Having had a long discussion with a friend recently about the merits of soy I thought it worthwhile looking at what the facts say about this often much maligned bean. Many of us know the image that our friends and colleagues have of vegans. A skinny hippie with hemp sandals eating a large bowl of lettuce and block of plain tofu.
Luckily, we know that this image doesn’t represent plant-based eating in the slightest and infact couldn’t be further from the truth. However along with this naive, partly funny and partly sad picture that might come to the uneducated mind is the health concern surrounding all things soy.
In this article, we want to look at the myths that follow soy and ascertain exactly what is true and what is not. So, let’s crack on and ask the question are soy products healthy?
What is Soy?
I guess we should start at the beginning and ask what is soy? The soybean is a legume (podded plant) that is native to East Asia. As a bean soy can be eaten “from the pod’ when cooked or fermented to produce both tempeh and miso paste. Tofu the white tasteless blocks often associate with soy are curdled soy.
Soy can also be process into milk or indeed many other products. Infact processed soy is now used in hundreds of products that are available today such as fake meats and veggie burgers, even some baby formulas contain processed soy
The Soy Controversy
Whenever we mention soy we find that someone has an opinion on it. I guess that is the world we live in where information and of course misinformation is all too readily available.
The majority of us are all too happy to read a headline or summary and take it as gospel without actually doing the research to see if the argument is justified.
So, what are some of the concerns regarding soy are they justified and where have they come from?
So are soy products healthy and what are the main concerns? Well soy contains a class of phytonutrient known as isoflavones. These isoflavones have a chemical structure very similar to estrogen hence why they are also known as phytoestrogens. It is these phytoestrogens that have been blamed for having a negative impact on health.
Some of the claims include decreased fertility and “man boobs” for men. For women, an increase in their risk of breast or cervical cancer and other hormone imbalance-related disorders. However, these claims have been made based on phytoestrogens acting the same in the human body as estrogen when infact they act quite differently.
Although as we have said isoflavones are structurally similar human estrogen, they cannot be created by the human endocrine system. By occupying our estrogen receptors, phytoestrogens actually lower the estrogen levels in our blood instead of raising it!
Addressing the concerns
In fact, it has been proven that consumption of isoflavones is beneficial to the body, not just reducing the risk of breast cancer but reducing the risk of cancer recurrence and improving rates of survival. The American Institute of Cancer Research and American Cancer Society have both conducted research in to soy consumption and concluded that soy is safe for breast cancer patients and the general population.
And as for “man boobs’ and lack of fertility a meta-analysis evaluated the data from 15 different placebo-controlled trials of soy foods, soy protein, or isoflavone supplements. These studies measured various indicators of testosterone levels. These included both total and free testosterone as well as the sex hormone binding globulin. The resulting data showed no effects on testosterone levels, estrogen levels, or sperm quality (1 see foot note).
It’s probably worth mentioning at this stage that soy isn’t the only food that contains phytoestrogens. There is a large range of foods that contain them including, to name just a few, apples, oats, yams, beans, mint, rice, carrots and both beer and bourbon!
Soy and the Thyroid
Another soy concern has been its possible effect on the function of the thyroid. Soy has been reported to cause goiters (an enlarged thyroid gland usually due to lack of iodine), hypothyroidism and even thyroid cancer.
However, studies have since disproved the causal relationship between soy and lowered thyroid function, due to the protective nature of isoflavones. Similarly, adequate intake of iodine stops the formation of goiters in a healthy individual. Good plant sources of iodine include iodised salt, sea vegetables and plants grown in iodine rich soil.
Additionally, population studies have shown that soy has a protective effect against thyroid cancer. A review paper of 14 studies looked at the effects of soy on the thyroid and couldn’t find any adverse effects.
The consumption of any foods with phytoestrogens is only of concern if iodine intake isn’t adequate which is why we should ensure we have a reliable source for iodine.
So where has the soy negativity come from?
