High in protein, affordable and easy to find on Britain’s supermarket shelves, it’s no wonder soy-based products are a popular meat-free alternative for vegans and meat-eaters alike. But with reports claiming soy can promote breast and other cancers, is it worth steering clear? We sat down with Nutritionist Melissa Pierson to sort fact from fiction...
First things first – why is soy so controversial?
The negative headlines stem from soy’s high content of phytoestrogens – plant compounds that behave similarly to oestrogen, the female sex hormone. As a result, they can have both oestrogen-stimulating and oestrogen-inhibiting effects, depending on the circumstance and individual. However, it’s also worth noting that scientific research is still lacking in this area and the controversy has been heightened by the fact most soy products on the market today tend to be overly processed and genetically modified.
Got you. So what does this mean for our hormones?
It’s believed highly-processed soy products can trigger hormonal imbalances, leading to fatigue, weight gain and mood swings. Phytoestrogens can even trigger breakouts, with hormonal blemishes occurring around the mouth and jaw line.
Can soy really cause cancer?
Not necessarily. Most breast cancers are sensitive to oestrogen – which can fuel their growth. There has been some concern over the consumption of soy and breast cancer, however studies have shown a diet high in soy may actually reduce the risk. In one study of more than 73,000 Chinese women, researchers found that those who ate at least 13g of soy protein a day were 11% less likely to develop breast cancer than those who consumed less than 5g. Studies have also suggested soy could cut the risk of heart disease, lower blood cholesterol and ease menopausal hot flushes.
Are all soy-based products created equal?
No. The real difference lies in how the soy is processed. If it’s genetically modified, research suggests this could cause more problems. Soy plays a prominent role in the Asian diet, although the soy consumed in Asia tends to be highly fermented (things like miso, tempeh, natto and tamari), which plays a part in its health benefits. It’s also worth noting soybeans are high in phytic acid (also known as phytates), which can hinder the uptake of some essential minerals, including calcium, magnesium, zinc and iron. However, research has found the negative effects of phytates only materialise when consumed frequently and in large quantities.
The bottom line?
If research is anything to go by, there’s no reason to cut out soy completely. Just be sure to choose organic, non-genetically modified and ideally fermented soy products, choosing tempeh over tofu, for example, and miso over soy sauce. The likes of tempeh and natto may sound strange, but they can be used just like tofu and are easy to find in Planet Organic, Wholefoods and on Ocado. If in doubt, stick to around 25g of good-quality soy protein per day as part of a balanced diet.