Chromium

What it does

Chromium is a trace mineral whose best-understood role is helping the hormone insulin work more effectively. Insulin is what allows cells to take up glucose from the blood for energy, and chromium appears to enhance insulin's action, supporting the body's handling of blood sugar. Because of this it is often discussed in the context of glucose metabolism, though the amounts needed are extremely small.

Through its influence on insulin, chromium is involved in the metabolism of carbohydrates, fats and proteins — the broad business of turning food into energy and building blocks. The scientific picture of exactly how it works, and how much difference supplements make in people who are not deficient, is less clear-cut than for the classic vitamins and minerals, and claims that chromium supplements aid weight loss or dramatically improve blood sugar in healthy people are not well supported.

Chromium is found in small amounts across many foods, including meat, wholegrains, some fruit and vegetables, and brewer's yeast. Because it is so widely distributed and needed only in trace quantities, deficiency is rare in people eating a normal, varied diet. The body absorbs only a small fraction of dietary chromium and excretes the rest, keeping levels naturally in check.