Chromium (3) in hypoglycemia and in impaired glucose utilization in kwashiorkor

Chromium picolinate intake and risk of type 2 diabetes: an evidence-based review by the United States Food and Drug Administration

The labeling of both health claims that meet significant scientific agreement (SSA) and qualified health claims on conventional foods and dietary supplements requires pre-market approval by the US Food and Drug Administration (FDA). Approval by the FDA involves, in part, a thorough review of the scientific evidence to support an SSA or a qualified health claim. This article discusses FDA's evidence-based review of the scientific evidence on the role of chromium picolinate supplements in reducing the risk of type 2 diabetes. Based on this evidence-based review, FDA issued a letter of enforcement discretion for one qualified health claim on chromium picolinate and risk of insulin resistance, a surrogate endpoint for type 2 diabetes. The agency concluded that the relationship between chromium picolinate intake and insulin resistance is highly uncertain.

Nutrient requirements for preterm infant formulas

Achieving appropriate growth and nutrient accretion of preterm and low birth weight (LBW) infants is often difficult during hospitalization because of metabolic and gastrointestinal immaturity and other complicating medical conditions. Advances in the care of preterm-LBW infants, including improved nutrition, have reduced mortality rates for these infants from 9.6 to 6.2% from 1983 to 1997. The Food and Drug Administration (FDA) has responsibility for ensuring the safety and nutritional quality of infant formulas based on current scientific knowledge. Consequently, under FDA contract, an ad hoc Expert Panel was convened by the Life Sciences Research Office of the American Society for Nutritional Sciences to make recommendations for the nutrient content of formulas for preterm-LBW infants based on current scientific knowledge and expert opinion. Recommendations were developed from different criteria than that used for recommendations for term infant formula. To ensure nutrient adequacy, the Panel considered intrauterine accretion rate, organ development, factorial estimates of requirements, nutrient interactions and supplemental feeding studies. Consideration was also given to long-term developmental outcome. Some recommendations were based on current use in domestic preterm formula. Included were recommendations for nutrients not required in formula for term infants such as lactose and arginine. Recommendations, examples, and sample calculations were based on a 1000 g preterm infant consuming 120 kcal/kg and 150 mL/d of an 810 kcal/L formula. A summary of recommendations for energy and 45 nutrient components of enteral formulas for preterm-LBW infants are presented. Recommendations for five nutrient:nutrient ratios are also presented. In addition, critical areas for future research on the nutritional requirements specific for preterm-LBW infants are identified.

Serum chromium does not predict glucose tolerance in late pregnancy

BACKGROUND

Chromium is an essential element in human nutrition. Serum concentrations of chromium are not well characterized during pregnancy or in gestational diabetes mellitus.

OBJECTIVE

The objective of this study was to determine whether low plasma chromium concentrations (< or =3 nmol/L) are associated with altered glucose, insulin, or lipid concentrations during pregnancy.

DESIGN

The study was conducted prospectively and took place at the medical obstetric clinic of a tertiary referral hospital. Seventy-nine women with abnormal results of a 50-g glucose challenge test in the third trimester of pregnancy were studied. All women had a formal 75-g oral-glucose-tolerance test, and fasting insulin, lipid, and chromium concentrations were determined. Chromium was measured by graphite furnace atomic absorption spectrometry.

RESULTS

The median chromium concentration was 2 nmol/L (95% CI: 0, 12). There were no significant differences in age, plasma glucose, insulin, lipids, calculated insulin resistance, or calculated ss cell function between women with normal and those with abnormal (< or =3 nmol/L) chromium concentrations.

CONCLUSIONS

Plasma chromium during pregnancy does not correlate with glucose intolerance, insulin resistance, or serum lipids. Plasma chromium concentrations may not accurately reflect tissue stores of chromium. Several trials showed a beneficial effect of chromium supplementation on glucose tolerance, insulin, and lipids. A method for assessing body chromium stores is required to allow further study.

Chromium as a supplement

Chromium (Cr) is an essential mineral element that has received considerable public attention. The suggestion that Cr intake is generally low has generated interest regarding the purported beneficial effects of Cr supplementation on biological function and health of animals and humans. This review briefly describes key aspects of Cr nutritional status and evaluates the effects of Cr supplementation on various components of biological function, body composition, and health. A novel biological role of Cr in regulation of insulin function is described. Although promising results of Cr supplementation are presented, the considerable challenge of developing methods for routine assessment of Cr nutriture in humans remains.

Chromium, glucose intolerance and diabetes

Within the last 5 years chromium (Cr) has been shown to play a role in glucose intolerance, Type 2 diabetes mellitus (Type 2 DM), and gestational diabetes. In addition, diabetes and the neuropathy of a patient on home parenteral nutrition were alleviated when supplemental Cr was added to total parenteral nutrition (TPN) solutions. In a study conducted in China that has been supported by studies in the United States, supplemental Cr as Cr picolinate improved the blood glucose, insulin, cholesterol, and hemoglobin A1C in people with Type 2 DM in a dose dependent manner. Follow-up studies of > 1 year have confirmed these studies. The requirement for Cr is related to the degree of glucose intolerance: 200 microg/day of supplemental Cr is adequate to improve glucose variables of those who are mildly glucose intolerant. However, people with more overt impairments in glucose tolerance and diabetes usually require more than 200 microg/day. Daily intake of 8 microg of Cr per kg body weight was also more effective than 4 microg/kg in women with gestational diabetes. The mechanism of action of Cr involves increased insulin binding, increased insulin receptor number, and increased insulin receptor phosphorylation. In summary, supplemental Cr has been shown to have beneficial effects without any documented side effects on people with varying degrees of glucose intolerance ranging from mild glucose intolerance to overt Type 2 DM.

