APOE and the Association of Fatty Acids With the Risk of Stroke, Coronary Heart Disease, and Mortality

[Kenny4/4]

An extremely important study related to apoe4 and fatty acid profile/consumption. The study looks to be well done and the effect of differences in fatty acid profile/consumption is profound. The pro or neutral saturated fatty acid theory takes a beating on this study.

https://www.ahajournals.org/doi/full/10 ... 118.022132

[Brainz]

I’m not sure I agree with your conclusions. It should be noted that the study looked at blood plasma concentrations of the fatty acids, not consumption of fatty acids by participants. Further, as carbohydrate consumption is known to increase plasma levels of Palmitic acid (the saturated fat the study associates with higher risk of cardio vascular disease, especially in E4s), one could draw a different conclusion: That E4s will do best on a low carb diet that reduces plasma levels of Palmitic acid. The study does not adequately address the risks of consumption of any of these fatty acids as it does not link such consumption to plasma levels of the same.


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[Julie G]

Brainz, this paper supports your perspective.

Recent meta-analyses have found no association between heart disease and dietary saturated fat; however, higher proportions of plasma saturated fatty acids (SFA) predict greater risk for developing type-2 diabetes and heart disease. These observations suggest a disconnect between dietary saturated fat and plasma SFA, but few controlled feeding studies have specifically examined how varying saturated fat intake across a broad range affects circulating SFA levels. Sixteen adults with metabolic syndrome (age 44.9±9.9 yr, BMI 37.9±6.3 kg/m2) were fed six 3-wk diets that progressively increased carbohydrate (from 47 to 346 g/day) with concomitant decreases in total and saturated fat. Despite a distinct increase in saturated fat intake from baseline to the low-carbohydrate diet (46 to 84 g/day), and then a gradual decrease in saturated fat to 32 g/day at the highest carbohydrate phase, there were no significant changes in the proportion of total SFA in any plasma lipid fractions. Whereas plasma saturated fat remained relatively stable, the proportion of palmitoleic acid in plasma triglyceride and cholesteryl ester was significantly and uniformly reduced as carbohydrate intake decreased, and then gradually increased as dietary carbohydrate was re-introduced. The results show that dietary and plasma saturated fat are not related, and that increasing dietary carbohydrate across a range of intakes promotes incremental increases in plasma palmitoleic acid, a biomarker consistently associated with adverse health outcomes.

[Kenny4/4]

How about Lineolic Acid consumption and plasma levels? I was always under the impression that type of fatty acid consumption determines fatty acid levels in the body. I have also heard that saturated fats are only ok if one is on a low carb diet. What do y’all think? That study is pretty powerful and perhaps Palmitic acid consumption and serum levels aren’t completely correlated but I would think only eating a very small amount of palmatic acid and keeping carbs down would result in low serum levels. Eh? Maybe carbs are a confounder in a direct consumption to serum level? The study does kind of throw a curveball at the oxidized cholesterol/omega 6 fatty acid theory of heart disease.

[Kenny4/4]

Excess carbohydrates in the body are converted to palmitic acid. Palmitic acid is the first fatty acid produced during fatty acid synthesis

Quote above is right out of Wikipedia.
Looks like excess carbs are a part of the palmatic acid process.

On to the lineolic acid side of the study. I believe essential fatty acid serum levels are directly related to consumption. They compete with one another and are limited by an enzyme. Maybe increasing that enzyme is the key?
That said I’m not eating any Palm oil or Saturated Fats tomorrow or hitting the sweets either.

I will say those results in the study are pretty profound.

[Kenny4/4]

I stand corrected on Saturated Fats and their consumption in the diet and the effect on serum palmitic acid levels. It looks like the levels are driven by carbs or and or excess carbs. Thanks for clarifying this Brainz and Julie.

[Creekside]

I stand corrected on Saturated Fats and their consumption in the diet and the effect on serum palmitic acid levels. It looks like the levels are driven by carbs or and or excess carbs. Thanks for clarifying this Brainz and Julie.

To be fair, the authors of that first study wrote a very misleading abstract:
The role of dietary fat on cardiovascular health and mortality remains under debate. Because the APOE is central to the transport and metabolism of lipids, we examined associations between plasma fatty acids and the risk of stroke, coronary heart disease, and mortality by APOE-ε4 genotype. (My empahsis)

When the abstract starts out talking about dietary fat, it definitely leaves the (mis)leading impression that the elevated plasma fatty acid levels are related to dietary fat consumption. They could have been much, much clearer in the abstract and conclusions section.

[mike]

And they are just looking at data to try to find correlations. Nothing causal. These things can help you to decide where to do research, but in itself doesn't tell you that much...

[Kenny4/4]

http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf
It appears from this study that yes eating more Palmitic Acid aka (C16:0 saturated fat) increases your plasma level of palmitate acid and possibly your stroke risk and survival time when it is paired with the first study. The associations could be completely independent but I wouldn’t bet on it. Food for thought.