Consumed in many traditional Asian populations for millennia, soya has only been a common part of the Western diet for around 60 years. Now, many of our supermarkets are full of soy milk alternatives, soy burgers and other soya-based meat replacements – not to mention traditional soy-based products like tofu, tempeh, soya milk, miso and soya sauce.

In the meantime, soya has been linked to a lower risk of heart disease compared to other diets. As a good source of protein, unsaturated fatty acids, B vitamins, fibre, iron, calcium and zinc, it is becoming increasingly popular in the West as a healthy substitute for meat. But despite more people associating soya with health over the last decade, one fear has come to the fore: the idea that soya can disrupt our hormones.

The controversy around soya comes down to its uniquely high content of isoflavones. These compounds have oestrogenic properties, which means they act like oestrogen, the primary female sex hormone, and bind to oestrogen receptors in the body – and oestrogen can fuel the growth of some types of breast cancer.

But while scientists have extensively researched the compound’s effects in the body over the last few decades, the answer about whether isoflavones themselves can contribute to cancer risk isn’t straightforward.

And often, it seems soya protects against cancer risk – rather than making it worse. But exactly why that is isn’t certain.

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To start, there are the observational findings. High soya intake among women in Asian countries has been linked to their 30% lower risk of developing breast cancer compared to US women, who eat much less soya. (The average person’s intake of isoflavones in Japan, for example, is between 30 and 50mg, compared to less than 3mg in Europe and the US.)