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It’s no Joke: Don’t Ditch the Yolk

The below article was issued for the South African Poultry Association (SAPA) by Protactic Strategic Communications

Do you ditch the egg yolk? Let’s crack open why you should put the nutrient-packed, golden egg yolk back on your menu.

It’s No Yolk!

While the egg white contains protein, selenium, and the B-vitamin riboflavin, did you know that most of the nutrition is actually found in the egg yolk? Egg yolks contain the heart healthy fats called monounsaturated fats. Added to this, egg yolks contain half of the protein of the whole egg. If you avoid eating the egg yolk, you are missing out on vitamin A, D, E and iron, too.

The Cholesterol Query

Found mostly in the egg yolk are fat and cholesterol, two nutrients with a bad reputation. Cholesterol has some important functions in the human body though. For example, cholesterol is a major part of the human brain, is an essential structural component in cell membranes and is a chemical precursor for some hormones.

Though it is true that eggs are high in cholesterol, scientists are starting to understand why whole egg, a source of dietary cholesterol, doesn’t raise blood cholesterol. In 2018, researchers found that cholesterol in whole egg is actually not well absorbed by the body1, giving us more insight as to why dietary cholesterol does not raise blood cholesterol. It appears that the body may have compensatory mechanisms to help deal with consumed cholesterol found in egg yolks.

Out of Sight, Out of Mind

Eggs are rich in carotenoids, a nutrient which gives egg yolk its golden colour. The two main carotenoids in egg yolk are lutein and zeaxanthin, found in high concentrations in the retina of the eye. For this reason, these key nutrients are linked to improved sight, reduced risk of cataracts and an age-related eye disease called macular degeneration. 2

The carotenoids in egg yolk are also associated with reduced risk of neurodegenerative disorders like Alzheimer’s disease3 and dementia.4

Power Food

A new study published in 2020 in Journal of Strength and Conditioning Research5 gave whole eggs the thumbs up. The Iranian researchers concluded that eating whole eggs when during resistance (weight) training helps with better muscle building, improvements in body fat, and greater strength. Other research in Canada also supported this: eating whole eggs immediately after resistance exercise resulted in better muscle building than if only the egg white was eaten.6 When following this up in another study, the same researchers confirmed better muscle building in participants who ate whole eggs.7

The muscle-building capability of eggs is also linked to the protein: one large egg contains 7g of protein. When combined with resistance training, protein provides the building blocks for muscle building. Protein is also needed to keep the immune system strong, which often takes a knock with hard training sessions.

So, it seems that removing the egg yolk may be counterproductive when trying to follow an egg-cellent diet. Go ahead – choose the whole egg in order to maximise on all the nutrient and health benefits that eggs have to offer up.

Photo by Haley Hamilton on Unsplash

References

  1. Kim, J.E., Campbell, W.W., 2018. Dietary Cholesterol Contained in Whole Eggs Is Not Well Absorbed and Does Not Acutely Affect Plasma Total Cholesterol Concentration in Men and Women: Results from 2 Randomized Controlled Crossover Studies. Nutrients. 10, 1272. Doi:10.3390/nu10091272.
  2. Zaheer, K., 2017. Hen egg carotenoids (lutein and zeaxanthin) and nutritional impacts on human health: a review. CYTA – Journal of Food. 15(3), 474–487.
  3. Nolan, J.M. et al., 2015. The impact of supplemental macular carotenoids in Alzheimer’s disease: A randomized clinical trial. Journal of Alzheimer’s Disease. 44, 1157–1169. Doi:10.3233/JAD-142265.
  4. Feart, C. et al., 2016. Plasma carotenoids are inversely associated with dementia risk in an elderly French cohort. The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences. 71, 683– 688. doi:10.1093/gerona/glv135.
  5. Bagheri, R. et al., 2020. Whole Egg Vs. Egg White Ingestion During 12 weeks of Resistance Training in Trained Young Males: A Randomized Controlled Trial. Journal of Strength and Conditioning Research. 5(2), 411–419.
  6. Vliet, S. et al., 2017. Consumption of whole eggs promotes greater stimulation of post exercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men. American Journal of Clinical Nutrition. 106, 1401–12.
  7. Sawan, S.A. et al., 2018. Whole egg, but not egg white, ingestion induces mTOR colocalization with the lysosome after resistance exercise. Am. J. Physiol. Cell Physiol. C537–C543.

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