Vitamin B9 (Folate)
Overview
Vitamin B9, commonly known as folate, is a water-soluble vitamin that plays a central role in one-carbon metabolism and methylation processes. The reduced form 5-methyltetrahydrofolate (5-MTHF) is an essential cofactor in the remethylation of homocysteine to methionine, which is then converted to S-adenosylmethionine (SAMe). SAMe fuels the synthesis of dopamine, norepinephrine, and serotonin and drives phospholipid methylation in neuronal membranes. Folate works synergistically with other B vitamins (B6, B2, B12) and minerals (zinc) in methylation processes, and deficiencies in these nutrients are correlated with ADHD symptoms.
Recipes
14 recipes containing this substance
Black Bean & Sweet Potato Vegetable Chilli
A fibre-rich bean and vegetable chilli with warming spices and slow carbohydrates for steady energy and satiety.
Broccoli, Potato and Onion Soup
A smooth broccoli, potato and onion soup for 4, with the broccoli blended and rested before a short simmer.
Creamed Corn on Roasted Sweet Potato
Roasted sweet potato with creamed corn and a mixed lipid phase to enhance carotenoid absorption; served with broccoli for fibre and glucosinolates.
Linguine alle vongole mantecate (Linguine with cockles in a silky emulsified sauce)
Whole-wheat linguine with cockles in a silky emulsified sauce; Italian emulsification technique without cream, supporting taurine, B12, and choline intake.
Matcha Mitochondria Smoothie
Mitochondrial energising smoothie rich in polyphenols, magnesium, and antioxidants
Mitochondrial Power Bowl
A nitrate-rich, polyphenol-dense bowl combining leafy greens, beets, berries, nuts, and early harvest olive oil
Mixed-Leaf Tahini Caesar Salad
A Caesar-style mixed-leaf salad with a tahini, anchovy, caper and Parmesan dressing, using extra virgin olive oil retained from oil-packed capers.
Neuroeshot (Roe, Lemon, Hot Sauce)
A small savory shot of roe, lemon juice, and fermented hot sauce for concentrated omega-3s and choline.
Roast Duck Breast with Berry Sauce
A rich main dish built around crisp-skinned duck breast with a bright blueberry and raspberry sauce, designed to balance richness with acidity and aromatic depth.
Rocket Lentil Avocado Midday Salad (Gut-Supporting)
Polyphenol-rich midday salad with quinoa or lentils, vegetables, avocado, and early harvest olive oil
Salmon & Grated Beetroot Toast (with Lemon)
A fast, brain-forward open sandwich combining omega-3 rich salmon, nitrate/polyphenol beetroot, and lemon acidity for a sharp, savoury bite.
Salmon Bowl-pistachio-cacao-nibs
A Mediterranean-style bowl combining salmon, avocado, pistachios, cacao nibs, and early harvest olive oil — rich in omega-3 fats, polyphenols, and fibre.
Savoury Greens & Egg Breakfast Skillet
A warm savoury breakfast skillet with eggs, greens, and slow carbohydrates for steady morning energy.
Turmeric Lentil Dahl
Turmeric- and ginger-spiced lentil dish rich in fibre, folate, and polyphenols
Foods
28 foods
Asparagus
Folate-rich vegetable providing fibre and modest inulin-type fructans
Beetroot
Root vegetable providing dietary nitrate and betalain pigments
Black Beans
Legume with polyphenols and protein; optimal soaking conditions detailed
Broccoli
Cruciferous vegetable rich in sulforaphane, folate, and glutathione precursors
Broccoli Sprouts
Young broccoli sprouts valued for glucoraphanin and sulforaphane potential, vitamin C, and Nrf2-supportive phytochemistry
Brussels Sprouts
Cruciferous vegetable providing glucosinolate-derived isothiocyanates, folate and vitamin C
Cabbage
Base for sauerkraut; fiber and vitamin C
Cauliflower
Cruciferous vegetable with fiber and B vitamins
Chickpeas
Legume providing protein, fiber, folate, magnesium, and B6
Chicory Root
High inulin content; coffee substitute
Edamame
Young soybeans providing NMN (NAD+ precursor) and complete plant protein
Kale
Leafy green providing vitamin C, vitamin K, calcium and carotenoids
Kidney Beans
Polyphenol-rich legume supporting gut health
Lentils
Folate-rich legume with plant protein, fibre and non-haem iron
Liver
Nutrient-dense organ meat with bioavailable B12, retinol, iron, and CoQ10
Nori
Red seaweed providing iodine and amino acid precursors for creatine synthesis
Oranges
Vitamin C for iron absorption enhancement
Parsley
Reduces harmful cholesterol oxidation products when added to cooking
Peanuts
Niacin, resveratrol, and plant protein for NAD+ and mitochondrial support
Peas
Plant protein, fiber, and thiamine source
Quinoa
Pseudograin with magnesium, iron, and balanced plant protein
Raspberries
Polyphenol-rich berries with fiber
Romaine Lettuce
Crisp salad lettuce providing vitamin K, folate and carotenoids
Salmon Roe
Premium salmon (ikura) eggs — phospholipid-bound EPA/DHA and choline
Soy
Complete plant protein with isoflavones (genistein) and choline
Spinach
Leafy green rich in iron, magnesium, folate, and carotenoids
Strawberries
Polyphenol-rich berries supporting cognitive function
Swiss Chard
Leafy green rich in iron, magnesium, folate, and carotenoids
Biological Mechanisms and Implications
References
- Methylation is a fundamental biochemical process playing a pivotal role in neurotransmitter synthesis, phospholipid metabolism, and gene expression; nutrient-dependent methylation supports recycling of homocysteine into methionine
- B vitamins, particularly B6, B2, folate (5-MTHF), and B12, are essential cofactors in remethylation of homocysteine to methionine, which is converted to SAMe
