The rigours of modern day life - for example, exposure to radiation from mobile phones and microwaves, to ozone or chlorine - may increase oxidation and speed up ageing and the death of cell tissues, says Margaret Lau, pharmacist director at Watsons. Antioxidants are known to counteract the deleterious effects of toxins in the environment.
Free radicals are by-products of oxidation, the body's natural energy-producing process. Free radicals can damage cells.
Antioxidants are able to neutralise free radicals, rendering them harmless.Vitamins A, C and E are antioxidants. Selenium is also known for its antioxidant properties. All occur naturally in foods. 'For example, vitamin A is found in abundance in dairy products, fish such as mackerel and salmon, and in dark leafy vegetables and carrots,' Ms Lau says.
Foods abundant in vitamin C include citrus fruits, broccoli and tomatoes, while cereals, soybeans, eggs and vegetable oils all contain vitamin E.
In addition to its antioxidant properties, vitamin A is good for the eyes, while vitamin C is good for immunity. Studies show that vitamin E is effective in reducing the risk of heart disease.
When considering supplements and the amounts to take, Ms Lau reminds us that we also must consider the foods that may be abundant in these vitamins. 'The recommended vitamin A intake, from diet and supplements, is up to 1.5 milligrams per day. People who consume too much vitamin A have a yellowish colouration on their skin and eyes,' she says.
An intake of up to 1,000mg of vitamin C is not likely to cause any harm, she says. There have been reports of diarrhoea with over-dosage. For vitamin E, up to 540mg per day can be consumed without any problem.
The combination of vitamins A, C and E and selenium is recommended.
'There is a synergistic effect if they are taken together,' Ms Lau says.
Grape-seed extract contains oligomeric procyanidins (OPCs), which have antioxidant properties.
'These OPCs are powerful antioxidants. The potency of grape-seed extract, when compared to vitamin C and vitamin E, is about 20 times and 50 times more respectively,' Ms Lau says.
Absorption is an important factor when consuming vitamin supplements. Ms Lau recommends taking the antioxidants on a full stomach.
With regard to the water-soluble vitamin C, Ms Lau says consuming more water with the vitamin may result in its faster elimination from the body.
A full stomach slows down the elimination process, giving the body time to absorb more of the vitamin.
Food aids absorption of the fat-soluble vitamins, so she recommends taking these on a full stomach as well.
Vitamins are available in several forms, with vitamin C available as chewable tablets, pastels and effervescent tablets.
'We find the effervescent tablet is good for children, as they like the taste. Most importantly, it is absorbed quickly, as it is readily soluble,' she says.
There is also a buffered vitamin C formulation to reduce the acidity from ascorbic acid without affecting efficacy.
Sustained-release versions are also available (these release the vitamins gradually, rather than at one time).
They apply primarily to the water soluble vitamins, which have to be absorbed slowly.
'For example, with vitamin C, you may have to take it a few times a day. So the sustained release is beneficial in this respect,' Ms Lau says.