The next treatment for depression may come not from a complex chemical compound developed in a lab but from a mineral found in everyday foods. But its safety remains in dispute.
Duke University scientists have found that ingesting chromium picolinate, a trace mineral naturally occurring in whole grains, mushrooms, liver and many other foods, has significant effects on individuals suffering from atypical depression. Contrary to its name, atypical depression is one of the most prevalent forms of the disorder.
It is characterized by excessive sleep, carbohydrate craving and overeating, and hypersensitivity to rejection. Atypical depression responds to monoamine oxidase inhibitors, but onerous dietary restrictions as well as side effects like sexual dysfunction and weight gain make treatment with these antidepressants troublesome or impractical for many.
In a small, double-blind pilot study at Duke University Medical Center, 15 people with atypical depression were given supplements of 600 micrograms of chromium picolinate, a dose that is more than five times higher than most Americans get in their diets. There is no Recommended Daily Allowance (RDA) for chromium. Five other persons in the study were given a placebo.
After eight weeks, seven of the 10 who were given chromium picolinate had a significant decrease in their depression symptoms, reports Jonathan Davidson, M.D., a professor of psychiatry and director of the Anxiety and Traumatic Stress program at Duke. Those taking the dietary supplement experienced no side effects.
"People who were overeating had really significant changes," reports Davidson. The study was sponsored by Nutrition 21, a commercial manufacturer of dietary supplements.
It's not clear how chromium picolinate affects depression, but Davidson, working with Chapel Hill psychiatrist Malcolm McLeod, M.D., suspects that it may be tied to insulin, the hormone that controls blood sugar.
Studies going back to the 1970s have shown that chromium picolinate increases the body's sensitivity to insulin and helps facilitate cellular uptake of glucose from the blood stream. The brain requires a constant supply of glucose to maintain proper function.
Scientists know that diabetics have a rate of depression that is at least twice that of the general population. The rate is even higher for diabetic women. Depression makes the body less sensitive to insulin.
Drs. MacLeod and Davidson suggest that under normal conditions insulin also increases the amount of tryptophan, an amino acid that is a precursor to serotonin, reaching the brain. Best known for its role in regulating mood, serotonin also reduces pain and decreases appetite as well as producing a state of calm.
Chromium picolinate may also have a direct effect on brain receptors for serotonin. Previous studies have shown that in some depressed people serotonin receptors get too "sticky," fail to release their payload of serotonin and limit its availability. Chromium may help free up serotonin receptors.
Chromium picolinate is already popular as a dietary supplement. It's marketed to athletes as a muscle-builder and touted as a treatment for weight loss and diabetes, although research has yet to prove any of these claims.
Moreover, chromium picolinate may have a dark side. Kidney problems have been linked to the supplement, as well as chromosomal mutations in lab animals.
With all of the contradictory claims, it's no wonder the Institute of Medicine chose chromium picolinate as one of six supplements to review in the first test of an evaluation program developed for the Food and Drug Administration. The FDA has been under increasing pressure to regulate dietary supplements.
Ongoing studies will reveal whether the mineral can work magic with mood.