Just last week, we reported that people who take high-dose fish oil enjoy significant improvements in their mood and reaction times.
And, they showed a large, beneficial decrease in the ratio of the pro-inflammatory omega-6 arachidonic acid to the anti-inflammatory "marine” omega-3 known as eicosapentaenoic acid (EPA).
However, these clinical results were recorded in study participants who took fish oil capsules containing high, concentrated doses of both of the two key marine omega-3s—1.6 gm of EPA and 0.8 gm of DHA—for only 35 days.
While this study helps confirm and further detail the benefits that dietary omega-3s bring to consumers’ mood and brain function, the doses consumed were at least four times higher than the amounts you’d get from two meals of fatty fish per week, which is the amount usually recommended to reduce the risk of heart disease.
Accordingly, we were pleasantly surprised to chance upon an earlier research report from 2004, whose results showed the long term positive benefits of moderate fish intake on brain functions.
Dutch team examined links between fish intake and brain improvements
To get at any possible associations between dietary fish and brain function, Dutch researchers analyzed the data collected during a population study among 1,613 subjects ranging from 45 to 70 years old.
During the five years from 1995 until 2000, participants were given an extensive battery of cognitive tests, including memory, psychomotor speed, cognitive flexibility (i.e., higher-order information processing), and overall cognition.
To determine what they were eating, subjects filled out food-frequency questionnaires.
Findings support brain benefits of fatty fish
The results showed that among the participants who ate fish, the 10 percent who ate the most fish—hence, the most marine omega-3s—enjoyed the lowest risk of impaired cognitive function and speed.
In other words, the more fish participants ate, the better they performed on several brain function tests.
Past research results suggest that high-cholesterol diets raise the risk of Alzheimer’s disease, and this study supports those findings. The Dutch team found that the participants’ brain performance and speed declined as cholesterol intake increased.
A saturated-fat surprise
Prior research results show that people in the upper fifth of saturated-fat intake suffer double the risk of getting Alzheimer’s disease, compared with people in the lowest fifth of saturated-fat intake.
Accordingly, the Dutch researchers expressed some surprise that increasing levels of saturated fat intake did not raise the risk of impaired brain function to a statistically significant extent.
The average American gets 12-13 percent of their total calories from saturated fat, which is more than the maximum of 10 percent most public health organizations recommend.
But it is important to note that the specific type of saturated fat that’s abundant in cocoa butter, chocolate, and lean (e.g., grass-fed) beef—called stearic acid—does not raise blood levels of LDL ("bad”) cholesterol or the risk of heart disease.
And, dark chocolate is high in antioxidants—specifically, epicatechin flavon-3-ols closely related to the flavon-3-ols in tea—shown to exert highly beneficial effects on some key risk factors for heart disease. Its antioxidants combine with the dominance of stearic acid in its fat profile to explain why eating this remarkably heart-healthful—albeit relatively high-calorie—treat does not raise cholesterol levels significantly.
However, given the difficulty of communicating fine nutritional distinctions, such as the varying effects of different saturated fats, it is not surprising that the authors of Harvard study from 1999 sounded this cautionary note: "A distinction between stearic acid and other saturated fats does not appear to be important in dietary advice to reduce CHD risk, in part because of the high correlation between stearic acid and other saturated fatty acids in typical diets.”
This viewpoint makes sense, since the standard corn-fed beef most Americans eat is relatively high in unhealthful saturated fats and raises the risk of cardiovascular disease. Thus, it is probably better to communicate simple guidance like "saturated fat is bad for the heart”, rather than confuse people with attempts to paint a more nuanced picture.
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