In research that literally suggests food for thought, scientists have found that omega-3 fatty acids and uridine (a natural substance found in foods) work as well as antidepressants in preventing signs of depression.
According to the researchers from Harvard-affiliated McLean Hospital in Belmont, Massachusetts, rat experiments use a well-established depression animal model. The rats were placed in a tank of water, where they had no choice but to swim. After a while, the rats realized swimming was futile. They simply began to float, a sign of surrender to depression. When administered an antidepressant drug, they started swimming again (according to researchers). 
"Combined doses of omega-3 fatty acids and uridine were as effective as three different antidepressants in prompting the rats to start swimming again," said study author William Carlezon, director of McLean's Behavioral Genetics Laboratory. "We administered these two components (omega-3 fatty acids and uridine) separately," Carlezon said. "When it became clear that each was having an effect, we decided to administer them together and see if there was a synergistic effect because they act on the same system."
"The drugs and the dietary components used in the study probably act on mitochondria in brain cells," he said. "Mitochondria produce energy for brain cells. Imagine what happens if your brain does not have enough energy. Basically, we were giving the brain more fuel to run on."
Omega-3 fatty acids are well-known ingredients in many fish and are most abundant in oily species such as salmon and tuna. Cardiologists recommend a diet rich in oily fish because omega-3 fatty acids are good for the circulatory system. "What's good for the heart is good for the brain," said Dr. Bruce Cohen, president and psychiatrist-in-chief at McLean Hospital. "If you study people around the world with similar backgrounds, the group eating more fish has a lower rate of heart disease and depressive illnesses," Cohen said.
"Omega-3 fatty acids are best obtained by eating fish, not in dietary supplements, he said. "In fish, they are fresh and in the needed form," Cohen said. “Uridine is different. It's not found in high levels in any particular food." Carlezon said, "It is an important element in mother's milk. Baby formula is enriched with uridine because it is essential for early nerve growth."
"There are no uridine supplements on the market. There might be a need for them," Carlezon suggested. "More studies are needed to see whether uridine in the diet affects mental capacity and learning." Added Carlezon: "There are growing indications that mitochondria are involved in psychiatric conditions other than depression." McLean researchers have found major alterations in the genes for mitochondria in people with bipolar disorder, a condition that includes cycles of depression.
More information
You can get more information from the "Guide to Depression" offered by The National Institute of Mental Health.
SOURCES: William Carlezon, Ph.D, director, McLean Hospital Behavioral Genetics Laboratory, and Bruce Cohen, M.D., Ph.D, president and psychiatrist-in-chief, McLean Hospital, both in Belmont, Mass.; Feb. 15, 2005, Biological Psychiatry.
