I'm 'Soy' Confused: The Real Scoop on Soy and Your Health

Let's debunk the myths about soy and understand its true value for your health.

Feeling Confused About Eating Soy? Read On to Be Informed

There is definitely a lot of confusion around eating soy because of its phytoestrogenic properties. But what if I told you the primary dietary source of phytoestrogens in the U.S. diet is actually from lignans found in legumes, whole grains, seeds, fruits, vegetables, tea, and coffee? Would you stop eating those foods as well? Probably not, because you would have little left to eat. So let's really get into the science behind soy and where people have gotten confused along the way.

Understanding Soy Components

Soybeans are composed of beneficial compounds including phytic acid, alpha-linolenic acid (ALA), lignans, and isoflavones. The component that often raises controversy is isoflavones, the primary phytoestrogens in soy, known as genistein and daidzein. These phytoestrogens have been shown to provide significant health benefits, such as reducing the risk of heart disease, certain cancers, and alleviating menopausal symptoms. However, uncertainty around soy often stems from misinformation and research that used soy protein isolate in large amounts, far beyond typical human consumption. The confusion has led to unfounded fears about soy's estrogenic effects. When consumed in its whole or minimally processed forms, soy is both safe and beneficial. It is important to understand that most studies showing adverse effects were based on unrealistic intake levels of isolated compounds, not on the consumption of natural soy foods like edamame, tofu, or tempeh.

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Types of Soy Products

Whole Soy Products

Edamame: These are whole, immature green soybeans. You may recognize them as an appetizer in Japanese restaurants.
Soy nuts: These are whole soybeans that have been soaked in water, then either baked or roasted, to get crisp and brown. They taste a little bit like peanuts but have more protein and less fat.
Tempeh: This product is made by softening soybeans and then adding a fermentation starter. It is often found in block form and has a nutty flavor.

Minimally Processed Soy Products

Soy milk: This plant-based milk is made from soybeans and filtered water. When choosing non-dairy milks, always read the labels. The best products are the ones that contain the main ingredient and water. Avoid sugars and carrageenan (a food additive used to preserve and thicken foods, including nut milks, meat products, and yogurt).
Miso: This is a fermented paste made from soybeans with koji (Aspergillus oryzae - cultivated from rice, barley, or soybeans). I am sure you have had a bowl of miso soup, so now you have already had soy.
Tofu: This is probably the most familiar for you. It is made from condensed soy milk and formed into a block, similar to cheesemaking.
Natto: This traditional Japanese food is made from fermented soybeans. It has a strong flavor and sticky texture, and is rich in probiotics, which are beneficial for gut health.

Let's ease into it by enjoying one of these selections a few times weekly.

Moderately Processed Soy Products

Soy yogurt: Just like any other yogurt, soy yogurt is made by using milk (soy in this case) and adding yogurt bacteria, and possibly sweeteners.
Soy cheese: Similar to how other cheeses are made, but note that soy cheese may contain casein, which is an animal-based product. Read your labels, and if you are vegan, this may come into consideration.
Soy isolate protein powders: This product is ultra-processed from soybean flakes that are washed in acid/water (acid washing) to remove sugars and fiber.

What Does the Research Say?

Breast Cancer and Soy

The Shanghai Breast Cancer Survival Study looked at this question in a population-based cohort study of 5,042 female breast cancer survivors in China who were followed for an average of 3.9 years. Among women with breast cancer, soy food consumption was significantly associated with decreased risk of death and recurrence.
Another cohort of 1,954 female breast cancer survivors who were prospectively followed for 6.31 years found that soy isoflavones consumed at levels comparable to those in Asian populations may reduce the risk of cancer recurrence in women receiving tamoxifen therapy and appeared not to interfere with tamoxifen efficacy.
In women without a previous history of cancer, a 2011 meta-analysis of prospective studies concluded that "soy isoflavones intake is associated with a significantly reduced risk of breast cancer incidence in Asian populations, but not in Western populations."
A large meta-analysis looking at studies from 2000-2013 found a statistically significant inverse association between soy intake and breast cancer, although this inverse association was stronger for Asian women than Western women.

Other Health Benefits

Prostate Cancer

Soy isoflavones, specifically genistein and daidzein, have been shown to inhibit prostate cancer growth in both in vivo and in vitro studies. They work by blocking hormone receptor activity, which inhibits cell proliferation and helps prevent the development and progression of prostate cancer.

Heart Disease

Soy consumption may lower rates of heart disease by improving heart-protective factors. Isoflavones have been found to reduce LDL cholesterol (often referred to as "bad" cholesterol) and increase HDL cholesterol ("good" cholesterol), contributing to a healthier lipid profile. Additionally, soy protein can improve arterial health by enhancing endothelial function, which is crucial for maintaining flexible and healthy blood vessels.

Menopausal Symptoms

Soy isoflavones can significantly reduce the frequency and severity of hot flashes and other menopausal symptoms in postmenopausal women. These phytoestrogens provide a mild estrogenic effect, which can help balance hormone levels naturally and alleviate discomfort during menopause.

Overall Cancer Risk

Regular consumption of soy is associated with a reduced risk of several cancers. For example, individuals who consume soy regularly reduce their risk of breast cancer by 30% overall. Women who eat soy products once a week have a 48-56% lower risk of developing breast cancer. This protective effect is thought to be due to the isoflavones' ability to modulate estrogen activity and inhibit the growth of cancer cells.

