Soya - healthy or unhealthy? The big fact check!
Vegetarian and vegan diets are becoming increasingly popular. Due to the growing demand for plant-based foods, the range of meat substitutes available is also expanding. This is where soya comes into play, often forming the basis of these alternatives. However, negative headlines keep cropping up about the harmful effects of soy in the body. The secondary metabolites of soy beans have been said to reduce men’s fertility and even increase our risk of developing cancer. We will clarify just how unhealthy soya actually is.
What exactly is soya?
When we talk about soy, we are referring to soya beans. As legumes, soya beans belong to the Fabaceae family of plants and serve as an integral part of many diets, particularly in the Asian region. Soya beans are primarily used in the production of tofu, soy sauce, and milk and yoghurt alternatives. Meat substitutes often play an important role in plant-based diets. Soy-based alternatives, such as veggie sausages and mince, can now be found in almost every supermarket.You may already know soya beans under the name “edamame” from dining in Japanese restaurants. This popular appetiser consists of harvested unripened soya beans, usually topped with coarse salt.
What is soya made of?
Natural soya products are appealing not only because they are very high in protein and nutrients, but also because of their low fat and cholesterol content. Soya protein has a high biological value, meaning it is very well utilised in the body. It contains all nine essential amino acids in sufficient amounts, and thus can be said to have a complete amino acid profile. Essential amino acids are protein building blocks that must be obtained from food, since the body cannot produce them by itself. Soya, as a high-quality protein source, is an ideal food choice for vegans and vegetarians.
Benefits of soya
- High protein content (34% → leader among legumes)
- Polyunsaturated fatty acids, B vitamins
- Lots of fibre
- Important minerals & trace elements (calcium, magnesium, iron & zinc)
This little green bean has a lot of power!
Nutritional values of soya beans
| Nutritional values of soybean per 100g | |
|---|---|
| Calories | 323 kcal |
| Protein | 34 g |
| Fat | 18 g |
| Carbohydrates | 6 g |
| Fibre | 22 g |
Rumours about soya
1. "Soya increases your risk of cancer"
The academic consensus on soya is not yet uniform, but studies in Asian countries have suggested that it has positive effects on health. People who regularly eat natural (i.e., not heavily processed) soya products have a lower risk of developing breast cancer and prostate cancer as well as cardiovascular diseases. Only people with thyroid problems need to watch their soya intake, as they must ensure they get enough iodine, and soya consumption can inhibit absorption of iodine in the body. Aside from this, the soya bean can be ascribed many health-promoting properties due to its valuable nutrients.
2. "Soya disrupts our hormonal balance"
Rumours about the alleged hormonal effects of soy continue to spread far and wide. Are these false or factual? Leave it to us to explain. The soya bean contains secondary metabolites, called isoflavones. These isoflavones belong to the group of phytoestrogens, which are indeed, as the name reveals, related to the female sex hormone oestrogen. Don’t panic, though: their effect on the body is not the same as that of mammalian oestrogen, therefore soy does not reduce testosterone levels in men. On the contrary, there are in fact studies that show it has a positive effect on fertility!
3. "Soya consumption is destroying rainforests"
Any criticism claiming that consumption of soya products in a plant-based diet is responsible for the destruction of rainforests is, quite frankly, completely unfounded. 80% of soya grown globally is used for animal feed in factory farming, while only a very small proportion is consumed directly by humans.
Antinutrients in soya
Like many other legumes, raw soya beans contain so-called protease inhibitors, which can inhibit the function of protein-splitting digestive enzymes. However, these are either deactivated through processes of heating, pasteurising, fermenting or during germination and are therefore no longer present in products such as soya milk and tofu. Due to this, all soya foods are heated in the course of production and antinutrients are therefore no longer a concern in the final product.
Criticism of phytic acid
Isoflavones belong to the group of phytoestrogens. Although these occur naturally in many plants, their levels in soya beans are strikingly high. Phytic acid reduces the bioavailability of essential minerals, as it binds zinc, iron, calcium and magnesium ingested with food, forming insoluble salts. As a result, these minerals can no longer be absorbed by the body. However, the concentration of phytic acid in soya products is still quite low due to the manufacturing process(es). Fermentation, for example, reduces the phytate content and therefore increases the bioavailability of minerals. As long as a balanced diet is maintained, the phytic acid in soya foods should not affect our calcium and iron balance.
