Introduction – what are soya beans?
In the current global environment, because of the ubiquitous rise in non-communicable diseases (e.g., obesity, cardiovascular disease, diabetes) and the advancing climate crisis due to global warming, there has been a shift in attitudes and consumer behaviour in favour of a healthy, sustainable plant-based diet. Soya has recently gained popularity in the Western world as a substitute for meat protein due to its health benefits, versatility, chewy texture, and nutty flavour and because people wish to adopt a healthier and/or more planet-friendly lifestyle.
Soya beans are legumes belonging to the Fabaceae family and are a staple, native crop in East Asia. They are also consumed worldwide – valued for their rich protein and nutrient properties. They are particularly beneficial to vegetarians and vegans as a good non-meat protein food source that is also high in nutrient content.6
Soya beans are consumed in a variety of forms, such as soya milk, tofu, tempeh, miso, protein powder, yoghurt, and edamame. Soya beans are an extremely nutrient-dense food that can provide you with almost all of your daily nutritional requirements, so with their high protein and nutrient content, they are good food for those who regularly engage in physical activity.1
In this blog, we'll dive deep into the world of soya beans, their benefits, uses, and possible side effects to help you understand why they deserve a place in your diet and how you can incorporate them correctly into your diet.
Soya beans are a rich source of protein, fibre, and various vitamins and minerals. According to the United States Department of Agriculture (USDA), one cup (172g) of cooked soya beans contains:
|Vitamin B6||0.402 mg|
Soya protein has several health benefits. Some of the most prominent are listed below:
- It is an excellent protein source – a nutritional powerhouse containing all nine of the essential amino acids required for optimal functioning of the human body. Soya beans are a good source of protein. Additional nutrient content like fibre, vitamins, and other minerals offer numerous health benefits that make soya an ideal addition to any diet. Additionally, soya protein is more easily digestible than other plant-based proteins such as pea or rice protein. This is because soya protein has a high bioavailability, which means that it is easily absorbed and utilized by the body.2, 3
- Mitigates the risk of heart disease – isoflavones, a phytoestrogen polyphenol found in soya beans, have been demonstrated to protect against age-related disorders, including heart disease. Heart disease is a major cause of mortality worldwide and is commonly caused by cholesterol deposits in the coronary arteries, which supply blood to the heart. Isoflavones raise HDL cholesterol (“the good cholesterol”) and control LDL cholesterol levels.2, 5
- Possibly reduces the risk of certain cancers – another potential health benefit of the isoflavones in soya is their anti-cancer effects arising from their oestrogenic and antioxidant properties. Consuming soya products has been linked to a lower risk of developing hormone-dependent cancers, including breast and prostate cancer, according to some studies.2
- Maintains bone health – high quantities of calcium, magnesium, and other minerals are present in soya beans, which are important for maintaining bone health. Isoflavones play a major role in this, too. Consuming soya products has been linked to improved bone density and a decreased risk of osteoporosis, particularly in people assigned female at birth (AFAB) who are postmenopausal2
- It may help relieve menopausal symptoms – isoflavones, a phytoestrogen, mimic the action of oestrogen (a female reproductive hormone) in the body. They may help reduce hot flashes and other symptoms linked to declining oestrogen levels, which may be helpful for women going through menopause.2
- Assists weight loss – some studies have shown that consumption of soya protein is linked with improvement in insulin resistance, reducing fat deposition and lowering plasma cholesterol and triglycerides. Also, soya is rich in soluble fibre, which can reduce appetite and, consequently, calorie intake, thus aiding weight loss.3 4
Uses of soya beans
Soya beans are used in a range of items, such as food and cosmetics. The following are a few of the most typical uses of soya:
Food items such as tofu, tempeh, soy milk, soy sauce, and miso are just a few of the foods made from soya beans. As a rich source of protein, these items are very popular among vegetarians and vegans.
Tofu is made by coagulating soya milk in a similar process to cheese-making and is one of the most frequently consumed soya-based food items. It may be incorporated into many different meals, including stir-fries and smoothies.
Another well-known soya product is tempeh, which has a nutty flavour and is produced by using a fungus to ferment cooked soya beans. It can be sliced and used in salads or sandwiches, etc.
Soya milk, the popular non-dairy milk substitute, is created by soaking and blending soya beans. It can be used as a replacement for dairy milk in many recipes, including those for smoothies and baked goods.
Another well-known item created from soya beans is soya protein powder, which can be added to shakes and smoothies to increase their protein content.
Some easy recipes for you to try include:
Goods for industry
Other than the food industry, soya beans are used in a wide range of industrial goods, including biodiesel, ink, and various polymers. Soya beans are also used in some beauty products, such as moisturizers and hair conditioners, because soya bean oil is high in vitamin E and other antioxidants, which can help nourish and protect the skin and hair.
A byproduct of soya bean processing known as soya bean meal can be used as fertiliser to enhance soil quality and supply plants with nutrients.
Side effects and other concerns
Generally harmless, there are a few potential side effects of soya beans and associated negative issues to be aware of:
Soya allergy is a widespread food allergy that affects a significant number of people globally. Soya can initiate an anaphylactic immune response in some individuals. It is challenging to completely identify soya within and eliminate soya from the diet, as it is an integral part of many traditional cuisines. Also, soya protein is also a common ingredient in off-the-shelf food due to its use as a substitute for casein.
Symptoms can range from mild itching, hives, swelling, vomiting, and diarrhoea to severe symptoms like breathing difficulties and anaphylaxis – a severe and potentially life-threatening allergic reaction.
