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The trace mineral grf chromium has become a superstar nutrient in the media, spurring many persons to buy supplements while confusing others. Advertisements and articles have proffered promotions such as:
"Lose the Fat; Keep the Muscle." "Chromium Pill Will Add 25 Years to Your Life." "Miracle substance: chromium picolinate...reduces cholesterol levels, wards off obesity, lowers the incidence of diabetes and improves overall health."
It is claimed that 90% of Americans are not getting sufficient dietary chromium. No wonder 10 million Americans now consume, each year, $150 million worth of chromium supplements! But critics say there is no credible evidence for the claims, and that chromium needs are inconsequential, and/or supplements may be harmful. Actually, data point to a middle ground between hyperbole and criticism.
In 1959, trivalent chromium was identified as an active component in the glucose tolerance factor (GTF), which alleviated impaired glucose tolerance and enhanced the synthesis of cholesterol and fatty acids in rats. Studies during the 1960s indicated chromium could benefit glucose tolerance in 40% to 50% of mildly diabetic humans or those with impaired glucose tolerance. Since 1966 researchers have described various degrees of glucose intolerance ranging from hypoglycemia (low blood sugar) to insulin-dependent diabetes. Chromium decreased serum cholesterol concentrations and normalized extreme insulin responses to glucose loads in somepeople. Benefits to blood lipid (cholesterol, phospholipids, etc.) levels have often been reported. GTF along with insulin make it easier for carbohydrates, fatty acids, and amino acids to pass from the blood into the cells of various tissues (e.g., muscle, adipose). "It also promotes the metabolism of nutrients within the cells." When GTF is lacking, more insulin is needed to perform these jobs.
GTF and insulin also promote (1) use of amino acids for protein synthesis, (2) improvement in phagocytic (engulfing and digesting of dead, damaged or foreign particles) ability of white blood cells, and (3) utilization of glucose by the lens of the eye. "Chromium is the spark plug which fires upcertain enzymes into vigorous metabolic activity." Most of these enzymes are involved in energy production, though it acts on the digestive enzyme trypsin also. (Other trace minerals may also be involved in activating these enzymes.) With other nutrients, chromium appears to stabilize nucleic acids (primarily RNA) against structural distortions. It is a natural stimulator for synthesis of fatty acids and cholesterol in the liver.
Each time GTF performs its work, there is a corresponding rise in chromium excreted in the urine. GTF is released into the blood (probably from tissues which store chromium such as liver, kidneys, spleen) whenever there is an increase in blood glucose or insulin levels.
In its biologically active form - when found in natural foods - chromium is part of the hormone-like glucose tolerance factor, and functions primarily as an insulin cofactor. GTF potentiates or aids insulin's ability to transport glucose (blood sugar) and amino acids inside cells for energy and tissue (protein) production. Deficiency may lead to insulin resistance - inability of the body to utilize insulin properly.
If insulin cannot work efficiently, the body tries to compensate by making more insulin. Obesity (increased fat storage); increased levels of total cholesterol or LDL (so-called ‘bad') cholesterol, decreased HDL (so called ‘good') cholesterol; neuropathy (nerve disease); hypertension, Type II diabetes (non-insulin dependent); and other disorders may involve insulin resistance and/or elevated insulin levels. Type II diabetics, for example, produce plenty of insulin (often too much), but do not utilize it properly. Some people developing adult onset diabetes may have experienced a gradual depletion of chromium stores leading to excess insulin.
GTF is apparently an integral part of cell membranes. The liver stores GTF; this is where glucose is removed from blood; glycogen is synthesized and stored; glycogen is then converted into fatty acids, carbon dioxide and water; and glucose is formed into amino acids.
Chromium always appears in foods as part of a complex, usually with nicotinic acid (niacinamide or vitamin B3) and amino acids - possibly glycine, cysteine, and glutamic acid. Vitamin C complex promotes absorption of chromium. There is more to be learned about chromium's collaboration with other nutrients. The GTF complex may be a category of closely related complexes, and has "a much superior biologic activity" than inorganic fractions.
