Question mark over nutritional supplements

PUBLISHED : Monday, 19 November, 2007, 12:00am
UPDATED : Monday, 19 November, 2007, 12:00am

Opinion is divided over whether nutritional supplements can help reduce the side effects associated with chemotherapy.

Chemotherapy involves the use of strong chemicals and drugs that are injected, or taken orally, into cancer patients to destroy malignant cells. The chemicals kill the cancer cells but also destroy healthy ones. One of the side effects of chemotherapy is weakening of the immune system.

There are many supplements available in the market and manufacturers claim their respective product can strengthen the immune system. However, patients are unsure of the effectiveness of these supplements.

Voicing his personal opinion, Kenny Lei Ieng-kit, specialist in medical oncology, Prince of Wales Hospital, said he did not think it was necessary for most patients to take nutritional supplements apart from exceptional cases. 'My advice is to have a normal and balanced diet. Other than patients with cancer affecting their digestive system, most patients do not need food supplements.'

When asked if Chinese herbal supplements made from ling zhi and yun zhi (essence of mushroom) were useful, Dr Lei said he was not aware of any proven benefit from this traditional medication. 'I believe some herbs have active ingredients which show cytotoxic effects, but until they are tested in clinical trials, I wouldn't recommend them to my patients.'

He added that some Chinese medicine practitioners claimed the herbs could reduce or 'neutralise' side effects. 'I think this is far from the truth. How can someone who has no training in cancer drug pharmacology predict the side effects? Even if they knew the drugs prescribed, they would not know the dosage.

Nutritionist Winsy Leung Wai-sze, external affairs officer of the Hong Kong Dietitians Association, said: 'Some patients may need more nutrients to replenish their weakened immune systems. They should be encouraged to eat a wide range of foods. Even foods with higher fat or calories are acceptable as they help restore energy.

'Obviously a diabetic patient should not eat sugary food. The patients will be assessed and they will be told to adopt a balanced diet as their appetite improves.'

Ms Leung suggested patients wanting to take supplements should look for reliable brands and tell doctors whether or not they worked.

She said the medical sector had raised concerns over the effectiveness of these supplements. She hoped patients' views would encourage more scientific research.

Vincy Chu Wing-sze, assistant brand manager for Novartis Medical Nutrition, said: 'As medical treatment improves, people are less affected by the side effects of chemotherapy, and they may not need additional health supplements. But for those who do, our products help.' She said patients receiving radiotherapy, whose lymphocytes took more than a year to function normally, would be advised to take Novartis products. Ms Chu stressed that its products were supported by more than 30 clinical papers.