Soy Science Update

Sharon Palmer

In honor of Soyfoods Month, I’m bringing you a science update by renowned soy expert, Mark Mesisina, PhD, which covers hot topics on soy and health, including cardiovascular disease, bone health, kidney function, breast cancer, prostate cancer, mental health, thyroid function and more. This deep-dive article cites more than 400 scientific sources.

#1: Soy Keeps Your Heart Pumping

Heart disease is the most common cause of death, and researchers are determined to find a solution. The U.S. Food and Drug Administration has stated that soy is the only protein that may reduce the risk of heart disease. Continuing research backs this claim, showing soy to reduce total cholesterol and low-density lipoprotein (LDL) or “bad” cholesterol levels.

Most recently, a randomized study with a 12-week nutrition intervention found whole soyfoods (corresponding to 30 g/day protein) significantly improved participants’ cardiovascular health. And, a statistical review of soy protein studies shows risk factors for heart disease and diabetes are significantly reduced when soy protein was a regular part of the diet for more than six months.

Additionally, researchers recently tested a traditional Japanese diet, high in soy, on middle-aged men brought up on Western foods. After six weeks, where soy consumption doubled, 91 percent of participants were found to show improvements in more than one cardiovascular risk factor.

#2: Gut Health

The microbiome, or your gut bacteria, is the hottest trend to improve overall health. Soyfoods’ interaction with the gut microbiota may critically influence many aspects of human development, immunity, and nutrition at different stages of life. In this review, researchers found that both animal and human studies have shown consumption of soyfoods can increase the levels of healthy gut bacteria leading to a stronger immune system and overall better health. Another study found similar results.

#3: Soy May Help Those with Breast Cancer

Researchers reviewing the connection between breast cancer and diet found moderate soyfood consumption (5–10 g of protein daily) within the Mediterranean dietary pattern shows the most promise for breast cancer patients. Researchers noted that soybeans contain a number of anti-carcinogens, suggesting that consumption may protect against breast cancer, with non-fermented products such as tofu and soymilk showing more promise. One of the key human intervention studies reviewed showed a dose-response relationship between decreasing risk of breast cancer with an increased soyfood intake, translating to a 16 percent risk reduction per 10 mg of daily soy isoflavone consumed. To put this into perspective, soymilk has 26 mg per cup.

Another study found that patients with triple-negative breast cancer who ate 12 g of soy protein per day had more expression of genes that suppress tumor growth.

#4: Reducing Cancer Risk

New findings support the growing body of evidence that shows long-term soy intake protects against many forms of cancer and promotes health at all stages of life. A meta-analysis found soy isoflavones consumed through soyfoods or supplements was associated with a 23 percent reduction in risk of colon cancer, the third most prevalent cancer in the world. Another meta-analysis of 29 studies showed that consumption of phytoestrogen, found in soy, was associated with a 23 percent reduction in the risk of prostate cancer.

#5: Helping You Get a Better Night’s Sleep

A recent study from the “Nutrition Journal” found higher isoflavone intake was associated with getting the best night’s sleep, in both duration and quality. Soyfoods are among the highest sources of isoflavones, for example, firm tofu has about 19 mg of isoflavones per half-cup serving.

#6: Relief for Women

As women face menopause, they are inundated with medicines and supplements to help ease their symptoms. Researchers found regular consumption of a soy beverage significantly reduced peri- and postmenopausal symptoms like hot flashes, mood swings, pain and more serious women’s health issues by 20 percent. Overall health-related quality of life measures for these women also improved by 18 percent. Another team of researchers found soy isoflavones offer the greatest reduction in length of hot flashes, when compared with non-hormonal drugs.

The benefits of soy extend to women of all ages. A study found soy isoflavones improve outcomes in women with polycystic ovary syndrome (PCOS), one of the most common hormone disorders in the U.S. among women ages 18-40 years of age. Isoflavones significantly decreased insulin levels and improved glucose utilization, which can decrease PCOS, a risk factor of diabetes.

#7: Having a Happy Pregnancy

BPA, or bisphenol A, a synthetic compound found in many plastics and household goods, has been linked to infertility and is found in more than 96 percent of Americans, according to the Centers for Disease Control and Prevention. A new observational study by Harvard researcher Dr. Jorge Chavarro found that soy fights some of the harmful effects, such as infertility, that is linked to BPA exposure.

Although pregnancy is often a happy time, up to 20 percent of moms-to-be struggle with depression. Past research has found a link between soy consumption and a decrease in depression in peri- and postmenopausal women, and new research shows similar findings in women who are pregnant.  A higher intake of total soyfoods such as tofu, fermented soybeans, boiled soybeans, miso soup, and soy isoflavones was independently related to a decrease of depression during pregnancy.

#8: Plus, Soy Helps Prevent Incontinence

Urinary incontinence, which is the loss of bladder control, is a common problem especially as we age – and it can be quite embarrassing.  Researchers looked at health-related habits, health factors and sociodemographic data and found a lower prevalence of incontinence in women who consumed soy products.

#9: Emerging Consensus on Protective Role of Soy Protein in Kidney Disease

A May review article of clinical trials concluded that soy protein shows beneficial effects during early stages of kidney disease through reductions in cholesterol, blood pressure, circulating fat, and blood sugar levels, which all contribute to the progression of the disease. Another potential benefit of soy protein intake relates to improved antioxidant status and decreases in inflammation. Taken together, the data suggest that both short-term (weeks) and long-term (years) consumption of soy-based diets are protective against kidney disease.

#10: Drinking Up to Reduce Spurs

Bone spurs, bony projections that form on the edges of bones, are one of many symptoms of osteoarthritis, a chronic and progressive joint disease.  Researchers found that people who drank soymilk daily had an almost 50 percent lower risk of developing bone spurs. This decrease in risk remained even after the data were adjusted for age, body mass index and gender.

#11: A Future of Soy Antibiotics?

As bacteria grow immune to the effects of antibiotics, medical and veterinary professionals search for new solutions to curb infection. Researchers found that soy protein components exhibited promise for antimicrobial properties against food borne illnesses including Pseudomonas and Listeria. With further investigation, soy peptides may be used for the development of plant-based, biodegradable alternatives to antibiotics.

#12: Long-Term Look at Genetic Engineering

In May 2016, the National Academies of Science released an extensive report about genetically engineered crops. Soybeans, one of three plants reviewed, were found over the past two decades to have no adverse side effects to humans or animals. Without a PhD in biochemistry, it is easy to become anxious from all of the negative press that surrounds these plants. When the extensive volume of research available is examined, these beans are not only safe to consume but they are a nutritional power house that can be safely incorporated into a healthy and well-rounded diet. And if you still want options, many soyfoods are not made with the GE soybean, such as all tofu, soymilk, and edamame.

Note: Image, Curried Papaya Tofu Wrap, from Plant-Powered for Life, Sharon Palmer, RD

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