Soya is one of the top eight allergens in the world. It has been linked to cancer, reproductive-system damage and severe flatulence. Some claim that soya lowers sperm count and that it has not even been proved safe.

The Good

Soya, a pulse, is really cheap, easy to grow and diverse in its uses, from tofu and soya milk to its properties as a texturizer and emulsifier. It also contains isoflavones - plant compounds that have a weak oestrogen-like action. These isoflavones have antioxidant properties, protecting your cells from free radicals, and they have been shown to improve bone density as they help the body to use calcium.

People who are allergic to cow's milk are often advised to use soya products instead, and vegetarians use it as a substitute for meat, as it is known as an excellent source of protein. Particularly in America, big claims have been made about soya being a miracle food. The Missing Link

While soya may be recommended as a substitute for sufferers of lactose intolerance or as part of a vegetarian diet, it needs to be treated with caution. Soya is an 'almost complete' protein with eight out of the nine amino acids your body needs for proper functioning. You need to combine a pulse (such as soya) and a cereal (such as wheat). Each of these are missing one amino acid, but together they contain all nine. A soya burger on a roll is a good example of a balanced protein meal.

The Allergies

Soya is widely accepted as one of ‘the big eight' that cause immediate hypersensitivity reactions. (The others are milk, eggs, peanuts, tree nuts, seafood, shellfish and wheat). While soya is an alternative if you have milk allergies, it can be an allergen itself. If you're allergic to dairy there's a chance that you might be allergic to soya as well, as they are both common food allergens.

About 70% of products on our market contain soya. It's used as an emulsifier - a food additive that prevents oil from separating in products such as mayonnaise and peanut butter. If you're allergic, read food labels carefully.

The 'C' Word

Soya contains phytoestrogens that can be really helpful for treating menopausal symptoms. But these are not recommended for those who have an oestrogen-positive cancer such as breast cancer.

Women with a family history of breast cancer should be cautious: lots of soya can increase the level of oestrogen in the body. Surprised? Just think of those stories about male body builders growing breasts or having reduced sperm counts. Most protein powders contain enough soya to pump their bodies full of female hormones.

Get the Benefits

While you don't have to condemn soya to the 'don't touch' pile, our experts recommend:

If you eat soya, buy fresher, less processed versions - organic if you can. A lot of the soya on the market is so processed you won't get any of the benefits of the isoflavones, which are damaged by extreme heat. Always cook raw soya products. Their proteins are a trypsin inhibitor, which means they cannot be digested by humans until they are heated. Steer clear of genetically modified soya products.

The effect on humans of changing food's DNA make-up hasn't been properly established yet. Eat everything in moderation. Your diet needs a good balance of all food types.

Sandra Prior runs her own bodybuilding website at http://bodybuild.rr.nu.