1.6.4 Vitamin B6 (pyridoxine)
Vitamin B6 is composed of pyridoxine and two closely related compounds. It is found in small quantities in many foods, though it can be destroyed in the cooking process. No clear deficiency disease has been recognised in humans as being directly caused by lack of this vitamin, since it is often found in conjunction with other B vitamins and their absence has greater effects. Its main role is in the conversion of some amino acids into other ones, depending on the requirements of the body. It also plays a role in fat metabolism (in the conversion of linoleic acid to arachidonic acid) and in carbohydrate metabolism. Thus, deficiency causes generalised problems such as anaemia, dermatitis and neuromuscular problems such as headaches, aching muscles and difficulty in walking. There is some evidence that low doses of vitamin B6 can be helpful in improving the symptoms of premenstrual syndrome (PMS), even when there is no evidence of deficiency in the diet.