It’s the key ingredient in tofu, tempeh, miso soup and soya milk, but has been mired in health controversy for decades. We quiz the experts on the nutritional status of soya…
Soya (or soy in the US market) may populate the health food ideas in the manner of a new “alternative” dairy and protein source, but the soybean plant has been a foodstuff for thousands of years, originally cultivated in China and widely consumed in Asia. In fact, women in Asia consume 10-20 times more soya based food than their Western counterparts, although the soya market is growing in the UK according to the Office of National Statistics, with soya milk being added to the CPI Index this year for the first time (gin is experiencing a boom too, incidentally).
“There is more awareness of the benefits of plant based diets, and thus a concentration on finding different protein sources, both for environmental and health reasons, for example, the Meat-Free Monday movement .”
From steaming, salty edamame beans at your local Japanese to lattes and protein-rich yogurt, meat and cheese substitutes, soya can crop up surprisingly frequently in our modern Western diets, but despite the fact that sales are soaring, the safety of soya has been called into question in the past, and not everyone can agree as to whether soya is healthful or harmful. Cue two nutrition specialists to present the ‘for’ and ‘againsts’ for soya, from cancer scandals to menopausal relief.
What a dietitian says
Rebecca McManamon is optimistic about soya’s general health profile:
“There is quite convincing evidence that eating soya on a regular basis can help to lower cholesterol and heart disease risk, however, to reap that benefit it does need to be eaten daily.”
As for the association between soya and an increased risk of breast cancer, originally thought to be linked to the effect of potentially harmful isoflavones that supposedly mimic the effect of oestrogen in the body, Rebecca stresses that advances in research have revealed that the opposite may in fact be true:
“A decade ago, dietitians were concerned that soya could make breast cancer worse, but over time the evidence emerged at first that it wasn't likely to cause harm, and more recently that it may even be beneficial in preventing recurrence of breast cancer.”
The British Dietetic Association provides further assurance that soya has had an unfair rap where links to cancer, and particularly breast cancer, are concerned:
“Many countries with high soya intakes also have a low rate of certain cancers including breast and prostate. In 2012, the American Institute for Cancer Research (AICR) reported no indication that eating soya places anyone at increased risk of breast cancer, or that soya foods were unsuitable for those either at risk of breast cancer, breast cancer patients or for survivors of breast cancer. The AICR latest review also mentions that in some cases, research indicates that soya isoflavones may in fact lower the risk of cancer.”
“Some studies suggest that lifelong soya consumption and exposure to isoflavones – especially before and during puberty – may protect against the development of breast cancer.”
Soya’s beneficial impact on women’s health apparently doesn’t stop there, as Rebecca explains:
“There are some studies that indicate that soya can be of benefit in reducing some menopausal symptoms . Unfortunately as women's female hormone levels reduce it increases the risk of heart disease, so it wouldn't be a bad idea for perimenopausal women to eat more soya, but not to pin all their hopes on it - if menopausal symptoms are impacting on daily life, advice from a GP or specialist menopause clinic is needed.”
Further possible evidence for soya as a menopausal crutch is the fact that, while 75% of Western women suffer with hot flushes, only 20% of Japanese and Chinese women who consume a diet rich in soya products experience such symptoms.
Potential health benefits include lowering cholesterol and reducing the severity of hot flushes
From a female point of view soya seems to be a positive dietary addition, but how about for men? Rumours that soya’s phytoestrogen content can affect male hormones are apparently unfounded according to the The British Dietetic Association:
“Studies consistently show that eating soya foods does not raise oestrogen levels, upset hormonal balance or reduce testosterone concentrations in men; no adverse effects on fertility or sexual health have been reported.”
Where soya doesn’t have quite such a clear bill of health is where thyroid issues are concerned:
“Soya isoflavones can interfere with the absorption of synthetic thyroid hormones. A recent study has indicated that soya isoflavones may worsen the condition for individuals with a mildly underactive thyroid.”
Rebecca underlines that this advice only applies to a relatively small group of people:
“People taking Levothyroxine for thyroid conditions may wish to avoid consuming soya products at the same time as their thyroid medication, to prevent interactions. There are limited studies as to how much impact soya may have on the medication interaction, so really it is precautionary to avoid it at the same time.”
If Rebecca’s advice has put your mind at rest regarding soya, how often, and for that matter, how should you be eating it? That old chestnut ‘moderation’ crops up…
“It's unclear if there is a set safe level of soya consumption as opinions differ. I view soya like safety for any other food; I wouldn't advise soya for breakfast, lunch and dinner, just as I wouldn't advise egg or fish or lentils at each meal! We need a variety of protein sources as each offers us a range of different nutrients- if we have too much of anything we will displace something else.”
