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

no recipes found

Nutrient Tables (per 100 g)

Core nutrients

Nutrient	Amount per 100 g	% RDA per 100 g
Energy	366 kcal	—
Protein	51.1 g	—
Total fat	3.3 g	—
Carbohydrates	32.9 g	—

Key micronutrients

Nutrient	Amount per 100 g	% RDA per 100 g
Iron	7.3 mg	40.8%
Zinc	4.4 mg	40.4%
Magnesium	313 mg	74.5%
Selenium	45.8 µg	83.3%
Calcium	338 mg	33.8%
Potassium	2480 mg	72.9%
Vitamin B6	0.6 mg	36.4%

Bioactive compounds

Values below are often from specialist compositional databases or literature, not the standard USDA panel. Asterisks (*) refer to source notes at the bottom of this section.

Compound / class	Amount per 100 g	Notes
ALA	2860 mg	—

Note: Bioactive-compound values vary substantially by cultivar, species, cocoa or oil percentage, processing, and brand formulation. Show quantitative values only where a defensible source exists; otherwise prefer qualitative presence statements or ranges in source notes.

Reference intakes: US Dietary Reference Intakes for adults (19–50 years; using the higher of male/female values where they differ).

Data provenance (core / micronutrient panel): USDA FoodData Central, Flour, soy, defatted, FDC ID 1104705, API, per 100 g edible portion, last checked 2026-03-14

Substances

Substances in this food: editorial (Overview / literature) plus analytical (nutrition table).

14 substances in this food

Choline

Acetylcholine precursor; methyl donor; phospholipid synthesis for membranes

Genistein

Soy isoflavone; ECS modulation via FAAH inhibition; anti-inflammatory/neuroprotective

Fe²⁺

Iron

Oxygen transport; dopamine synthesis (tyrosine hydroxylase cofactor)

Quercetin (and Isoquercetin)

Polyphenol; antioxidant; mitochondrial support; bioavailability improved with vitamin C

Tryptophan

Serotonin/melatonin precursor; NAD+ pathway substrate; LAT1 transport dynamics

Tyrosine

Dopamine and norepinephrine precursor; LAT1 competition with LNAAs

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

Zn²⁺

Zinc

Cofactor in neurotransmission and antioxidant enzymes; dopamine modulation

Mg²⁺

Magnesium

Enzymatic cofactor (>300 reactions); neurotransmitters; mitochondria; redox balance

Se^2-

Selenium

Antioxidant enzyme cofactor (GPx); supports redox balance

Ca²⁺

Calcium

Bone health; neurotransmission; interacts with vitamin D and K2

K⁺

Potassium

Electrolyte for nerve transmission, muscle function, and blood pressure regulation

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