(NaturalNews) Men who do not get enough folic acid in their diets may be more susceptible to depression, studies have shown.
Folic acid is the dietary form of vitamin B9 and is found primarily in green leafy vegetables, citrus fruit, beans and other legumes, liver, and yeast (including homebrewed alcohol and live yeast cultures). Folic acid is processed by the body into folate (the biologically active form) and plays a number of critical functions in sustaining human health. High blood levels of folate are particularly critical for women during the earliest phase of pregnancy to prevent certain birth defects.
As early as the 1970s, studies indicated that depressed psychiatric patients had significantly lower blood folate levels than non-depressed patients. More recently, a number of studies have delved deeper into this correlation. A 2003 study found that participants with a low dietary intake of folic acid had a 67 percent higher risk of developing depression than those with a high folic acid intake. In addition, depressed participants with a low folic acid intake had worse symptoms than depressed patients with a higher intake.
A large research review conducted by scientists from the University of York and Hull York Medical School found that in 11 separate studies involving a total of 15,315 participants, low blood levels of folate were significantly associated with higher rates of depression.
Men most affected
More recent studies have indicated, however, that vitamin B9 may actually only have a significant effect on mood in men, not in women.
In one study, conducted by researchers from the International Medical Center of Japan and the National Institute of Health and Nutrition and published in the journal Nutrition in 2007, researchers assessed the dietary intake and depressive symptoms of 517 adults of average age 43. While roughly equal percentages of male and female participants suffered from depression, higher blood folate levels were only associated with lower depression rates in men.
The effects of folate among men were striking, however. Those participants with the highest average vitamin B9 intake were 50 percent less likely to have symptoms of depression than men with the lowest intake.
"Although more research is needed to confirm the causality of the association, dietary modification to increase intake of folate may be an important strategy for the prevention of depression," the researchers wrote.
These findings were supported by a later study, conducted by researchers from the National Institute on Aging and published in the Journal of Nutrition in 2010. The researchers found that among 1,681 participants between the ages of 30 and 64, men with a higher vitamin B9 intake were significantly less likely to be depressed than those in the lower intake. No effect was seen in women. Notably, folate in men appeared to interact with the mood-boosting effects of a better diet in general.
"Depressive symptoms in our study may be alleviated by improving overall dietary quality, with plasma folate playing a potential mediating role only among men," the researchers concluded.