Cr – Chromium is found in igneous rocks at 100 ppm; shales at 90 ppm; sandstones 35 ppm and limestone at 11 ppm; fresh water at 0.00018 ppm; sea water 0.00005 ppm; soils at 5 to 3,000 ppm (highest in soils derived from basalt and serpentine); marine plants 1 ppm; land plants 0.23 ppm; marine animals 0.2- 1.0 ppm; land animals 0.075 ppm; accumulated by RNA and insulin.
Chromium activates phosphoglucosonetase and other enzymes and is tightly associated with GTF (glucose tolerance factor – a combination of Chromium III, dinicotinic acid and glutithione). The reported plasma levels of chromium in humans over the past 20 years has ranged from 0.075 to 13 ng/ml. Concentrations of chromium in human hair is ten times greater than in blood making hair analysis a much more accurate view of chromium stores and function in the human (there is 1.5mg in the human body).
Very little inorganic chromium is stored in the body, once inorganic chromium is absorbed, it is almost entirely excreted in the urine (therefore urine chromium levels can be used to estimate dietary chromium status). Dietary sugar loads (i.e.- colas, apple juice, grape juice, honey, candy, sugar, fructose, etc.) increase the natural rate of urinary Chromium loss by 300 % for 12 hours.
Diseases and Symptoms of Chromium Deficiency.
- Low blood sugar
- Diabetes (ulcers/gangrene) (Fig.
- Learning disabilities
- Manic depression
- “Bi-polar” disease
- Dr. Jykell/Mr. Hyde rages (“Bad Seeds”)
- Impaired growth
- Peripheral neuropathy
- Negative nitrogen balance (protein loss)
- Elevated blood triglycerides
- Elevated blood cholesterol
- Coronary blood vessel disease
- Aortic cholesterol plaque
- Infertility and decreased sperm count
- Shortened life span
The average intake of 50 to 100 ug of inorganic chromium from food and water supplies only 0.25 to 0.5 ug of usable chromium, by contrast 25 % of chelated chromium is absorbed. The chromium RDA for humans is a range of 50 to 200 ug per day for adults.
The concentration of chromium is higher in newborn animals and humans than it is in later life. In fact, the chromium levels of unsupplemented human tissue steadily decreases throughout life — of even more concern has been the steady decline in the average American serum chromium since 1948: from 28-1000 mcg/l in 1948 to 0.73-1.6 mcg/l in 1973 to 0.13 mcg/l in 1985.
The fasting chromium plasma level of pregnant women is lower than that of nonpregnant women. Increasing impairment of glucose tolerance in “normal” pregnancy is well documented and reflects a chromium deficiency oftentimes resulting in pregnancy onset diabetes. One study demonstrated abnormal glucose tolerance in 77 percent of clinically “normal” adults over the age of 70. According to Richard Anderson, USDA, “90 percent of Americans are deficient in chromium.”
Gary Evans, Bemidji State University, Minnesota, very clearly showed an increased life span in laboratory animals by 33.3 per cent when they were supplemented with chromium. Prior to this study gerontologists felt a severe restriction of calories was the only way to extend life past the expected average.
Deficiencies of chromium in humans are characterized by a wide variety of clinical diseases as well as a shortened life expectancy. The clinical diseases of chromium deficiency are aggravated by vanadium deficiency.
Chromium is a trace mineral nutrient, needed only in minute amounts to help increase the body’s sensitivity to the hormone insulin for efficient utilization of surplus GLUCOSE. Chromium represents one of the most recently identified nutrients, and its role in metabolism was discovered in 1969. Chromium is converted in yeast and in tissues to GLUCOSE TOLERANCE FACTOR, in which chromium is complexed with nutrients like amino acids and niacin. In this form chromium can assist insulin. As a supplement, chromium may be effective in alleviating elevated blood sugar (hyperglycemia) in some elderly patients, and in some diabetics, as well as in healthy, non-diabetic people. It may protect against a form of non-insulin-dependent diabetes. However, clinical studies of this aspect have yielded mixed results. Chromium may protect against cardiovascular disease by helping to regulate fat and cholesterol synthesis in the liver and by raising HDL (“desirable” cholesterol) and by lowering LDL (‘”undesirable”) in the blood. Chromium also seems to help reduce high blood pressure (hypertension) in some cases.