Cholesterol Reduction

Soy is effective in lowering cholesterol levels, particularly LDL cholesterol, which is a significant risk factor for heart disease. The bioactive peptides in soy protein inhibit cholesterol absorption in the intestines and enhance its excretion, leading to lower overall cholesterol levels in the bloodstream.

Weight Management

Incorporating soy into the diet can aid in weight management. Soy protein is known to enhance satiety, helping individuals feel fuller for longer periods. This can reduce overall calorie intake and support weight loss or maintenance. Additionally, soy foods are generally low in saturated fat and high in essential nutrients, making them a healthy choice for those looking to manage their weight.

Bone Health

Soy isoflavones play a crucial role in maintaining bone health, especially in postmenopausal women who are at increased risk of osteoporosis. These compounds help preserve bone density by exerting estrogen-like effects on bone tissue, which can slow down bone resorption and promote bone formation. Regular consumption of soy foods can, therefore, contribute to stronger, healthier bones and reduce the risk of fractures.

Longevity

Regular consumption of soy has been linked to increased longevity. The isoflavones in soy have antioxidant properties that help reduce inflammation and oxidative stress, two key factors in aging and chronic disease development. Additionally, soy's ability to improve heart health, reduce the risk of certain cancers, and maintain bone density contributes to a longer, healthier life. Incorporating soy into a balanced diet can thus support overall longevity and well-being.

Personal Insights and Recommendations

So let me break it down for you. I do eat soy. I am not afraid to eat soy, but I am careful about what soy I eat. I do not put soy protein isolates in my shakes. I choose organic soy products to avoid artificial foods that can cause inflammation. I eat soy products at least seven times a week, including tofu, edamame, and tempeh. These are some of my main sources of protein. As someone who has diagnosed over 100,000 breast cancers, I feel the research actually shows us that eating real soy foods is protective for a number of health conditions.

Actionable Steps: How to Get Started Incorporating Soy

Start with Whole Soy Products:

Edamame: Add edamame to your salads or enjoy it as a snack. It's a simple and nutritious way to start incorporating soy into your diet.

Use Soy Milk in Your Drinks and Meals:

Smoothies: Blend soy milk into your smoothies for a creamy texture. Ensure it’s free from added sugars and unnecessary additives.
Lattes: Substitute regular milk with soy milk in your lattes for a delicious and dairy-free option.

Experiment with Tofu:

Stir-fries and Soups: Incorporate tofu into your stir-fries or soups. It absorbs flavors well and adds a great source of protein.
Desserts: Use silken tofu in desserts like chocolate mousse or puddings for a smooth and creamy texture.
Rice Bowls: Try sprouted tofu in your rice bowls. It's packed with nutrients and adds a delightful texture to your meals.

Recipes to Try

Stress-Relieving Chocolate Tofu Mousse: A delicious and healthy dessert option.
Rainbow Spring Rolls with Watercress and Avocado: A fresh and nutritious meal that's perfect for any season.

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REFERENCES:

Peterson J, Dwyer J, Adlercreutz H, Scalbert A, Jacques P, McCullough ML. Dietary lignans: physiology and potential for cardiovascular disease risk reduction. Nutrition reviews 68(10):571-603 Oct, 2010.
Kyrø C, Zamora-Ros R, Scalbert A, et al. Pre-diagnostic polyphenol intake and breast cancer survival: the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Breast Cancer Res Treat. 2015;154(2):389-401.
Chen MN, Lin CC, Liu CF. Efficacy of phytoestrogens for menopausal symptoms: a meta-analysis and systematic review. Climacteric 18(2):260-9 Apr, 2015
Messina M, McCaskill-Stevens W, Lampe JW. Addressing the soy and breast cancer relationship: review, commentary, and workshop proceedings. Journal of the National Cancer Institute 98(18):1275-84 Sep, 2006.
Shu XO, Zheng Y, Cai H, Gu K, Chen Z, Zheng W, Lu W. Soy food intake and breast cancer survival. JAMA : the journal of the American Medical Association 302(22):2437-43 Dec, 2009.
Dong JY, Qin LQ. Soy isoflavones consumption and risk of breast cancer incidence or recurrence: a meta-analysis of prospective studies. Breast cancer research and treatment 125(2):315-23 Jan, 2011.
Mourouti N, Panagiotakos DB. Soy food consumption and breast cancer. Maturitas 76(2):118-22 Oct, 2013.
Pavese JM, Krishna SN, Bergan RC. Genistein inhibits human prostate cancer cell detachment, invasion, and metastasis. Am. J. Clin. Nutr. 100 Suppl 1:431S-6S Jul, 2014.
Mitchell JH, Cawood E, Kinniburgh D, Provan A, Collins AR, Irvine DS. Effect of a phytoestrogen food supplement on reproductive health in normal males. Clinical science (London, England : 1979) 100(6):613-8 Jun, 2001.
Bouchenak M, Lamri-Senhadji M. Nutritional quality of legumes, and their role in cardiometabolic risk prevention: a review. J Med Food. 2013;16(3):185-198.
Goodman-Gruen D, Kritz-Silverstein D. Usual dietary isoflavone intake is associated with cardiovascular disease risk factors in postmenopausal women. J Nutr. 2001;131(4):1202-1206.
Zhang C, Ho SC, Lin F, Cheng S, Fu J, Chen Y. Soy product and isoflavone intake and breast cancer risk defined by hormone receptor status. Cancer Sci. 2010;101(2):501-507.
Douglas CC, Johnson SA, Arjmandi BH. Soy and its isoflavones: the truth behind the science in breast cancer. Anticancer Agents Med Chem. 2013;13(8):1178-1187.

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