But times have changed and the more applicable saying now would be: "One vitamin tablet a day keeps the doctor away."

Vitamins, one of the six most important kinds of nutrition found in the human body, can help balance the composition of the other five - protein, fat, water, minerals and carbohydrates, and assure the body functions properly.

"In principle, if a person's diet is well balanced and properly managed, there's no need to take extra vitamins through tablets," said Zhao Faji, honourary president of the Chinese Nutrition Society (CNS).

"In practice, however, people rarely get exactly the required amount of vitamins in daily life either because of cooking and eating habits, or different needs of different individuals, making an intake of vitamin pills essential."

Vitamin A

Vitamin A is helpful for the growth of the body, the bones, fertility, good eyesight, and activates the body's anti-infection and immune systems.

Many types of meat, especially animals' organs, and green, reddish or yellowish vegetables are rich in vitamin A.

However, in China, because of the diet, most people are lacking vitamin A and the situation is especially serious with children according to a recent survey of several big cities including Shanghai and Beijing, said professor Zhao.

"In other countries, people eat more milk, meat and quite a lot of raw vegetables, which helps them get more vitamin A," said Zhao. "In Shanghai people don't tend to eat animal organs as much as people from other parts of China do; expatriates - any vegetarians in particular - should pay special attention to making sure they get enough vitamin A through other means."

A lack of vitamin A will lead to night blindness, when the eyes are very slow to adjust to sudden darkness.

In more serious cases, this can develop into xeroma - a kind of eye disease.

Vitamin C

Vegetables and fruit are usually rich in vitamin C. Many Chinese believe that pepper, though it is thought to increase body heat, is especially rich in vitamin C.

If you lack vitamin C, you may see blood on your toothbrush bristles after brushing teeth - in minor cases, but a serious deficiency can cause scurvy - a kind of disease of the blood, said Zhao.

A lack of vitamins A, C or E is also manifested in dryness of skin as well as deterioration of the immune system, especially among children who will become very vulnerable to infection.

Vitamin B1

Professor Zhao emphasized the problems of a lack of vitamin B1 because it is especially serious in countries or places which have high standards of living and use more and more refined rice and oil.

"This is harmful to the metabolism of saccharides," said Zhao.

Good for health in moderation

Multiple vitamin tablets are now available at local drug stores and some supermarkets, as are single vitamin and also vitamin C effervescent tablets.

For those who aren't sure which vitamins they are lacking, "multiple vitamin tablets are recommended," said Zhao.

But if people know exactly what they are lacking, single vitamin tablets are recommended, since excessive vitamin intake, especially synthetic ones, is not good for the health.

"Don't imagine it's a case of the more, the better," said Zhao.

Vitamin A in synthetic form, for example, is difficult for the body to discharge. Excessive vitamin A, if accumulated in the body, will cause toxicity.

Vitamin supplements available on the Shanghai market:

Producer:

Sino-American Shanghai

Squibb Pharmaceutical Ltd:

Theragran Junior (for Kids): 25.50 yuan ($3.10)/30 tablets

Theragran (for adults): 24.70 yuan ($3)/30 tablets

Golden Theragran (for adults): 32.90 yuan ($4)/30 tablets

UPSA-C (Vitamin C Effervescent):

Shanghai Roche

Pharmaceutical Co Ltd

Redoxon (Vitamin C Effervescent), 26.50 yuan ($3.20)/10 tablets

Suzhou Lederle

Pharmaceutical Co Ltd:

Centrum (for adults) 43 yuan ($5.20)/bottle

Centrum (for kids) 34 yuan ($4.10)/bottle