I don’t normally like to comment on anyone else’s opinions or claims preferring to look at the data but with soy I think it is worth mentioning that a tremendous amount of anti-soy stories can be traced back to one single group in the US called the Weston A Price Foundation (WAPF).
This organisation says it is dedicated to promoting healthy nutrition by restoring nutrient-dense animal products to the diet. This includes unpasteurised “raw” milk. It says that saturated animal fat is essential for good health and that animal fat intake and high cholesterol levels have no link with heart disease or cancer.
They also claim that vegetarians and vegans have lower life expectancy than meat-eaters. This misinformation of course, completely contradicts the science and the message of The World Health Organisation, The American Dietetic Association and the British Medical Association.
So why would it do this, well maybe we should look at its funding for an answer to that question, but instead let’s move on.
But isn’t soy bad for the planet?
I love this argument. It is true that a high percentage of the soy grown today is GM and the way it is farmed is not the best for soil nutrients. We then must ask why is that? The answer is due primarily to the fact that only a small portion of soy is consumed directly by humans.
Infact according to the WWF the majority, approximately 85% is used as animal feed, including you may be surprised to know even farmed fish! The demand for meat has increased substantially over the past few decades along with the world population.
Because of this soy harvesting has also increased substantially and is now a major contributor to deforestation. So, soy itself is not the problem here but big agriculture is. The answer then is not to demonise soy but to stop eating so many animal products and to encourage sustainable farming with correct crop rotation.
It is worth remembering that the animal industry is the largest pollutant on the planet bar none. Yes, that includes all transport and all oil extraction. Unfortunately, as humans much of what we do will likely have a negative effect on the environment. As such it is our responsibility to purchase our food from responsible sources preferably local and to encourage this behaviour in others.
The health benefits of soy
Ok so enough of the negativity let’s look at the positives and why there are lots of reasons to include soy in your diet. Nutritionally speaking soy is loaded with goodness. More protein than most legumes with lots of fibre, omega 3 and fatty acids, calcium, iron, magnesium, phosphorus, potassium, and vitamins B1, B2, B3, B5, B6, B9, C, and zinc! Few that was a mouthful!
Let’s also not forget the health promoting phytonutrients like isoflavones that reduce the risk of cancer as well as levels of cholesterol. Research also consistently shows that soy consumption is linked to a decrease in LDL (bad) cholesterol, with an increase of ((good) HDL cholesterol.
The scientific consensus is clear that soy is an excellent source nutrition and should, therefore, be part of a healthy vegan diet as described here in a position paper on vegetarian and vegan diets by the Academy of Nutrition and Dietetics.
The British Dietetic Association comes to a similar conclusion stating that “it is clear that soya is a nutritious, safe and palatable part of the diet which fits well with healthy eating guidelines and may have multiple health benefits”. You can see their report here.
And finally, to leave you with another positive statistic. Okinawa, Japan (a blue zone) has a higher percentage of centurions than anywhere else on planet. Their diet is high carb, plant based with lots of soy products which along spiritual well being and exercise is attributed to the root of their longevity.
Are soy products healthy?
Well I think the evidence is clear that non-GM soy foods are not only safe for everyone but are a nutrient dense food that can provide health benefits. To enjoy soy foods, we recommend that you eat soy from whole food or minimally process sources such as tempeh, edamame, miso, soybean sprouts and tofu.
Ideally try to minimise or avoid processed soy products particularly soy protein isolates that are found in protein supplements, faux meats and cereals. Any women who are worried about Thyroid function should ensure an adequate level of iodine in their diet.
Any finally do mix it up, it’s easy to let soy be the number one go to product for everything but share the love with other great foods such as lentils, beans and quinoa for proteins.
So are soy products healthy, absolutley! Do you regularly eat soy, have you been challenged about its health benefits? We would love to know your thoughts and which soy products you most use? Let us know in the comments below.
(1)Hamilton-Reeves JM, Vazquez G, Duval SJ, et al. Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis. Fertil Steril 2010, 94:997-1007.