CHROMIUM in HEALTH and DISEASE
Chromium is a mineral that humans require in trace amounts. It is found in all living things: man, animal and plant. The amount of chromium that humans and animals need is very minute - measured in micrograms. Hence the mineral is termed a trace element.
The mechanism of action of chromium in the human body is not well defined.
Chromium is a metal, symbol Cr, number 24 in the Periodic Table.
It is found primarily in two forms:
· Trivalent - chromium 3+. This is the biologically active form and is found in food.
· Hexavalent - chromium 6+. This is a toxic form that is used industry and is found in industrial pollution. It is also said to be mutagenic.
This newsletter focuses exclusively on trivalent (3+) chromium in humans.
Actions of Chromium
More than four decades ago, chromium was shown to enhance the action of insulin. Insulin, a hormone produced by the pancreas and secreted directly into the blood stream, is critical to the metabolism and storage of carbohydrate, fat and protein in the body.
Chromium has been identified as the active ingredient of glucose tolerance factor (GTF). GTF has been hypothesised to be a metalloprotein complex that is formed when the oligopeptide chromodulin (which consists of the four amino acids residues aspartate, cysteine, glutamate and glycine) is bonded with four chromium (3+) centres. However, the existence of GTF is questioned by some academics.
Chromium also appears to be directly involved in carbohydrate, fat and protein metabolism.
More research is needed to determine the full range of its roles in the body.
Food sources of Chromium
Trivalent chromium is found in a wide range of foods. However most foods provide only small amounts (less than 2 micrograms [mcg]) per serving.
Relatively good sources include whole-grain products, meats, nuts, green beans, broccoli, grapes, potatoes, oranges, apples and bananas. Also some wines, especially red, and some herbs, for example basil, are good sources.
Other fruits and vegetables and dairy products only contain low amounts.
Unfortunately, some of the chromium in the diet may come from processing and storage of food in cans made of stainless steel, which can contain up to 18% chromium (the toxic form).
Recommended Intake of Chromium
The recommended dietary allowance (RDA) is the average daily intake of a substance (food, vitamin, mineral etc) that meets the nutrient requirement of healthy individuals.
In 1989, the National Academy of Sciences established an “estimated safe and adequate daily dietary intake” for chromium. For adults and adolescents that range was 50-200mcg. These figures were lowered in 2001 to 30-35mcg (adult male) and 20-25mcg (adult female). These amounts were set to be the same as the average amounts consumed by healthy individuals.
Metabolism of Chromium
Approximately 2% of ingested chromium is absorbed, with the remainder being excreted in the faeces.
The following enhance the uptake of chromium from the intestinal tract: Vitamins C, E, B1, B2, B3, B6, amino acids and the minerals magnesium, potassium and zinc.
Absorbed chromium is stored in the liver, spleen, soft tissue and bone.
A diet high in simple sugars increases the excretion of chromium through the urine.
Infection, acute exercise, pregnancy, lactation and stressful states can increase chromium losses and can lead to deficiency, especially if chromium intakes are already low.
Reports of actual chromium deficiency in humans, in Western countries, are rare.
Chromium deficiency can occur in long-term intravenous nutrition, and the symptoms include severely impaired glucose tolerance, weight loss and confusion.
Older people are more vulnerable to chromium depletion.
When is a Supplement of Chromium Indicated?
Chromium has long been of interest for its possible connection to various health conditions. Among the most active areas of chromium research are its use as a supplement in the following:
· Intravenous Feeding/Nutrition
· Type 2 Diabetes
Chromium deficiency impairs the body’s ability to use glucose to meet its energy needs and raises insulin requirements. It has therefore been suggested that chromium supplements might help in the control of type 2 diabetes and in the glucose and insulin responses of those at high risk of developing the disease. Unfortunately, the results overall, of many studies looking at the value of chromium supplements in diabetes, are inconclusive and controversial. There is some evidence that adequate chromium levels in the body may retard long-term diabetic complications.
Chromium supplements can be beneficial in the control of reactive hypoglycaemia, when combined with the appropriate diet.
· Lipid Metabolism
In some studies, supplemental chromium 150-1000mcg/day, has decreased total cholesterol, low density lipoprotein (LDL or ‘bad’) cholesterol and triglyceride levels, in subjects with elevated cholesterol or atherosclerosis. However no favourable effects have been shown in other studies. This may be due to the researchers’ failure to control dietary factors that influence blood lipid levels.
· Body Weight
Some studies have shown that supplements of chromium help with weight loss when compared to placebo, but the differences were small. Further studies are needed, with other dietary factors more strictly controlled. It appears that the supplement reduces carbohydrate cravings and regulates appetite.
Supplementation of Chromium
Chromium picolinate is the most commonly used synthetic supplement. Other forms include chromium chloride, chromium nicotinate and chromium citrate. Chromium picolinate and other chromium salts as supplements are different to the trivalent chromium found in food.
As already mentioned, chromium deficiency is rare in countries like Australia, so a supplement to correct deficiencies is generally not necessary.
Care should be exercised when taking supplements of chromium since chromium is toxic at high levels.
Supplement dosage: 50-200mcg daily.
A supplement of chromium could be considered in type 2 diabetes, prediabetes, and those at risk of developing diabetes.
It is beneficial in the management of hypoglycaemia (chapter 16 of my book How To Stop Feeling So Awful, see home page).
Hospital patients who are fed liquid diets intravenously for long periods of time should receive a chromium supplement.
Eating a wide variety of whole grains, fruits and vegetables and some meats should provide sufficient chromium. It should be remembered that dietary supplements, while recommended for specific purposes, cannot replace a healthful diet.
*Copyright 2010: The Huntly Centre.
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