Soy
Overview
Soy provides complete plant protein (DIAAS 92-96), isoflavones (genistein), and choline, supporting neurotransmitter synthesis and neuroprotection. Soy protein isolate has a DIAAS score of 92-96, indicating high protein quality, though it is methionine-limited and should be paired with grains. Genistein, a soy-derived isoflavonoid, has shown potential as a modulator of several biochemical pathways, including the endocannabinoid system and neuroinflammation. Soy is listed as a source for choline, tryptophan, tyrosine, and B6.
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 | 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.
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
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
Zinc
Cofactor in neurotransmission and antioxidant enzymes; dopamine modulation
Magnesium
Enzymatic cofactor (>300 reactions); neurotransmitters; mitochondria; redox balance
Selenium
Antioxidant enzyme cofactor (GPx); supports redox balance
Calcium
Bone health; neurotransmission; interacts with vitamin D and K2
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
- Soy protein isolate: DIAAS 92-96, Methionine-limited; supports neurotransmitter synthesis; contains isoflavones with neuroprotective potential
- Genistein, a soy-derived isoflavonoid, has shown potential as a modulator of several biochemical pathways, including the endocannabinoid system and neuroinflammation
- Polyphenols such as genistein may further enhance ECS tone by inhibiting fatty acid amide hydrolase (FAAH), the enzyme responsible for anandamide degradation Gibellini and Smith 2010
- Quercetin is abundant in capers, apples, onions, berries, kale and soybeans
- Acetylcholine and choline: Memory, learning, neuroplasticity; food sources include egg yolks, fish roe, soy, wheat germ, liver
- B6 (chickpeas, potatoes, bananas, whole grains, soy) is a cofactor in the development of all key neurotransmitters
- Serotonin: Mood regulation, emotional control, impulse moderation; food sources include turkey, eggs, dairy, soy, seeds, oats, bananas
- Dopamine: Attention, motivation, executive function; food sources include lean poultry, beef, fish, dairy, soy, pumpkin seeds; omega-3 rich fish