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.
NOTE: The Soyfoods Association has not sponsored or paid for any of these studies.
Here’s what you need to know from the best research of late:
#1: Gaining and Retaining Muscle
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.
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.
#2: 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.
#3: 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 and bone calcium retention.
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.
#4: Reducing Cancer Risk for All Ages
Prostate Cancer: 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 spreading throughout the body. Another study found that in early stage prostate cancer patients, soy intake led to an improved immune system response, reduced inflammation, and encouraged an active immune system.
Breast Cancer: 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. In another study, researchers found that patients with triple-negative breast cancer who ate 12 grams of soy protein per day had more expression of genes that suppress tumor growth.
Colon Cancer: 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.
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.
#5: Preventing Chronic Disease Risk
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.
Soy for Healthy Living and Active People
The Academy of Nutrition and Dietetics published, Soy for Healthy Living and Active People, which provides evidence-based information about soy as a nutrient-dense source of high-quality protein, vitamins and minerals. The article 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.