Egg Yolks Contain Leucine : So Get Them Down Ya!

The vibrant yellow part of the egg is the yolk, but I’m not meaning to tell people how to suck eggs here! This nourishing part of the egg is quite often discarded by gym goers because that’s where the cholesterol is. The problem with this is that actually, the cholesterol in the yolk is no more harmful to us than a squat is to your knees (for the record, squats are pretty good for your knees).

An average medium egg in its shell weighs approx 30g, so using this standard weight we can ascertain that an average egg contains 0.7g of Leucine, 0.3g coming from the white and 0.4g from the yolk. This said, the majority of the protein in an egg is found in the egg white, and all of the saturated fat can be found in the yolk. It’s for this reason that many athletes will mainly consume egg whites, avoiding the yolk! The issue I have with this is that the majority of the yolks get discarded down the sink…really, why!?

The saturated fat content of the yolks can be an issue if consumed in excess, particularly if you have an increased risk of heart disease.

Why is saturated fat a problem?

According to current guidelines, saturated fat is a concern because of it’s negative effect on cholesterol ratios, in particular the HDL (good) and LDL (bad) cholesterol. It is desirable to have a higher ratio of HDL to LDL cholesterol in the blood. An excess of LDL’s can become vLDL (very low density lipoprotein) and oLDL (oxidised LDL), these can deposit in the arteries causing inflammation and contributing to atheromas (arterial plaques). Saturated fat is fine in moderation, the odd egg yolk (maybe 1 yolk per every 3 eggs) is fine. Mann & Truswell (2009) state that 3 yolks a week is fine, and depending on your body weight, maybe 4-5 is acceptable, although this is largely dependant on your goals and overall health.

Nutritional value of an egg

The egg is known as a marvel to the kitchen as well as to nature for its role as a convenient nutritional package providing all of the amino acids, a high number of micronutrients and particularly (for fitness and bodybuilding athletes) all of the Branched Chain Amino Acids (BCAAs), Leucine, Isoleucine and Valine. Eggs are abundant in riboflavin, zinc, iron, folate, vitamin B12 and vitamin A. Eggs also contain the antioxidants lutein and zeaxanthin, these amazing scavengers whizz around your body soaking up damaging free radicals helping to preserve cell health and integrity (Mann & Truswell, 2007).

An egg’s unique selling point is its capacity to deliver all of the essential amino acids (including BCAAs). Of particular interest is it’s Leucine content, this is the main amino acid found in the popular BCAA supplements. As previously mentioned, many people discard the vibrant yellow yolks because of their fat and cholesterol content, however it’s worth noting the following…Dietary cholesterol DOES NOT effect your bodies cholesterol levels, saturated fat does, and 2-3 yolks a week won’t cause you too many issues provided you don’t have an inherent or elevated risk of heart disease. What if I was to tell you that the yolks contain more Leucine per egg than the egg white does, it is the yolk that provides the nourishment to the growing embryo because of its nutritional density. Consequently you get 0.4g Leucine from the yolk, and 0.3g from the white, potentially delivering 0.7g of muscle building Leucine per egg, not to mention the 6g of biologically available protein!

About the Author

Job Role Qualified Dietitian and Sports Nutritionist Qualifications BSc (Hons) Sports Science | BSc (Hons) Dietetics Tom has always participated in sport both recreationally and competitively which led to an unquenchable thirst for information on anything health, nutrition and fitness. After leaving school Tom went on to play for a football academy during which time he studied Sport and Exercise Science. From here he went on to study a BSc (Hons) Sport Science at UEA followed by his second BSc (Hons) degree, this time at the University of Hertfordshire studying Dietetics. Tom has worked in the fitness, educational and clinical nutrition industry starting out at David Lloyd Health and Leisure Clubs. He then went on to work as a Dietitian (RD) in the NHS, during which time he conducted clinics for healthy eating, weight loss and weight gain, as well as specialised consultations on Diabetes, IBS and Coeliac disease to name a few. He has vast amounts of experience at devising diet plans and supplement regimens, as well as working in the community with schools and competitive athletes. As Head Nutritionist and Supplement expert at Discount Supplements Tom is here to provide current and evidence based health and nutrition information to help you reach your health and fitness goals!
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