GTF - trivalent chromium (Cr3+++) surrounded by two molecules of B3 (niacinamide) and three amino acids (possibly glutathione, a tripeptide of glutamic acid, cysteine, and glycine) -- was first identified in brewer's yeast, one of the richest sources of organic chromium. Though many attempts have been made to isolate or synthesize GTF, "none has been successful." Scientists have synthesized "biologically active chromium complexes" to be manufactured as supplements, but these compounds only "appear similar to but not identical with the naturally occurring GTF complex. The exact structure(s) remain unknown." And, whether it is only the biologically active form of chromium that interacts with insulin or insulin receptors also remains uncertain. Therefore, most supplements must be inferior imitations of the synergistic complexes occurring in whole foods. GTF is a property of food, a complex "that despite much investigation still remains to be characterized and purified..."
Simply, in the body's energy department, insulin and GTF "stoke the stoves, vent the waste gases, and add future fuel to the woodpile." With insufficient GTF, there is plenty of fuel, but a "log jam" occurs so the fuel cannot get to where it belongs. Insulin puts in "overtime" trying to get the job done, but it is never enough. Should the beta cells of the pancreas become exhausted, cellular breakdown and diabetes can occur.
Chromium in foods varies in form from the "less biologically functional" chromium salt to the preformed biologically active GTF. Yet in foods the GTF form does not appear to be required for ‘normal' individuals (with properly functioning glucose metabolisms), since the body can convert inactive chromium food compounds into forms that function physiologically.
Foods rich in GTF include nutritional or brewer's yeast, liver, kidney, whole grains, eggs, whole sugar cane juice, buckwheat; natural cheeses; other fermented (nonpasteurized) foods such as apple cider, yeast-leavened or sourdough whole grain breads, sauerkraut, etc.; mushrooms, beets, prunes, nuts, peanuts, potatoes with skin, apples with skin, thyme, ‘hard' water, and other whole, natural foods. In fact, "most fresh foods" in their natural state - with no tampering -- "are good sources of dietary chromium" complexes.
Refined and processed foods have as much as 80% of their naturally-occurring chromium removed. Refined carbohydrates, including refined sugars -- a large part of the typical American diet -- not only lack chromium, but promote the loss of chromium (and other nutrients) from the body. Diets high in refined sugars will increase chromium losses up to 300%! Excessive alcohol (a refined carbohydrate) depletes chromium stores and, with a deficit, intolerance to alcohol may develop.
U.S. Department of Agriculture (USDA) researcher Richard Anderson contends that food refining and modern agricultural processes (synthetic fertilizers, pesticides, soil depletion, etc.) have led to widespread chromium deficits in the food supply. The nutrient content of the soil, influenced by farming methods, has an obvious influence on trace mineral levels. Barley grown in some Middle Eastern countries, for example, was found to have a chromium content much higher than whole wheat and 10 times higher than brewer's yeast (considered the richest source).
It is not yet known how much chromium the body requires, and, as with other nutrients, biochemical individuality determines needs. The National Academy of Sciences proposed an intake of 50 to 200 micrograms (mcg) daily. A USDA study found that nine out of 10 Americans tested had diets containing less than the proposed minimum: about 33 mcg per day for men and 25 mcg for women. This is how the "90% of Americans aren't getting enough chromium" claim originated.
Yet studies show adults consuming less than 50 mcg of chromium a day may still maintain chromium equilibrium. The body has "the ability to homeostatically control chromium states by adjusting absorption and excretion." The exact needs of individuals differ and undoubtedly much depends on the quality of the diet.
Data indicate that a chromium intake of less than 20 mcg per day is definitely inadequate. A significant number of Americans consume less than this and could benefit from increased intake. Two studies found that 40% of middle-aged Americans (with no history of diabetes) develop moderate glucose intolerance, and 77% of Americans over 70 years of age show impaired glucose tolerance. Inadequate chromium intake and excessive chromium losses over the years - primarily due to consumption of refined and processed foods - takes its toll.
