Soy
Overview
Soy provides complete plant protein, isoflavones (especially genistein), and choline, supporting neurotransmitter synthesis and membrane phospholipid pathways. Defatted soy flour and soy protein concentrates score highly on protein-quality metrics, though methionine remains relatively limiting and grain pairing improves amino-acid balance.
Within the BRAIN Diet framework, soy is a core plant-protein anchor for vegan and plant-forward patterns. Genistein and related isoflavones are studied for metabolic and neuroinflammatory modulation [1], while soy's protein density supports essential amino-acid intake within legume–grain complementary pairings [2].
Key Nutritional Highlights
- Genistein and related soy isoflavones are studied for neuroinflammatory and metabolic pathways [1].
- High plant-protein density with favourable digestibility for a legume; pair with grains for methionine balance [2].
- Provides choline, tryptophan, tyrosine, and B vitamins relevant to neurotransmitter synthesis.
- Fermented forms (tempeh, miso, natto) add fermentation-derived benefits beyond raw soy ingredients.
Food Context
Synergies
- Pair with grains for complete amino acid profile; grain-legume complementarity improves essential amino-acid coverage
- Part of diverse plant protein strategy
Preparation
- Fermented forms (tempeh, miso, natto) may have additional benefits including probiotics and improved digestibility
- Supports choline and neurotransmitter synthesis
- Vegans should ensure adequate choline intake (e.g., soy or sunflower lecithin, soy foods, quinoa, broccoli) to support phosphatidylcholine synthesis
Essential Amino Acid Profile
Soy provide a relatively complete plant protein (higher in lysine than most grains). Pairing with grains or other legumes still supports dietary variety and amino acid balance.
Recipes
Nutrient Tables (per 100 g)
Core nutrients
| Nutrient | Amount per 100 g | % RDA per 100 g |
|---|---|---|
| Energy | 446 kcal | — |
| Protein | 36.5 g | — |
| Total fat | 19.9 g | — |
| Saturated fat | 2.9 g | — |
| Carbohydrates | 30.2 g | — |
| Sugars | 7.3 g | — |
| Fibre | 9.3 g | — |
Key vitamins and minerals
| Nutrient | Amount per 100 g | % RDA per 100 g |
|---|---|---|
| Iron | 15.7 mg | 87.2% |
| Choline | 115.9 mg | 21.1% |
| Folate | 375 µg | 93.8% |
| Vitamin B6 | 0.4 mg | 29% |
Bioactive compounds
Explicitly identified compounds, including individual fatty acids, with a defensible quantity or an explicit qualitative status. Asterisks (*) identify supplementary sources below. Unquantified or trace constituents are not automatically admitted to the Substances list.
| Compound / class | Amount per 100 g | Notes |
|---|---|---|
| Alpha-linolenic acid (ALA; 18:3 n-3) | 1.3 g * | USDA 18:3 quantity; isomer from USDA soybean oil nutrient 1404 |
| Quercetin | Present — quantity not established * | — |
| Genistein | Present — quantity not established * | — |
- * Alpha-linolenic acid (ALA; 18:3 n-3): This value uses a documented composition interpretation. See FCIR-007.
- * Quercetin: USDA Database for the Flavonoid Content of Selected Foods (Release 3.3) reports quercetin glycosides in Soy; a single defensible per-100 g value is not taken from the abbreviated USDA nutrient panel.
- * Genistein: USDA Database for the Isoflavone Content of Selected Foods lists genistein in Soy; the selected SR Legacy proximate panel does not include isoflavones.
Substances
Substances admitted through a supported nutrition-table row. Not every table row appears here. Cards are not BRS mappings.
7 substances in this food
Choline
Acetylcholine precursor; methyl donor; phospholipid synthesis for membranes
Genistein
Soy isoflavone; ECS modulation via FAAH inhibition; anti-inflammatory/neuroprotective
Iron
Oxygen transport; dopamine synthesis (tyrosine hydroxylase cofactor)
Quercetin (and Isoquercetin)
Polyphenol; antioxidant; mitochondrial support; bioavailability improved with vitamin C
Vitamin B6 (Pyridoxine → PLP)
PLP cofactor for neurotransmitter synthesis; relies on brain PDXK activation
Vitamin B9 (Folate; 5-MTHF)
One-carbon metabolism; methylation; homocysteine recycling
ALA (Alpha-Linolenic Acid)
Essential omega-3 precursor; limited conversion to DHA/EPA
References
[1] Genistein and related soy isoflavones are studied for neuroinflammatory and metabolic pathways. Fuloria et al. 2022. Genistein: A Potential Natural Lead Molecule for New Drug Design and Development for Treating Memory Impairment
[2] Soy provides highly digestible plant protein; legume–grain pairing improves essential amino-acid balance. FAO 2013. Dietary Protein Quality Evaluation in Human Nutrition: Report of an FAO Expert Consultation