nutritional supplement
Meaning of nutritional supplement: Sold as a food rather than as a medicine in many countries, which changes what a maker must demonstrate before a product reaches a shelf.
Definition of nutritional supplement
A nutritional supplement is a product taken by mouth to add to the diet rather than to replace food. It carries one or more dietary ingredients, such as a vitamin, mineral, herb, amino acid or enzyme, in concentrated form as a tablet, capsule, softgel, powder or liquid. Some contain a single nutrient, others combine many.
Why are they used?
The reasons vary more than the products do. One is correcting a measured deficiency, where a specific nutrient is low and the supplement is prescribed for that purpose. Another is covering a nutrient that a restricted diet makes hard to obtain, as with vitamin B12 on a strict plant based diet. A third is a defined medical use, such as folic acid taken around the time of conception. The largest group by volume is general use, taken in the belief that it supports health rather than to treat anything identified. These situations are not equivalent, and evidence supporting one says nothing about the others.
How does regulation differ from medicines?
| Prescription medicine | Nutritional supplement | |
|---|---|---|
| Approval before sale | Required, with trial evidence | Generally not required in jurisdictions that regulate it as food |
| Claims permitted | Specific diseases named on the label | General wording about supporting normal body function |
| Content consistency | Tightly specified and verified | Varies between manufacturers and between batches |
The same framework covers a plain vitamin C tablet, a herbal supplement and a multi ingredient blend, which is why the strength of evidence behind two products sitting side by side can be wildly different. The term dietary supplement is used interchangeably in most regulatory writing.
Can a supplement interact with medication?
Concentrated doses behave more like drugs than like food, and interactions are documented. Certain herbal ingredients speed up the liver enzymes that clear medicines, lowering the level of a drug in the blood without any obvious sign. High doses of vitamin K work against medication that thins the blood by that route. Calcium and iron bind some antibiotics and thyroid tablets in the gut, so less of the medicine is absorbed. Supplements also tend to be left off medication lists, since many people class them as food rather than as something a clinician needs to know about.
Also known as
Used in a sentence
The patient reported taking a daily nutritional supplement in addition to a regular diet.
Good to know
Nutritional supplements are regulated differently from prescription medication in many jurisdictions, so the strength of evidence behind a given product's claimed benefit varies considerably from one supplement to another.