Chromium is an element (Cr), and is commonly found as a mineral in the earth’s crust and soil (typically in trivalent or hexavalent form).^[8] Trivalent chromium, Cr(III), is the form discussed on this page. It is generally considered safe and is found in various supplements and foods (e.g., grains, meats, brewer’s yeast, fruits, vegetables).^[9] In contrast, hexavalent chromium, Cr(VI), is an environmental pollutant and carcinogen produced by industrial metal processing and found in exhaust fumes and cigarette smoke.^[10]

Trivalent chromium (from here on referred to as chromium) has been considered an essential trace mineral for many years, meaning that the body needs it in small amounts to function properly. However, while it has been proposed that chromium is required for the proper functioning of insulin and the metabolism of carbohydrates, proteins, and fats,^[11] there is currently no global consensus as to whether chromium is truly essential for the human body.^[12][7]

Chromium is best known for its effects on blood sugar regulation in type 2 diabetes, but it may also have mild antioxidant,^[13] anti-inflammatory,^[14] and appetite-suppressing effects.^[15] Even though chromium is a popular dietary supplement, the research on chromium is fairly mixed, and where benefits have been found, they tend to be small or negligible.

Chromium seems to modestly reduce hemoglobin A1c (HbA1c), by an average of 0.54%,^[1][16] and may improve insulin sensitivity, as indicated by reductions in HOMA-IR, but there are no clear effects on fasting blood glucose.^[16] Notably, these benefits have not been observed in people with normal glucose tolerance.^[1]

Beyond blood sugar regulation, chromium may have slight weight loss benefits in people with overweight and obesity, possibly reducing weight, body mass index (BMI), and body fat percentage. However, these effects are small, likely have little clinical relevance, and are not consistently observed in people with type 2 diabetes.^[15] Chromium may also reduce oxidative stress, as suggested by increased total antioxidant capacity and reduced malondialdehyde in people with type 2 diabetes, metabolic syndrome, non-alcoholic fatty liver disease, and polycystic ovary syndrome (PCOS), but this effect is poorly understood and also has questionable clinical relevance.^[13]

Chromium seems to be well-tolerated. Studies have generally not found side effects in those taking chromium compared to placebo, but thorough safety analyses have also not been done. Currently, the Institute of Medicine has no safe upper limit for chromium due to a lack of evidence.^[6] There have been isolated case reports of anemia (low red blood cells), thrombocytopenia (low platelets), liver and kidney dysfunction, dermatitis, low blood sugar, and rhabdomyolysis (a severe type of muscle injury).^{[17][18][19][20][21]} Some of these cases involved chromium doses exceeding 1,000 µg daily, but others were taking doses of 200–600 µg daily, which are considered to be within normal range. However, none of these side effects have been observed in clinical trials to date.

Chromium’s mechanisms of action are not well-understood, although it’s generally accepted that it enhances the effect of insulin and promotes glucose transport into insulin-sensitive tissues.^[1][22] It is currently thought that these actions occur via a biological complex (an oligopeptide called chromodulin, also known as low-molecular weight chromium-binding substance (LMWCr)) with which chromium binds. In vitro research has found that insulin has a greater capacity to facilitate glucose metabolism in the presence of chromodulin,^[23] and that the ability of chromodulin to stimulate glucose metabolism is proportional to the chromium content of the complex.^[24] Chromodulin is thought to bind intracellularly to activated insulin receptors, essentially amplifying insulin signaling.^[25] In terms of chromium’s weight loss effects, chromium seems to reduce appetite and food cravings. Preliminary research suggests that chromium may act directly on the brain to induce these effects, possibly by impacting neurotransmission,^[15][26] but more research is needed to confirm this.