Sunday, August 31, 2008

Spilling the beans on soya

Spilling the beans on soya
Mon, Sep 01, 2008
The Straits Times

So far soya's good. Millions of Asians have grown up slurping down the milky goodness of the humble yellow bean, be it in the form of tofu or tempeh or soya bean milk.

Ms Pauline Chan, senior nutrition consultant at Food and Nutrition Specialists, said: 'Soya beans and the products derived from them play an important role in the lives and diets of Asians, providing a nutritious option high in protein and low in saturated fat.'

However, in recent months, the ubiquitous legume has been caught in a storm of controversy.

Last month, researchers in the United States found that eating half a serving of soya-based foods a day could significantly lower a man's sperm count.

In June, a Canadian study published in The Journal Of Nutrition on the health benefits of soya in humans concluded that consumption of soya protein appears to consistently lower blood LDL (or bad) cholesterol but the effects of soya protein and isoflavones in relieving menopause symptoms and prevention of breast cancer are not evident.

Isoflavones are a type of plant oestrogen found mainly in soya beans which are purported to possess preventive health benefits.

In contrast, a study by the National University of Singapore (NUS) and two American universities, which tracked more than 34,000 Chinese women for a decade, found that eating a serving of soya beancurd or drinking a glass of the milk every day reduced the risk of breast cancer in those women.

For sure, the soya bean usually gets good press. It contains all three macro-nutrients essential for health: protein, carbohydrate and fat.

Ms Breda Gavin, senior nutrition consultant at Food and Nutrition Specialists, said: 'Soya is the only plant food considered to be a complete protein in that it contains all the essential amino acids needed by the human body.'

Soya beans are also low in fat and a good source of fibre, iron, calcium, zinc, magnesium and B vitamins.

While fibre is necessary for healthy bowel function, B vitamins are important for releasing and metabolising energy from the food we eat. Minerals like zinc and magnesium are critical aids in coping with enzymatic reactions.

In 1999, the US Food and Drug Administration approved a health claim for soya beans which stated that 25g of soya protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.

Since then, countries like Britain, South Korea and Malaysia have also approved health claims which say that soya protein helps reduce cholesterol levels.

Ms Grace Quek, dietitian at KK Women's and Children's Hospital, said that soya has no cholesterol and is low in saturated fat. Therefore using it to replace animal protein foods such as red meats, which have high saturated fat content, will benefit those who are following a heart-healthy diet.

Ms Lim Su Lin, chief dietitian and manager of the dietetics department at National University Hospital, added that this could be related to the fact that soya contains phytoestrogens that could help lower blood pressure and cholesterol.

Phytoestrogens are compounds found in plants which are similar to oestrogen in humans.

As more countries adopt such health claims and endorse its health benefits, more people everywhere have become soya converts.

Ms Lynn Pang, business development manager of Jollibean Foods, said: 'Singaporeans have been consuming soya products in recent years as they are more informed about the goodness of soya.'

Asked if one can consume too much of the yellow bean, Raffles Hospital dietitian Nehal Kamdar said that over-consumption of soya products could be dangerous for women with or at risk of oestrogen-sensitive cancers.

'Soya isoflavones can interfere with thyroid function in susceptible individuals, and naturally occurring phytates in soya can inhibit the absorption of calcium and other minerals,' she said.

Madam Koay Saw Lan, head of dietetics and nutrition services at Singapore General Hospital, summed it up: 'The golden rule to keep in mind is still a well-balanced diet.'

Indeed, while doubt has been cast of late on the potential health benefits of soya, dietitians Mind Your Body spoke to said that most people derive health benefits from eating soya as it provides many important nutrients.

Ms Chan said: 'It is fair to say that based on its nutritional profile alone, soya fits in well with current healthy eating guidelines.'

No comments: