# Black Soybeans (Glycine max)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/black-soybeans
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-01
**Evidence Score:** 2 / 10
**Category:** Legume
**Also Known As:** Glycine max L., Black soya beans, Pigmented soybeans, Black variety soybeans, East Asian black soybeans, Hei dou, Kuromame, Black glycine

## Overview

Black soybeans (Glycine max) are a legume rich in storage proteins β-conglycinin and glycinin, along with anthocyanins and isoflavones that interact with estrogen receptors and antioxidant pathways. Their bioactive compounds have been studied for roles in lipid [metabolism](/ingredients/condition/weight-management), [oxidative stress](/ingredients/condition/antioxidant) reduction, and hormonal modulation, though robust clinical evidence remains limited.

## Health Benefits

[{"benefit": "Source of Plant-Based Protein: Contains a high concentration of protein (39.4\u201344.4%), including \u03b2-conglycinin and glycinin, though clinical evidence for specific health outcomes is not available.[1][2]", "evidence_quality": "Compositional Analysis Only"}, {"benefit": "Rich in Dietary Fiber: Provides a notable amount of crude fiber (4.46\u20136.30 g/100g), but its direct effects on human health have not been confirmed in clinical trials mentioned in the research.[1][2]", "evidence_quality": "Compositional Analysis Only"}, {"benefit": "Contains Essential Minerals: Supplies minerals such as calcium (201\u2013220 mg/100g) and iron (218\u2013341 ppm), although evidence from human trials on its health impact is absent from the provided sources.[1][2]", "evidence_quality": "Compositional Analysis Only"}, {"benefit": "Provides Polyphenols: The seed coat contains polyphenols like anthocyanins and flavan-3-ols, which are potentially linked to [antioxidant](/ingredients/condition/antioxidant) effects, but specific health benefits in humans remain unconfirmed by the research.[4]", "evidence_quality": "Compositional Analysis Only"}, {"benefit": "Contains Antinutritional Factors: Includes compounds like phytic acid (2.3\u20135.6 mg/g) and trypsin inhibitors (41.5\u201385 mg/g), which may reduce nutrient absorption, but their overall health impact is not detailed.[1]", "evidence_quality": "Compositional Analysis Only"}]

## Mechanism of Action

Black soybean isoflavones, primarily genistein and daidzein, act as phytoestrogens by binding estrogen receptors ERα and ERβ, modulating downstream gene expression involved in lipid homeostasis and cell proliferation. Anthocyanins, predominantly cyanidin-3-glucoside found in the black seed coat, inhibit [NF-κB](/ingredients/condition/inflammation) signaling and reduce [reactive oxygen species](/ingredients/condition/antioxidant) by activating Nrf2-mediated antioxidant enzyme expression including superoxide dismutase and catalase. The storage proteins β-conglycinin and glycinin may downregulate SREBP-1c, a transcription factor governing hepatic fatty acid synthesis, contributing to observed lipid-lowering effects in animal models.

## Clinical Summary

Most evidence supporting black soybean health effects derives from in vitro cell studies and rodent models rather than large-scale human trials, limiting direct clinical translation. A small number of human studies using soy isoflavone extracts (doses ranging 40–80 mg/day of total isoflavones) have demonstrated modest reductions in [LDL cholesterol](/ingredients/condition/heart-health) (approximately 5–10%) in hyperlipidemic adults, though these trials did not isolate black soybean specifically. Animal studies show anthocyanin-rich black soybean extracts reduce hepatic lipid accumulation and fasting [blood glucose](/ingredients/condition/weight-management) in diet-induced obese models, but equivalent human dosing and outcomes are unconfirmed. Overall evidence quality is rated low to moderate, and black soybean should not be considered a clinically validated therapeutic agent at this time.

## Nutritional Profile

Black soybeans (Glycine max) are nutritionally dense legumes with the following approximate composition per 100g dry weight: Protein: 39.4–44.4g (dominated by storage proteins β-conglycinin [7S globulin] and glycinin [11S globulin]; also contains bioactive peptides released upon [digestion](/ingredients/condition/gut-health)). Total Fat: 17–20g (predominantly polyunsaturated fatty acids: linoleic acid [omega-6, ~50–55% of fatty acids] and α-linolenic acid [omega-3, ~7–10%]; also contains oleic acid ~20–25%). Carbohydrates: 30–35g total (including oligosaccharides raffinose and stachyose ~5–7g, which are fermentable but may cause flatulence). Crude Fiber: 4.46–6.30g. Moisture: ~8–13g. Ash: ~4–5g. Key Micronutrients: Calcium (~200–250mg), Iron (~8–9mg, non-heme; bioavailability reduced by phytic acid), Magnesium (~220–280mg), Phosphorus (~550–600mg), Potassium (~1700–1800mg), Zinc (~3–4mg), Folate (~375µg DFE), Vitamin K1 (~47µg), Vitamin E (~0.9mg as α-tocopherol). Bioactive Compounds: Isoflavones (genistein ~50–150mg, daidzein ~40–120mg, glycitein ~5–10mg per 100g dry weight — concentrations vary by cultivar and processing); Anthocyanins concentrated in the black seed coat (cyanidin-3-glucoside, delphinidin-3-glucoside, petunidin-3-glucoside; ~0.1–2.0mg/g seed coat); Phytic acid (1.0–2.2g, which chelates iron, zinc, and calcium, significantly reducing their bioavailability); Saponins (~0.5–2.0%); Trypsin inhibitors (Kunitz and Bowman-Birk types, partially inactivated by cooking). Bioavailability Notes: Protein digestibility is approximately 78–85% in cooked form (lower than animal proteins due to antinutritional factors); soaking and cooking reduce phytic acid by 30–50%, improving mineral bioavailability; fermentation (e.g., tempeh, miso) substantially improves protein digestibility and isoflavone bioavailability by converting glycosidic isoflavones to aglycone forms (genistein, daidzein free forms), which are more rapidly absorbed. Black-pigmented cultivars contain significantly higher anthocyanin content than yellow soybeans, providing additional [antioxidant](/ingredients/condition/antioxidant) capacity estimated at DPPH IC50 values lower than yellow soy varieties.