In the U.S., low chromium levels have been found in tissues from deceased persons of various ages and nationalities, and of both sexes. Concentrations gradually dropped with age. However, people from less well developed areas in Europe, Africa, and Asia who consume a much less refined and processed diet (and where fewer artificial fertilizers and pesticides are used), had, on average, several times more chromium in their aortas, hearts, kidneys, livers, and spleens as the average American. Thus, aging itself may not deplete chromium levels, but aging plus a diet lacking sufficient chromium and other natural nutrient complexes can and does so.
The body's chromium supply can also be drained by strenuous exercise, injury, inflammatory processes, extreme heat or cold, illness, other forms of stress, and pregnancy. Severely traumatized individuals had urinary losses of chromium more than 50 times above normal levels for the initial 25 hours following trauma and were still elevated 72 hours after injury.
During pregnancy women may excrete more chromium than normal. Many women in developed countries are so deficient in chromium that their white blood cell chromium level decreases about 50% with each pregnancy. Chromium is crucial for the proper development and metabolism of a growing fetus. Since the developing baby has priority, the mother's nutritive levels can be severely depleted. In recent years glucose tolerance impairment during pregnancy has become increasingly prevalent and "gestational diabetes" is being diagnosed more frequently.
PICOLINATE AND POLYNICOTINATE
In the early 1980s it was found that zinc chelated (combined) with picolinate, compared with zinc sulfate, was assimilated more readily. Later it was found that other metal picolinates were better absorbed than mineral salt forms. Picolinic acid is an isomer (offshoot) of nicotinic acid, which is synthetic niacin. Dr. Gary Evans, then working for the USDA, decided to patent the process of synthesizing picolinic acid complexes. After leaving the USDA, Dr. Evans was heavily involved with Nutrition 21 (a manufacturer of chromium picolinate) resulting in reports that sparked the publicity and popularity of the supplement.
After research during the 1960s and 1970s, Dr. Walter Mertz of the USDA identified some of the GTF complex from brewer's yeast, set up criteria for "a true GTF-likecomplex" (an imitation) and declared niacin bound chromium as the active chromium compound in brewer's yeast. (Niacinamide is the biologically active vitamin B3 in natural foods and the body, whereas niacin is synthetic.) According to Dr. Mertz, niacin-bound chromium strongly potentiates insulin, whereas other forms including chromium picolinate and chromium chloride do not. So a niacin-bound chromium nicotinate complex (polynicotinate) was developed, patented as ChromeMate, and promoted as more bioavailable than other forms. Brewer's yeast and other foods contain different forms of chromium and many cooperative nutrients including other trace minerals, minerals, amino acids, enzymes, vitamin B complex, other vitamin complexes, etc. Again, "the exact structure of GTF has never been elucidated."
Simple chromium salts (chromium chloride) do not meet the imposed criteria: (1) They do not have access to the fetus in utero. (2) They do not balance with physiologically important body pools (sources of blood chromium that respond to increases in circulating insulin). (3) They do not potentiate insulin activity. (4) They are poorly absorbed. The inorganic chromium chloride accumulates in the kidneys - a toxic effect probably due to the body's efforts to excrete it.
Synthesized GTF complexes are said to be: (1) "three to four times less toxic than trivalent chromium chloride" [though not devoid of toxic effects], (2) different in tissue distribution than chromium salts, concentrating in areas such as the liver [which could be for blood sugar metabolism or for detoxification - removal of toxic substances], and (3) transported across the placenta and taken up by fetal tissue [which could be beneficial to fetal development orstressful to the fetus]. Obviously, questions and problems remain.
Chromium picolinate and polynicotinate compounds are better absorbed than most chromium found in foods. Yet, is it wise to outmaneuver or trick nature? High intakes of synthesized forms "may circumvent" some of the homeostatic control of chromium absorption and, though quickly clearing the blood (a possible xenobiotic or foreign substance response), may allow excess amounts to accumulate in tissues and/or imbalance other nutrients.
