Soy is one of the most researched foods on Earth. From sustainable growing practices to its effects on lowering blood cholesterol and weight loss, hundreds of studies are conducted on this unique bean each year. The Soyfoods Association of North America has scoured the data for you, and determined what is sound science based on study design, outcome, sample size and more.
Here's what you need to know from the best research of late:
#1: Good News for Women
No more hot flashes, mood changes or problems sleeping: post-menopausal women can celebrate with a tall soy latte! The European Food Safety Authority (EFSA) said that soy isoflavones, or phytoestrogens, are safe with no negative effects on mammary glands, uterus or thyroid, adding to a growing body of evidence that shows women can benefit from phytoestrogens and relieve menopause symptoms, such as hot flashes.
Another benefit of soy isoflavones was found in a study that found them to 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. In a randomized, double-blind, placebo-controlled trial, isoflavones significantly decreased insulin levels and improved glucose utilization, which can decrease the risk of diabetes, and lowered levels of triglycerides and LDL levels, which can reduce the risk of heart disease.
A study by Purdue University found an additional benefit of isoflavones for post-menopausal women - bone calcium retention. Over a 50-day period, women increased bone calcium retention by 7.6 percent.
#2: Keeping Men Healthy
Men were definitely not left out of the soy research benefits this year. A Chinese study analyzing isoflavone levels in the blood discovered that those who consumed soy had the lowest likelihood of developing prostate cancer, and, even more, soy greatly reduced the risk of the cancer metastasizing, or spreading throughout the body.
Researchers at The Ohio State University found that soy decreases multiple inflammatory markers that can impact prostate cancer and progression, including reducing infections. In early stage prostate cancer patients, soy intake led to an improved immune system response, reduced inflammation related to early development of cancer cells, and encouraged an active immune system throughout cancer progression.
#3: Gaining Muscle Strength
Soy is a lean, green, protein machine - the only plant protein equivalent to animal protein with all nine essential amino acids in ratios needed for muscle growth and recovery. And, after exercise, the intake of complete protein is key to muscle building and repair. Soy provides a more sustained release of protein's building blocks than whey, so when these proteins are combined, the latest research shows it creates an ideal, prolonged release of protein for long-term increase in lean muscle mass.
#4: Retaining Muscle Strength
For those of us whose gym membership card has been collecting dust - only 21 percent of adults in the U.S. meet the recommendations for physical activity - researchers in Japan found that soy protein prevented the weakening of skeletal muscle caused by immobilization or sedentary lifestyles.
#5: Reducing Cancer Risk for All Ages
University of Washington doctors determined that high soy consumption has no effect on women getting breast cancer for the first time, and, even more, discovered that women who eat a lot of soyfoods have reduced risk of breast cancer recurrence.
Soyfoods have demonstrated anti-cancer properties such as regulating cell growth and programming the death of mutated cells. Researchers from Vanderbilt University studied genes and RNA fragments in tumor tissue of patients with triple-negative breast cancer, and found that eating soyfoods during the year prior to cancer diagnosis led to more expression of the genes that suppress tumor growth and less expression of genes that can cause cancerous mutations. The people who were found to have this protective affect averaged 12 grams of soy protein per day, which is about two servings.
These 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 study that looked at biomarkers found that in young girls, high levels of soy isoflavone genistein along with low exposure to BPA showed long-term decreased risk of breast, gynecological, esophageal, lung and urological cancers, cardiovascular disease and Alzheimer's disease. And 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.
#6: Non-Fermented Soyfoods Protect the Stomach
Researchers in Japan evaluated more than 30,000 men and women, over a period of 15 years, and found people that consumed the most soyfoods had a significantly decreased relative risk of stomach cancer, the leading cause of cancer-related deaths. Specifically, higher intakes of non-fermented soyfoods such as tofu, soymilk and edamame were significantly associated with a lower risk of stomach cancer and were found to actually have a protective effect against developing the cancer.
#7: Cholesterol-Lowering Capabilities
We have known for some time that soy protein helps lower cholesterol. But a 2015 meta-analysis showed soy significantly lowered LDL-cholesterol by 4.8 percent and lowered triglycerides by 4.9 percent, with even great impact for people who were diabetic or hypertensive - reducing LDL-cholesterol by 7.5 percent. We also found out why soy helps lower cholesterol; soy protein particles activated the pathway that increased the uptake of LDL-cholesterol.
Each year about 1.4 millions of Americans are diagnosed with diabetes, a condition characterized by elevated blood glucose and metabolic disturbances that can lead to heart and kidney disease, and a new meta-analysis shows soy protein supplementation can significantly improve risk factors for these conditions. The metabolic syndrome markers of diastolic blood pressure, LDL cholesterol, total cholesterol, and C-reactive protein were all significantly lowered when soy protein was a regular part of the diet for more than six months.
#8: Pumping Iron for Vegetarians
There is often concern over vegans and vegetarians not getting enough iron in their diets, however; nearly all studies show that vegetarian iron status is within the healthy "normal" range. New research may explain why these vegetarians and vegans are still getting plenty of iron - your body adapts to regular consumption of a high-phytate diet and counteracts the nutrient-absorption inhibiting effects.
#9: 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. Chinese 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.
#10: Mice Are Not Men
For years we've seen conflicting research on soy - first a rodent study shows some negative effect, but in human clinical studies we do not see similar results. Why is this? A new study out of the Netherlands show us that rats' breast tissue activates soy isoflavones at a rate 30 times more than humans, leading to an extreme and distorted hormonal effect, that is not seen in humans. This raises the question: Why are we still using rodents for soy research?
Soy for Healthy Living and Active People
The Academy of Nutrition and Dietetics published a feature, Soy for Healthy Living and Active People, which provides dietitians and nutrition professionals with evidence-based information to assist their clients and patients in understanding the value of soy as a nutrient-dense source of high-quality protein, vitamins and minerals. The article also cites research to firmly dispel common myths around soyfoods, including: men's health, nutrient absorption, and breast cancer. Authors encourage active individuals to enjoy soyfoods as part of a diet that can reduce heart disease risk, promote satiety, optimize health, and enhance performance.
This blog was provided to ACSM by the Soyfoods Association of North America (SANA). To learn more visit http://www.soyfoods.org/.