The Best Sources of Soy Isoflavones

by Natalie Stein

Roasted soybeans are low in saturated fat and high in isoflavones.

Soy beans on green leaf image by Monika 3 Steps Ahead from Fotolia.com

Soy isoflavones may support bone health and improve your cholesterol levels, according to the Linus Pauling Institute Micronutrient Information Center. The specific processing method used to extract the final edible soy product from the raw soy plant after harvest determines the exact amount of soy isoflavones in a product. Many foods are rich in this substance, which is classified as a phytoestrogen for its estrogen-like action. A few foods, however, stand out as the best sources of soy isoflavones.


Soy protein concentrate can be the most concentrated source of soy isoflavones, with up to 102 mg total isoflavones in 3.5 oz. of soy protein. This serving size has 57 g protein, or more than 100 percent of the daily value, and 5 g heart-healthy dietary fiber. Other pure soy products with isoflavones include boiled soybeans, with 47 mg per 1/2 cup, roasted soybeans, with 37 mg and boiled green soybeans, with 12 mg isoflavones per 1/2 cup.

Fermented Sources

A 1/2-cup serving of miso, used to make soup or as flavoring for sauces, provides 59 mg isoflavones. There are about 37 mg isoflavones in a 3-oz. serving of tempeh, a fermented soybean paste for soups, stews or casseroles. Tofu, the curd from pressed soybean milk, has 20 mg isoflavones per 1/2 cup. These fermented soy-derived products may contain probiotics, which are healthy bacteria that live in your gut and support a healthy immune system, according to MayoClinic.com.

Dairy Substitutes

Soy milk has 30 mg isoflavones per cup, non-dairy yogurt has 21 mg per cup, and a 1 oz. of soy-based mozzarella cheese has 2 mg isoflavones, according to the Linus Pauling Institute Micronutrient Information Center. Fortified soy-based dairy substitutes can be as high in calcium as milk, yogurt or cheese made with real milk. Flavored soy milk and soy yogurt may be high in calories from added sugars, so choose plain varieties.

Meat Substitutes

Soy-based meatless hot dogs have about 11 mg isoflavones each, and meatless sausage provides 3 mg. Eating plant-based protein foods, such as soy-based meat substitutes, as alternatives to animal proteins may lower your risk for heart disease, according to Mayo Clinic. They are cholesterol-free and very low in unhealthy saturated fat. Substitute them for chicken, beef or sandwich meat.