BLOG BY Rhiannon Lambert

Is Soy Good Or Bad For Your Health?

Soy is a type of legume, native to Asia and consumed in a variety of ways, most known in the form of soy milk and tofu. Commonly you can find these in; yoghurts, soybeans, cheeses, meat substitutes such as chicken pieces and the above mentioned.

Do you need to include these if following a plant based diet?

Soy is extremely nutrient dense so a wonderful component of plant based diets, providing good quality protein, which can sometimes be tricky if you are new to eating this way. It of course has lots of other nutrients, for example one cup of edamame (155g) contains; 189 calories 11.5 grams of carbs, 16.9 grams of protein, 8.1 grams of fats (of what we call healthy fats), 8.1 grams of fibre, Vitamin C, Vitamin K, Thiamine, Riboflavin, Folate, Iron, Magnesium, Phosphorus, Potassium, Zinc,Manganese, Copper

How much soy should we be eating?

There is no exact limit and any misinformation seems to stem from poor studies conducted on animals providing very weak evidence whereas, lots of research conducted on humans has proven otherwise that soy may be beneficial for menopause, cholesterol and fertility. Ultimately, be sensible and use soy as a source of protein at a meal and stick to the recommended serving sizes on the packets or use the a stretched out palm.

Should we be avoiding processed fast food that has soy in it?

The word processed applies to any food that has undergone a transformation and process, tofu is therefore technically also processed, you can enjoy different forms of soy foods in your diet in moderation just stick to sensible variety and serving suggestions.

Is soy good or bad for you?

This can be complex and the internet is full of misleading information. There is now scientific agreement that the controversy around isoflavones’ potential to have bad side effects in humans is fuelled only by findings from laboratory or animal studies using pure isoflavones or high doses. It is well established that animals metabolise isoflavones in a different and much more efficient way to humans and results from such studies cannot be compared to any human outcomes. Additionally, using high doses of pure isoflavones cannot be compared to consuming isoflavones from whole soya foods as they provide lower quantities and are a combination of many biologically active molecules. Comprehensive reviews by the European Food Safety Authority, World Cancer Research Fund and the World Health Organisation all conclude that soya foods as part of a healthy balanced diet are safe.

In fact, Soya beans are the main dietary source of isoflavones. A large glass of soya drink (250ml) will provide approximately 25mg isoflavones, but not all soya foods contain isoflavones with some processing methods removing 80-90% of the isoflavones such as the case for isolated soya protein. Isoflavones are often termed as phytoestrogens as they have a chemical structure similar to the human hormone oestrogen. However, it is now well established that in the human body, isoflavones do not behave like the human hormone oestrogen: they are weaker, they only have effects on some body tissues and in some situations they can have opposite effect to oestrogen. Isoflavones may help reduce the symptoms of menopause.

Is eating soy food contributing to deforestation?

The government’s new dietary recommendations, the Eatwell Guide (2016), clearly recommends a significant shift towards more plant-based eating both for the nation’s health as well as a more sustainable planet. Over 75% of the Eatwell Guide is dominated by plant foods with the most notable change to the protein section, where plant-based proteins are recommended over animal proteins. As soya provides a high quality protein source, this is an ideal option for the nation. (BDA Fact Sheet, 2017)

Can eating soy affect men's hormone and testosterone levels?

Because soy contains phytoestrogens, men may worry about including it in their diet. However, studies [1]do not indicate that soy negatively impacts the production of testosterone in men. In a review of 15 studies in men, intake of soy foods, protein powders or isoflavone supplements up to 70 grams of soy protein and 240 mg of soy isoflavones per day did not affect free testosterone or total testosterone levels. What’s more, soy may reduce the risk [2]of prostate cancer in men. In a review [3]of 30 studies, high soy consumption was linked to a significantly lower risk of developing the disease 

Can soya interfere with our thyroid function?

A review of 14 studies has confirmed that there is no harmful effect of soya food consumption in healthy humans with a normal functioning thyroid gland. Soya foods do not interfere with thyroid function but they can interfere with the absorption of thyroid medication levothyroxine like many herbs, drugs, fibres and calcium supplements. For this reason, thyroxine medication is always advised to be taken on an empty stomach and soya should not be excluded by those with an under active thyroid gland as their medication dose can easily be modified. [4]

Might soy promote cancer cell growth, decrease chance of breast cancer and protect against prostate cancer in men?

A review by the American Institute for Cancer Research, the American Cancer Society and the World Cancer Research Fund all indicate that soya foods as part of healthy balanced diet are perfectly safe for women with and without cancer diagnosis and there is a potential for soya food consumption to reduce breast cancer recurrence. Additionally, the protective effect of soya against breast cancer seems to be related to consuming soya foods as a child or teenager.






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