The proven health benefits of soya

Soya and soybeans are rapidly rising in popularity among people of all diets as a rich source of protein with proven benefits including building muscle, heart health, women's health, and for our environment. 

What is Soya?

Soya (also known as soybeans) is a highly digestible, high quality protein which can play a key role in a healthy plant-based or vegan diet, and is a great protein source to include in all diets. Including more plant proteins in the diet benefits the environment too so it’s not surprising that interest in soya is increasing. You may also enjoy reading 'Best sources of protein on a plant-based diet'. 

Soya drinks, which are the most popular way of consuming soya, have seen a 16% increase this year compared to the same period last year. However, there is sometimes confusion on the effects of soya on health, particularly in terms of whether eating soya influences hormones. Here we share the facts and benefits of soya.

Soya foods and soya drinks

There are a variety of ways to include soya in the diet. Most common is soya drinks (including soya milk), tofu, soya meat alternative products and edamame beans (the young, green soya beans). Fermented soya products include miso, natto, tempeh and soya alternatives to yoghurt. Soya protein is widely used by the food industry to boost the protein content of products, so you may see ingredients such as soya protein isolate in protein bars, or in meat replacement products. Learn more about the risks of meal replacements and sweeteners. 

Soya beans are quite different to other beans and pulses as they are much higher in protein, lower in carbohydrates and have significantly more fat – mainly healthy polyunsaturated fat including essential omega-3 and omega-6 fatty acids.

Read more on what foods to include in vegan diets: Top 6 foods every vegan should eat and why.

How much soya should we be consuming?

The recommended daily soya intaking is around 1-2 portions of soya foods and/or drinks a day as part of a balanced diet, which can also provide benefits to your health and the environment.  Below are some examples of serving soya:

• 250ml soya milk (Read: What is the best plant-based milk?)
• 125g soya alternative to yogurt
• 100g soya mince
• About half a block of tofu
• About half a block of tempeh
• 1 soya burger
• 2 soya sausages
• 80g edamame beans (about a handful or 3 tablespoons)

Soya is great for muscle building

Soya is just as effective as whey or other animal proteins in terms of building muscle. Consuming adequate protein, spaced across the day, alongside regular strength exercises is key for maintaining and building muscle. As long as you are eating adequate energy and protein sources within a balanced diet, there will be no difference in muscle gains for those following a plant-based, vegan, vegetarian or meat diet. 

Soya is beneficial for heart health

Too much saturated fat in your diet is a major risk factor for high cholesterol and heart disease.  Soya foods are naturally low in saturated fats and can provide heart healthy unsaturated fats.  Also, the protein found in soya has been shown to modestly lower blood cholesterol levels.  Including soya foods and drinks as part of a healthy balanced diet has been linked with improved heart health.

Does soya impact hormones?

Soya foods and drinks are uniquely rich sources of isoflavones.  Isoflavones are naturally occurring plant compounds, sometimes referred to as phytoestrogens or plant oestrogens.  This is often the reason why soya is sometimes linked with hormones.  However, extensive research has demonstrated that isoflavones act differently to oestrogen in the human body, and do not negatively impact on women’s or men’s health. 

Below are some examples:

Men's health and soya

A common question asked is if soya is good for men's health? Men need not worry about consuming soya. Consuming soya foods does not adversely affect testosterone levels, nor will it negatively impact fertility.  Those messages about soya causing man-boobs (or 'moobs') you can ignore too - there is no evidence of a cause-and-effect relationship between soya intake and male reproductive hormones. 

Breast cancer and soya

Including soya in the diet is safe for women at risk of developing or who have breast cancer. The isoflavones in soya don’t act in the same way as oestrogen in the body. Evidence from studies in breast cancer patients consistently show that soya foods and drinks are safe and do not increase risk of breast cancer. It’s perfectly safe for breast cancer survivors and those at high risk to include soya as part of a healthy balanced diet. There is even some evidence that soya may actually help protect women against breast cancer.

Menopause and soya

Is soya good for menopause? Soya foods and drinks could help reduce menopausal hot flushes which are a common symptom of menopause, affecting around 80% of women. It’s thought that the isoflavones in soya have a weak oestrogen-like effect, but as they are a different compound to oestrogen, they don’t alter oestrogen levels in the body. Including two servings of soya foods and/or drinks a day could help reduce the severity and frequency of hot flushes. You may also enjoy learning about the uncommon symptoms of menopause. 

Soya and the environment

Including more plant-based proteins will significantly reduce the environmental impact of our diet. Soya produced for human consumption produces significantly lower greenhouse gas emissions than animal proteins. Additionally, as a legume, soya plants are able to fix nitrogen into the soil. This is important as it reduces the need for using nitrogen fertilisers which have a damaging impact on the environment as they produce nitrous oxide, a potent greenhouse gas. 

The deforestation of the Amazon rainforests to grow soya is having a huge negative impact on the environment. However, most of the soya from the Amazon region is used for animal feed, especially for pigs and poultry.  Over 90% of soya produced for human consumption in Europe comes from North America, Europe, or Asia. 

Conclusion

In summary, soya is a great source of high-quality protein, healthy fats as well as important vitamins, minerals and beneficial bioactive components. Including soya foods and drinks in your daily diet has benefits for both health and the environment. 

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References

International society of sports nutrition position stand: nutrient timing.  Kerksick CM et al. J Int Soc Sports Nutr 2017;14: 33. doi: 10.1186/s12970-017-0189-4

Neither soyfoods nor isoflavones warrant classification as endocrine disruptors: a technical review of the observational clinical data. Messina M et al. Crit Rev Food Sci Nutr 2021;1-57. doi: 10.1080/10408398.2021.1895054.

Beyond the Cholesterol-Lowering Effect of Soy Protein: A Review of the Effects of Dietary Soy and Its Constituents on Risk Factors for Cardiovascular Disease.  Ramdath DD et al. Nutrients 2017; 9(4): 324. doi: 10.3390/nu9040324

Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials. Taku K et al. Menopause 2012;19(7):776-90. doi: 10.1097/gme.0b013e3182410159