It’s one of the most common elements in the earth’s crust and in seawater, but only tiny amounts are present in the human body. Its role in treating diabetes in animals was described in the 1950s, but its role in human health is still unclear. It’s wildly popular in the United States as a supplement for weight loss, but it’s not effective in that role. It’s chromium “” a forgotten nutrient that may finally get some respect because of new studies of chromium and heart disease, diabetes, and cholesterol.
What is chromium?
Most men who think of chromium remember it as the shiny metal in the bumpers of their first cars. Chrome bumpers have gone the way of eight-track tapes, but the metal has a crucial, if incompletely understood, role in human health.
Chromium’s best-defined task is to facilitate the action of insulin. Patients deficient in chromium develop severe diabetes that does not respond well to insulin but is corrected by chromium replacement. Big-time chromium deficiency is uncommon, but it used to develop in patients who depended on intravenous feedings. Fortunately, nutritionists have eliminated the problem by adding chromium to total parenteral nutrition (TPN) solutions.
Severe chromium deficiency is rare because the mineral is present in many foods, including high-fiber bran cereals and other whole-grain products, coffee, nuts, green beans, broccoli, brewer’s yeast, and some brands of beer and wine. The chromium content of fruits, most vegetables, fish, poultry, and meat varies widely. Foods made with refined grains and simple sugars are a double whammy for the body’s chromium balance, since they are low in the mineral and they also promote chromium loss.
How much chromium do you need? Thirty-five micrograms (mcg) is considered adequate for men, 25 mcg for women. Although precise data are not available, studies from around the world indicate that a substantial proportion of people do not get enough chromium. Perhaps, then, subclinical or mild chromium deficiencies may contribute to the worrisome burden of diabetes and heart disease in Western societies.
Chromium and diabetes
Since chromium has a well-documented role in insulin action and glucose (sugar) metabolism, diabetes is a logical candidate for chromium replacement therapy. Animal experiments show that chromium deficiency can cause diabetes, and the mineral’s crucial value for preventing and treating diabetes in TPN patients was discovered in the late 1970s. However, human studies in less extreme circumstances have yielded conflicting results.
Some of the problem stems from the difficulty in measuring the very low levels of chromium that are normally present in the blood and body fluids. A better way is to measure how much chromium is present in toenail clippings; using this technique, low chromium levels have been linked to an increased risk of diabetes.
Another problem is that studies of chromium therapy have used many different forms of the metal, ranging from brewer’s yeast to glucose tolerance factor; an organic (carbon-containing) form of chromium extracted from brewer’s yeast, to chromium salts such as chromium picolinate and chromium chloride. The doses have also varied, and most of the studies have been short-term interventions in a small number of subjects. As a result, perhaps, chromium supplements have not been consistently beneficial in treating diabetes; the most hopeful results come from the studies of diabetes in pregnancy and steroid-induced diabetes.
The American Diabetes Association states that “at present, benefit from chromium supplements has not been conclusively demonstrated.” It’s a fair conclusion, but it is also an invitation to more scientific study.
Chromium and weight loss
Scientists disagree about whether chromium supplements may help treat diabetes, but they agree that supplements are not effective in producing meaningful, sustained weight loss. It’s ironic, since chromium picolinate is selling fast as a “nutritional supplement” for weight loss “” another case of caveat emptor, buyer beware.
Chromium and cholesterol
In rats, chromium deficiency leads to high cholesterol levels and to the formation of atherosclerotic plaques. In humans, though, the results have been contradictory. In seven studies of diabetic patients, scientists reported that chromium supplements produced improved blood lipid profiles, but in four studies, no changes were evident. Similar disparities have been reported in nondiabetic subjects, with five studies finding benefit for blood cholesterol levels but three finding none.
With such scattered results, it’s clearly too early to recommend chromium supplements for cholesterol. But there may be an exception to that rule. Although many medications do an excellent job of lowering LDL (“bad”) cholesterol levels, most are much less successful at boosting HDL (“good”) cholesterol levels. Niacin is an exception, but it can have unpleasant side effects. The best ways to boost HDL levels include weight loss, exercise, smoking cessation, and reducing the consumption of trans fats and simple sugars and other rapidly absorbed carbohydrates; low-dose alcohol can help people who can drink responsibly and safely. But if lifestyle changes don’t help, chromium may be worth a try. Four randomized clinical trials have reported a benefit; the preparations and doses varied from 200 mcg a day of chromium chloride to 600 mcg a day of glucose tolerance factor. Several trials have been disappointing, and more study is needed to sort things out. But since chromium supplements are inexpensive and safe, it is reasonable for people with low HDLs to try them for two to four months to see if they can help.
Chromium and heart disease
Despite interesting hints of clinical importance, chromium has been on the scientific back burner, but a new study of chromium and heart disease may restore some of its shine.
Scientists from the United States, Europe, and Israel evaluated 1,408 men from eight European countries and Israel. Nearly half were enrolled in the EURAMIC study shortly after suffering their first heart attacks; the other men had not had heart attacks. The researchers collected toenail clippings from all ten toes of each volunteer. The clippings were stored carefully until they could undergo neutron activation analysis, a precise way to determine chromium levels. The men were also evaluated for obesity, diabetes, hypertension, cholesterol, smoking, and alcohol use.
When the results were analyzed, low chromium levels were linked to an increased risk of heart attacks: the lower the level, the higher the risk. The association between low chromium and heart attacks did not depend on diabetes or dietary patterns that affect chromium consumption. In all, men with the highest chromium levels were 41% less likely to have a heart attack than men with the lowest levels.
A Harvard study of 1,247 American men supports the hypothesis that chromium may reduce the risk of cardiovascular disease. As in the EURAMIC study, the Harvard scientists used toenail clippings to evaluate chromium levels. Compared with healthy men, those with diabetes had lower chromium levels, while men with both diabetes and coronary artery disease had the lowest levels of all.
Is chromium right for you?
When it comes to dietary chromium, the answer is yes; even if chromium itself is not beneficial, whole grains, nuts, broccoli, and green beans are all healthful foods. And for many of us, moderate amounts of beer or wine are beneficial, while coffee is harmless. Similarly, minimizing your consumption of simple sugars will be good for you regardless of its effect in chromium.
Diet is one thing, supplements another. Before you shell out for supplements, you should know if they are safe and effective. Since dietary supplements are exempt from FDA regulation, their safety and purity cannot be assured. Given that limitation, though, chromium appears safe. Very high concentrations of chromium picolinate can damage the DNA of cells in tissue culture, but clinical doses are much lower, and the Institute of Medicine has concluded that chromium picolinate is safe.
Do chromium supplements help? It’s the $64,000 question, but doctors will not be able to answer it until more research is completed. At present, it might be reasonable to try chromium to boost HDL cholesterol levels that have remained low despite lifestyle alterations. The preparations that have raised HDL cholesterol levels include glucose tolerance factor in a dose of 200 mcg three times a day and chromium chloride in doses of 200 or 250 mcg a day.
If you decide to try chromium, discuss it with your doctor and have your cholesterol profile checked before and after a four-month trial. If your HDL cholesterol doesn’t improve, there is little reason to continue the supplement. But if your levels rise, you and your doctor may take a shine to this neglected nutrient.
Source: Harvard.edu