Dr. Maxine Gossell-Williams, Contributor
OVER THE years, there has been controversy as to whether eggs should be included in the diet and whether they can increase cholesterol levels in the blood. The American Egg Board (AEB) was formed out of a need to communicate to Americans the significant health benefits of eating eggs and to alleviate the fears surrounding egg consumption. In December 2004, AEB held its first international meeting looking at the health benefits of eggs discovered by eminent scientists in the United States, England and Canada.
Eggs are a rich source of many nutrients. Proteins are found mainly in the egg white. The yolk (yellow portion) makes up about 33 per cent of the liquid weight of the egg and contains all of the fats and vitamins A, B, D and E.
NEGATIVE COMMENTS
Most of the negative comments surrounding egg consumption arise from the fact that one large egg contains over 200 milligrams of cholesterol and the fact that high blood cholesterol is linked to cardiovascular diseases, such as hypertension and stroke. Consistently, however, several clinical studies show that the amount of cholesterol present in the diet has little effect on the amount of cholesterol in the blood of most individuals. Additionally, scientists at the Harvard School of Public Health conducted a 14-year study involving over 117,000 participants and reported in 1999 that eating one egg daily did not increase the risk of heart disease. This is the largest study to date on the topic and was documented in the Journal of American Medical Association. It lead researchers to conclude that for a healthy person, 'an egg a day is OK!' The influence it may have on chronically-ill persons, such as diabetics or persons with a family history of high blood cholesterol remains to be investigated.
One egg provides over 200 mg of choline, a nutrient that was reclassified in 1998 as a necessary component of the diet. Choline is a major building block and signalling compound of cells. The liver also depends on dietary choline to prevent the accumulation of fats. Choline also acts to reduce the formation of homocysteine, a compound that increases the risk of cardiovascular diseases by damaging blood vessels.
MEMORY FUNCTION
The current interest in choline and ensuring adequate supply by the diet comes, however, from the role it plays in ensuring proper memory function. The body uses choline to synthesise acetylcholine, which is a major substance in the brain and plays a significant role in the formation of memory. Studies conducted in animals report that lack of choline in the diet not only destroys their ability to form memory but also causes structural changes in the areas of the brain responsible for memory formation. In one small study reported in 1993 in Clinical Neuropharmacology, 80 students attending West Valley College (USA), given choline supplements showed better memory.
CHOLINE BENEFITS
Most of the current research focuses on the benefits of giving pregnant women choline. Many animal studies conducted at the Duke University in the U.S.A., have confirmed that litters from animals given additional choline during pregnancy had improved memory capacity, including retaining memory longer. Evidence that this can also occur in humans is currently the interest of Professor Steven Zeisel of the School of Medicine at the University of North Carolina in the USA, who has pioneered many of the advances made in choline research.
Presently, not enough scientific data is available to set a recommended daily allowance for choline and thus only an adequate intake amount is assigned. For children, 14 years and older, and adults, the range is 425 -550 milligrams, while for children under 14 years old, it is 125-375 milligrams.
Foods that supply over 110 mg of choline per serving are classified as excellent sources of choline while foods supplying 55 milligrams per serving are classified as good sources of choline.
The incredible edible egg is one of two foods classified as excellent sources of choline (beef liver is the other) and therefore holds an important position in ensuring adequate supply of choline.
Dr. Maxine Gossell-Williams, lecturer/researcher, Department of Basic Medical Sciences, University of the West Indies (Mona).
