Chromium was long thought to be a toxic mineral until it was discovered in 1957 to be the essential part of Glucose Tolerance Factor (GTF). Because of the low absorption and high excretion rates of chromium, toxicity is not at all common in humans, especially with the usual forms of chromium used for supplementation. The amount of chromium that would cause toxicity is estimated to be much more than the amount commonly supplied in supplements.
Chromium deficiency is another story, however, with an estimated 25-50% of the U.S. population being deficient in chromium. The United States has a greater incidence of deficiency than any other country, because of very low soil levels of chromium and the loss of this mineral from refined foods, especially sugar and flours. Even though chromium is needed in such small amounts, it is difficult to obtain. Given these factors, and the fact that the already-low chromium absorption rate decreases even further with age, chromium deficiency is of great concern.
Chromium is really considered an "ultra-trace" mineral, since it is needed in such small quantities to perform its essential functions. The blood contains about 20 parts per billion (ppb) – a fraction of a microgram. Even though it is found in such small concentrations, this mineral is important to health. There are about 6mg of chromium stored in the bodies of people who live in the United States; tissue levels of people in other countries are usually higher, and those higher levels tend to be associated with a lower incidence of diabetes and atherosclerosis. There is less hardening of the arteries in people of Asian countries, who it is estimated have five times higher chromium tissue levels than Americans. People of Near Eastern countries who have about four times the average U.S. levels and African people who have twice our chromium levels seem to experience less diabetes than Americans. These higher tissue levels of chromium are due primarily to better soil supplies and a less refined diet. Chromium may be only one of the factors accounting for the differences in rates of diabetes and atherosclerosis between cultures, but it is probably a major one.
Diagnosing and treating chromium deficiency is simple and should be done as early as possible, as it is much easier to prevent diabetes than to treat it.
Tissue levels of chromium tend to decrease with age, which may be a factor in the increase of adult-onset diabetes, a disease whose incidence rose more than sixfold during the second half of the 20th century. This increase may also mirror the loss of chromium from our diets because of soil deficiency and the refinement of foods. Much of the chromium in whole grains and sugarcane is lost in making refined flour (40% loss) and white sugar (93% loss). In addition, there is some evidence that refined flour and sugar deplete even more chromium from the body.
Reduced absorption related to aging, diets that are stressful to the digestive system, and the modern refined diet all contribute to chromium deficiency. Higher fat intake also may inhibit chromium absorption. If chromium is as important as we think it is to blood sugar metabolism, its deficiency may be in part responsible, along with the refined and processed diet, for the third leading cause of death (more than 300,000 yearly) in this country, diabetes mellitus, and this figure does not reflect other deaths that may be related to chromium deficiency, since high blood sugar levels seen in diabetes also increase the progression of atherosclerosis and cardiovascular disease, our number one killer.
People who eat a diet high in sugar and refined foods are more at risk for not getting enough chromium. Sugar increases chromium loss and refined foods are very low in chromium. Athletes may also have increased chromium loss through exercise.
Milk and other high-phosphorus foods tend to bind with chromium in the gut to make chromium phosphates that travel through the intestines and are not absorbed.
Chromium deficiency can resemble diabetes.
To Avoid Deficiency and Maintain a Good Intake of Chromium:
Impaired chromium utilization may be a cause of gestational diabetes. By impairing pancreatic insulin production, chromium deficiency may increase the tendency towards hyperglycemia in gestational diabetes. [J Am Coll Nutr 15(1): pp.14-20, 1996] Hair chromium concentrations were significantly lower in 68 samples taken from non-diabetic pregnant women than in 42 samples from gestational diabetics (472ng/gm versus 734ng/gm). [Am J Clin Nutr 55: pp.104-7, 1992]