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Soy: the Good, the Bad and the Ugly

Soy is the ultimate bean. For any vegan or veggie it can be the answer to anything: milk, yoghurt, burgers, sausages, mince, soy sauce, tofu… it really can do anything! However everything has its limits, and in this article I’m going to try and work out if soy is all it’s cracked up to be.

Considering the current debate over the health impacts of meat consumption, soy may seem like even more of a magic bean. Switching to soy substitutes instead of meat can lower cholesterol, and provide the body with a rich source of nutrients, including B vitamins and iron. Meat consumption, in comparison, whilst providing similar nutrients, can increase the risk of CHD, diabetes, and certain cancers. A study that began in 1980, involving 120,000 Americans, revealed that an extra serving of unprocessed red meat per day increased total mortality risk by 13%, and that an extra serving of processed red meat increased it by 20%. If soy can be utilised to avoid these stats then surely it must be great! Moreover, if it replaces meat and reduces animal suffering, greenhouse gas emissions and water consumption, it has even more of an appeal.

Whilst soy does contain a range of minerals and vitamins, it also contains phytates, which prevent absorption of certain minerals during digestion. For example, there’s less zinc in soy than in meat anyway, and the phytates make it even less nutritious. It’s worth considering the T&Cs of soy consumption before taking the positive statements at face value.

Since eating vegan food for the past eight months, I’ve eaten masses of soy substitutes, in attempt to keep exactly the same lifestyle as I had before (I’m not sure if I’ll ever be able to give up nuggs). I’ve never really had bad skin before, but the only difference to my health that I’ve noticed is a lot more spots on my skin. Soy beans contain isoflavones, which mimic the action of oestrogen, changing the balance between male and female sex hormones in the body. This could result in a number of effects, for example more blemishes. However, my sample size of one is hardly anything to go by, and there are many reported incidents of improved skin due to drinking soy milk. This could be because cow’s milk might have even more of an effect on hormone balances. Perhaps another milk alternative such as oat or almond is the solution.

There is also debate over the other effects that hormone changes could have on human health. For example, the NHS website has a page on the relation between soy and male fertility, which discusses a small study on the topic. Their interpretation is that the study was too small and that it is unlikely that there is a causal link between fertility and soy. A scientific article I found online similarly states that soy is unlikely to affect fertility in women. However, is “unlikely” a premise persuasive enough on which to base a diet choice?

Other impacts of soy on health could be attributed to glyphosate: a chemical found in pesticides used in soy farming. Glyphosate can cause various biological issues due to its ability to inhibit some of the body’s critical cytochrome P450 enzymes. These enzymes cover a wide range of functions; for example, one type of P450 enzyme is responsible for the biosynthesis of oestrogen, hence hormone levels could be altered by soy consumption. Maybe this has contributed to the effect on my skin.

Although enzyme inhibition may sound bad in theory, most research strongly indicates that there are no adverse effects related to consumption of glyphosate. It’s been determined that nearly all (98%) of the glyphosate ingested by humans is egested and so doesn’t harm the body at all. Moreover in short-term studies on rodents there appears to be no toxicity, and the only paper I found that supported the idea that glyphosphate increases cancer risk had been retracted due to scientific invalidity. In addition, the pesticides containing glyphosate are used on many other crops including sugar and corn, so maybe singling out soy is a bit harsh and close-minded.

The adverse health effects often attributed to soy seem to be rumours for the most part; there is insufficient evidence from studies to back them up, and many health organisations acknowledge that soy doesn’t have adverse effects. In 2017, a Canadian study involving 6000 women was published, which debunked the myth that soy increases chances of developing breast cancer. The evidence of the benefits of soy appears much more sound, and compared with other protein sources soy seems to be a healthy alternative. Nevertheless, it should be kept in mind that the number of studies is fairly small, and that the topic is wildly controversial within the scientific community. So some caution should still be taken when consuming soy.

Credits: 1, 2, 3

Second year Josephine Butler Chemist from Croydon. Love adventures, animals, food, drinks, and HerCampus!
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