Why eat egg yolk and not just the whites? Science, answer me!

crackedegg

Egg yolks have a bad rep; not only do dieters avoid them (and order egg white omelets) to reduce calorie intake, earlier this year some people insisted that eating yolks is like smoking.

Let’s take a look at the facts:

  1. Egg yolks are usually rated at 55 calories, whereas whole eggs are rated at 70 calories. 70-55=15 calories in just the whites.
  2. Egg white contains most of the protein content in eggs.
  3. A jumbo chicken yolk is estimated to contain 237 mg of cholesterol. The American Heart Association (AHA) dietary guidelines recommend an adult ingest up to 300 mg of cholesterol a day.
  4. A publication in Atherosclerosis found that eating egg yolks leads to arterial (carotid) plague buildup comparable to that of regular tobacco smokers. They conclude:

Our findings suggest that regular consumption of egg yolk should be avoided by persons at risk of cardiovascular disease. This hypothesis should be tested in a prospective study with more detailed information about diet, and other possible confounders such as exercise and waist circumference.

Structure of cholesterol

Structure of cholesterol

On the other hand, yolk has plenty of benefits:

  1. Yolk contains lutein and zeaxanthin, carotinoid alcohols with plenty of known benefits to the eyes and vision, such as reducing the risk of macular degeneration and cataracts. They function as anti-oxidants in the retina.
  2. The Harvard School of Public Health found no difference between people who ate 1 egg weekly and those who age more among 117,000 nurses followed for 8-14 years.
  3. Yolk contains vitamins A, D, E, and K (not in whites). Egg yolk is among the few natural sources of vitamin D.
  4. 90% of calcium and 93% of iron in the whole egg are contained in the yolk.
  5. Yolk contains choline, an essential nutrient linked to cardiovascular health benefits. The University of North Carolina at Chapel Hill published  that women with higher choline intake were less likely to develop breast cancer.
  6. Yolk contains docosahexaenoic acid (DHA), an omega-3 fatty acid essential to brain, sperm, skin, testicle, and retina development and growth. Some studies have suggested DHA can reduce heart disease, and insufficient dietary DHA is linked to Alzheimer’s disease.
Structure of zeaxanthin

Structure of zeaxanthin

 

A lot of the benefits yolk provide, such as vitamin D or omega-3 fatty acids, can be attained through supplements or other foods. Whether you opt for egg-white when eating omelets depends on you.

Source 1, 2, 3, 4, 5, 6, 7

Supeding

Pastry Chef (https://butterhub.org), software engineer (http://jamesding.org), and fitness enthusiast.

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