Is soya good for you?

Discover our full range of health benefit guides, including green tea, kimchi and ginger. Then check out the best vegetarian sources of protein.

Nutritional profile of soya

An 80g serving of soya beans (boiled) provides:

• 113kcal / 472KJ
• 11.2g protein
• 5.8g fat
• 0.7g saturated fat
• 4.1g carbohydrate
• 6.5g fibre

Health benefits of soya beans

1. Source of protective antioxidants

Soya beans contain natural compounds called isoflavones. These are categorised as a type of antioxidant and as such help minimise the damage (called oxidative stress), which is caused by free radicals. It’s this oxidative stress which is involved in both aging and the onset of chronic disease. Soya beans are especially rich in isoflavones and provide other active plant compounds including saponins.

2. May alleviate menopausal symptoms

Soya isoflavones (daidzein and genistein) have attracted a great deal of attention because they are phyto-oestrogens, plant compounds that mimic a weak form of the hormone oestrogen. Some women find including these in their diet helps with peri-menopausal symptoms, including poor mood and hot flushes. However, genetics, your gut microbiota and environmental factors all play a part in how our bodies react to certain foods, so as yet, we can’t say whether a diet rich in phyto-estrogenic foods is beneficial for all women or not.

3. Plant source of ‘complete’ protein

Soya beans are a useful source of plant protein, providing all nine of the essential amino acids (making them a ‘complete’ source) we need for growth, repair and functions like immunity. The digestibility of the protein in soya, which refers to how well our body can make use of the protein is also good, with some studies suggesting it may even be comparable to that of animal protein.

4. May support cholesterol balance

Soya beans contain phytosterols, these plant compounds are structurally similar to cholesterol and work in the body by inhibiting cholesterol absorption. This explains why regularly eating foods like soya has been associated with reduced cholesterol levels. Studies also suggest this includes a reduction in low-density lipoprotein (LDL), the type often referred to as ‘bad’ cholesterol, as well as total cholesterol.

5. May support heart health

Regular consumption of legumes, including soya beans, has also been linked to a lower risk of heart disease; this is thought to be because they are a rich source of phytochemicals as well as fibre.

6. May support bone health

Soya foods may be a beneficial inclusion for mid-life women, this is because lower levels of oestrogen after the menopause may lead to a greater reduction in calcium levels in the bone. Some studies suggest that including 40-110mg of soy isoflavones each day may reduce this bone loss and improve bone mineral density. From a practical perspective, this would be the equivalent to eating 35-100g of cooked soya beans (or 140-440g of tofu) each day.

7. May help in the fight against cancer

A moderate intake of soy foods rich in isoflavones, may reduce the risk of breast cancer in pre- and post-menopausal women. Furthermore, studies appear to suggest that intakes, comparable to those of Asian populations, have no detrimental effects on the risk of breast cancer recurrence. This may be of particular relevance to women who may be at increased risk due to their genetic profile.

8. May support blood sugar balance

One study of post-menopausal women who consumed 100mg of soy isoflavones each day saw a reduction in fasting blood sugar levels by 15 per cent and insulin levels by 23 per cent. Similarly, diabetic post-menopausal women who supplemented with isolated soy protein saw a reduction in fasting insulin levels, insulin resistance and an improvement in cholesterol management.

However, other studies have generated mixed findings with a meta-analysis suggesting there is still more for us to learn in this area. In the meantime, it appears consuming soya beans and foods made from them may be useful, but more studies are needed.

9. May support gut health

Soya beans are a good source of fibre, especially, the type known to be prebiotic. This fibre acts as a fuel source for the beneficial bacteria in the gut, helping them thrive and increase in number. Many of these gut bacteria produce compounds called short-chain fatty acids, which have beneficial effects on the gut as well as for our wider health.

10. May lift your mood

Studies suggest a regular intake of soy foods may have a beneficial effect on the mental health of older adults with a higher intake being associated with a lower risk of depression. However, if you are medicated for depression speak to your GP or health practitioner before making significant changes to your soya intake.

Could soya be bad for you?

Soya beans are generally recognised as safe for most people, unless you have a soy allergy, when they should be avoided. There are some other considerations relevant for certain people, these include:

• Soya beans are goitrogenic, which means they interfere with the activity of the thyroid gland. In practice this effect may be minimal, however, if you have a thyroid condition you may wish to monitor your intake.
• Soya beans and products made from them, also contain oxalate so people with a history of calcium oxalate kidney stones may choose to avoid over-consuming them. However, study findings are mixed in this area with some suggesting that, although soya beans contain some oxalate and moderate amounts of phytates, they may actually be advantageous for kidney stone patients.
• Like other beans, soya contains antinutrients including trypsin inhibitors and phytates, these may inhibit your absorption of some of the bean’s valuable nutrients. Soaking or fermenting before cooking may minimise these compounds – this is why choosing traditional soya products, like tempeh and miso, may provide superior nutritional value.
• Similar to other beans, soya contains types of fibre classed as FODMAPs, these fibres may worsen symptoms of irritable bowel syndrome (IBS).

The consumption of soya has become controversial over recent years, with some animal studies suggesting a link with certain cancers. In support of the food’s safety, the European Food Safety Authority has concluded that soya isoflavones do not adversely affect the thyroid, breast or uterus in postmenopausal women.

Is soy sauce healthy?

Made from fermented soya beans and wheat, this salty condiment is a popular way to add flavour to a dish. How healthy it is may be influenced by its production method – natural fermentation is generally a better choice over that subjected to chemical hydrolysis. Look closely at the product label and check it does not include colourings or flavour enhancers, and that it has been ‘naturally brewed.’

Like most foods, soy sauce may be enjoyed in moderation as part of a varied, balanced diet. However, if you have been advised to cut down on your salt intake, use sparingly.

Overall, are soya beans healthy?

Soya beans offer an excellent source of plant-based protein and contain an array of vitamins, minerals and plant compounds, including isoflavones. Regular consumption of the beans may help manage cholesterol levels, and for some women, help with the symptoms of the peri-menopause. However, those with an allergy, thyroid condition or digestive complaint influenced by FODMAPs, should limit their intake.

Enjoyed this? Read more…

What is a plant-based diet?
10 ways to lower cholesterol
Spotlight on… heart disease
What is menopause?

Before changing your diet, it is advisable that you speak to your GP or alternative health professional.

Recipe suggestions

Tofu is a vegetarian alternative to meat that is an excellent substitute:
Soba noodle & edamame salad with grilled tofu
Tofu, greens & cashew stir-fry
Spicy tofu kedgeree
Tofu & spinach cannelloni

Soya beans make a tasty, nutritious accompaniment to fish:
Lemon cod with basil bean mash
Soy tuna with wasabi mash
Zingy salmon & brown rice salad
Salmon & soya bean salad

Edamame is simple to prepare and makes a great snack or appetiser. A favourite with kids, too:
Edamame & chilli dip with crudités
Lemony three bean & feta salad

Not just for vegetarians, soya beans go well with chicken, too:
Chicken, edamame & ginger pilaf

Don’t forget about miso:
Miso steak
Miso-marinated salmon
Miso brown rice & chicken salad

This article was reviewed on 27 March 2024 by Kerry Torrens.

Kerry Torrens is a qualified nutritionist (MBANT) with a postgraduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the past 15 years she has been a contributing author to a number of nutritional and cookery publications including Good Food.

Jo Lewin is a registered nutritionist (RNutr) with the Association for Nutrition with a specialism in public health. Follow her on Twitter @nutri_jo.

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