Vyvienne Evans, of Dunedin, asks :-

Why is vitamin C essential to humans?

Rana Ravindran, of Massey University's Institute of Food, Nutrition and Human Health, responded.

A deficiency of vitamin C leads to scurvy, which has symptoms of soft, swollen, bleeding gums; loosened teeth; bruised skin, slow haemorrhaging and wound healing, rupture of capillaries, osteoporosis and anaemia. Scurvy, a problem in Egyptian and Roman times, is also a disease of winter in snowbound northern countries (and long sea voyages), due to the unavailability of fresh fruits and vegetables in winter. Today, with fresh fruits and vegetables grown in glass-houses and/or shipped in from other countries during our winter, it shouldn't be a problem.

Vitamin C is also a key immune system nutrient and a potent free-radical fighter. Therefore it is also known as an antioxidant vitamin. It can scavenge reactive oxygen species before these destructive substances have a chance to damage the fats. It works along with free radical-fighting enzymes in the body such as glutathione peroxidase, to stop destructive free radical chain reactions, thereby a protective effect for coronary heart diseases.

Vitamin C is required for the synthesis and maintenance of normal connective tissue as well as for wound healing since synthesis of connective tissue is the first event in wound tissue remodelling. Connective tissue holds body cells and tissues together, thereby strengthening bones, teeth and muscles.

Vitamin C is a natural antihistamine. There is also evidence in being anti-carcinogenic! Vitamin C prevents the development of nitrosamines, the cancer-causing chemicals that stem from the nitrates contained in some foods.

Whether vitamin C is helpful as a cold preventative remains a controversy. Vitamin C does not reduce the occurrence or severity of the common cold in the normal population, but it may reduce the duration of the cold.

The take home message is ‘Eat plenty of fresh fruits and vegetables daily to keep healthy’. They provide not just vitamin C, but also other micronutrients and dietary fibre with additional health benefits.