Soy and traditional Asian foods made from soy, such as tofu, soy milk, and miso, are also unique among commonly consumed foods due to their isoflavone content. Although isoflavones are classified as phytoestrogens (plant estrogens), they differ from estrogens in important ways.
In traditional Asian soy foods, each gram of protein is associated with about 3.5 mg of isoflavones. Many protein powders contain less than this amount. The average isoflavone intake in Japan is about 40 mg per day.
Heart disease: The protein, fat, and isoflavone content of soy foods can all reduce the risk of heart disease. Soy protein directly lowers blood cholesterol levels. The polyunsaturated fats in soy foods also lower cholesterol levels when they replace foods high in saturated fat. Isoflavones can directly improve the health of arteries.
Breast cancer: Historically low breast cancer rates in some Asian countries have sparked interest in the potential benefits of soy foods. Research has shown that among Asian populations, breast cancer is less common in women who regularly eat soy compared to women who eat less soy. Studies have shown that early consumption of soy can protect against breast cancer later in life. As little as one serving per day during childhood and/or adolescence is enough to reduce the lifetime risk of breast cancer by 25% to 50%.
Cognitive health: Isoflavones have been found to have beneficial effects on cognitive function and visual memory, according to three analyzes of clinical studies involving older men and women.
Hot flashes: According to the statistical analysis of clinical studies, isoflavone supplementation can reduce the frequency of hot flashes in postmenopausal women by 50%. They are equally effective in reducing the severity of hot flashes. According to the study, the amount of isoflavones found in two servings of traditional soy foods was sufficient to affect hot flashes.
Muscle mass and strength: Resistance exercise such as weightlifting along with adequate protein intake can be effective in building and maintaining muscle and strength, especially as we age. Soy protein has been found to be as effective as animal protein (including whey protein) in promoting muscle mass and strength in those who engage in resistance exercise training.
How Much Soy Should You Be Eating?
One serving of tofu, miso, soy milk, or tempeh provides 6 to 10 grams of protein and about 25 mg of isoflavones, and two servings of soy foods per day provide about 50 mg of isoflavones, enough to produce many of the benefits associated with soy intake. To lower cholesterol, a daily intake of 25 grams of soy protein is recommended. While higher amounts of soy haven’t been shown to be harmful, limiting your intake to 4 servings per day is one way to ensure your diet has enough variety, a key element of a healthy diet.