Only the less oxidized form of chromium (Cr3+) is biologically active and can be used by cells. The more oxidized form (Cr+6) is a toxic industrial waste product, which is not formed in the body. The human body contains only very low levels of chromium (an estimated 6 mg or less). Chromium in food is poorly assimilated and only 1% to 5% of dietary chromium is absorbed. It is estimated that 90% of Americans consume less than 40 mcg of chromium daily, and many people may be chromium deficient, especially elderly persons, pregnant or lactating women, athletes, and healthy people who rely on processed food. Chromium loss increases with injury, stress, aging and strenuous exercise. Consuming excessive sugar increases chromium losses from the body and lost chromium is slow to be replaced. Consequently chromium levels decline with age.
Chromium deficient animals exhibit weight loss, lowered male fertility, elevated blood sugar, atherosclerosis and nerve degeneration. Deficiency symptoms in humans include intolerance of alcohol and a decreased ability to use insulin to help metabolize blood sugar, a pre-diabetic condition. Chromium supplementation, either as chromium chloride or as chromium picolinate, did not increase strength or improve body composition (in terms of increased muscle mass or decreased body fat) in male volunteers participating in an eight-week weight-training program. Possibly the beneficial effects of chromium can occur when people are deficient in chromium. Chromium supplementation can lower iron transport and distribution in the body, possibly placing the individual at risk for iron deficiency.
Optimum chromium intake
The chromium intake for optimum health isn’t known. A safe and adequate dose is thought to be 50mcg to 200 mcg daily. Brewers yeast is the best food source. Other sources are liver, oysters, whole potatoes, egg yolks, prunes, mushrooms, wine, beer, meat and beets. Fruits are low in chromium; so are polished rice and bleached flour. Chromium levels in grains and vegetables depend upon the amount of chromium in the soil in which they were grown; however, chromium in vegetables isn’t well absorbed. Surprisingly, Calcium-fortified breakfast cereals are often good sources of the mineral because added calcium contains chromium as a contaminant. Supplemental chromium is available as chromium chloride. When taken together with niacin, its effect on lowering blood lipids is significantly improved, and the combination is as effective as taking yeast glucose tolerance factor. Several organically complexed forms of chromium such as chromium picolinate may be more readily absorbed than chromium chloride as supplements. Mertz, Walter, “‘Chromium: History and Nutritional, Importance,”
Biological Trace Element Research, 32 (Jan.-March 1992), pp. 3-8.
Chromium – Biochemical function
Chromium is an essential nutrient that potentiates Insulin action and thus influences carbohydrate, lipid and protein metabolism. However, the nature of the relationship between chromium and insulin function has not been defined.
Mertz et al. suggested that the biologically active form of chromium (glucose tolerance factor) is a complex of chromium, nicotinic acid and possibly the amino acids glycine, cysteine and glutamic acid. Many attempts have been made to isolate or synthesize the glucose tolerance factor; none has been successful. Thus, the precise structure of the glucose tolerance factor, and whether it is the biologically active form of chromium, remains uncertain.
Chromium may have a biochemical function that affects the ability of the insulin receptor to interact with insulin. For example, it has been found that in vitro RNA synthesis directed by free DNA is enhanced by the binding of chromium to the template; this suggests that chromium may act similarly to zinc in regulating gene expression, so that it may be regulating the synthesis of a molecule that potentiates insulin action. This suggestion is supported by the finding that there is a 4-hour lag period between the administration of biologically active chromium and its optimal effects on insulin action in vivo.
Further Chromium Function
Chromium is an essential trace element required for normal carbohydrate and lipid metabolism. The biological function of chromium is closely associated with that of insulin and most chromium-potentiated reactions are also insulin dependent. Sufficient dietary chromium leads to a decreased requirement for insulin and an improved blood lipid profile. Dietary intake of chromium is marginal and marginal Cr status is exacerbated by increased urinary losses due to pregnancy, strenuous exercise, infection, physical trauma, and other forms of stress. Chromium functions in vivo as an organic chromium complex that is postulated to contain, in addition to Cr, nicotinic acid and glutathione or its constituent amino acids, glycine, cysteine, and glutamic acid. This organic form of chromium, which potentiates insulin activity, can be measured in vitro by determining the increase in apparent insulin activity due to organic forms of Cr in the breakdown of glucose by adipose tissue or cells. In vitro insulin potentiation by Cr is relatively specific since inorganic Cr compounds and most organic complexes do not potentiate insulin activity.