When in vitro (laboratory dish) studies showed that chromium picolinate caused 3 to 18 times more chromosomal damage (supposedly a cancer-causing potential) to hamster ovary cells than other chromium compounds (chloride, polynicotinate), questions and concerns were raised. Findings from cells in dishes cannot usually be applied to people. The amounts of chromium picolinate used were extremely high, 10 times the recommended dosage. But considering the amounts of chromium picolinate taken by some people, for example, 600 mcg per day consumed for five years could lead to an accumulation in tissues in a concentration close to that used in the studies. The chromosomal damage appeared to be induced by picolinic acid, not the chromium.
It is alleged that milk is a food source of picolinate because it contains the amino acid tryptophan, a precursor of vitamin B3. Further, it is claimed that a nursing infant, consuming half a liter of breast milk daily would, for his/her size, be getting 40 times the amount of picolinate than a 150-pound adult taking 600 mcg of chromium picolinate. However, the "picolinate" in milk is a far cry from that in supplements. Foods contain natural complexes with many associated co-workers. Foods allow selective absorption (choice of nutrients and amounts needed), and are not synthetically manufactured chemicals.
Short-term tests have indicated that chromium picolinate is "relatively nontoxic," but long-term tests need to be done. Human studies have indicated the potential of nonfood chromium to be retained and accumulate in the body. Synthesized compounds have been shown to have adverse effects on animals. In November 1996, the Federal Trade Commission forced three leading marketers of chromium picolinate to stop claiming their supplement builds muscle, burns fat, promotes weight loss, regulates blood sugar, treats or prevents diabetes, or lowers cholesterol. Scientific studies have "not substantiated" these claims, although some studies have shown that GTF may have a beneficial effect in some of these areas.
Results of a study in 1989 suggested that chromium (especially chromium picolinate) helped build muscles in young men participating in a weight-training program. After six weeks, the 16 students taking chromium added six pounds of muscle and lost seven pounds of fat.
Chromium potentiates insulin; insulin has an anabolic effect on skeletal muscle and other tissues by promoting amino acid uptake and protein synthesis while retarding protein degradation. But "changes like that [in the study] in such a short period of time are preposterous, as anyone familiar with training knows...You can't even get results like that using anabolic steroids." The researchers in the study used hand-held skin-fold calipers to measure fat - an inexact subjective method. Subsequent studies, using more precise and sensitive tools (dual x-ray absorptiometry and underwater weighing anthropometry) did not show increased muscle mass or decreased fat mass. Even when skin-fold thickness measurements were also used, no effects on muscle or fat were found, though some females had small weight increases. So data regarding chromium changing strength, lean body mass and athletic performance are mostly negative.
Some of the studies, though, hint that a few individuals had beneficial effects, perhaps because they had a low chromium status before entering the studies. Athletes are at higher risk for chromium deficiency. They consume large amounts of carbohydrates (often refined) and exercise excessively aerobically, both which raise chromium requirements.
As shown, the zealous claims of fat loss or muscle gain from chromium supplementation are greatly overstated. Chromium's insulin potentiating function led to the conjecture it could assist weight control by: (1) enhancing the insulin-mediated production of serotonin, a brain chemical involved in decreasing appetite; (2) increasing carbohydrate metabolism, converting it into energy rather than fat; and (3) stimulating protein (muscle) formation and suppressing protein breakdown.
A report on one study indicated chromium picolinate (minimum 200 mcg a day) could lead to significant fat loss without altering food intake or exercise levels. There was, though, an amazing lack of substantial data for the claim of effortless weight loss. Only a few studies reported very small reductions in weight. In one study, there was only a loss of 2.8 pounds over 10 weeks. In another, the weight loss program was not limited to chromium supplementation. Moderate caloric restriction, fiber, L-carnitine, and chromium picolinate were all included. The "respectable" average weight loss of 15.1 pounds in eight weeks could not be attributed exclusively to the chromium picolinate. In most other reports, participants receiving chromium supplements in weight-training programs gainedweight. "Thus, a high intake of chromium is unlikely to lead to a significant weight loss." Besides, the studies were designed to measure a pharmacologic effect on appetite and body composition not a nutritional effect.
