What’s all the fuss about Soy?
Soybeans are getting some bad press – there seems to be confusion whether they are healthy to eat or pose possible health concerns.
Soybeans have been around many years, the Chinese started farming them around 1100BC! In the 1940’s America’s soy farming took off. Soybean meal is the most widely used feed for livestock.
In the 1940’s Hong Kong started producing soymilk as a competitor for soft drink rather than as a milk alternative, even bottling in soft drink shaped bottles. By 1974 sales exceeded those of Coca Cola in Hong Kong.
Traditional soymilk didn’t do so well in the West – the “beany” flavour didn’t appeal. There is now quite a lot of processing involved to have the taste and texture attract Western consumers. To make it more appealing the process can lose some of the protein and good fat content so it’s important to look at the organic brands that use whole soybeans in their products to ensure this loss of nutrients is minimal. Look for this on the label.
Soy sauce was the first processed soy product imported to the Western world in the 1770’s. There is some processing involved as soy sauce is fermented. Regular soy sauce uses wheat in the fermentation process, if wanting to avoid wheat, then Tamari soy sauce is ideal. Also look for reduced salt varieties, as soy sauce is quite high in salt.
Miso, (soybean paste) and tempeh are fermented soy products with tempeh being considered as a highly beneficial fermented food product. Tempeh is the only fermented soy product that doesn’t have salt added to it. Tempeh originated in Indonesia/Malaysia.
Tofu (bean curd) can be fermented but most commercial tofu products aren’t. Tofu comes in various textures but does start off in the same way that soymilk is processed.
If you want to enjoy soy with no processing at all, then Edamame is for you! They are the green soybeans fresh in the pod. You can buy them frozen (steam them briefly) or order at any Japanese restaurant.
My advice when it comes to soy products is definitely only organic/non-GMO soy products and read labels to select products that contain whole soybeans (if possible). And remember that a lot of livestock are fed soybean meal so it can’t be all that bad!
Choosing certified organic soy products is a must.
Another main concern surrounding soy is the fact that it is a “phyto-oestrogen”. It is given this name as it possesses a particular structural similarity to the oestrogen molecule, which can allow the phyto-oestrogen to bind to oestrogen receptor sites. What does need to be emphasised is that there are two oestrogen receptors – oestrogen receptor alpha (ER-α) and oestrogen receptor beta (ER-β). ER-α and oestrogen is responsible for growth of hormone-sensitive tissues and is key in the female menstrual cycle and pregnancy. Over-activation of ER-α is related to hormonal cancers such as breast, endometrial and prostate as well as being related to osteoporosis.
Most phyto-oestrogens, especially isoflavones, bind to and activate ER-β rather than ER-α which can give oppositional effects and can have a balancing effect. Therefore activating ER-β with soy isoflavones protects tissues from excessive oestrogenic effects. These positive effects can be reduced menopausal symptoms, decreased risk of developing breast and endometrial cancers, beneficial changes to bone density and can help reduce cholesterol and other cardiovascular risks.
There is also evidence of Asian cultures having lower rates of breast cancer and menopausal symptoms than the western world attributable to their soy intake.
Did you know linseeds are also high in phyto-oestrogens? They are safe to consume.
Soy protein is a complete protein (similar to meat). Soy is high in fibre, low saturated fat, high in vitamins E, B6, calcium and lecithin. Fermented soy products such as miso, tempeh and fermented tofu have more nutrients and are the best forms of soy to eat – making sure they are organic.
If in doubt, leave soy out, but I feel there is more proof that soy has health benefits than detriments!
Thyroid, Heart and Bone Health
How does soy impact our thyroid?
Our thyroid gland is two lobes of glandular tissue located in the throat, which produces thyroid hormones T4 and T3 amongst other thyroid hormones. It has been shown that soy can impair iodine absorption. Iodine is an essential trace element necessary for human growth, concentrated in the thyroid gland and used by the thyroid to produce the thyroid hormones. High levels of the isoflavones genistein and daidzen can inhibit T4 and T3 production, these being highest in soy. Other foods that contain genistein and daidzen (in higher levels but not as high as soy) include other legumes, currants and raisins, alfalfa and red clover. The majority of foods when cooked in boiling water decreases the genistein and daidzen content of foods.
Some menopausal products on the market contain high levels of genistein and daidzen which are extremely beneficial for menopausal symptoms. Studies show that although genistein and daidzen do inhibit thyroid peroxidise, there is not enough effect on the free thyroid hormones.
Therefore a phyto-oestrogen dietary supplement would not be associated with the development of thyroid disorders if there is adequate iodine intake in the diet. If you have an underactive thyroid or any thyroid health concerns then avoiding soy might be an option for you, but most important is your iodine status. If you have adequate iodine levels in your body you could enjoy soy in small amounts. If you have an overactive thyroid then soy could perhaps help to reduce excess iodine if this applies to you.
Soy is extremely beneficial for our heart health!
Because soy is rich in isoflavones, protein, polyunsaturated fatty acids and are high in soluble fibre they have been shown to have positive effects on cardiovascular health with studies suggesting soy foods may prevent or delay cardiovascular disease development.
Soy protein has been shown to reduce total cholesterol, triglycerides, particularly the “bad” cholesterol (LDL) with limited impact on the “good” cholesterol (HDL). Some studies have shown that soy can help increase HDL cholesterol. Soy, being a complete protein, can be a great alternative to meat products when trying to reduce cholesterol.
Research has also shown that more than 25g of soy consumed per day was associated with reductions in systolic and diastolic blood pressure especially in women over 60 years of age.
Osteoporosis and Soy
Soy has been shown to significantly inhibit bone resorption and stimulates bone formation in menopausal women. Most studies have shown that soy can increase bone mineral density (BMD) in the spine with not enough studies yet completed on BMD of the hip. Soy has been shown to help reduce fracture risk of post menopausal women, although consuming soy during peri menopause and early menopause will have a greater effect on bone loss than waiting until post-menopause. Soy should be used in conjunction with other osteoporosis treatments to receive the most benefit.
Side note – Soy does contain phytic acid which can potentially bind to certain minerals such as calcium, magnesium, manganese, zinc, copper and iron so if you are concerned take these mineral supplements 2 hours away from when you have your soy products. Soybeans do naturally contain high levels of calcium, iron, potassium and phosphorus so this needs to be taken into account.
Hopefully you are feeling a bit more relaxed and positive towards soy if you have been starting to get a bit confused by the conflicting information that is out there about soy. My opinion is that most people can safely include organic soy products in their diet in moderate amounts.
By Megan Crockart
Megan is a qualified nutritionist who specialises in digestive issues, food allergy testing, women’s health and creating eating plans to suit and address many health conditions and/or intolerances.