Could your next meal help relieve depression? Perhaps, if the menu includes fatty fish like salmon or herring fish, walnuts, sugar beets or beet molasses.

Those foods contain substances that had an antidepressant effect in tests on rats, researchers report in the Feb. 15 issue of Biological Psychiatry.

The substances are omega-3 fatty acids (search) and uridine (search). Abundant omega-3 fatty acids are found in certain fish — especially in fatty fish like salmon and herring — as well as walnuts and flaxseed. Uridine occurs in sugar beets and molasses made from those beets. Uridine hasn't been clinically tested on people with mood disorders, say the researchers.

Omega-3 fatty acids from fish have drawn a lot of attention in recent years. They've been studied for benefits against heart disease, stroke, sudden death and arthritis, as well as depression. Studies have found that societies that eat lots of fish have lower depression rates, possibly due to omega-3 fatty acids.

But in America, where fish isn't a dietary staple, depression is common. Nearly 19 million people per year in the U.S. have depression, says the National Institute of Mental Health (search).

Tests on Rats

The new study comes from William Carlezon Jr., PhD, and colleagues from McLean Hospital's psychiatry department. The Massachusetts hospital is affiliated with Harvard Medical School (search).

The experiment didn't involve people. Instead, the researchers tested dietary omega-3 fatty acids and uridine injections in rats.

To induce a depression-like state, the rats took a forced swim test that thwarted them at every turn. The rats quickly became helpless, since they couldn't escape, no matter how hard they tried.

The researchers tried three approaches. They injected the rats with uridine. Later, they fed the rats a diet high in omega-3 fatty acids. Lastly, they tried combining lower doses of both uridine and omega-3 fatty acids.

Depression Relief Reported

All three approaches worked. Uridine and omega-3 fatty acids both had antidepressant-like effects, say the researchers. The rats stopped acting helpless and did their best, even though the test was still stacked against them.

The uridine injections acted right away, but the omega-3 fatty acids took 30 days to kick in. That's about as long as it takes for people to get depression relief from many antidepressant drugs like selective serotonin reuptake inhibitors (search) (SSRIs), say the researchers. SSRIs include Paxil, Prozac and Zoloft.

Combining lower doses of uridine and omega-3 fatty acids was even more helpful.

"Less of each agent is required for effectiveness when the treatments are administered together," say the researchers.

For comparison, the scientists also tested the depression drugs Norpramin, Prozac and Celexa. Those medications also helped the rats overcome helplessness.

Dietary Sources of Omega-3

Not all fish have the same amount of omega-3 fatty acids, so check levels for your favorite kind.

Can't stand fish? Walnuts, flaxseed and their oils have high quantities of plant-derived omega-3 fatty acids. Omega-3 supplements are also widely available, but they're not regulated by the FDA. Any supplements added to your regular medications have the potential to cause a serious interaction, so check with your health care provider to make sure it's safe.

As for uridine, sugar beets and beet molasses are food sources.

Don't Go It Alone

If you suspect that you are depressed, seek professional help. Diet may be one piece of the puzzle, but depression is too serious to handle on your own. An abundance of help is available, from diet and exercise to medication and counseling. All you have to do is ask.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Carlezon, W. Biological Psychiatry, Feb. 15, 2005; vol 57: pp 343-350. Covington, M. American Family Physician, July 1, 2004; vol 70: pp 133-140. National Institute of Mental Health. News release, McLean Hospital.