Researchers from Université Laval in Canada report that feeding mice a diet rich in DHA for three months significantly reduced the severity of a stroke.
"The consumption of omega-3s creates an anti-inflammatory and neuroprotective environment in the brain that mitigates damage following a stroke," said Professor Jasna Kriz from Laval's Faculty of Medicine. "It prevents an acute inflammatory response that, if not controlled, is harmful to brain tissue."
The study adds to an ever-growing body of science supporting the potential cardiovascular and brain health benefits of omega-3 fatty acids.
The heart health benefits of fish oil, and the omega-3 fatty acids it contains, are well-documented, being first reported in the early 1970s by Dr Jorn Dyerberg and his co-workers in The Lancet and The American Journal of Clinical Nutrition. To date, the polyunsaturated fatty acids (PUFAs) have been linked to improvements in blood lipid levels, a reduced tendency of thrombosis, blood pressure and heart rate improvements, and improved vascular function.
The new study, reported in the journal Stroke, indicates that DHA may reduce levels of molecules that stimulate tissue inflammation and, conversely, produce a larger quantity of molecules that prevent the activation of cell death.
"This is the first convincing demonstration of the powerful anti-inflammatory effect of DHA in the brain," added Professor Frédéric Calon, co-author of the study.
According to the Canadian researchers, the effects are linked to DHA partially replacing arachidonic acid (AA), an omega-6 fatty acid known for its inflammatory properties.
Mice that were genetically pre-disposed to stroke were divided into three groups: One group was fed a control diet, the second group was fed a diet with low levels of DHA, and the third group was fed a DHA-enriched diet.
The daily dose of DHA in the third group was about 0.7 grams of DHA per kg of body weight per day, which would be equivalent to a dose of 42 grams for a 60 kg human – a massive DHA dose.
Following three months of intervention, the researcher report that the high DHA group displayed an inhibition of levels of pro-inflammatory compounds, including COX2 and IL-1beta, but no changes in other inflammatory compounds.
A favorable change in the ratio of omega-3:omega-6 fatty acids in the brain was also observed.
“Since DHA is readily available, inexpensive, and reduces the risk of a number of health problems without causing significant side effects, the risk–benefit ratio tends to favor the regular consumption of fish or DHA,” added Prof Calon.
In an email with NutraIngredients-USA.com, Prof Calon added that major differences exist between the mouse and the human metabolism, and that comparing doses and their respective impact is "quite difficult". He noted, however, that since a 25 g mouse eats approximately 3 g of food per day, the DHA/EPA dose sums up to a dosage of approx 0.7 g per kg of mouse per day or approx 1.3% of calories intake.
"A mouse eats more than a human relative to its weight and has a much higher metabolism rate, therefore extrapolation of dosage from across species is challenging," he added.
"However, given a consumption of 2,000 calories per day on average for humans, this high dose would represent approximately between 2.5 to 3 g of DHA/EPA per day, which is still reasonable from a nutraceutical point of view."
The Laval-based researcher added that a lower dose may be sufficient in humans since mice have much higher fat metabolism.
Published online ahead of print, doi: 10.1161/STROKEAHA.111.620856
“Accumulation of Dietary Docosahexaenoic Acid in the Brain Attenuates Acute Immune Response and Development of Postischemic Neuronal Damage”
Authors: M. Lalancette-Hebert, C. Julien, P. Cordeau, I. Bohacek, Y-C. Weng, F. Calon, J. Kriz