Chromium, glucose tolerance, and diabetes

Chromium functions in maintaining normal glucose tolerance primarily by regulating insulin action. In the presence of optimal amounts of biologically active chromium, much lower amounts of insulin are required. Glucose intolerance, related to insufficient dietary chromium, appears to be widespread. Improved chromium nutrition leads to improved sugar metabolism in hypoglycemics, hyperglycemics, and diabetics.

Chromium content of foods and diets

Comparatively few valid data are available on the chromium content of foods and on the dietary chromium (Cr) intake of various populations. This is chiefly because of the difficulties encountered in contamination control during sampling, sample pretreatment, and analysis. Moreover, there are several analytical problems involved that are mostly owing to the low concentration level of Cr in foods. However, with the recent establishment of food reference materials with certified low concentrations of Cr, the analytical validity of studies on Cr content of foods and on its dietary intake by various populations can be ascertained. With the exception of herbs and condiments, and certain other special food items with a relatively low average consumption rate, such as tea, coffee, and some candies, most foods contain Cr below 100 micrograms/kg. Staple foods, particularly cereals and milk, are very low (less than or equal to 10 micrograms/kg) in Cr, showing little or no geographic variation. Food processing may increase food Cr content depending on the process. Processes, such as meat grinding and homogenization using stainless-steel equipment, very strongly increase the Cr content of foods. Also, acidic fruit juices in contact with steel cans are high in Cr, whereas cooking in aluminium vessels reduces the Cr content of foods. Average dietary Cr intake seems to fluctuate considerably among countries. In many developing countries, such as Brazil, the Sudan, and Iran, the dietary intake is high, from 50-100 micrograms/d, whereas in certain developed countries, such as Finland, Sweden, Switzerland, and the US, the intake is 50 micrograms/d or lower and, consequently, at or below the estimated safe and adequate daily dietary intake range of 50-200 micrograms/d established by the US National Academy of Sciences. The average Cr content of human milk is below 0.5 micrograms/L, thus resulting in a very low average intake of 0.3 microgram Cr/d by exclusively breast-fed infants in the US and Finland.

Chromium in human milk from American mothers

The chromium concentration was determined in 261 samples of breast milk collected by manual expression from forty-five American women. Cr was measured in whole, liquid milk by graphite-furnace atomic absorption spectrophotometry, using the method of standard additions. The mean Cr content of the breast milk samples was 0.30 ng/ml. The range of individual values was 0.06-1.56 ng/ml and did not change significantly with duration of lactation. The Cr content of breast milk from these American women is similar to levels reported recently in milk from Finnish women.

Determination of chromium in human milk, serum and urine by electrothermal atomic absorption spectrometry without preliminary ashing

In the present study a Perkin-Elmer 5000 atomic absorption spectrometer equipped with a tungsten--iodide lamp for improved background correction at the 357.9 nm chromium absorption line and an HGA 500 graphite furnace were employed for the direct determination of chromium in human serum, milk and urine. The method of standard additions was used: 0.25-0.75 ng Cr was added to 1 ml samples. Except for urine samples, a dilution of 1 + 1 to 1 + 2 with H2O was necessary in order to obtain correct calibration curves. The average concentration of chromium in all the samples of normal subjects was less than 0.5 ng Cr ml-1. The day-to-day variation for all of the pooled samples was around 10% (relative standard deviation). For urine, the accuracy of the method was tested by comparing the results of another laboratory for the same two round robin samples. Excellent agreement was found between the present method and those of the other laboratory that had used isotope dilution--mass spectrometry and continuum source wavelength modulated echelle--atomic absorption spectrometry to define the chromium concentration in the samples. The detection limit of the method, 0.05 ng Cr ml-1 for urine and serum and 0.1 ng Cr ml-1 for human milk, was sufficient for the biological fluids analyzed. The method was employed for the determination of chromium in 24-h urine samples of maturity onset diabetics supplemented with 20 or 200 micrograms Cr3+ d-1 for six weeks. It was shown that the 24-h urinary chromium excretion accurately indicates the daily dietary chromium intake of these patients.

Comparison of intravenous glucose tolerance tests and serum insulin levels in kwashiorkor and pellagra

Intravenous glucose tolerance tests and serum insulin responses were estimated on admission to hospital as well as after recovery in 16 kwashiorkor and 15 pellagra children. Only the kwashiorkor group showed impairment of glucose utilization on admission, and the glucose disappearance rate of the two groups differed significantly. After clinical recovery the glucose utilization of the kwashiorkor patients was much improved, and similar to that of the pellagra patients. These findings are different from those of others who reported persistent glucose intolerance after kwashiorkor. The glucose tolerance tests were normal in the pellagra group, both on admission and after recovery. The kwashiorkor group's insulin response was less than that of the pellagra group on admission, and the values of the two groups differed significantly at 5, 15, and 30 minutes after glucose administration. After recovery, the insulin levels of the two groups were similar. The improvement in glucose utilization which took place on recovery of the kwashiorkor patients, as well as the low incidence of diabetes mellitus in the Bantu, cast doubt on the concept of permanent impairment of pancreatic endocrine function as a result of protein-calorie-malnutrition. It is speculated that glucose intolerance may be related to body potassium deficiency.

Effect of kwashiorkor on absorption and excretion of N, fat, and minerals

Balance experiments were carried out on 6 children being treated for kwashiorkor. The intakes and excretions of N, fat, Na, K, Ca, Mg, P, Cu, Zn, Mn, and Cr were measured. The absorptions were all thought to be in the normal range and the retentions were high. The stools were bulky and contained much undetermined matter, probably unavailable carbohydrate derived from the matooke which formed part of their diet. In the light of previous and present findings the ratios of K/N and Mg/N retained, though higher than those found in muscle or in the whole body, cannot be taken to mean that the children were K or Mg deficient.