“Soya mince is an easy way to try soya if you haven't eaten much before- simply substitute or mix half and half with regular mince in dishes such as shepherd's pie or pasta. Coming into the summer, soya beans can be enjoyed in salads or cold rice and pasta dishes.”
With soya mince packing the most soya protein per gram, it’s an energising meal option, but make sure to check packaging before you buy to check that there aren’t any unwelcome additives or high levels of salt or sugar. Given that soya is also very often consumed in its fermented form across Asia (such as in miso soup and tempeh), and that the fermentation process boosts soya’s amino acid, vitamin and mineral profile, it could be worth opting for fermented over unfermented soya sources, and avoiding soya that’s overly processed.
The bottom line from dietitians? The British Dietetic Association are giving soya the green light:
“Research on soya foods is ongoing, but it is clear that soya is nutritious, safe and healthy. Potential health benefits include lowering cholesterol and reducing the severity of hot flushes. Evidence shows that soya foods can be consumed by all members of the population including men and women with breast cancer. Soya foods can also help us to achieve an increasingly plant-based diet by reducing our intakes of animal protein which can also benefit the environment and food sustainability.”
Despite this, some members of the nutrition community are still to be swayed that soya is healthy for all...
What a nutritional therapist says
Registered nutritional therapist Daniel O’Shaughnessy has a bone to pick with soybean and its derivatives:
“It’s not something I would recommend to clients as it’s a heavily GMO crop and full of glyphosate (a pesticide).”
Daniel points out that health implications of GMO “include links to cancer and kidney disease.” He outlines the issue:
“The genetic modification is carried out to impart resistance to the toxic herbicide Roundup . While this is intended to increase farming efficiency and provide consumers with less expensive soya, the downside is that your soya is loaded with this toxic pesticides. The plants also contain genes from bacteria that produce a protein that has never been part of the human food supply.”
So far, so worrying, and for Daniel it’s not just the manufacturing process that poses problems.
Daniel’s not convinced that men in particular stand to benefit from consuming soya either:
“If men have low testosterone levels and consume large amounts of soya, they may be at risk of developing gynecomastia (in other words, man boobs)”
The above being said, soya doesn’t deserve to be written off altogether, as Daniel comments that it could have advantages for women’s health:
“It’s possible that it may have a balancing effect on oestrogen, but you would have to consume a lot of soya. Personally I prefer non-soya phytoestrogen sources for hormone balancing, such as oats, beans, lentils, alfalfa, licorice root, mint, fennel and red clover.”
As for soya milk, given the bitter taste of soya beans in their natural form, many brands go heavy on added sugar and sweetener to disguise this. Daniel favours a different kind of dairy alternative:
“Try almond or cashew milk (Plenish make some of the best on the market), use coconut or olive oil as a spread and look out for coconut yogurt and cream (Marks and Spencer are onto this.)”
So is soya in all its guises a no-go for Daniel?
“Fermented soya can be beneficial to health. Try natto (fermented soybeans). To be honest natto can be disgusting, or it can be delicious- it’s all in the preparation. Either way, it’s very rich in vitamin K2 and good bacteria .”
If you’re not a fan of natto, make sure that the soya you’re buying is as close to its natural form as possible:
“Try to avoid soya in its processed form- it’s used widely in stocks, bouillon, protein powders, as a bulker or in the form of soybean oil. Definitely buy organic and choose fermented forms such a tempeh, soy sauce and tamari. The fermentation destroys lectins and phytic acid, so overall it’s better for you. Nevertheless, the fermentation process may increase the histamine content of the food, which is another story (get more insight into histamine in food here .)”
What we say
We’re not looking to drop our edamame bean habit completely, especially seeing as a serving delivers an impressive roster of fibre, vitamins and minerals, not to mention plant protein, but we’ll be investigating the source of our soya and keeping an eye out for more conclusive studies concerning the effects of phytoestrogens- genetics and environment appear to play a part as to whether they are positive, potentially detrimental or simply neutral in their health effects. As with most types of food, choosing unprocessed and organic options where possible will maximise nutritional and environmental gain. Moderate intake of high quality soya is unlikely to pose a risk to health, and could in fact give it a boost, but, such is life, going overboard is unlikely to result in additional benefits.
Want to know more about soya milk in particular? Peta Bee analyses nine cow’s milk alternatives here