Is soya really so good for you?

Many of those recommended to buy the growing number of products such as soya milk and tofu are menopausal women looking for an alternative to hormone replacement therapy (HRT), men hoping to protect themselves against prostate cancer and people wanting to take care of their heart.

There have also been claims soya can lower cholesterol, ward off osteoporosis and reduce the risk of some cancers.

But as the industry has grown, so has the research - and the concerns!

Now alarming new studies link soya to reduced fertility in men, an increased risk of other types of cancer, altered menstrual cycles and suppressed thyroid glands.

There are also growing fears about its impact on children.

With more children developing allergies to cow's milk, many parents are feeding soya-based formula to their babies.

Shockingly, one report claims babies who are fed only soya milk consume the equivalent of five contraceptive pills a day.

This is because soya contains chemicals called phytoestrogens, also referred to as plant hormones or plant-oestrogens, which mimic or block the action of the female hormone, oestrogen.

Brighton mum Sue Dibb, senior policy officer of the National Consumer Council, was on an independent committee's expert working group which published a report in 2003 looking at the information on the possible side effects and benefits of the plant hormones.

She warns: "It would be a great mistake for anybody to think they were doing themselves a lot of health favours by loading their diet with a lot of soya.

"For adults, soya is helpful in moderation in that it is a low-fat alternative product for people who don't eat meat.

"But don't see it as a superfood and be cautious about basing your whole diet around soya. Some claims about soya have been overstated and we concluded the evidence was often quite weak. There was also concern about the high levels of consumption."

But don't think you are safe just because you don't drink soya milk.

Most people consume soya on a daily basis - they just don't know it.

Soya no longer just fills the shelves of health food shops - it's hidden in most supermarket foods. Pork pies, breakfast cereals, mayonnaise and margarines all contain it.

Manufacturers often add it to processed foods such as sausages, lasagne, beefburgers and chicken nuggets to bulk them out and bind them. Not only does it have the advantage of being cheap, it also means they can claim a higher content of protein on the label.

Soya is present in more than 70 per cent of all supermarket products, some research estimates, and it's often used by fast-food chains.

More worrying though is the fact that few products list it in their contents, choosing instead to list soya oil as vegetable oil.

But Dr Alan Stewart, medical director of the Woman's Nutrition Clinic based in Lewes, says people have to consume a lot of soya products for it to do any harm.

"It is technically possible to have too much but it has got to be a very huge amount," he says.

"In order to do harm, it looks as if you have to consume at least a litre a day. That would be the minimum you would have to consume to do even the minimum chance of harm.

"Moderate consumption of soya is unlikely to cause problems. The inclusion of soya and other vegetarian products is likely to be very beneficial to many people who are not eating that well in the UK."

The problem is though, when it's invisible in so many foods, how do we know how much we are eating? Should we be supplementing our diet with extra soya products or could they be doing us more harm than good?

What seemed to be the answer to many health scares could now be a health concern itself.

Once again, the customer is faced with the decision on whether to buy or boycott.

Here, we have summarised the pros and cons so whatever your choice, you can be as informed as possible.

Pros

• For people who can't tolerate milk or lactose which is in dairy products, soya is an alternative. Soya milk contains nutrients found in normal milk, including calcium.
• Soya is thought to be good for the heart. It's believed the lower incidence of heart disease in China and Japan may be linked to the amount of soya in Far Eastern diets. Isoflavones, a type of plant-oestrogen in soya, are known for their strong antioxident properties which may help reduce the risk of coronary heart disease and soya is a source of soluble fibre which may help lower cholesterol levels.
• The risk of breast cancer could be reduced after research showed those who ate soya-rich diets have less 'high-risk' dense breast tissue, thought to be due to the plant-oestrogens. Previous research has shown the fewer menstrual cycles a woman has in a lifetime, the lower the risk of breast cancer and eating soya also appears to lengthen the menstrual cycle.
• Soya could protect against osteoporosis, the brittle-bone condition which usually affects women after the menopause.
• Soya milk with its plant-oestrogens is often a recommended natural alternative which many menopausal women swear by to balance hormones, as controversy surrounds HRT. Studies found Japanese women suffer less menopausal symptoms such as hot flushes than Western women.
• Men could be protected against prostate cancer by eating soya, according to scientists in the US.
• Soya could help your diet because it's low in saturated fat and cholesterol free. It has also been suggested the plant hormones can fight obesity and diabetes.
• Other benefits could be a reduced risk of Alzheimer's disease, it may help your memory and could protect men from going bald.

Cons

• Your periods might be affected. Women fed soya formula as babies could experience long and painful periods, according to a study. A woman drinking two glasses of soya milk a day may see her menstrual cycle alter.
• Men's fertility could be affected. The more soya a man eats, the more difficulty he will have in fertilising an egg, was the conclusion of Dr Lorraine Anderson who discovered sperm moved slower when the liquid surrounding it contained female-like hormones. In animals, large amounts of female-like plant hormones have been shown to reduce fertility. When marmosets, (small monkeys) were fed soya milk formula in a study it suppressed their testosterone levels. Pregnant women in the US were advised by scientists to avoid soya after tests on rats suggested a chemical in it could damage unborn boys' reproductive organs.
• Children with a cow's milk allergy could become sensitive to soya if they are fed only on baby soya milk.
• Mothers are advised not to feed babies soya milk baby formula as their sole source of food before six months, except on medical advice. This recommendation came from paediatric experts and the Government following the working group report. After six months, babies are generally eating solids and the risk is considered not so great. Sue Dibb, senior policy officer of the National Consumer Council, advises parents to be cautious. "You're giving the baby a dose of a hormonally active substance at a time when babies are developing. That is a concern even when the evidence is not very clear cut," she says.
• Eating soya for a long time can suppress the working of the thyroid gland, which is associated with metabolism, according to research.
• There is some evidence plant oestrogens can encourage the growth of oestrogen-dependent breast cancer.