It is reasonable to surmise that chromium in its natural, complex food form may nutritionally reduce the craving for sweets and other refined carbohydrates, assist appetite control if there is a deficiency, and aid the transport of glucose into muscle cells which could improve energy levels and the ability for physical activity to "burn" fat and build muscle. Unexplained weight lossmay be a sign of uncontrolled diabetes, or, in some cases, a deficiency of chromium. Chromium supplements have been found to increase weight gain in babies suffering with protein malnutrition.
The possibility of aiding the prevention of osteoporosis with chromium was raised after it was found that postmenopausal women taking chromium picolinate had increased plasma dehydroepiandrosterone (DHEA), a steroid secreted by the adrenal cortex (and testes in men) and a precursor of estrogens (and testosterone). Estrogen inhibits bone loss. There was also decreased urinary excretion (loss) of calcium and hydroxyproline (a form of an amino acid in connective tissue proteins, particularly collagen), which are indirect indicators of bone loss. Insulin resistance impairs calcium deposition in bone. This leads to excess insulin levels, and impairs DHEA synthesis. Supplementation with chromium chloride for eight weeks decreased serum osteocalcin (another index of bone loss) in adults over 50 years of age. These encouraging findings need more study and confirmation.
Many other factors affect susceptibility to osteoporosis including smoking, alcohol, exercise, bioavailable protein, nutrients such as calcium, magnesium, manganese, boron, silica, vitamins D complex, C complex, and others. It would not be amiss to speculate that chromium could play a role in the health and maintenance of musculoskeletal tissues.
The claim that chromium picolinate can increase the average life span from 75 to 100 years is based mostly on "some limited animal data." After 41 months, rats fed chromium nicotinate or chromium chloride had died, whereas 80% of rats fed chromium picolinate were still alive. The extended lifetime (a 36% increase in the median life span) was associated with decreased glycated hemoglobin (an indicator of blood glucose concentrations over a period of time).
An older study (1968) reported that chromium chloride (and chromium acetate) decreased mortality in mice at 17 months, but not at 21 months. The findings of both these studies were assumed to apply to humans.
There is some doubt that chromium was the primary factor in the chromium picolinate study (1994) since the other forms of chromium provided adequate amounts easily absorbed by scavenger rats. And, the chromium acetate used in the 1968 study would be metabolized in a similar manner to chromium chloride or chromium nicotinate. Thus, the two studies are actually contradictory! Something other than chromium picolinate may have had an effect on the life span of the rats. If the picolinate was a factor, the effects "were pharmacologic and not nutritional." Did the picolinate affect other nutrients or stimulate circulation in glands or organs? Picolinic acid and/or chromium picolinate have been found to affect copper and iron metabolism,
both of which can affect glucose and glycated hemoglobin metabolism. Since the method was pharmacologic, there would be side effects including possible biochemical imbalances. Essentially, there is no scientific support for the life-extending contention for humans.
In 1993 in China, 180 people with Type II diabetes (non-insulin dependent) were split into: (1) a placebo group, (2) a group with a "normal" diet supplemented with 200 mcg of chromium picolinate, and (3) a group given 1000 mcg of the chromium. After four months, blood glucose decreased closer to normal in those taking 1000 mcg; insulin and glycated hemoglobin also dropped. Findings from a study in Israel showed that insulin requirements were reduced in 118 of 162 diabetic patients by supplementing 200 mcg of chromium as picolinate.
Numerous other studies have indicated some diabetics benefit from chromium supplementation, findings not surprising considering its insulin-potentiating action, and the fact that insulin-dependent diabetics excrete almost three times the amount of chromium than normal, non-diabetic people.
Nevertheless, none of the studies lasted more than a few months, so long-term effects of the supplements are not known. The modest declines in blood sugar levels were not enough to bring glucose levels down to normal. There are more pieces to the puzzle and no doubt the multiplicity of synergistic nutrients in whole foods and the improved function of involved glands and organs would fill in much of the picture.
