Sources: Food refinement, and the loss of topsoil through poor agricultural practices reduce the level of chromium in foods. There are, however, still many good food sources. Since GTF is better absorbed than inorganic chromium, the level and activity of GTF in foods affect how well they supply us with this mineral. GTF activity may not always correspond to the actual amount of chromium in foods; however, many foods with good GTF activity also have good amounts of chromium. Hard water often contains some chromium; it may supply up to half of the daily needs of an adult.
Brewer's yeast is likely the best available source of chromium as well as having the highest GTF activity. About two tablespoons, or six tablets, per day supply most of our chromium needs; however, many people, maybe 30-40 percent, do not tolerate yeast very well and find that it causes digestive upset or bloating. If yeast is tolerated, it supplies a great many nutrients and is a low-calorie and low-fat source.
Following yeast in chromium concentration are beef, liver, whole wheat, rye, fresh chilies, oysters, potatoes, wheat germ, green peppers, eggs, chicken, apples, butter, bananas, and spinach. Yeast (44 ppm), black pepper (10 ppm), and molasses (2 ppm) are good sources of chromium, but since they are usually consumed in small quantities, it is best to have other chromium foods in the diet. In general, the whole grains, meats, shellfish, chicken, wheat germ and bran, and many vegetables, especially potato skins, are adequate sources. Beets and mushrooms may contain chromium.
Functions: Chromium is an essential mineral-that is, it is not made by the body and must be obtained from the diet. As the central part of GTF, it enhances the effect of insulin in the body. GTF is necessary for proper insulin function in the utilization of glucose and is needed in both human and animal nutrition for carbohydrate metabolism. Specifically, chromium/GTF improves the uptake of glucose into the cells so it can be metabolized to produce energy (ATP). GTF is thought to bind both to insulin and to the cell receptors to utilize and thus help lower the blood sugar. This function of the glucose tolerance factor prevents continued elevations of blood sugar, which can lead to diabetes. If glucose does not enter the cells, the excess circulating sugar can cause damage to the cells, the retina of the eye, and the arteries, for example. Therefore, proper control of blood sugar may help to prevent atherosclerosis and its subsequent problems.
Chromium recently has been shown to lower blood cholesterol while mildly raising HDL (high-density lipoprotein), the good portion of cholesterol. This lowers the risk ratio for coronary artery disease. (Exercise is a key factor in raising HDL cholesterol and reducing coronary artery disease risk. Exercise also promotes the efficiency of insulin-mediated uptake of glucose into cells.)
Uses: Chromium and GTF are used in the treatment of both hypoglycemia and diabetes mellitus, two problems of blood sugar utilization and metabolism. Preventing chromium deficiency is the key here. The earlier treatment is begun, especially with potential diabetes, the more helpful it may be. Preformed GTF is not readily available, though formulas that contain all of its components seem to work better than chromium alone, and small amounts given daily have been shown to both increase glucose tolerance and decrease blood fats, both cholesterol and triglycerides, as well as to raise HDL. Chromium also does this and has been used along with niacin (also a part of GTF) in the treatment of high blood cholesterol.