The not soy clear debate

HILIT MILNER

Soy and the history of its mystery

Soybeans are legumes that can be eaten in their whole, natural form, namely edamame beans. Other traditional sources include tofu, soya sauce and soya milk. Soy can also be found in its fermented form such as miso and tempeh. In fact, soybean oil and soy protein are used in the production of many food items without us even realising it. More Westernised processed forms include soy burgers and sausages.

Soy offers an array of nutrients such as B vitamins, fibre, magnesium and calcium, and they are considered complete proteins – offering all nine essential amino acids.

Studies of soy consumption as early as the 1940s showed oestrogenic and adverse effects in animals, sparking more worldwide research. However, soy is metabolised differently in animals, and this can cause confusion.

Soy and breast cancer

Soy products have a uniquely high content of compounds called isoflavones. Chemically, these have a very similar structure to the hormone oestrogen. This means they can mimic oestrogen, binding to oestrogen receptors, causing our body’s oestrogen levels to increase. An imbalance of oestrogen in the body can result in an increased risk of breast cancer, but does this mean we shouldn’t be eating soy?

It isn’t as clear-cut as we once thought. While historical research suggests that soy stimulates the growth of oestrogen-dependent cancer cells, studies over the past 20 years show that natural sources of phytoestrogens (like soy and other legume-based foods) are safe and are, in fact, beneficial.

Research published in the journal Cancer in 2007 showed the lack of association between soy and breast cancer, emphasising that using natural sources of soy to replace a diet that is high in alcohol and processed and refined foods aids in the reduction of weight and breast cancer. However, a diet rich in natural soy products is less effective when introduced later in life.

A recent long-term study including 6 235 participants (as well as other smaller studies) has shown that consumption of soy products is not only safe, but also beneficial when it comes to avoiding the risk of breast cancer.

Soy and thyroid function

Studies done on thyroid function and soy show no effect of soy on people with normal thyroid function. For those with an underactive thyroid who are taking thyroid hormone replacement therapy, research shows that soy interferes with the medication’s absorption, and may result in the need for a higher dose. Having said this, there is no evidence that those with an underactive thyroid should avoid soy. Rather, they should wait a few hours after taking their medication before consuming soy products.

Soy and cardiovascular health

Soy intake has been found to reduce the risk of cardiovascular disease. Soy contains compounds which lower our LDL cholesterol (the bad cholesterol). In addition, soy products replace fatty, processed meat-based alternatives, contributing to a reduction in the risk of inflammation, cholesterol and cardiac problems.

Back to the source

Soy’s varied health effects stem from the form of soy being consumed. Natural, traditional soy products contain a variety of nutrients and are a healthy option. Fermented soy further helps feed the bacteria in our gut, creating a healthy gut-bacteria balance.

Processed soy products are, however, genetically modified and the crops are sprayed with the herbicide Roundup, painting a not-so-beneficial health picture. Most people don’t consume appreciable levels of soy, and when they do, they are in their processed, unfavourable forms.

Take-home message

Whether listening to the popular press or researching soy, some debate remains. Increasing evidence, however, is showing the product’s benefits over possible harm. Unfortunately, with most conclusions there are conditions and a “but”, especially when it comes to science.

Although no single study is perfect, there is sufficient evidence for soy’s safety and benefit when it comes to avoiding the risk of breast cancer and maintaining cardiovascular health, if consumed correctly. It’s important to remember that this can vary, depending on when you start consuming soy, your current hormonal status, the way you break down soy, and your medical history.

It’s also important to consider the type of soy you are eating. Natural or fermented forms such as edamame beans, tempeh, miso and tofu are beneficial, while processed products can be harmful.

Always remember to check the other ingredients when choosing soy products, and go for organic or non-GMO sources where possible.

As with everything, moderation is key. If you’re unsure, seek medical advice.