American women with higher blood levels of omega-3 fatty acids have a 49% reduction in risk of elevated depressive symptoms, according to a new study to be published in the Journal of Nutrition.
“Our study findings support the hypothesis of a protective effect of n–3 fatty acids against depressive symptoms, particularly among women,” stated the authors in the Journal of Nutrition. “Whereas reverse causality cannot be ruled out, it is more likely that reduced concentrations of n–3 fatty acids may contribute to symptoms of depression, and not vice-versa. “Thus, these findings support the need for Dietary Reference Intake recommendations in the US, particularly for DHA and EPA given their strong impact on depressive symptoms, particularly the domain of positive affect.”
“Results from this well-designed and conducted study corroborate the hypothesis that the long-chain n-3 PUFAS, EPA & DHA, offer protection against depression, with reduced concentrations of EPA & DHA contributing to symptoms of depression. While additional studies are necessary to verify a cause and affect relationship, the authors rightfully acknowledged this,” added Dr Rice.
Led by May Beydoun, PhD, from the National Institute on Aging, the researchers assessed if there was an association between omega-3 intakes and symptoms of depression using the 20-item Center for Epidemiologic Studies–Depression Scale (CES-D) in 1,746 adults aged between 30 and 65.
The data showed that elevated depressive symptoms (EDS) were prevalent in 25.6% of women, and 18.1% of men. Adequate intakes of linoleic acid (LA) and alpha-linolenic acid (ALA) were observed in 43 to 59% of men and women. However, significantly fewer men and women achieved adequate intakes of EPA and DHA ranged from 5.2 and 17.2%.
Further crunching of the numbers showed that the highest intakes of omega-3 PUFAs was associated with a significant 49% reduction in the risk of elevated depressive symptoms in women. A similar result was obtained for the ratio of omega-3 HUFA to omega-6 HUFA in women, they added.
Dr Beydoun and her co-workers proposed three mechanisms to explain the associations. The first involves the serotonergic neurotransmitter system, which is known to be regulated by omega-3s. The second is called the ‘macrophage theory of depression’, and is related to inflammatory responses. Omega-3s are known to promote the formation of anti-inflammatory compounds, while omega-6s promote proinflammatory eicosanoids, which can cause psychiatric disturbances and emulate symptoms of depression. The third mechanism involves “impaired phospholipid metabolism and impaired fatty acid–related signal transduction in the etiology of both depression and bipolar disorder and attempts to link depression to cardiovascular and autoimmune disease through these metabolic impairments”, they said.
“Additional prospective observational studies are needed to strengthen evidence of a causal association in the hypothesized direction,” wrote Dr Beydoun and her co-workers. “This should possibly include supplemental n–3 fatty acid intakes in addition to their main dietary source as well as a biomarker for intake of n–3 fatty acids, while considering the balance of n–3 to n–6 fatty acids.”
Source: Journal of Nutrition
Published online ahead of print, doi:10.3945/jn.113.179119
“Omega-3 Fatty Acid Intakes Are Inversely Related to Elevated Depressive Symptoms among United States Women”
Authors: M.A. Beydoun, M.T. Fanelli Kuczmarski, H.A. Beydoun, J.R. Hibbeln, M.K. Evans, A.B. Zonderman
Vitamin D and Autoimmune Diseases
AUTOIMMUNE DISEASE, IMMUNITY – Vitamin D, Cholecalciferol, Vitamin D3
“High-dose cholecalciferol supplementation significantly increases peripheral CD4+ Tregs in healthy adults without negatively affecting the frequency of other immune cells,” Prietl B, Treiber G, et al, Eur J Nutr, 2013 Sept 3; [Epub ahead of print]. (Address: Department of Endocrinology and Metabolism, Medical University of Graz, Auenbruggerplatz 15, 8036, Graz, Austria).
In a double-blind, placebo-controlled study involving 60 healthy volunteers, 12 weeks of supplementation with high-dose cholecalciferol (vitamin D3, 140,000 IU/month) was found to be associated with significantly increased numbers of peripheral Tregs (regulatory T cells) in vivo, which play a key role in maintaing “self-tolerance” and thereby reducing the risk of autoimmunity. While this beneficial effect was attained, the function of Tregs and the frequency of other immune cells remained unchanged. The authors also conducted studies in human peripheral blood mononuclear cells and found that cholecalciferol showed the same effects. The authors conclude, “Our results indicate a substantial effect of a supplementation with inactive vitamin D on the immune system of healthy humans in vivo and provide a rationale for future studies to investigate the immunomodulatory effects of vitamin D in autoimmune diseases.”
Effect of Vegetarian Diet on Risk of Non-Communicable Diseases
DIET, VEGETARIAN, NON-COMMUNICABLE DISEASE – Vegetarian, Omnivore, Vitamin B12, Folic Acid, Omega-3 Fatty Acids
“Effect of the vegetarian diet on non-communicable diseases,” Li D, J Sci Food Agric, 2013 Aug 21; [Epub ahead of print]. (Address: Department of Food Science & Nutrition, Zhejiang University, China).
In a review of research comparing vegetarians with omnivores, mortalities from all-cause, ischemic heart disease, circulatory disease, and cerebrovascular disease were lower in vegetarians. In addition, the incidences of cancer and type 2 diabetes were lower in vegetarians. On the other hand, risk factors for non-communicable diseases including increased homocysteine, mean platelet volume and platelet aggregability were higher among vegetarians. The authors suggest that this may be associated with low intakes of vitamin B12 and omega-3 fatty acids among vegetarians. The authors state, “Based on the present data, it would seem appropriate for vegetarians to carefully design their diet, specifically focusing on increasing their intake of vitamin B12 and n-3 PUFA to further reduce already low mortality and morbidity of non-communicable diseases.”