CARDIOVASCULAR DISEASE/ FATS
Since the late 1960s, evidence has accumulated showing a link between chromium deficiency and the onset and progression of cardiovascular disease (atherosclerosis). Impaired tissue responsiveness to insulin is being researched as a risk factor.
In cholesterol-fed rabbits (animals that do not normally ingest cholesterol), atherosclerosis of the aorta was reversed when chromium was injected daily (as a "drug," not as a nutrient).
Of eight controlled studies, four concluded chromium had no effect on blood fat levels, while the other four reported chromium lowered blood cholesterol. Some animal studies have shown that chromium deficits increase plasma cholesterol and serum uric acid. Some human studies have shown decreased total blood cholesterol and/or low-density lipoprotein (so-called "bad" cholesterol) and/or triglycerides after supplementation. Still other studies have come up empty. So far, then, results using the supplements are "inconclusive."
However, researchers have found that chromium cannot be detected in the aortas of individuals who die from atherosclerosis, yet it is almost always present in the aortas of accident (non-atherosclerotic) victims.
A group of people with high levels of cholesterol and triglycerides had lower levels after their diets were supplemented with either inorganic chromium (which they were able to convert to the organic form) or with brewer's yeast (which contains natural GTF). The declines for the short duration of the study were only about 14%, but a faster and more significant drop would be a pharmacological, notnutritional, result. More time is needed for nutritional benefits, particularly from whole food complexes.
Subjects given chromium polynicotinate had a lower fasting glucose - though not uniform and with wider variations -- than the control group. Those supplemented generally had lower triglycerides and glycohemoglobins, but little difference in cholesterols. "Patient predisposition is important in order to determine individual responsiveness." And it may be asked if all the subjects' cholesterol levels actually needed lowering.
Researchers found that a combination of chromium and niacin can reduce the levels of niacin required to lower cholesterol. Again, this is a pharmacologic action not a nutritional action.
Thus, the link between chromium and cardiovascular disease is not yet clear cut by any scientific method or standards. Empirical/clinical evidence, particularly when whole food complexes are utilized, seems favorable for chromium's usefulness.
EYES AND NERVES
In laboratory animals, a chromium-deficient diet produces eye pathologies such as dilatation of the iris vascular system and corneal opacities. There is accumulating evidence that chromium may assist the eye in focusing (e.g. myopia). Myopia in children and teenagers has been linked to excessive consumption of refined sugars which depletes many nutrients such as chromium. The role of this trace mineral in myopia may be due to its role in facilitating the use of glucose by ciliary muscles. Chromium deficiency becomes a problem in daily-repeated, sustained stimulus to accommodation, leading to fatigue and an elevation of intraocular pressure "as if in an attempt to elongate the eyeball and thereby reduce the need for accommodation."
The brain, of course, has high requirements for blood glucose as a fuel, so GTF is an important nutrient. Neurological disorders commonly develop in diabetics, and some doctors believe chromium deficiency could be involved.
Schizophrenics often have impaired glucose tolerance and have a need for niacinamide. Thus it is possible they would benefit from GTF supplementation. The usefulness for GTF in various mood disorders would no doubt be a productive area of study.
Growing evidence indicates that chromium is an essential trace mineral when in its natural, complex food form. The body contains about 6 milligrams of chromium; blood concentration is about 20 parts per billion. Minute amounts are required, yet with its natural whole food synergists, it has considerable importance.
GTF is being recognized as significant in blood sugar metabolism, improving insulin effectiveness, enzyme activity (especially in production of energy, synthesis of fatty acids and cholesterol), protein transport and synthesis, and more.
Since refined and processed foods are virtually stripped of chromium, it is important to advocate a diet of whole, natural foods and, when indicated, include a food concentrate GTF supplement in the comprehensive adjunctive schedule.
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Originally published as an issue of Nutrition News and Views,reproduced with permission by the author, Judith A. DeCava, CNC, LNC.