Chromium is a trace mineral increasingly thought to be vital in the production of diabetes, but
so far the work has mostly been done on Type 2 diabetes. Early research in rats found that
abnormal glucose metabolism could be corrected by adding chromium (as brewer’s yeast) to the
diet.
The biological significance of this trace element has only recently been recognized, but now that it has been there are signs that many people are short of it. Chromium is physiologically active in the body in only one inorganic form (the trivalent form). This inorganic (non-living) type of chromium is very inactive in the body compared with another chromium-containing compound-the organic complex called the glucose tolerance factor (GTF). It is not known exactly what this is but it appears that animals have only a limited ability to produce it themselves and so need external sources. GFT is the only known form in which chromium can cross the placenta. When trivalent chromium is given orally less than 1 per cent is absorbed.
Chromium’s main function is to help insulin control the body’s sugar levels. Experiments with
animals have found that glucose (sugar) metabolism is quickly impaired if the animals are fed
diets poor in chromium and that giving the element soon returns the situation to normal.
Because animal work has found that chromium-deficient animals develop diabetes-like
symptoms, it was natural to ask whether a similar mechanism could be at fault in human
diabetics. Several reports have suggested that giving chromium has had beneficial effects on
diabetics and in one study four out of six maturity -onset diabetics improved with a dose of 250 micrograms of chromium a day. Other studies have found that diabetics put out more chromium in their urine than do non-diabetics. Studies of poorly-nourished children in Jordan, Turkey and Nigeria found that they grew faster when given extra chromium. In spite of this circumstantial evidence there are no definite indications that diabetes is caused by a deficiency of chromium, and it is certain that many diabetics will not be improved simply by taking chromium.
Unfortunately, the refining of foods removes a very substantial part of their chromium. Blackstrap molasses, honey and raw sugar are rich in chromium but white sugar has almost none. This is especially unfortunate since chromium is needed if the body is to handle sugar effectively, as we have seen. White bread contains only one third of the chromium of the original whole wheat and this, of course, goes for anything made from white flour.
The food richest in chromium is brewer’s yeast but whole-grain bread, nuts, shellfish, liver, kidneys, grape juice, beef and beer are also rich sources.
As with many other trace elements, absorption is very poor, especially from tablets. Overall, only about 3 per cent of the chromium in our food is absorbed, so with our relatively chromium-deficient diet there is not much of a safety margin.
The recommended daily intake of chromium varies from 5 to 100 micrograms a day. Given that the body needs to absorb about 10 micrograms a day and that only 3 per cent is absorbed, perhaps the amount we consume should be even higher than 100 micrograms.
*3/72/5*
