What’s the deal with soy? Should I be avoiding it or eating it?
What is soy?
Soy is a product of soybeans, a legume native to East Asia. In fact, soy has been a traditional food in Asian cuisine for thousands of years.
Soy is a great vegetarian and vegan option for protein, as it contains all essential amino acids, making it a complete protein. In addition to its great protein content, it also contains little saturated fat, no cholesterol, and some omega 3 and omega 6 fatty acids, along with other important nutrients.
However, when it comes to soy there is a lot of controversy in regards to its potential positive or negative health outcomes. In fact, I often get asked by women I work with whether or not they should consume or avoid soy.
So, in today’s blog I thought I’d share more about soy and more specifically what the research says when it comes to women’s health.
Where do you find soy?
Tempeh (fermented soy)
Texturized vegetable protein (usually found in veggie substitute ‘meats’)
Soy protein isolate
When we look at actual nutrient content of soy based products, for example tofu….it actually contains a lot of great nutrients.
In 1/4th (85g) of a typical tofu package there is:
8 g fat
1.5 g saturated fat
200 mg sodium
2 g carbohydrates
1 g fibre
14 g protein
It also contains 10% of your daily value for iron and 25% of your daily value for calcium.
But wait...isn’t there estrogen in soy?
Soy contains isoflavones, a type of phytoestrogen. Phytoestrogens are naturally found in plants, including soy.
Phytoestrogens have a similar structure to estrogen and when consumed could react similarly to estrogens in the body. In fact, they have the ability to bind to our body’s estrogen receptors which can disrupt hormone functioning. It should be noted that when bound to our estrogen receptors, the bind tends to be weaker than that of estrogen and therefore will likely have weaker effects in our bodies. In addition, these phytoestrogens don’t always act like estrogen in our bodies.
Phytoestrogens are found in many different foods, including:
Nuts and seeds (i.e., flaxseed, sunflower seeds, walnuts, almonds)
Fruits and veggies (i.e., apples, carrots, strawberries, grapes, lentils, yams, mung beans, sprouts)
Grains (i.e., oat, barely, wheat germ)
Beverages (i.e., red wine, beer, coffee)
Much of the controversy we hear around soy regards phytoestrogens, however there is a lot of research to support their role in the body when it comes to women’s health.
What does the research say when it comes to women’s health?
When soy comes into conversation, inevitably someone asks about soy and its relationship to breast cancer. We know that lifetime estrogen exposure is associated with elevated breast cancer risk and therefore it makes sense to think that high phytoestrogen consumption can potentially increase risk for breast cancer or the rate of return for cancer survivors. So, let’s break down some of the research here.
Much of the recent research examining associated between breast cancer and soy consumption has actually found positive effects in terms of reducing risk of breast cancer and improving survival risk, especially in post-menopausal women. Currently, the Canadian Cancer Society states that women (including breast cancer survivors) can eat up to 3 servings of soy based foods each day, unless told otherwise by their health care professional or doctor.
A 2009 study conducted with over 5000 female breast cancer survivors in China found among women with breast cancer, soy consumption was associated with reduced risk of reoccurrence.
In addition, another study from 2009 conducted with over 30,000 post menopausal women found soy products to reduce risk of post menopausal breast cancer.
Another 2015 study found that the association is complex and likely related to menopausal status of each woman.
A systematic review looking at 24 different studies found no association between increased breast cancer risk and soy or isoflavone consumption. In fact, there is some evidence to suggest that isoflavones and soy might actually reduce the risk of breast cancer in post-menopausal women. However, it should be noted that many of these large studies have studied Asian populations, with only a few looking at Western populations, where soy consumption is quite different and overall dietary intake differs drastically.
Relieving Menopausal Symptoms
A 2016 systematic review examining 62 studies with over 6000 women found the use of phytoestrogens effective in reducing hot flashes and vaginal dryness, but unfortunately no effect on night sweats. However, much more research is needed.
Menopause involves the loss of estrogen, which increases women’s risk of developing osteoporosis, as estrogens play a supportive role in maintaining bone mass and reducing the degradation of it post menopause. A 2012 systematic literature review found that soy isoflavones significantly increased bone mineral density by 54%, however findings were relative to menopausal status, supplement type, intervention dose, and isoflavone dose.
Another recent review conducted in 2018 compared animal versus plant protein in regards to adult bone health and risk of osteoporosis. They did not find any significant outcomes, thus suggesting that soy protein consumption is not necessarily more beneficial than other sources of protein.
When it comes to osteoporosis and bone health, more research is needed.
There is some research to support soy’s effect on lowering cholesterol and supporting heart health. In fact, the American Heart Association promotes the consumption of more soy based products in the place of high animal fat foods.
In addition, a 2015 meta-analysis found reduced LDL (bad cholesterol) and increased HDL (good cholesterol) markers in those consuming soy, with the effects being greater in individuals with high cholesterol who consumed whole soy products (e.g., soy milk, nuts or beans).
But wait….what about GMOs?
The soybean plant is one of the most commonly genetically modified foods. If you are concerned about GMOs be sure to read the label, as there are non GMO soy products available on the market.
What about men?
I could write an entire other blog about men, but the research actually shows positive associations with reduced risk of prostate cancer and soy consumption.
In addition, a meta-analysis from 2010 found soy foods and isoflavone supplements to create no altered measurements of testosterone levels in men, the most common concern I hear.
Soy may have the ability to reduce risk of certain cancers, lower cholesterol levels and improve menopausal symptoms in women, however more research is needed.
In addition, much of the research done has been conducted in Asian populations (especially when it comes to breast cancers) where soy intake and diet in general looks quite different.
Based on all the research out there thus far, I would argue it’s safe to consume soy products in moderation as a part of healthy diet, whether you are a female or male. In fact, as women age and head into menopause or the post menopausal period, it might be even more beneficial.
Not sure what to make with soy, today I am sharing four delicious recipes, including my amazing sticky tofu recipe (photographed above) and even kids like it!
If you have any questions or any experiences with consuming soy, please let me know. I always love to hear from all of you.
Cheers to happy and healthy eating!
Until next time,
Eat Right Feel Right - Angela XO