Calories in Soybeans: Full Nutrition Breakdown

Soybeans are one of the most protein-rich legumes available, providing a complete source of plant-based protein with all essential amino acids. One cup of cooked mature soybeans delivers roughly 29 grams of protein, 10 grams of fiber, and is an excellent source of iron, manganese, phosphorus, and folate. They serve as the foundation for many foods including tofu, tempeh, soy milk, and miso.

Calories by serving size:

Soybeans have a notably higher fat content than most legumes, with about 15 grams per cooked cup, the majority being polyunsaturated and monounsaturated fats including omega-3 alpha-linolenic acid. They are also one of the richest food sources of isoflavones, a class of phytoestrogens that have been extensively studied for their potential cardiovascular and bone health benefits.

Frequently Asked Questions (FAQ)

What is the difference between soybeans and edamame?

Soybeans and edamame come from the same plant (Glycine max) but are harvested at different stages of maturity. Edamame are picked while still green and immature, giving them a softer texture and milder flavor with about 188 calories per cup. Mature soybeans are harvested after the pods have fully dried, resulting in a denser, higher-calorie bean with more protein and fat per serving.

How much protein is in a cup of cooked soybeans?

One cup of cooked mature soybeans provides approximately 29 grams of protein, which is the highest among common legumes. This is nearly double the protein found in a cup of cooked black beans or chickpeas. Soy protein is also considered a complete protein, containing sufficient amounts of all nine essential amino acids for human nutrition.

Are soybeans healthy to eat regularly?

Soybeans are considered one of the most nutritious legumes, providing an exceptional combination of protein, fiber, healthy fats, and micronutrients. Research consistently shows that regular soy consumption is associated with lower LDL cholesterol, improved bone density, and reduced risk of certain cancers. Major health organizations, including the American Heart Association, recognize soy as part of a heart-healthy diet.

Do soybeans contain estrogen or affect hormone levels?

Soybeans contain isoflavones, which are plant compounds called phytoestrogens that have a much weaker effect than human estrogen. Clinical studies have shown that normal dietary soy intake does not raise estrogen levels, lower testosterone, or negatively affect fertility in men or women. The confusion stems from the word "phytoestrogen," but these compounds behave very differently from human hormones in the body.

Are soybeans a complete protein?

Yes, soybeans are one of the few plant foods that provide a complete protein, meaning they contain all nine essential amino acids in adequate proportions. The protein quality of soy, measured by the Protein Digestibility Corrected Amino Acid Score (PDCAAS), is rated at 1.0 — the same as animal proteins like eggs and milk. This makes soybeans and soy-based products particularly valuable for vegetarians and vegans seeking high-quality plant protein.