Soy beans should not be eaten raw!
Important: Supplementation of vitamin B12
In an omnivorous diet, sufficient vitamin B12 can be obtained from animal products, however this vitamin is not found in plant-based foods, unless fortified. Therefore, be aware that, in vegan diets especially, vitamin B12 must be supplemented in order to prevent deficiency.
How much soya is healthy?
According to the British Dietetic Association (BDA), soya is compatible with UK government dietary recommendations for healthy and environmentally sustainable diets. In general, there are no large health organisations worldwide which advise against soy consumption. The Food and Drug Administration (FDA) recommends a maximum intake of 25 g of soy protein per day as a guideline. This corresponds to about 300 g of tofu or 800 ml of soy milk. But don’t worry – you don’t usually reach these amounts in a balanced and varied diet. Would you rather not have to think about your nutrition everyday and instead just be able to relax and enjoy eating? Well, you’re in luck. Our personalised meal plans are meticulously tailored to your preferences and needs!
Note: Pay attention to where the soy comes from
When buying soya products, keep in mind that they may have been genetically modified. Tip: look out for the organic certification. This guarantees that no genetically modified organisms have been used in their production.
Consumption of soy in childhood
When it comes to feeding infants, dairy products should not be replaced with soya products. In about half of all children, soy allergies disappear by the time they reach school age and 70% of affected children have developed a tolerance to soy by the age of ten. Therefore, according to the NHS, it is okay to give your child soy products as part of a healthy, balanced diet. One thing to note, however, is that soy products which serve as milk substitutes should be fortified with calcium in order to ensure a sufficient intake. However, there is a need for further research in this area.
Conclusion
Soya is a versatile food source and boasts flavour as well as high nutritional value. Legumes aren’t just high in protein, but provide a lot of other important nutrients too. Soya products, such as tofu or tempeh, can make an essential contribution to a balanced and healthy plant-based diet. Of course, you don’t have to eat soya to be healthy, but, from a nutritional viewpoint, there is no reason to exclude it from your diet.
Frequently Asked Questions
Why is soya bad for men?
Soya isn’t bad for men. In fact, consumption of soya is recommendable regardless of gender. The myth that soya reduces fertility in men is simply wrong. There is not yet a uniform consensus amongst academics, but this legume certainly seems to have health-promoting properties.
What are the symptoms of a soya intolerance?
An intolerance to soya may materialise in various ways. The symptoms may be mild or more severe and can include:
- gastrointestinal problems (vomiting, nausea, diarrhea, abdominal pain)
- skin irritation (itching, eczema)
- Dizziness, lightheadedness
Whilst you may be born with a soya intolerance, this often goes away during childhood.
Which milk is better almond or soya?
This depends on many factors and both can be enjoyed as part of a varied and balanced diet. When it comes to taste, that is down to personal preference. In terms of environmental friendliness, almond production is more water intensive than soya production. Furthermore, soya milk is the cheaper option of the two. Therefore, certain factors point to soya milk being better than almond milk, however this isn’t to mean that almond milk can’t be enjoyed for a bit of variety too.
Sources
- Bundesinstitut für Risikobewertungen (BfR, 2008)
- Verband für Unabhängige Gesundheitsberatung
- Food and Drug Administration (2020)
- Backes, G. (2012). Soja—das Fleisch des Feldes
- Mörixbauer, A. Soja, Sojaisoflavone und gesundheitliche Auswirkungen
- Messina, M., Rogero, M. M., Fisberg, M., & Waitzberg, D. (2017). Health impact of childhood and adolescent soy consumption
- Korde, L et al. (2009). Childhood soy intake and breast cancer risk in Asian American women
- Trock, B. J., Hilakivi-Clarke, L., & Clarke, R. (2006). Meta-analysis of soy intake and breast cancer risk
- Messina, M. J., Persky, V., Setchell, K. D., & Barnes, S. (1994). Soy intake and cancer risk: a review of the in vitro and in vivo data. Nutrition and cancer
- Messina, M., Rogero, M. M., Fisberg, M., & Waitzberg, D. (2017). Health impact of childhood and adolescent soy consumption
- Bolland, A. (2006). Pro Gesundheit–Contra Gluten
