Men with the highest blood levels of folate were50 per cent less likely to have symptoms of depression, compared to men with the lowest levels, according to findings published in the European Journal of Clinical Nutrition.
Led by researchers from the International Medical Center of Japan in Tokyo, the study also reports that increased levels of the amino acid homocysteine were associated with increased risk of depressive symptoms in men.
The research adds to a growing body of research linking folate and folic acid intake to improved mood, and follows a review by scientists at the University of York and Hull York Medical School of 11 studies and involving 15,315 participants that reported low folate levels were linked to increased depression (Journal of Epidemology and Community Health, Vol. 61, No. 7).
A previous study by the same Japanese researchers also reported, for the first time they claimed, of a link between nutrient intake and depressive symptoms in a non-Western population (Nutrition, 2008, Vol. 24, pp. 140-147).
The World Health Organization (WHO) forecasts that within 20 years more people will be affected by depression than any other health problem; it ranks depression as the leading cause of disability worldwide, with around 120 million people affected.
The new research looked to further examine the role of folate and homocysteine could help in people with depression.
Folate is found in foods such as green leafy vegetables, chick peas and lentils, while folic acid is the synthetic, bioavailable form of the vitamin used in fortification programmes worldwide, as well as in supplements and other fortified foods.
Folate and homocysteine blood levels in 530 Japanese people, 217 of whom were women, were compared with depressive symptoms measured using the Center for Epidemiologic Studies Depression (CES-D) scale. Just over 36 per cent of male and female participants had depressive symptoms, said the researchers.
Results showed that depressive symptoms were less common in men with higher folate levels. Indeed, the highest levels were associated with a 50 per cent reduction in the prevalence of depressive symptoms, compared to the lowest folate levels.
On the other hand, a link between higher homocysteine levels and a higher prevalence of depressive symptoms in men was observed.
“In women, neither folate nor homocysteine was associated with depressive symptoms,” added the researchers.
Potential of supplements
Tufts and Harvard University-based researchers reported in 2003 that folic acid supplements may help reduce the prevalence of depressive symptoms.
Writing in the journal Psychotherapy and Psychosomatics (2003, Vol. 72, pp. 80-87) they noted that depressed people among the general US population often had low blood folate levels. They say that folate supplementation during the year following a depressive episode may help recovery.
Source: European Journal of Clinical Nutrition
Published online ahead of print, doi: 10.1038/ejcn.2009.143
“Serum folate and homocysteine and depressive symptoms among Japanese men and women”
Authors: A. Nanri, T. Mizoue, Y. Matsushita, S. Sasaki, M. Ohta, M. Sato, N. Mishim