Signs of Chromium Deficiency
Impaired glucose tolerance Elevated circulating insulin Glycosuria – sugar in the urine Fasting hyperglycemia – increased sugar in the blood Impaired growth Decreased longevity Elevated serum cholesterol and triglycerides Increased incidence of aortic plaques Peripheral neuropathy Brain disorders Decreased fertility and sperm count
TITLE: Dietary chromium decreases insulin resistance in
rats fed a high-fat, mineral-imbalanced diet.
AUTHOR: Striffler JS; Polansky MM; Anderson RA
AUTHOR AFFILIATION: Nutrient Requirements and Functions Laboratory,
Beltsville Human Nutrition Research Center, MD 20705-2350, USA.
SOURCE: Metabolism 1998 Apr;47(4):396-400
NLM CIT. ID: 98209906
ABSTRACT: The effects of chromium (Cr) supplementation on diet-induced insulin resistance produced by feeding a high-fat, low-Cr diet were studied in rats to ascertain the role of Cr in insulin resistance. Wistar male rats were maintained for 16 weeks after weaning on a basal diet containing 40% lard, 30% sucrose, and 25% casein by weight and adequate vitamins and minerals without added Cr (-Cr). Fasting levels of insulin, glucose, and triglycerides and the responses during an intravenous glucose tolerance test (IVGTT) were compared as indices of insulin resistance and the effectiveness of dietary Cr. IVGTTs and blood sampling for data analyses were performed over a 40-minute period after IV glucose injection (1.25 g/kg body weight) in overnight-fasted animals under pentobarbital anesthesia (40 mg/kg body weight). All animals were normoglycemic (-Cr, 109 +/- 3 mg/dL; +Cr, 119 +/- 5), with fasting insulin levels elevated in the -Cr group (65 +/- 10 microU/mL) versus the +Cr group (31 +/- 4 microU/mL). Increases in plasma triglycerides in the -Cr group were not significant. Following glucose injection, the rate of glucose clearance was lower in the -Cr group (1.74 +/- 0.22 v2.39 +/- 0.11%/min), and 40-minute glucose areas in the -Cr group tended to be higher than in the +Cr group. The insulin response to glucose injection was 20% higher in the -Cr group. Forty-minute plasma triglyceride areas were lower in +Cr rats (875 +/- 62 v 1,143 +/- 97 mg/dL.min in -Cr rats). These data demonstrate that the insulin resistance induced by feeding a high-fat, nutrient-stressed diet is improved by Cr.
Role of Chromium in Glucose Tolerance & Lipid Metabolism
Chromium is an essential trace element required for normal carbohydrate and lipid metabolism. Insufficient dietary Cr leads to signs and symptoms similar to those observed for individuals with diabetes and/or cardiovascular disease. Dietary intake of Cr from self-selected diets appears to be approximately half of the minimum suggested safe and adequate intake. Children with protein calorie malnutrition, diabetics, elderly, individuals of varying ages with marginally impaired glucose tolerance and hypoglycemics have all been shown to respond to supplemental Cr by improvements in glucose tolerance and/or serum lipids.
Metal Metabolism and Disease, 9th ann. Meet. NACB. Atlanta, Ga., 1985
Clin. Physiol. Biochem.4:31-41 (1986)
Chromium Metabolism and Its Role in Disease Processes in Man
Chromium is an essential element required for normal carbohydrate and lipid metabolism. Insufficient dietary Cr has been linked to maturity-onset diabetes and cardiovascular diseases. The dietary Cr intake of most individuals is considerably less than the suggested safe and adequate intake. Consumption of refined foods, including simple sugars, exacerbates the problem of insufficient dietary Cr since these foods are not only low in dietary Cr but also enhance additional Cr losses. Chromium losses are also increased due to pregnancy, strenuous exercise, infection, physical trauma and other forms of stress. Supplementation of Cr to normal free-living individuals often leads to significant improvements in glucose tolerance, serum lipids including high-density lipoprotein cholesterol, insulin and insulin binding. Chromium also tends to normalize blood sugar. Chromium supplementation of subjects with elevated blood sugar following a glucose load leads to a decrease in blood sugar while hypoglycemics respond to supplemental Cr by an increase in hypoglycemic glucose values, increased insulin binding and alleviation of hypoglycemic symptoms. In summary, dietary intake of Cr is suboptimal and this is exacerbated by increased Cr losses due to stress and certain refined foods including simple sugars that enhance Cr losses. Supplemental Cr is associated with improvements of risk factors associated with maturity-onset diabetes and cardiovascular diseases.