At first, they say soya is good for me. So I try to have soya of some sort every day. Then they say soya is actually not so good. I don’t quite believe them, but to be on the safe side, I cut down on my soya intake.
Now they are saying that it is good for some people in a certain state of health and set of circumstances, and not so good for others in another state of health, and set of circumstances.
I might not be a scientist, nor a dietician, but I have a couple of conclusions of my own. Firstly, all food is good for the body, as long as taken in moderation. Secondly, whatever scientists claims, take it with a pitch of salt. Give them enough time and they will come up with a counter-claim.
To bean or not to bean, that is the question facing many health-conscious consumers when it comes to soya goods.
With tons of studies being published on the effects of the soya bean on human health in the last few decades, the soya bean has been both celebrated and vilified.
Mind Your Body (a weekly health supplement of the local paper) sifts through the conflicting claims.
1. Reduced breast cancer risk
Soya beans, not diamonds, may be a girl’s best friend. A recent study by the National University of Singapore and two American universities found that eating a serving of soy bean curd or drinking a glass of the milk every day reduces the risk of breast cancer in Chinese women in Singapore.
2. Male fertility unaffected
Men who enjoy soya can take heart and hang loose again. Dietitians Mind Your Body spoke to were skeptical about recent reports claiming that eating half a serving of soya-based foods a day could lower a man’s sperm count.
Ms Pauline Chan, senior nutrition consultant at Food and Nutrition Specialists, said that scientific reviews from the Soyfood Association of North America showed that the study, which had only 100 subjects, actually found that soya food intake was unrelated to sperm quality and male fertility. Instead, obesity maybe a cause for the low sperm concentration found in the men with high soya intakes.
3. Increased risk of gout and kidney stones
Eating too much soya products can lead to kidney stones or gout, many studies suggest. Soya contains oxalates which cannot be absorbed by the body and are excreted only through urine. Oxalates bind to calcium to form kidney stones which can block the urinary system.
Gout is caused by the build-up of uric acid in the blood stream, which occurs when the body breaks down substances called purines, found in foods like liver, soya beans, tofu and meat.
Mr. Benjamin Lee, nutrition manager of the adult and elderly health division at the Health Promotion Board, said that doctors usually recommend that those with kidney problems to eat fewer of these products as oxalates may increase the risk of developing kidney stones.
However, Ms Grace Quek, dietitian at KK Women’s and Children’s Hospital, said: “Soya per se is not the culprit. It is the total intake of purines including those from protein foods like meat, milk, seafood and organ meats.”
4. Good for the heart
Many studies conducted in the last two decades have found that soya can lower cholesterol levels and reduce the risk of heart disease.
Ms Breda Gavin, senior nutrition consultant at Food and Nutrition Specialists, explained that soya protein helps to reduce the LDL (or bad) cholesterol. The presence of soluble fibre in soya also helps to reduce cholesterol in the blood.
5. Higher risk of memory loss
A study released in July by Britain’s Loughborough University suggested that eating high levels of some soya products – including tofu – may raise the risk of memory loss.
Asked if the ingredients in tofu can lead to higher incidences of dementia, Dr. Reshma A. Merchant, consultant geriatrician at National University Hospital’s department of medicine, said: “Tofu is made form coagulants including salts and acids which could be contributory factors.”
She added that soya has been found to reduce brain derived neurotrophic factor (BDNF) in male rats. Reduced BDNF is known to cause brain cell atrophy and is associated with Alzheimer’s disease.
However, she qualified: “Further studies are needed.”
6. Post-menopausal women reap benefits
Soya is kinder to the fairer sex, it seems – but read the fine print.
A Canadian study on the health effects of soya protein published in The Journal Of Nutrition in June concluded that soya intake helps to prevent bone loss in post-menopausal women but does not improve hot flashes or other menopausal symptoms.
Ms Lim Su Lin, chief dietitian and manager at the dietetics department at National University Hospital, said: “People of all ages, races and both genders benefit from eating soya. However, most studies that indicate the benefits of soya are skewed towards post-menopausal women in terms of lowering blood pressure, cholesterol and breast cancer risk.”