Edamame are Japanese soybeans that are still in their green pods. The small, kidney-shaped beans are popular snacks in Japan and other Asian countries, although they are now fairly common in North American grocery stores. They're an excellent source of complete protein and contain many beneficial nutrients, although they're also rich in phytoestrogens, which may cause hormonal issues in some people. Consult a nutritionist about the benefits and potential problems of incorporating edamame into your diet.
Complete Protein Source
A complete protein contains all the essential amino acids that the human body cannot make. All animal-based protein such as meat, fish and dairy contain the eight essential amino acids that are important for building muscles, connective tissue, hormones and enzymes. Most plant-based protein sources are incomplete, although soybeans are one of the few types that contain all the amino acids, which makes them especially important to vegetarians. For comparison, 100 grams of raw edamame beans contain a little over 10 grams of protein, according to “The Nutribase Complete Book of Food Counts."
Good Source of Fiber and Other Nutrients
Edamame are also a good source of dietary fiber, with 100 grams containing about 5 grams of total fiber. Water-soluble fiber helps control blood cholesterol levels and keeps you feeling fuller for longer because it takes more time to digest. Insoluble fiber helps to clean out your intestines and promotes regular bowel movements. Edamame beans are also a reasonably good source of calcium, iron, phosphorus, sodium and vitamins A and C. They also contain some omega-3 fatty acids, which is unusual for foods other than fish. Omega-3 fats help reduce the risk of heart disease by naturally lowering levels of the “bad” LDL cholesterol in your blood.
Rich in Isoflavones
Like all soy-based food, edamame beans are rich in isoflavones such as genistein and glycitein. Soy isoflavones are compounds that are similar to human estrogen, which is why they are also referred to as phytoestrogens. Isoflavones are strong antioxidants, which target free radicals and reduce tissue damage and aging. Isoflavones are also linked to lower risks of heart disease, osteoporosis and prostate problems in various studies, and are reported to ease the symptoms of menopause, according to the book “Contemporary Nutrition: Functional Approach." However, isoflavones may be harmful in certain circumstances.
Potential Issues with Phytoestrogens
The phytoestrogens in edamame beans may not be good for women at higher risk of breast cancer or for those who either have breast cancer or have had it in the past. Breast cancer cells are stimulated by higher estrogen levels and isoflavones can mimic the female hormone. Isoflavones may also worsen hypothyroidism and interact with a variety of medications. Consequently, it’s important to consult with your doctor before adding significant amounts of edamame to your diet, because the phytoestrogens in the beans may compound a serious health issue.
- The Nutribase Complete Book of Food Counts; Art Ulene
- Contemporary Nutrition: Functional Approach; Gordon M. Wardlaw et al.
- Public Health Nutrition: From Principles to Practice; Mark Lawrence and Tony Worsley
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.