Chromium and Glucose Tolerance

Chromium Containing Foods

According to the Centers for Disease Control (CDC)- National Diabetes Statistics Report for 2017, cases of diabetes have risen to an estimated 30.3 million in the United States. The report states that 23.1 million Americans are diagnosed while 7.2 million go undiagnosed; and of those diagnosed, Type 2 diabetes accounts for 90% to 95% of all diabetic cases. While almost 84 million Americans have pre-diabetes, elevated blood glucose levels, but not yet Diabetic.[2]

The concern is great and solutions to address the growing epidemic is felt in many communities. Intervention and Health promotion programs have included a Diabetes education component.

The cost of treating Diabetes is felt on the patient-side and the healthcare side. According to research conducted by the American Diabetes Association in 2017, to treat and care for cases of diagnosed Diabetes, it costs $327 billion dollars a year. Included in continued research by the organization there has been a 26% increase in diagnoses since 2012. Of those, 1 in 4 healthcare dollars are spent to treat diabetes and its complications. In addition, 295 Americans will undergo amputation due to the disease along with 137 will enter end-stage renal failure.[1] The complications of educating, treating, and caring for Diabetes is a daunting task.

Impaired Glucose Tolerance or Impaired Fasting Glucose are essentially the first stage towards Diabetes Mellitus. Impaired Glucose Tolerance or Impaired Fasting Glucose can also be described as Pre-Diabetes. It is defined by a two-hour glucose levels of 140 to 199 mg per dL (7.8 to 11.0 mmol) on the 75-g oral glucose tolerance test; or an impaired fasting glucose of 100 to 125 mg per dL (5.6 to 6.9 mmol per L) while fasting.[1] These glucose levels are above normal however lower than the level that is required diagnostically for a diagnosis of Diabetes. When individuals have impaired glucose tolerance or impaired fasting glucose they are more likely to develop Diabetes; therefore, education and prevention is extremely important for this group of individuals. An analysis of research concerning the effects of Chromium on glucose intolerance has shown that Chromium supplementation does not provide significant affects on lowering blood glucose, impaired glucose tolerance or impaired fasting glucose. Chromium is an essential trace mineral that is needed in trace amounts for human health. Chromium is responsible for uptake of glucose into the cells and enhances the function of insulin.[1] Chromium binds to transferrin receptors when they are released through a process of endocytosis resulting from a change in pH of vesicles containing transferrin molecules. The free chromium binds to lower molecule weight chromium binding substances (LMWCr). These molecules are also known as oligopeptides, they contain four amino acid residues; aspartate, cysteine, glutamate and glycine bonded with four chromium centers. LMWCr binds to insulin receptors enhancing tyrosine kinase activity which improves glucose absorption.

Soil greatly effects Chromium content in plants

The exact amount of Chromium needed is heavily debated. Since there are two major limitations regarding chromium content in food. The first is that the amount of chromium content is heavily affected by agricultural and manufacturing processes. Chromium is absorbed by plants with the highest concentrations contained in the leaves or the roots, but very little in the fruit. This is dependent on the concentration available in farming soil. The second limitation is that when food is analyzed for its Chromium content it can easily be contaminated by the measuring instruments. There are primarily two forms of Chromium, the first is known as trivalent or chromium 3+ which is the biologically active form found in food. While the second form of chromium is hexavalent or chromium 6+, which is the toxic form resulting from industrial pollution. Chromium bioavailability and absorption from consumption can be very low from 0.4% to 2.5%. Its absorption is enhanced by vitamin C and niacin, while any unabsorbed Chromium is excreted in feces or urine. Absorbed Chromium is stored in the liver, spleen, bone and soft tissue. It’s important to note that the increased urinary excretion of chromium can result from; diets high in simple sugars, an infection, strenuous and prolonged exercise, pregnancy and lactation, or major physical trauma. These incidents can lead to potential deficiency.[1]

