or contains one or more of the following dietary ingredients: a vitamin, a mineral, a herb or other botanical, an amino acid, a dietary substance for use by man to supplement the diet by increasing the total daily intake, or a concentrate, metabolite, constituent, extract or combinations of these ingredients. It is intended for ingestion in pill, capsule, tablet or liquid form, is not represented for use as a conventional food or as the sole item of a meal or diet and is labelled as a dietary supplement.

This definition, like that in the UK, also expands the meaning of dietary supplements beyond essential nutrients, to include such substances as ginseng, garlic, psyllium, other plant ingredients, enzymes, fish oils and mixtures of these. The EU definition does not currently include substances apart from vitamins and minerals,but other substances may be included in the future.

One of the key points in these definitions is that dietary supplements are products consumed in unit quantities in addition to normal food intake. This differentiates supplements from other foods, such as fortified foods and functional foods, to which nutrients are added. However, a major difference in the US definition is the explicit inclusion of ‘herbs or other botanicals’ in the list of dietary ingredients. In the UK, herbal products are currently marketed under a variety of arrangements – either as fully licensed medicines, under the Traditional Herbal Medicines Product (THMP)

Directive, ‘medicines exempt from licensing’ under section 12 of the 1968 Medicines Act, or as cosmetics or foods, so they do not fall entirely in the food supplements category. Enteral feeds (e.g. Complan and Ensure) and slimming aids are also classified as dietary supplements by nutritionists and dieticians, but for the purposes of this book, these products will be ignored.