A common argument in the wellness sphere is “people have been doing it for centuries so it must be safe”. Yet when it comes to soy and soy products, the fact that certain populations have been eating and enjoying it for thousands of years doesn’t seem to matter.
The myths around soy are pervasive and persistent: it messes with your hormones and therefore isn’t good for you.
It’s time to call bollocks on soy myths.
Soya contains compounds called phytoestrogens, which are plant-oestrogens that occur naturally in plants. These are slightly different to the oestrogen hormones humans produce, but similar enough that they can have some weak biological effects.
But don’t panic! This can actually be a good thing. For example, menopausal women often experience hot flushes, and consuming soy products can help reduce these [ref]. It’s worth noting though, that hormone replacement therapy (HRT) is still the most effective treatment, so please don’t see this as a way to stop taking it!
Soy products can help reduce the risk of heart disease, as it reduces blood cholesterol levels [ref]. It does this most likely in two ways: firstly, it reduces the liver’s cholesterol output, and secondly often soy products like tofu are eaten as a replacement for meat products, which are higher in saturated fat. By replacing meat with tofu, it may reduce the saturated fat content of the meal, thereby reducing heart disease risk! As you can see it’s not necessarily straightforward, with a lot of ‘can’ and ‘may’. And the research isn’t even conclusive. Such is the nature of nutrition science!
Rat studies initially suggested that the plant oestrogens from soy products would lead to increased risk of breast cancer. However, rodents and humans metabolise these compounds differently, and soy products have actually been deemed to reduce cancer risk in humans [ref]. In terms of breast cancer, eating up to 2 servings of soy per day doesn’t affect the risk of recurrence or death.
Again soy comes out well. Consuming soy products is linked to decreased risk of osteoporosis, particularly in post-menopausal women [ref]. But more research is definitely needed here. If you’re looking to switch dairy milk for a non-dairy option such as soy, it’s important to remember to choose an option that’s fortified with calcium – you don’t want to miss out on this key nutrient!
Soy is safe to consume for pretty much everyone. The scares about harmful effects come from lab and rodent studies that use especially high levels of phytoestrogens. As mentioned before, rodents metabolise these compounds differently from humans, and it’s difficult to extrapolate what happens in a petri dish to the complexity of the human body. Consuming soy products excessively isn’t recommended (like basically all foods!) but having 1-2 servings per day shouldn’t cause you any harm!
Additional reading: BDA fact sheet on soy