The results of the study, carried out at the Ohio State University Department of Nutrition and presented yesterday at the annual meeting of the Federation of American Societies for Experimental Biology in San Diego, showed that the mean value for chromium picolinate as a percent increase over baseline was 625 percent.
Chromium nicotinate showed a percentage increase over baseline of 270 percent, chromium niacin amino acid chelate of 183 percent and chromium chloride just 40 percent.
Chromium is an essential trace mineral that occurs naturally in small amounts in some foods, including brewer's yeast, lean meat, cheese, pork kidney and whole grain bread and cereals. It is poorly absorbed by the human body but is known to play an important role in the metabolism of carbohydrate, fat and protein.
A body of scientific evidence also indicates that chromium supplementation can improve insulin function and blood sugar control in people with insulin resistance and type 2 diabetes.
"Knowing which form of chromium is best absorbed by the body is important information for consumers who hope to achieve the optimal health benefits associated with chromium supplementation," said lead researcher Dr Robert DiSilvestro.
Dr DiSilvestro's team compared the absorption of the four types of chromium, each administered in a dose of 200 mcg, by 12 healthy young adult women with normal body weight.
It determined how much chromium the subjects had absorbed by testing the subjects' urine collected over 24 hours after supplementation. The test was repeated at two-week intervals, each time with a different type of chromium, to ensure that no chromium from the previous test remained in the women's systems.
Although chromium chloride produced the worst results in the study, it is used in many multivitamin-mineral supplements including Centrum and One-A-Day Complete.
Chromium chloride may be an attractive ingredient because it is cheaper than the alternatives and smaller for fitting into multi-vitamin-mineral pills, Dr DiSilvestro told NutraIngredients-USA.com.
"It seems to be clear that replacing the chromium chloride with chromium picolinate would give better absorption of the chromium," he said.
Chromium picolinate is already widely used in stand-alone chromium supplements marketed to people concerned about developing diabetes or cardiovascular disease.
Controlling blood sugar is thought to reduce the risk of developing cardiovascular disease, even in some non-diabetes sufferers.
The chromium picolinate used in the study was Chromax supplied by Nutrition 21.
DiSilvestro's findings seem to dispel the belief held in some quarters of the scientific community that chromium nicotinate is a better absorbed than chromium picolinate. This was the conclusion drawn from one particular study but, according to DiSilvestro, it did not have a direct demonstration of chromium nicotinate's superior absorption.
"Our study does the direct comparison and finds picolinate to be better absorbed," he said.
The potential of chromium picolinate has come under the spotlight in recent years since the labor/health subcommittee bill was signed into law by President Bush in December 2002.
This bill gave an $800 million boost to the National Institutes of Health's budget for further research into disease. It is conducting four clinical trials using chromium picolinate this year.
The first clinical trial into the effects of chromium supplementation in children with type 1 diabetes is currently underway at the Childrens' Hospital in Los Angeles, also using Chromax chromium picolinate supplied by Nutrition 21.