Stroke is the number three cause of death in the U.S., which makes it bad enough.
Worse yet, stroke is the leading cause of adult disability, with catastrophic consequences to families and an annual $74 billion cost to American society.
The most common strokes by far are the ischemic (iss-keem-ik) type, which doctors sometimes call “brain attacks”.
Like heart attacks, ischemic strokes usually result when inflamed plaque in an artery ruptures and constricts blood flow.
Fish and their omega-3s linked to reduced stroke damage and risk
Population studies suggest that the risk of ischemic stroke is reduced by one-quarter or more among people who eat fish frequently (Bouzan C et al. 2005; Mozaffarian D et al. 2005; Psota TL et al. 2006).
And growing evidence from animal studies indicates that omega-3 DHA from fish fat may reduce brain damage caused by stroke, traumatic brain injury, and concussions.
Last fall, a team from Louisiana State University reported that rats suffered much less stroke-related brain damage when given small doses of DHA within three hours of the event … see “Omega-3 DHA Protected Rats from Stroke Damage”.
Most recently, researchers from West Virginia University reported that rats who received the highest dose of DHA supplementation prior to traumatic brain injury experienced the least amount of tissue damage … see “Omega-3 Curbed Traumatic Brain Injury in Rats”.
Now, scientists from Croatia and Quebec’s Université Laval say that mice fed omega-3 DHA daily for three months suffered 25 percent less brain damage following an artificially induced stroke.
As they wrote, “This is the first convincing demonstration of the powerful anti-inflammatory effect of DHA in the brain. This protective effect results from the substitution of molecules in the neuronal membrane: DHA partially replaces arachidonic acid, an omega-6 fatty acid known for its inflammatory properties.” (Lalancette-Hébert M et al. 2011)
In other words, as the researchers put it, daily consumption of omega-3 DHA from fish fat creates an “anti-inflammatory and neuroprotective environment in the brain that mitigates damage following a stroke. It prevents an acute inflammatory response that, if not controlled, is harmful to brain tissue.” (UPI 2011)
Mouse diet rich in omega-3 DHA curbed brain damage after a stroke
The joint Croatian-Canadian team divided mice into three groups:
Following three months on the assigned diets, strokes were induced in all of the mice, and the High-DHA group showed several advantages with regard to inflammation and brain damage:
Smaller areas of “ischemic lesions” (tissue damage)
Higher levels of a molecule (Bcl-2) that curbs cell death.
Higher ratio of omega-3 to omega-6 fatty acids in the brain.
Smaller rises in levels of some pro-inflammatory compounds (i.e., COX2 and IL-1beta).
As the Croatian/Quebecois team wrote, “… these data indicate that diet-induced accumulation of DHA in the brain protects against post-ischemic inflammation and injury.”
“Because DHA is widely available at low cost and has an excellent safety profile, our data suggest that increased DHA intake may provide protection against acute immune response/brain damage in ischemic stroke.” (Lalancette-Hébert M et al. 2011)
Protective dose of omega-3 DHA seen practical for people, too
Animal studies often use quite high doses of a test drug or nutrient to ensure that any effect will be measureable.
The High-DHA group got about 0.7 grams of DHA per kilogram (2.2 pounds) of body weight per day.
This equals a dose of 42 grams of DHA for a 60 kilogram (132-pound) person: an impractically large – and likely unhealthful – amount.
However, as the researchers noted, a mouse eats much more than a human relative to its weight, and has a much higher metabolism rate, including much faster metabolism (breakdown) of dietary omega-3s and other fats.
This difference means that, compared with a mouse, a person retains more dietary DHA and more of it gets into their cells.
(Omega-3 DHA constitutes a whopping 60 percent of all of the fats in the brain, and is absolutely essential to basic and optimal brain function … and to resolving inflammation.)
The test dose given the High-DHA group equaled about 1.3 percent of the animals’ daily calories.
Although it is impossible to translate omega-3 intakes from mice to humans precisely, the researchers estimated that the equivalent human dose would be about 2.8 grams of DHA per day.
Heart patients with high triglyceride levels are advised to take 4 grams of fish-form omega-3s (DHA and EPA) daily, including about 2 grams of DHA.
Accordingly, it seems plausible that people might gain some stroke-damage protection by taking high – but decidedly reasonable – daily doses of DHA.
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