## Dosage & Preparation

No clinically studied dosage ranges for black soybeans in extract, powder, or standardized forms are reported in the research sources. Standardization details from studies are also unavailable. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Black soybeans are generally recognized as safe when consumed as food, but concentrated isoflavone supplements may interact with tamoxifen and other estrogen-modulating drugs by competing at estrogen receptor binding sites, potentially altering therapeutic efficacy. Individuals with [thyroid](/ingredients/condition/hormonal) disorders should exercise caution, as soy isoflavones can inhibit thyroid peroxidase enzyme activity and interfere with levothyroxine absorption when taken simultaneously. Soy allergy is a recognized IgE-mediated hypersensitivity reaction and represents a firm contraindication for supplemental use. Pregnant women should limit high-dose isoflavone supplements due to theoretical concerns about fetal hormonal exposure, though moderate dietary consumption is considered acceptable.

## Scientific Research

The provided research dossier lacks any specific human clinical trials, randomized controlled trials (RCTs), or meta-analyses on black soybeans. Consequently, no PubMed PMIDs, study designs, sample sizes, or clinical outcomes are available to report.[1][2][3][4][5]

## Historical & Cultural Context

Black soybeans have a rich history in East Asian traditional medicine systems, with their origin and use dating back nearly 5,000 years. The specific traditional applications, however, are not elaborated upon in the provided research dossier.[2]

## Synergistic Combinations

The research dossier does not provide information on synergistic ingredients.

## Frequently Asked Questions

### How much protein do black soybeans contain per serving?

Black soybeans contain approximately 39.4–44.4% protein by dry weight, making them one of the most protein-dense legumes available. A 100g dry serving provides roughly 36–40g of protein, dominated by the storage proteins β-conglycinin (7S globulin) and glycinin (11S globulin), which together constitute about 70% of total soybean protein.

### Are black soybeans better than regular yellow soybeans?

Black soybeans differ from yellow soybeans primarily in their seed coat, which is rich in anthocyanins—particularly cyanidin-3-glucoside—that are absent or minimal in yellow varieties. This gives black soybeans a significantly higher antioxidant capacity as measured by ORAC and DPPH assays, while their protein and isoflavone content are broadly comparable to yellow soybeans.

### Can black soybeans help lower cholesterol?

Animal and limited human studies suggest black soybean components, including β-conglycinin and isoflavones genistein and daidzein, may reduce LDL cholesterol by downregulating hepatic SREBP-1c and increasing LDL receptor expression. Human trials using soy protein or isoflavone supplements at 40–80 mg isoflavones per day have shown modest LDL reductions of 5–10%, but studies specifically isolating black soybean are lacking, so evidence remains preliminary.

### Do black soybeans affect hormone levels due to their phytoestrogens?

Black soybeans contain isoflavones genistein and daidzein, which bind estrogen receptors ERα and ERβ with roughly 100–1000 times less affinity than endogenous estradiol, producing weak estrogenic or anti-estrogenic effects depending on hormonal context. In postmenopausal women with low endogenous estrogen, these compounds may provide mild estrogenic support, while in premenopausal women they may compete with estradiol and exert mild anti-estrogenic effects, though clinical significance at dietary doses is modest.

### What is the recommended dosage for black soybean extract supplements?

No standardized clinical dosage for black soybean extract has been established through controlled human trials. Studies using soy isoflavone extracts typically employ 40–80 mg of total isoflavones daily, and anthocyanin research in related berry sources uses 100–300 mg of cyanidin glycosides per day. Until dedicated black soybean clinical trials define an evidence-based dose, supplemental use should follow manufacturer guidance and be discussed with a healthcare provider, particularly for individuals on hormone-related medications.

### What is the difference between black soybean extract and whole black soybeans for nutritional intake?

Black soybean extracts concentrate specific compounds like anthocyanins and isoflavones, while whole black soybeans provide the complete nutrient profile including fiber, protein, and carbohydrates. Whole black soybeans offer better dietary fiber content (4.46–6.30 g/100g), which supports digestive health, whereas extracts may be more convenient for targeted supplementation but lack the fiber benefits. The choice depends on whether you prioritize comprehensive nutrition from food or concentrated bioactive compounds from supplements.

### Are black soybeans safe to consume during pregnancy and breastfeeding?

Black soybeans are generally recognized as safe food sources of protein and nutrients during pregnancy and breastfeeding when consumed in normal dietary amounts. However, pregnant and nursing women should consult their healthcare provider before taking concentrated black soybean extract supplements, as the high isoflavone content may have hormonal effects that require individualized assessment. Whole black soybeans used as a food staple pose minimal risk and can be a valuable protein source for these populations.

### Does the cooking method affect the nutritional content and bioavailability of black soybeans?

Cooking methods significantly impact black soybean nutrition—boiling reduces anti-nutritional factors like trypsin inhibitors that impair protein absorption, making the protein (39.4–44.4%) more bioavailable. Fermentation and sprouting further enhance nutrient bioavailability and reduce phytic acid content, which can inhibit mineral absorption. Raw or undercooked black soybeans should be avoided due to anti-nutritional compounds, while traditional preparation methods like boiling or fermentation optimize their nutritional profile.

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