Chromium deficiency is defined as impaired blood glucose control, elevated triglycerides and elevated blood cholesterol. Low intakes of Chromium can eventually lead to Impaired Glucose Tolerance and Impaired Fasting Glucose potentially leading to Diabetes Mellitus. Chromium deficiency is especially noted in individuals on intravenous nutrition which is not supplemented with Chromium in acute settings. Children who are malnourished also exhibit Chromium deficiency. Other concerns during supplementation is if a patient or individual is ingesting large amounts of Chromium while taking a hypoglycemic agent and/or insulin may result in hypoglycemic reactions, which should be monitored closely.[5]

Glucose affects

The dose of insulin or the hypoglycemic agent may need to be decreased. This is especially important for patients receiving parental nutrition contained with Chromium supplementation. [4] Chromium deficiency is important in the elderly population due to age-related decreases. However, there have not been reliable diagnostics for measuring chromium levels because blood, urine, and hair levels, do not reflect body stores. Chromium doesn’t have a specific enzyme or biochemical marker available to assist with assessing Chromium levels.[1]

There are no official recommendations for Chromium supplementation, it is found in supplementation form as Chromium Picolinate. Multi-vitamins also contain Chloride Salt of Chromium. About 50 to 200 mcg/day is within a normal range for adults, with a breakdown of 25 to 35 mcg/day is an Adequate Intake (AI) amount with a balanced diet. Food and supplementation Daily Value labels are around 120 mcg. No Upper Limit has been set for toxicity because no toxicity has been found from food sources. Excellent food sources of meat, whole grains, eggs, broccoli, mushrooms, nuts, and spices. Brewer’s yeast has been shown to be an excellent source of Chromium.[4]

Much of the research done concerning Chromium supplementation effects on glucose intolerance and insulin efficacy has been mixed. Studies of randomized controlled clinical trials based on meta-analysis of Chromium supplementation on three markers of diabetes in blood; including insulin, glucose and glycated hemoglobin A1C. Data summarized from 15 trials and a total of 618 participants yielded little to no changes on glucose or insulin concentrations in subjects without and with diabetes.

One study out of China with a higher than recommended dose of either 200 mcg/day or 1000 mcg/day of Chromium or a placebo, showed a change in glucose and insulin concentrations.[1] This perhaps is due to the sample size, chromium deficiency, or the high dosage. Another study conducted by Yale scientists with a similar sample size and study structure also conducted with a placebo, but with a dosage of 500 mcg/day and 1000 mcg/day for a 6-month period yielded no significant changes in blood glucose and insulin concentrations as well. [3]

A careful analysis of Chromium supplementation research has shown that there are no significant effects on blood glucose and insulin efficacy. Many of its limitations with bio-availability has proven to be difficult to measure the exact supplementation amount for optimal efficacy. Along with the complication of Chromium not having accessible biomarkers for measurement of adequate concentration. However, due to the mechanism of action of Chromium as enhancing the function of insulin by increasing the uptake of glucose into the cells, it has some promise and potential. It remains to be seen what can be developed in the future regarding Chromium supplementation and glucose intolerance as studies continue.

References: [1] (2020) Chromium: Dietary Supplement Fact Sheet. National Institutes of Health: Office of Dietary Supplements.

[2] (2017) National Diabetes Statistics Report, 2017. Centers for Disease Control and Prevention. [3] Ali et al. (2011) Chromium Effects on Glucose Tolerance and Insulin Sensitivity in Persons at Risk for Diabetes Mellitus. Endocrinology Practice,17 (1),16–25. [4] Kee et al. (2015) Chapter 15: Vitamin and Mineral Replacement: Chromium. Pharmacology: A Patient Centered Nursing Process Approach, 8, 220. [5] Smith et al. (2019) Chapter 9: Water and Minerals: Chromium. Wardlaw’s Contemporary Nutrition,11, 398-399.

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