Data on US adults from the National Health and Nutrition Examination Survey (NHANES) show elevated depressive symptoms were inversely associated with folate status, particularly among women.
“We found that the odds of having elevated depressive symptoms among individuals with the highest serum folate levels were about half that of those with the lowest levels,” lead investigator May A. Beydoun, PhD, MPH, National Institute on Aging, told Medscape Medical News.
First Nationally Representative Study
Previous research indicates that high levels of total homocysteine (tHcy) and low levels of folate and vitamin B12 are associated with depression or elevated depressive symptoms in adults.
However, investigators note that earlier studies examining the impact of low folate, low vitamin B12, and elevated tHcy status simultaneously on depressive symptoms did not examine interaction among those 3 risk factors and have had inconsistent findings as to the individual associations.
“To our knowledge this is the first nationally representative study conducted among U.S. adults after mandatory fortification of food with folic acid that examines associations of serum folate, vitamin B12, and tHcy levels with depressive symptoms,” they write.
Study effects of folate especially evident in women
The likelihood of women in the highest serum folate to experience elevated depressive symptoms was about a third that of their counterparts with the lowest serum folate levels.
Elevated homocysteine level was positively associated with elevated depressive symptoms in adults 50 years and older. Although a significant association between folate levels and risk for elevated depressive symptoms was only observed in women, the investigators believe this is because the study was underpowered to detect the effect in men.
Boosting Folate Levels
Dr. Beydoun, clinicians should consider screening patients with depressive symptoms for serum folate and, if indicated, consider supplementation in addition to standard antidepressant therapy. In addition, dietary and lifestyle advice to enhance serum folate should also be considered. Such counseling, she said, should include education about folate-rich foods, the beneficial effect of physical activity on folate levels, and the negative impact of cigarette smoking.
Diet Important in Mental Health
Commenting on the study, Felice Jacka, PhD, a researcher from the University of Melbourne in Australia, who has conducted a number of studies examining the impact of diet on mental health status, said given the fact that previous studies have reported this relationship the results are not surprising. “However,” she said, “the NHANES data are very good quality and, therefore, a very good vehicle to examine the relationships between nutritional status and mental health.”
“This is the first large-scale population-based study in the US to show that folate status is associated with the presence of depressive symptoms since the fortification of foods with folate became mandatory,” she added.
Dr. Jacka said this study also lends further support to the premise that diet is an important factor for mental health in the general population.”It also suggests that blood tests to examine folate and homocysteine levels (and levels of other nutrients) in individuals with depressive symptoms may be of utility in clinical settings. If nutrient deficiencies and/or excess homocysteine are identified, dietary and/or supplementation strategies could then be considered,” she said.
Psychosom Med. Published online September 14, 2010.
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