|Three whole eggs deliver the most effec-tive "dose" of egg yolk to improve your blood lipid levels - mores specifically: triglycerides ↓ and LDL ↓ but HDL ↑|
Since you know all that, it may seem less important for you than your doctor and other people who may still believe that cholesterol was a dietary villain you'd better avoid altogether to read about egg yolks recently discovered ability to significantly decrease your blood lipid levels.
Ok, eventually, this preliminary study confirms the ability of egg yolks to reduce the blood lipid levels in rats, not men. Its results are yet in line with human studies (Fernandez. 2006) and case reports such as Fred Kern Jr's paper with the telling title "Normal plasma cholesterol in an 88-year-old man who eats 25 eggs a day", a paper that was published in the New England Journal of Medicine in 1991, a decade during which the number of people, let alone well-known scientists who questioned the detrimental health effects of cholesterol was low, if not zero.
|Table 1: Fatty acid profile and cholesterol content of pork belly oil and egg yolk (% of total fatty acid | Park. 2016)|
Question: Do the eggs have to be raw? No, probably not. As you've learned in my often-cited article on oxysterols (~oxidized cholesterol), it may yet be a bad idea to eat hard-boiled eggs. Why's that? Learn more in this SuppVersity Classic: "True or False? Butter, Ghee, Lard & Tallow - Are Saturated Animals Fats the Kings and Queens of the Frying Pan?" | read it!This alone may not sound exciting enough for yet another rodent study to make it into the SuppVersity news. What is exciting enough, though, is the fact that the study is the first study to include another high cholesterol product in a control diet: pork belly oil - an "egg yolk analogue" that has a similar, but not identical fatty acid content as egg yolk (see Table 1); and here's how the study that obviously had a saline control group, as well, worked:
- rats were fed, ad libitum, a purified pellet diet and drinking water for 6 weeks, and egg yolk or other treatments were orally administered every day at a fixed time;
- the amount of egg yolk / pork belly oil, namely 5mg/kg, i.e. the human equivalent of approximately 3-4 egg yolks, had been determined based on data from preliminary experiments in which the authors found that this was the amount of egg yolk where the blood lipid lowering effects plateaued (i.e. didn't increase further, when more egg yolk was fed);
- feces, blood, weight and food intake were measured and/or analyzed daily / weekly;
- liver and abdominal fat were determined at the end of the 6-week study
|Figure 1: Body weight gain and diet intake of rats after oral dosing of egg yolk (Park. 2016).|
Beyond cholesterol: weight and body composition improve as well
Against that background, it is not really surprising that the animals "pork belly group" had also accumulated more abdominal and liver fat than those who were fed with egg yolk and ended up being a non-significant 10% leaner (as in having 10% lower abdominal fat masses) than their peers who received nothing but slightly salted water (saline placebo) on top of their std. rodent diet.
|Figure 2: Liver weight and abdominal fat weight in gram per 100g body weight (Park. 2016).|
What's the latest on egg yolks: While egg yolk is more and more appreciated "as a source of valuable biologically active substances" (Zdrojewicz. 2016 | learn more in FFT), I am pretty sure that future studies will add to the increasing evidence of the health benefits of egg yolk consumption, such as the recently confirmed anti-NAFLD effects in low protein diets (Erami. 2016), or the previously discussed high amount of 'active' vitamin D in egg yolks. Needless to say that the SuppVersity is the place to learn about these studies, first.
|Figure 3: Atherogenic index (top, left), liver enzymes (transaminases ALT and AST | top, right) and lipid levels (triglycerides - TG; total cholesterol - TC; HDL; LDL | bottom | Park. 2016).|
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