Chromium, best known as a shiny metal used in bathroom fittings, is also sold as a dietary supplement claimed to improve athletic performance and regulate blood sugar. However, despite being recommended as a dietary requirement by health agencies in the US and elsewhere, eight decades of research have yielded little evidence that humans derive significant health benefits from this mineral.
Essential trace elements like iron, zinc, and copper are needed in tiny amounts for optimal health, and their roles are well understood. For example, iron is essential for oxygen transport, and deficiency causes anaemia. In contrast, chromium deficiency is extremely rare, and no clearly defined disease has been linked to low chromium levels. Moreover, the gut absorbs only about 1% of ingested chromium, compared to around 25% for certain forms of iron.
Critically, scientists have not found any protein that requires chromium to function. The only known chromium-binding protein likely helps the kidneys remove it from the blood. While some studies suggest chromium may be involved in blood glucose regulation, research on chromium supplements improving sugar metabolism has been inconclusive.
The notion that chromium is essential dates back to flawed 1950s studies on rats, where a diet inducing Type 2 diabetes symptoms seemed to be cured by chromium supplements. These experiments lacked proper controls and statistical analysis. Later, more rigorous studies produced ambiguous results, with some showing slight improvements in blood sugar control and others finding no effect. Rats raised on chromium-free diets remained perfectly healthy.
Well-designed clinical trials in humans are scarce, and results remain ambiguous. Based on current biochemistry, there is no evidence that humans require chromium for any specific function. The mineral's status as an essential nutrient appears to be a legacy of early, poorly conducted research.
