Is soy unhealthy?


The same old stories about soy still pop up in the media every now and then, and given I get asked pretty regularly about whether soy is unhealthy, inflammatory, or hormone disrupting. Despite overwhelming evidence that soy is not harmful and is in fact very healthy, a surprising number of people remain afraid of soy because of some bad science, media hype and propaganda. In this article I briefly touch on some of the misinformation and link to resources where you can get more details.

What is soy?

Soy is a legume – similar to other legumes such as peanuts, chickpeas and black beans. It’s been a staple human food since it’s domestication in 1100BC.

Soy is a versatile, cheap, and high quality source of protein and is also a great source lots of other nutrients – like choline, magnesium, omega 3, zinc and iron.

Effects on human health

Soy is one of the most researched foods on earth, and an ever growing body of evidence shows that soy is beneficial for health, especially cardiovascular disease prevention. There is also good evidence that soy decreases the risk of both mortality, and cancer reoccurrence in breast cancer survivors.

The chemical structure of isoflavones is similar to that of human oestrogen, hence the name “phyto-estrogen”. Many plant foods contain isoflavones, but soy is among the richest sources. Isoflavones have a mild estrogenic effect because they can bind to certain human oestrogen receptors. However, in reproductive tissues, soy has anti-oestrogenic effects which may reduce the risk of cancer.

Conversely, the true estrogen found in dairy may negatively impact human health.

Additionally, there is emerging evidence that soy may protect bone density in post menopausal women. This may be due to its oestrogen modulating effects.

Soy and the Amazon

Another misconception is about soy’s sustainability.

It’s true wildlife habit and ecosystems, including rainforests, are destroyed to grow soy crops- however 70-75% of this is to feed cattle that people eat. In fact, 88-93% of soy grown on Earth goes to feed livestock (cows, sheep, pigs and chickens). Soy for human consumption accounts for only a small portion of the remaining 7-12%. The rest used for industrial purposes such as biofuel.

Soy is GMO

Organic soy produced for human consumption (at least in Australia) is not genetically modified. Even some non-organic soy is certified non-GMO. However, soy grown to feed cattle, chickens and pigs are genetically modified. People who want to avoid consuming GMO soy should avoid meat, chicken, fish and dairy as well.

Soy may improve fertility

Studies have shown that higher soy intakes are associated with increased fertilisation and live births in women undergoing IVF.

It’s incredibly nutritious

Soy is a powerhouse of nutrition. It is a rich source of high quality protein, and is packed with vitamins and minerals. In fact, it is comparable to cows milk and chicken in terms of nutrition (minus the B12 of course).

The bottom line

The science on soy is clear. It is not only safe, but is also cheap, super healthy, and sustainable when grown for human consumption.