An expert is revealing the reality of a popular supplement that has been touted as an ‘essential nutrient.’

Trivalent chromium, a metal, is included in multivitamin pills and sold as a dietary supplement that companies claim can improve athletic performance and help regulate blood sugar.

But Neil Marsh, a professor of chemistry and biological chemistry at the University of Michigan, said although health agencies in the US recommend chromium as a dietary requirement, eight decades of research have resulted in slim evidence that people derive any significant health benefits from this mineral.

Still, chromium has come to be considered essential for human health. 

To stay healthy, people need essential trace elements, very small amounts, in their diet. These include metals such as iron, zinc, manganese, cobalt and copper. 

For most of these trace elements, decades of research have shown they are genuinely essential for health. 

Iron is essential for carrying oxygen in your blood, and many proteins – complex molecules that carry out all of the functions necessary for life – require iron to function properly. 

A deficiency of iron leads to anemia, a condition that results in fatigue, weakness, headaches and brittle nails, among other symptoms. Iron supplements can help reverse these symptoms.

Importantly, biochemists have pinpointed exactly how iron helps proteins perform essential chemical reactions, not just for humans but all living organisms. Researchers know not only that iron is essential but also why it is essential.

However, the same cannot be said for chromium.

Chromium deficiency – having little to no chromium in your body – is extremely rare, and researchers have not identified any clearly defined disease caused by low chromium levels.

Like all food, essential metals must be absorbed by your digestive system. However, the gut absorbs only about 1 percent of ingested chromium. Other essential metals are absorbed more efficiently – for example, the average person absorbs around 25 percent of certain forms of ingested iron.

Despite many studies, scientists have yet to find any protein that requires chromium to carry out its biological function. Only one protein is known to bind to chromium, and this protein most likely helps your kidneys remove the metal from your blood. 

While some studies in people suggest chromium might be involved to some degree in regulating blood glucose levels, research on whether adding extra chromium to your body through supplements can substantially improve your body’s ability to break down and use sugar has been inconclusive.

Thus, based on biochemistry, there is currently no evidence that humans, or other animals, actually require chromium for any particular function.

The idea that chromium might be essential for health stems from studies in the 1950s, a time when nutritionists knew very little about what trace metals are required to maintain good health.

One influential study involved feeding lab rats a diet that induced symptoms of Type 2 diabetes. 

Supplementing their diet with chromium seemed to cure the rats of Type 2 diabetes, and medical researchers were enticed by the suggestion that chromium might provide a treatment for this disease. 

Today’s widespread claims that chromium is important for regulating blood sugar can be traced to these experiments.

Unfortunately, these early experiments were very flawed by today’s standards. They lacked the statistical analyses needed to show that their results were not due to random chance. 

Furthermore, they lacked important controls, including measuring how much chromium was in the rats’ diet to start with.

Later studies that were more rigorously designed provided ambiguous results. 

While some found that rats fed chromium supplements controlled their blood sugar slightly better than rats raised on a chromium-free diet, others found no significant differences. But what was clear was that rats raised on diets that excluded chromium were perfectly healthy.

Experiments on people are much harder to control for than experiments on rats, and there are few well-designed clinical trials investigating the effects of chromium on patients with diabetes. Just as with the rat studies, the results are ambiguous. If there is an effect, it is very small.

Still, there has been a recommended dietary intake for chromium despite its lack of documented health benefits. 

The idea that chromium is needed for health persists due in large part to a 2001 report from the National Institute of Medicine’s Panel on Micronutrients. 

This panel of nutritional researchers and clinicians was formed to evaluate available research on human nutrition and set ‘adequate intake’ levels of vitamins and minerals. 

Their recommendations form the basis of the recommended daily intake labels found on food and vitamin packaging and the NIH guidelines for clinicians.

Despite acknowledging the lack of research demonstrating clear-cut health benefits for chromium, the panel still recommended adults get about 30 micrograms per day of chromium in their diet. 

This recommendation was not based on science but rather on previous estimates of how much chromium adult Americans already ingest each day. Notably, much of this chromium is leached from stainless steel cookware and food processing equipment, rather than coming from our food.

So, while there may not be confirmed health risks from taking chromium supplements, there’s probably no benefit either.

This article is adapted from The Conversation, a nonprofit news organization dedicated to sharing the knowledge of experts. It was written by Neil Marsh, a professor of chemistry and biological chemistry at the University of Michigan.