While many self-styled experts continue to decry eating eggs, research shows that eggs are not only one of the best protein sources but also among the most beneficial from a health standpoint. One recent study found that eating a low-carb diet boosted high-density-lipoprotein cholesterol—but only in those whose diet included eggs. High-density lipoprotein (HDL) is thought to offer protective effects against the onset of cardiovascular disease through helping to remove excess cholesterol in the blood. Interestingly, it was the higher cholesterol content of the eggs that was thought to be the active factor in elevating HDL. Those who ate a low-carb diet without eggs showed no rise in HDL.
The same researchers recently published a follow-up study. The objective was to observe the effects of eggs and a low-carb diet on markers of inflammation. The subjects were 28 men, 15 of whom ate three eggs daily and 13 who ate no eggs. Results: Those who ate the eggs had a 21 percent increase in levels of adiponectin, a substance released by fat cells. Adiponectin is a polypeptide, or protein-based, hormone containing a string of 244 amino acids. It provides potent anti-inflammatory effects and is often low in those with higher bodyfat levels. Adiponectin favors the loss of excess fat and is positively associated with increased insulin sensitivity. Those in the egg group also showed lower levels of C-reactive protein, a general marker of inflammation. The authors suggest that the effect may have been due to the high lutein content in eggs. Lutein is an antioxidant most often associated with eye health, but it also exerts overall antioxidant activity. An important point here is that the protective factors are found only in the yolks, and those who eat only egg whites—like bodybuilders—are making a huge mistake.
Another recent study featured 3,000 adult women and found that those with the highest intake of choline—an average of 455 milligrams daily, mostly from eggs—showed a 24 percent decreased risk of breast cancer. That followed a 2003 study from Harvard, which found that women who ate more eggs, vegetable fat and fiber during adolescence had a lower risk of developing breast cancer as adults. Eating one egg a day led to an 18 percent reduced risk of breast cancer in the women. Another recent study found that eating soy foods also offered breast cancer protection, but again, only if they were eaten during adolescence. A Chinese study published in 2005 found that women who reported eating at least six eggs per week showed a 44 percent lower risk of breast cancer than women who ate two or fewer eggs weekly. Studies show that only 10 percent of Americans get the recommended amount of choline (550 milligrams a day for men; 425 for women). One egg supplies 125.5 grams of choline—only in the yolk.
Besides helping to prevent breast cancer, choline also helps to prevent birth defects, such as spina bifida; improves memory because it is a precursor of acetylcholine, a major brain neurotransmitter involved in memory and learning; and helps reduce cardiovascular disease by acting as a methyl donor to lower elevated blood homocysteine, a toxic by-product of the metabolism of the amino acid methionine.
In years past, choline was touted as a fat burner. In fact, choline is not directly involved in the oxidation, or burning, of fats. It is, however, required by the liver to synthesize lipoproteins, which transport fats in the blood. One sign of a choline deficiency is an increase of fat in the liver, considered an early sign of liver failure.
One recent study, however, suggests that taking excess choline could present problems. It examined the effects of choline and its metabolite, betaine, in 7,074 men and women in two age groups (47 to 49 and 71 to 74). The study found that higher amounts of choline in the blood were associated with a greater prevalence of symptoms related to the metabolic syndrome—higher serum triglycerides, glucose, percent bodyfat and waist circumference. On the other hand, higher blood choline was also related to higher HDL and lower total cholesterol. The effect was thought to be linked to a disruption of an enzyme that’s involved in choline metabolism. A confusing aspect of the study was the finding that betaine, which is produced from choline, provided nothing but benefical effects. That’s likely related to the fact that betaine acts as a methyl donor to reduce elevated homocysteine.
References
Ratliff, J.C., et al. (2008). Eggs modulate the inflammatory response to carbohydrate-restricted diets in overweight men. Nutr Metabol. 5:6.
Xu, X., et al. (2008). Choline metabolism and risk of breast cancer in a population-based study. FASEB. 22(6):2045-52.
Konstantinova, S.V., et al. (2008). Divergent associations of plasma choline and betaine with components of metabolic syndrome in middle age and elderly men and women. J Nutr. 138:914-20.
©,2012, Jerry Brainum.Any reprinting in any type of media, including electronic and foreign is expressly prohibited.
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