What micronutrients do eggs contain and what do these do?

Our body requires us to eat not just for fuel but also for growth, development and materials for our bodily functions. Macronutrients provide our body with energy whilst micronutrients do not provide the body directly with any energy but are essential for the proper functioning of the body.

There are two types of micronutrient: vitamins and minerals. They are essential for all metabolic processes (all the reactions that keep you alive!) and many others such as production of hormones and strengthening teeth and bones, so it is very important to consume enough of them!

Vitamins (the vital amino acids) are vital to our growth and development and for maintaining good health. Our body also requires small amounts of inorganic chemicals, minerals, to support formation of bone, teeth, nails and blood cells. Each vitamin and mineral has a specific role in the body. As each food source contains different amounts of each vitamin and mineral, it is important that we eat a varied diet with lots of fruits and vegetables to ensure that that we get sufficient amounts for our body to function.

Vitamins and essential minerals, (with the exception of vitamin D) cannot be synthesised by humans, they need to be ingested in the diet to prevent disorders of metabolism. Vitamin deficiency is actually higher in Western diets than is generally believed due to our modern diets. Small deficiencies in several vitamins and minerals are associated with increased risk of chronic diseases such as cancer, heart disease, osteoporosis and diabetes.

An egg is full of micronutrients which are important in muscle strength, brain function, eye healthy, healthy pregnancy and weight management. Eggs are a good source of vitamins B12 and B2, vitamin D, antioxidants and trace minerals as well as choline.

Vitamin B12 (cobalamin) is found in animals food, meat, eggs, fish, milk and shellfish. Whilst the vitamin B12 in eggs may be less bioavailable than that found in meat, it is important for vegetarians as vitamin B12 is required for making DNA, red blood cells and promoting a healthy nervous system. Vitamin B2 (riboflavin) is important in energy metabolism, antioxidant protection of glutathione and promotes iron metabolism.

Vitamin D status is below optimum levels in many countries due to lack of sunshine which makes it especially important to ensure that you have sufficient intakes in your diet. Egg yolks are a good source of vitamin D and the most important vegetarian source. Doctors are concerned as research is discovering that vitamin D deficiency is a risk factor for a whole host of diseases such as heart disease, cancer and diabetes. Whilst our bodies do store vitamin D for some months, by late autumn our stored levels are decreasing and the best way to ensure you have sufficient vitamin D is to include oily fish such as salmon, sardines and mackerel in our diet along with eggs, fortified cereals and other products, mushrooms, cheese. Anyone at risk would be advised to take an oral vitamin D supplement.

Choline is an essential nutrient required for fetal brain development and prevents brain defects in pregnancy. In adults, it is important for maintaining the structure of brain cell membranes and in the production of an important neurotransmitter that passes messages from the brain to muscles via the nerves. Egg yolks are an excellent source of choline – 2 eggs will provide half the daily intake required for a pregnant or breast-feeding woman.

Egg yolks also contain lutein and zeaxanthin, two of the most important antioxidants for eye health. The amount of these nutrients depends on the hen’s diet but research has shown that these antioxidants are more bioavailable than those found in leafy spinach.

Eggs are a good source of several trace minerals such as selenium, iodine and molybdenum and a small amount of iron. Selenium is required for a healthy immune system, preventing cellular damage and regulating the thyroid hormones. Molybdenum is an important component of sulphite oxidase and this is important for metabolizing amino acids and building protein. Iodine is also important for thyroid health.

References

Zeisel SH. Choline: Critical role during fetal development and dietary requirements in adults. Annu Rev Nutr, 2006; 26:229-50.

Moeller SM, et al. 2000. The Potential Role of Dietary Xanthophylls in Cataract and Age-Related Macular Degeneration. J Am Coll Nutr. 19(5):522S-527S.

Chung HY, et al. Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men. J Nutr. 2004; 134:1887-1893.