Last time I was interviewed for BBC Radio London, the presenter asked if soya foods were safe, then fell about laughing saying he didn't want to grow man-boobs. I've been asked if soya is safe for babies, can it interfere with the thyroid, does it contribute to deforestation, some people even think it may cause cancer…

Soya is the great divider; you're either for it, or against it. Is this humble pulse really such a demon bean, or is the anti-soya brigade using scare stories and pseudo science to further their own agenda? If you look carefully, most anti-soya stories can be traced back to one single group in the US called the Weston A Price Foundation (WAPF).

WAPF claims to be dedicated to promoting good nutrition by restoring nutrient-dense animal products to the diet – particularly unpasteurised "raw" whole milk. It claims that saturated animal fat is essential for good health and that animal fat intake and high cholesterol levels have no link with heart disease or cancer. They say that vegetarians have lower life expectancy than meat-eaters, and that historically humans have always eaten large amounts of animal fat. All this, of course, contradicts all the leading health advisory bodies in the world, including the World Health Organisation, American Dietetic Association and the British Medical Association.

This US-based fringe organisation is bent on citing scientifically flawed studies to promote their own agenda and has influenced a vast number of consumers, duping them into thinking of soya as some sort of dietary pariah.

The soya story dates back to New Zealand in the early 1990s, when a successful lawyer, Richard James, a millionaire on a mission, approached toxicologist Mike Fitzpatrick and asked him to investigate what was killing his expensive parrots (very Monty Python, I know). Anyway, Fitzpatrick agreed it was soya and has since campaigned vigorously against it as a food for humans –nonsense, since people have been eating soya for 3,000 years.

I have been interviewed for Radio New Zealand with Mike Fitzpatrick who campaigns against soya there. He was so aggressive they couldn't broadcast the interview. Fitzpatrick is a supporter of WAPF (actually an honorary board member).

Another of the organisation's supporters is a man called Dr Stephen Byrnes, who published an article in the Ecologist magazine claiming that vegetarianism is unhealthy and is destroying the environment. He boasted of his high animal fat diet and robust health – and, unfortunately, died of a stroke at 42. There were more than 40 scientific inaccuracies in the said article, including the direct misquoting of scientific studies. Incidentally, the editor of the Ecologist, Zac Goldsmith, is also an honorary board member of the WAPF.

Another of the organisation's supporters, Kaayla Daniel PhD, sits on the board of directors and has written an entire book attacking soya (The Whole Soy Story). Curiously, this group appears to spend more time attacking soya than promoting the foods they say we should be eating (unpasteurised "raw" milk, cream, cheese, eggs, liver, etc).

One of the concerns raised about soya is that the phytoestrogens (plant hormones) found in soya foods may disrupt sexual development and affect fertility. If there was any evidence for this in humans at all, the UK government would have banned soya infant formula or at least issued health warnings.

Even after commissioning a 440-page investigation into the safety of soya – they have not issued such warnings because there was no evidence for any harmful effect. The 2003 Department of Health's committee on toxicity report acknowledged that there was no evidence that people who regularly eat high quantities of soya, such as the Chinese and Japanese, have altered sexual development or impaired fertility. It should be remembered that China is the world's most populous nation, with over 1.3 billion citizens, and who have been consuming soya for over 3,000 years.

In reality, there is no scientific evidence that the consumption of soya is harmful to humans. The majority of what the WAPF says is anecdotal, untrue or based on scientifically flawed animal experiments. First, phytoestrogens behave differently in different species, so animal studies are not applicable to humans. Second, the intestines act as a barrier to phytoestrogens, so artificially boosting levels in animals by injection has no relevance. Finally, many of these experiments have exposed animals to phytoestrogens at levels many, many times higher than those absorbed by people eating soya.

More and more scientists and doctors are acknowledging that the results of animal experiments should not form the basis of a public health policy. Dr Kenneth Setchell, professor of paediatrics at Cincinnati Children's Hospital, states that mice, rats and monkeys all metabolise soya isoflavones differently from humans and that the only appropriate model for examining human reproductive development is the human infant. About 25% of infants in the US are fed soya formula. Many of them are now well into their late 30s and early 40s. The absence of any reported ill-effects would suggest there are none, either biological or clinical.

In fact, soya beans contain a wide range of valuable nutrients and are an excellent source of protein. Evidence shows that soya protein lowers cholesterol and protects against cardiovascular disease. Soya foods protect against diabetes, menopausal hot flushes and certain cancers. There is good evidence that eating soya foods in adolescence and as an adult lowers the risk of breast cancer. Recent evidence showed that this protective effect of soya also applies to women who have been diagnosed with breast cancer. Soya foods may also help boost bone health and cognitive ability in some people. The number of peer-reviewed scientific studies reporting the beneficial health effects of soya continues to grow.

As a last resort, the soya detractors have attempted to condemn soya by citing the environmental impact soya farming is having on the Amazonian rain forest. They are quite right to be concerned, but people eating soya is not the problem; 80% of the world's soya production is fed to livestock so that people can eat meat and dairy foods.

Both the rain forests and our health would benefit tremendously if more people switched from animal-based foods to a more plant-based diet, including soya.

The next time you hear some daft story about soya wreaking havoc on human health or the environment, ask where the evidence is.