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The not so humble Egg….

Eggs

Forget egg white omelettes – it’s the yolks that we should be eating!

Eggs are one of my pet subjects, so here goes….

There seems to be some confusion over the number of eggs one can eat on a regular basis because the recommendation has changed over the years; in the past a restriction on eggs was advised because it was thought that foods which are high in cholesterol could raise cholesterol levels in one’s body, but it is now known to not have a significant impact on blood cholesterol levels. So eggs, shellfish, liver and kidney can all be eaten without guilt as part of a varied and balanced diet. (I have to admit to never having restricted my egg consumption – even when the official recommendations used to be to limit them to one or two a week. I’m now waiting for the guidelines on butter to change…..)

The myth that eating eggs is bad for your heart can now be laid to rest – a large study to look at the impact of egg consumption on heart disease found no connection between them.

The yolk contains most of the nutrients in an egg; they are full of cholesterol but like most cholesterol-rich foods, they are jam-packed full of important nutrients, especially fat-soluble vitamins and essential fatty acids. Egg whites, on the other hand, contain mainly protein and not many other nutrients – the only justification for eating them is their attachment to the yolk! A common misconception is that yolks don’t contain much protein; in fact they contain 43% of the total protein of a whole egg. Yolks are also a good source of choline, which has been linked with preserving memory, and lutein and zeaxanthin, which may protect against certain visual problems (macular degeneration and cataracts).

Don’t believe it? Look at the table below which compares the nutritional value of egg whites and yolks.

Egg Yolks Versus Egg Whites (Data taken from the USDA Nutrient Database for Standard Reference).

Nutrient % Total in White % Total in Yolk
Protein 57% 43%
Vitamin A 0% 100%
Vitamin E 0% 100%
Vitamin D 0% 100%
Vitamin K 0% 100%
DHA and AA 0% 100%
Carotenoids 0% 100%
Thiamin (Vitamin B1) 3.2% 96.8%
Riboflavin (Vitamin B2) 61.7% 48.3%
Niacin (Vitamin B3) 89.7% 9.3%
Pantothenic acid (Vitamin B5) 11% 89%
Vitamin B6 3.3% 96.7%
Folic acid (Vitamin B9) 5% 95%
Vitamin B12 8.3% 91.7%
Calcium 9.5% 90.5%
Magnesium 80.8% 19.2%
Iron 6.2% 93.8%
Phosphorus 7% 93%
Potassium 74.4% 25.6%
Sodium 87% 13%
Zinc 0.2% 99.8%
Copper 38% 62%
Manganese 30.8% 69.2%
Selenium 41% 59%

From a study at the Department of Nutritional Sciences, University of Connecticut:
The lack of connection between heart disease and egg intake could partially be explained by the fact that dietary cholesterol increases the concentrations of both circulating LDL and high-density lipoprotein (HDL) cholesterol in those individuals who experience an increase in plasma cholesterol following egg consumption. It is also important to note that 70% of the population experiences a mild increase or no alterations in plasma cholesterol concentrations when challenged with high amounts of dietary cholesterol. Egg intake has been shown to promote the formation of large LDL (which is not harmful), in addition to shifting individuals from the LDL pattern B to pattern A, which is less atherogenic (i.e. less likely to block your arteries).

More below on eggs from the pubmed website – peer-reviewed primary research reports in the life sciences. Pubmed is a free database accessing primarily the Medline Database of references and abstracts on life sciences and biomedical topics. The US National library of Medicine at the National Institutes of Health maintains the database:

Exploring the factors that affect blood cholesterol and heart disease risk: is dietary cholesterol as bad for you as history leads us to believe? [1]
This paper summarizes presentations given at the 2011 Experimental Biology meetings about the latest research and a paleoanthropological perspective pertaining to the relationship between dietary cholesterol intake and cardiovascular disease risk. For much of the past 50 years, a great deal of the scientific literature regarding dietary fat and cholesterol intake has indicated a strong positive correlation with heart disease. In recent years, however, there have been a number of epidemiological studies that did not support a relationship between cholesterol intake and cardiovascular disease. Further, a number of recent clinical trials that looked at the effects of long-term egg consumption (as a vehicle for dietary cholesterol) reported no negative impact on various indices of cardiovascular health and disease. Coupled with data indicating that the impact of lowering dietary cholesterol intake on serum LDL levels is small compared with other dietary and lifestyle factors, there is a need to consider how otherwise healthy foods can be incorporated in the diet to meet current dietary cholesterol recommendations. Because eggs are a healthful food, it is particularly important that sensible strategies be recommended for inclusions of eggs in a healthy diet.

