Vitamin K

Vitamin K is a fat soluble vitamin and can be stored by the body. There are really three vitamin Ks: K1, K2 and K3. K1 was isolated from alfalfa by a Danish chemist Dr Henrik Dam in 1939 and shortly afterwards K2 was isolated from decayed fishmeal by an American Dr Edward Doisy. Both men were awarded the Nobel Prize in 1943. K3 is a synthetic (man made) vitamin.

As well as being found in various foods K is also produced in the body by bacteria in the intestines.

• It helps blood coagulate (i.e. harden and form a seal or scab over a cut). The letter K, chosen to describe this vitamin, comes from the Danish word for coagulation, "Koagulation".
• It aids the prevention of internal bleeding.

Important

• Beef liver (100g serving)
• Green and leafy vegetables, e.g. broccoli, spinach,
• cabbage, cauliflower (60-100g serving)
• Soya beans, cooked (100g serving)
• Potatoes (120g)

Moderate

• Fresh vegetables - peas, carrots, beans (60-100g serving)
• Full cream/skim milk (250ml serving)
• Pork and chicken liver (100g serving)
• Beef (100g serving)
• Wheat germ (10g serving)

Low or Nil

• Fruit
• Cereals

Vitamin K survives most cooking processes but losses do occur in commercial food processing, particularly in freezing.

Oxygen and light can cause vitamin loss in dark green vegetables such as spinach.

Food eaten by adults, together with the body's naturally manufactured supply, would normally provide more than sufficient vitamin K.

For new born babies, however, the story is a little different. Their bacteria-free intestines are not yet able to produce K and are therefore at risk of deficiency.

This risk is increased by the fact that vitamin K, because It is fat soluble, is not easily transferred from the mother's placenta (food source) to the fetus (unborn baby). There is also a low level of vitamin K in breast milk.

Alcoholics are a group at risk of deficiency since an excessive intake of alcohol generally prevents the absorption of all vitamins. In addition to this, vitamin K's main function is in the liver which can become diseased in an alcoholic.

These have not been set by nutritional authorities. This is mainly because vitamin K is available in a wide range of foods and is also manufactured by the body itself. In addition, there is very little evidence of deficiency.

Research has suggested that the daily requirement is in the vicinity of 2 micrograms per kilo of body weight per day, but half could come from intestinal bacteria.

Supplements are used in the treatment of hemorrhaging diseases occurring in new born babies.

They are also used in cases where antibiotic medication is destroying intestinal bacteria and so preventing the formation of vitamin K.

It has been suggested that vitamin K should be given to all pregnant women, though scientific opinion remains divided on this point.

A supplement is sometimes used where a specific disease (often a liver problem) prevents the proper absorption of vitamin K in the body.

Sometimes used to counteract the anticoagulant drugs given to heart condition patients in order to prevent blood clotting.

There have been no reports of toxicity. The synthetic vitamin K3, however, does have toxic effects if taken in large doses.