Soya allergy can be diagnosed through a physical exam, a review of the patient's medical history, and allergy testing. Skin prick testing and blood tests can help identify whether a person has a soya allergy.
As a precautionary measure, an individual diagnosed with a soya allergy should avoid soya products entirely, so it's essential that they read food labels carefully. For those suffering from severe allergic reactions, carrying an epinephrine (adrenaline) auto-injector pen can be life-saving. In the event of an allergic reaction, the auto-injector can quickly deliver a dose of epinephrine to alleviate the symptoms.6
It's essential to speak with a healthcare provider about the potential risks and management strategies for soya bean allergy.
As soya beans contain phytoestrogen, they can potentially lead to hormonal imbalance, as suggested by some studies. However, most studies indicate moderate soya consumption (up to three servings per day) is safe and unlikely to have any significant hormonal effects.
An important potential hormonal effect is on oestrogen levels. Isoflavones, mimicking the action of oestrogen, can bind with its receptor, either blocking or amplifying its function. For instance, in premenopausal women, soya isoflavones can bind to oestrogen receptors in breast tissue and potentially lower the risk of breast cancer.7 On the other hand, in postmenopausal women, soya isoflavones may simulate the effects of oestrogen, but an increased risk of breast cancer is not found in large reviews of research literature.2,7 In men, a few studies suggest soya isoflavones may possibly impact the levels of testosterone in the body, but this is contradicted by many other studies. Some studies have suggested that soya isoflavones can also reduce the risk of prostate cancer, while others have found no significant impact.2
Additionally, some early animal-based studies created concern that soya isoflavones could negatively alter thyroid function, but a large-scale analysis of more recent studies does not support this. However, soya protein can affect the absorption of levothyroxine medication used to treat hypothyroidism (lack of thyroxine ), but since this medication is taken with an empty stomach, this is not significant2 It's worth noting that the hormonal effects of soya beans are still a grey area regarding research findings, and more studies are needed to fully understand the impact of soya on hormonal health.8
Genetically modified soya bean (GMO) plants are genetically enhanced breeds, altered using biotechnology to produce specific desired traits, such as resistance to pests or herbicides. GMO soya beans have been widely adopted in agriculture, and they now represent a significant portion of the world's soya bean production. GMO soya beans increase yields and curb the need for chemical pesticides and herbicides, which are harmful to the environment and human health. However, the use of GMO soya beans has also raised concerns about the potential risks. There are concerns about the long-term health effects of consuming GMO soya beans, although studies on this topic have produced mixed results. To address this issue, countries have implemented regulations and labelling requirements for GMO foods. In the United States, the Food and Drug Administration (FDA) regulates GMO crops, including soya beans, and requires safety assessments before they can be sold to the public.
Soya beans contain compounds called antinutrients, which can interfere with the absorption of certain other nutrients in the body. However, most of these compounds can be reduced or eliminated through proper processing and cooking methods.
Soya beans are versatile and nutrient-dense food with a variety of health benefits. They are a good source of protein, fibre, vitamins, and minerals and have been shown to help reduce the risk of heart disease, certain cancers, and other health conditions. Soya beans can be used in a variety of ways, from food products like tofu and soya milk to industrial products like biodiesel. While soya beans are generally considered safe for most people, it's important to be aware of potential side effects and concerns, such as allergies and hormonal effects. Overall, soya beans can be a healthy and delicious addition to a balanced diet.
- FoodData Central [Internet]. fdc.nal.usda.gov. Available from: https://fdc.nal.usda.gov/fdc-app.html#/food-details/174271/nutrients
- Messina M. soya and Health Update: Evaluation of the Clinical and Epidemiologic Literature. Nutrients [Internet]. 2016 Nov 24;8(12):754. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5188409/
- Velasquez MT, Bhathena SJ. Role of Dietary soya Protein in Obesity. International Journal of Medical Sciences [Internet]. 2007 Feb 26;4(2):72–82. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1838825/
- Heng WK, Choo JY, Ng YP, Loh KS, Chua YH. Effect of soya-based meal replacement on weight loss: A systematic review and meta-analyses protocol. Nutrition and Health. 2022 Apr 11;28(4):489–93. Available from: https://pubmed.ncbi.nlm.nih.gov/35404174/
- Anderson JW, Johnstone BM, Cook-Newell ME. Meta-analysis of the effects of soya protein intake on serum lipids. The New England journal of medicine [Internet]. 1995;333(5):276–82. Available from: https://www.ncbi.nlm.nih.gov/pubmed/7596371
- Messina M, Messina V. The Role of Soya in Vegetarian Diets. Nutrients. 2010 Aug 6;2(8):855–88. Available from: https://pubmed.ncbi.nlm.nih.gov/22254060/
- Fritz H, Seely D, Flower G, Skidmore B, Fernandes R, Vadeboncoeur S, et al. soya, Red Clover, and Isoflavones and Breast Cancer: A Systematic Review. Shioda T, editor. PLoS ONE [Internet]. 2013 Nov 28;8(11):e81968. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3842968/
- Hooper L, Ryder JJ, Kurzer MS, Lampe JW, Messina MJ, Phipps WR, et al. Effects of soya protein and isoflavones on circulating hormone concentrations in pre-and post-menopausal women: a systematic review and meta-analysis. Human Reproduction Update [Internet]. 2009;15(4):423–40. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2691652/