Chromium

Chromium is an essential mineral that is required by the body in trace amounts. Its role in maintaining blood sugar levels was first identified in 1957 by a research scientist named Walter Mertz who discovered a naturally occurring substance that normalized blood glucose levels. He called this substance glucose tolerance factor (GTF). Chromium is currently thought to be the most active component of GTF with other nutrients related to GTF including nicotinic acid (vitamin B3) and the amino acids that constitute the antioxidant molecule, glutathione (glutamic acid, cysteine and glycine).

Whether GTF is an actual chemical compound or not has not been clarified by scientists. Yet, they are clear that the nutrients that are related to GTF whether or not they actually assembled into a single chemical structure play an important role in blood sugar balance.

Physiological functions of chromium

• Helps maintain normal blood sugar and insulin levels
• Supports normal cholesterol levels

 

Physiological events that may signal a need for greater chromium intake

• Hyperinsulinemia (elevated blood levels of insulin)
• Insulin resistance
• High blood sugar levels
• High triglyceride levels
• High cholesterol levels
• Low HDL cholesterol
• High blood pressure

 

Functions of chromium

 

Control of blood sugar levels

As an active component of glucose tolerance factor (GTF), chromium plays an integral role in controlling blood sugar levels. The primary function of GTF is to increase the action of insulin, the hormone responsible for ushering glucose into the cells where it can be used as an energy source.

When blood sugar levels begin to rise after the consumption of a meal, this alerts the pancreas to secrete insulin in response since insulin lowers blood glucose levels by increasing the rate in which glucose can enter the cells. GTF is thought to initiate the attachment of insulin to the cells insulin receptors, a process necessary for insulins ability to function properly.

Metabolism of nucleic acids and cholesterol

Chromium is involved in the metabolism of nucleic acids, the building blocks of DNA in every cell. Additionally, chromium is also thought to participate in cholesterol metabolism and may therefore play a role in normalizing blood cholesterol levels.

Causes and symptoms of chromium deficiency

Conditions such as diabetes and heart disease increase chromium excretion and therefore increase the amount of chromium needed by the body. Mental stress as well as physical injury and trauma also increase chromium excretion, plus they increase the bodys need for chromium through another mechanism. When the body is under stress, it increases its output of certain hormones that can consequently alter blood sugar balance, creating the demand for more chromium.

Because commercial food processing methods remove most of the naturally occurring chromium from commonly consumed foods, dietary chromium deficiency is believed to be widespread in the United States. Insulin resistance, a condition where body\'s cells do not respond to the presence of insulin signaling them to usher in glucose from the bloodstream, is a manifestation of chromium deficiency. Insulin resistance can consequently cause hyperinsulinemia and hyperglycemia, and lead to the development of diabetes and/or heart disease.

Chromium deficiency need not be severe for related consequences to occur. Mild dietary chromium deficiency is associated with Syndrome X, a medical condition that manifests in an array of symptoms including hyperinsulinemia, hypertension, elevated triglyceride levels, hyperglycemia, and low HDL cholesterol levels. All of these symptoms increase a persons risk for developing heart disease.

Causes and symptoms of toxicity

In 2001, when the Institute of Medicine at the National Academy of Sciences reviewed research on chromium, they concluded that excessive intake from foods or supplements was not associated with any adverse effects and therefore they did not establish a Tolerable Upper Intake Level (UL) for this mineral. They did caution that individuals who have liver or kidney disease should avoid taking chromium supplements in higher than recommended amounts since these persons are more susceptible to adverse effects from excessive intake.

The effect of cooking, storage and processing on chromium

Most food processing methods reduce the chromium content of foods. While chromium naturally occurs in the bran and germ of whole grains, these components are removed when whole grains are milled to make flour. Additionally, the refinement process used to turn sugar cane and sugar beets into table sugar (sucrose) removes most of the chromium that occurs in these plants.

Yet, there are a few conditions where chromium is increased during cooking. One example is that when acidic foods are cooked in stainless steel cookware chromium is leached from the cookware and can accumulate in the food.

Interactions between medications and chromium

If you are taking insulin or an oral glucose-lowering medication (i.e., Diabeta or Micronase), speak with your healthcare practitioner before taking chromium since the mineral can cause blood sugar levels to drop. S/he may need to decrease your current dose of medication so that your blood sugar levels do not significantly decrease.

Medications that decrease absorption of chromium:

• Calcium carbonate as found in antacids and calcium supplements

Medications believed to increase the absorption of chromium:

• Aspirin

Interactions that occur between chromium and other nutrients

Simple sugars increase urinary chromium excretion, therefore reducing chromium status.

Phytic acid, a compound found in grains, can bind to chromium, forming an insoluble complex that prevents the mineral from being absorbed. Yet, whole grains do contain significant chromium content, and it does seems that the activity of the phytic acid in grains does not prevent chromium absorption. Therefore, a diet that is rich in whole grains does not seem likely to be able to increase your risk of developing chromium deficiency.

The absorption of chromium is enhanced by ascorbic acid (vitamin C).

Health conditions that require special emphasis on chromium

Individuals who have the following health conditions should pay special attention to their chromium status:

• Acne
• Glaucoma
• High cholesterol levels
• High triglyceride levels
• Hypoglycemia
• Non-insulin dependent diabetes mellitus (NIDDM)
• Obesity
• Psoriasis

 

Forms in which chromium is found in dietary supplements.

The question of which of the supplemental chromium forms chromium picolinate, chromium polynicotinate, chromium chloride and chromium-enriched yeast is preferable is a topic of substantial debate. Studies have found that the better-absorbed forms are those that are chelated - chromium picolinate, which is chromium attached to picolinic acid, and chromium polynicotinate, which is chromium attached to several vitamin B3 molecules.

Yet, since the picolinic acid binds chromium so tightly in the chromium picolinate form, the two substances stay complexed all the way through the bloodstream and the kidney and then out through the urine. So while the chromium picolinate itself may have good absorption, it seems that the chromium in this form does not. Since vitamin B3 has value in helping to regulate blood sugar, chromium polynicotinate is the form most often used in treatment of blood sugar problems.

Foods that are concentrated sources of chromium

While chromium occurs naturally in a wide array of foods, many food processing methods often remove much of it. Additionally, for the foods that do retain their chromium content, many are believed to only contain a small amount, in the range of 1 to 2 micrograms (mcg). Therefore, unfortunately, it can be difficult to easily obtain a sufficient amount of chromium from dietary sources. What compounds this problem further is that the determination of a foods chromium content is difficult due to inadequate analytical tools. Consequently, currently available food composition databases do not contain accurate information about the amount of chromium found in various foods.

Taking this into consideration, the following foods are thought to provide a significant amount of chromium: bran cereals, brewers yeast, liver, onions, oysters, potatoes, tomatoes and whole grains. Since beer and wine can accumulate chromium during the fermentation process, they are therefore considered to be dietary sources of the mineral.