Re thinking dietary cholesterol [2]
The perceived notion that dietary cholesterol is associated with increased risk for coronary heart disease (CHD) has led to dietary recommendations of no more than 300  mg/day for healthy populations in the USA. This study will review the recent evidence that challenges the current dietary restrictions regarding cholesterol while it presents some beneficial effects of eggs (an icon for dietary cholesterol) in healthy individuals.

Although numerous clinical studies have shown that dietary cholesterol challenges may increase plasma LDL cholesterol in certain individuals, who are more sensitive to dietary cholesterol (about one-quarter of the population), HDL cholesterol also rises resulting in the maintenance of the LDL/HDL cholesterol ratio, a key marker of CHD risk.

The lines of evidence coming from current epidemiological studies and from clinical interventions utilizing different types of cholesterol challenges support the notion that the recommendations limiting dietary cholesterol should be reconsidered.

Effects of eggs on plasma lipoproteins in healthy populations [3]
Department of Nutritional Sciences, The University of Connecticut

Extensive research has not clearly established a link between egg consumption and risk for coronary heart disease. This lack of connection can be explained by two major reasons: First, eggs are a good source of numerous nutrients including lutein and zeaxanthin, potent antioxidants, which may exert a protective effect against lipoprotein oxidation. Second, it has been well established that dietary cholesterol increases the concentrations of both circulating LDL and HDL cholesterol in those individuals who experience a higher increase in plasma cholesterol following egg consumption (hyper-responders). It is also important to note that 75% of the population experiences a mild increase or no alterations in plasma cholesterol concentrations when challenged with high amounts of dietary cholesterol (normal responders and hypo-responders). Egg intake has been shown to promote the formation of large LDL and HDL subclasses in addition to shifting individuals from the LDL pattern B to pattern A, which is less atherogenic. For these reasons, dietary recommendations aimed at restricting egg consumption should be taken with caution and not include all individuals. We need to acknowledge that diverse healthy populations experience no risk in developing coronary heart disease by increasing their intake of cholesterol but in contrast, they may have multiple beneficial effects by the inclusion of eggs in their regular diet.

Dietary cholesterol provided by eggs and plasma lipoproteins in healthy populations [4]
Department of Nutritional Sciences, The University of Connecticut
The lack of connection between heart disease and egg intake could partially be explained by the fact that dietary cholesterol increases the concentrations of both circulating LDL and high-density lipoprotein (HDL) cholesterol in those individuals who experience an increase in plasma cholesterol following egg consumption (hyperresponders). It is also important to note that 70% of the population experiences a mild increase or no alterations in plasma cholesterol concentrations when challenged with high amounts of dietary cholesterol (hyporesponders). Egg intake has been shown to promote the formation of large LDL, in addition to shifting individuals from the LDL pattern B to pattern A, which is less atherogenic. Eggs are also good sources of antioxidants known to protect the eye; therefore, increased plasma concentrations of lutein and zeaxanthin in individuals consuming eggs are also of interest, especially in those populations susceptible to developing macular degeneration and eye cataracts.
SUMMARY:
For these reasons, dietary recommendations aimed at restricting egg consumption should not be generalized to include all individuals. We need to acknowledge that diverse healthy populations experience no risk in developing coronary heart disease by increasing their intake of cholesterol but, in contrast, they may have multiple beneficial effects by the inclusion of eggs in their regular diet.

Eggs: The new-superfood? (from The Daily Telegraph) [5]
They’re rich in vitamins and minerals and have been found to have anti-inflammatory properties. Could eggs be the new super-food?