Are you really in need of vitamin and mineral supplements?
People who habitually take them seldom give much thought to this question.
In collaboration with the Drug Education Resources Centre, the Society of Hospital Pharmacists of Hong Kong, the Consumer Council has this simple advice to consumers taking or contemplating to take vitamins or minerals or both.
If you are in good health, follow a balanced diet with regular exercise and weight control, then you probably are not in any need of these supplements.
For the fact is that for most people, the necessary daily amounts of vitamins and minerals can be obtained from a well-balanced diet with adequate intake of fruit and vegetables.
For example, fish is rich in vitamin A and B, calcium, iodine, zinc; meat contains plenty of vitamin B, sodium, calcium, phosphorous, selenium; beef provides iron; vegetables are good sources of vitamin B, C, E, K, calcium and magnesium.
The exceptions are for some special groups of people such as vegetarians, pregnant women, elderly, alcoholics and smokers. They are recommended to consult doctors or pharmacists before taking these supplements to avoid potential adverse effects.
Consumers are reminded that while vitamins and minerals are nutrients necessary for normal metabolism and sound health, they should not be taken in excess.
There have been reported cases in the media of vitamin A overdoses leading to cirrhosis and hepatic fibrosis in Hong Kong.
According to the WHO "Vitamin and mineral requirements in human nutrition", the recommended vitamin C intake of a healthy adult is 45 mg/day. In general, an orange could provide enough vitamin C for the daily requirement.
In susceptible people, taking doses higher than 1,000 mg a day, over a prolonged period of time, may cause kidney stones, and changes in the menstrual cycle. Some people who stop taking high does abruptly, may develop rebound scurvy.
The study also notes that high dose of vitamin C (500 mg to 10,000 mg) have been recommended to prevent the common cold - or even schizophrenia, cancer, hypercholesterolemia and atherosclerosis. But these recommendations seem to have little or no scientific support.
In addition, the attention of consumers is drawn to the glucosamine supplements being promoted to treat and prevent cartilage injury or breakdown, and osteoarthritis.
Glucosamine has been shown to alleviate subjective pain and improve symptoms of osteoarthritis, although studies on glucosamine reported so far are limited.
While the adverse effects of glucosamine have not been systematically studied, overall, glucosamine appears to be well tolerated.
It is unknown whether glucosamine administration can affect blood sugar. People with diabetes or glucose intolerance are therefore advised to seek medical advice before taking glucosamine supplements.
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