In this article

Vitamin A Vitamin D

Vitamin E Vitamin K

Role

Vitamin E is a powerful antioxidant that protects the body against free radicals. It helps to make red blood cells and prevents blood from clotting.

Sources

Foods containing large amounts of polyunsaturated fatty acids will generally contain large amounts of vitamin E. Good sources include wheat germ, prawns, almonds, hazelnuts, peanuts, pistachio nuts, soya beans and sunflower seeds.

Deficiency

A dietary deficiency of vitamin E is extremely rare. However, the signs and symptoms to be aware of include problems in the nervous, vascular and reproductive systems. Vitamin E may also exacerbate the effects of any vitamin K deficiency, thus affecting blood clotting.

Toxicity

Vitamin E has low toxicity and it's unlikely that you'll take in too much from your diet. Very high doses of vitamin E from supplements can cause headaches, fatigue, gastrointestinal distress, double vision and muscle weakness.

Role

This is an essential component in the body’s normal blood-clotting process and plays an important role in maintaining bone health.

Sources

Most vitamin K is produced by micro-organisms in the intestine, and is stored in the liver. Dietary vitamin K is largely obtained from green leafy vegetables such as spinach, Brussels sprouts, broccoli and cabbage, and some vegetable oils including soybean and rapeseed.

Deficiency

Newborn infants are at risk of haemorrhagic disease, a bleeding disorder that may occur because vitamin K production is not established in the intestine until after the first week of life. To tackle this problem, newborn infants are given a vitamin K injection at birth. Otherwise, vitamin K deficiency is rare.

Many studies report that low vitamin K intake increases the risk of developing osteoporosis. Vitamin K is essential for the normal formation of a protein in bones called osteocalcin. This protein binds to calcium and helps to hold the calcium in the bones. Too few studies have been carried out to determine the range of adult vitamin K requirements. One microgram for every kilogram of body weight per day is recommended to maintain the normal blood-clotting process.

Toxicity

Vitamin K has low toxicity from dietary sources.

This article was written by the MRC Human Nutrition Research and published in August 2008.