- Folic acid supplementation (0.5-5 mg/day) typically reduces plasma homocysteine by ~25%; adding B12 gives an additional ~7% reduction Collaboration 1998
- While folate is normally considered the primary nutrient for homocysteine reduction, long-chain omega-3 fatty acids and vitamin B12 also contribute meaningfully; B12+fish oil lowered plasma homocysteine by 39% Tao Huang et al. 2015
- B vitamin supplementation slowed cognitive decline only in participants with adequate omega-3 status, supporting a nutrient synergy model Oulhaj et al. 2016
- Elevated plasma homocysteine is frequently elevated in ADHD and other neurodegenerative disorders Tao Huang et al. 2015
- Homocysteine is implicated in the induction of oxidative stress, modulation of oxygen levels, and initiation of lipid peroxidation pathway Lukovac et al. 2024
- MTHFR polymorphisms reduce the efficiency of folate cycling and methylation, increasing susceptibility to cognitive dysfunction and ADHD-related symptoms
- Research indicates that deficiencies in vitamins and minerals essential for methylation, such as folate, vitamin B12, and zinc, are correlated to ADHD symptoms Razavinia et al. 2024
- Dietary patterns rich in fibre, folate, and omega-3 fatty acids were associated with reduced ADHD symptoms Millichap and Yee 2012
- Isoquercetin bioavailability is improved by simultaneous ingestion with vitamin C, folate, and additional flavonoids Y. Li et al. 2016
BRS matrix — individual KC inputs
| BRS / PM | Relationship | Biological role and limitation |
|---|---|---|
| BRS1 · BRS1-FM1-PM3 BRS2(KC1) | Supported upstream supply | Folate supplies the methyl group through BRS2 PM1 — Folate/B12 remethylation, replenishing methionine used by BRS2 PM3 — MAT/SAM synthesis. SAM is the methyl donor used by COMT during dopamine metabolism. Limitation: This requires functional B12-dependent remethylation. The connected reaction chain does not measure dietary folate contribution to regional brain SAM or clearance; alternative methionine supply and tissue turnover matter. A limiting effect and benefit from extra intake remain unresolved. Froese et al. (2019) [24] Bailey et al. (2021) [26] Lotta et al. (1995) [29] |
| BRS1 · BRS1-FM1-PM4 BRS2(KC1) | Supported upstream supply | Folate supplies the methyl group through BRS2 PM1 — Folate/B12 remethylation, replenishing methionine used by BRS2 PM3 — MAT/SAM synthesis. SAM is the methyl donor used by COMT during noradrenaline metabolism. Limitation: This requires functional B12-dependent remethylation. The connected reaction chain does not measure dietary folate contribution to regional brain SAM or clearance; alternative methionine supply and tissue turnover matter. A limiting effect and benefit from extra intake remain unresolved. Froese et al. (2019) [19] Bailey et al. (2021) [21] Lotta et al. (1995) [24] |
| BRS1 · BRS1-FM3-PM7 BRS2(KC1) | Supported upstream supply | Folate-derived one-carbon units support BRS2 PM1 — remethylation, replenishing methionine for SAM-dependent BRS2 PM7 — PEMT formation, upstream of DHA-bearing LPC carrier delivery. Limitation: Supported biochemical supply chain, not a demonstrated increase in net adult brain DHA incorporation. Folate/choline compensation, hepatic BHMT, SAM turnover and carrier remodelling vary by context. Mouse folate effects were sex/tissue dependent; betaine rescue used ethanol-exposed rats. The downstream human tracer study administered choline, not folate or betaine. A donor-specific limiting effect and extra-intake benefit remain unresolved. Froese et al. (2019) [15] Chew et al. (2011) [13] Bailey et al. (2021) [16] Klatt et al. (2019) [11] Nguyen et al. (2014) [12] |
| BRS2 · BRS2-FM1-PM1 BRS2(KC1) | Supported upstream supply | Dietary folate, including folic acid reduced by dihydrofolate reductase, is converted through the folate cycle to 5-methyltetrahydrofolate, the methyl donor used by methionine synthase. Limitation: This conversion pathway does not show that increasing folate intake increases tissue remethylation flux. Folic acid lowers blood homocysteine, which is a circulating marker. Froese et al. (2019) [9] |
| BRS2 · BRS2-FM1-PM3 BRS2(KC1) | Supported upstream supply | Folate supplies 5-methyltetrahydrofolate to PM1 — Folate/B12-dependent remethylation, regenerating methionine that PM3 can use to form SAMe. Limitation: This is upstream methionine supply, not a MAT substrate or cofactor. The route depends on functional vitamin B12-dependent methionine synthase; alternative methionine supply and tissue context affect its contribution. Increased MAT flux or benefit from extra folate in replete individuals is not established. Froese et al. (2019) [7] Obeid (2013) [8] |
| BRS2 · BRS2-FM1-PM4 BRS2(KC1) | Supported upstream supply | Supplies 5-methyltetrahydrofolate, the methyl donor used when the cycle remethylates homocysteine Limitation: Folic acid can lower blood homocysteine concentration. That concentration change is not a measured change in remethylation or transsulfuration rate. Finkelstein (1998) [12] Froese et al. (2019) [15] Collaboration (1998) [6] |
| BRS2 · BRS2-FM3-PM7 BRS2(KC1) | Conditional constraint | Folate availability contributes to the methyl-donor supply used by hepatic PEMT; folate restriction with choline maintained reduced hepatic methyl-derived PC enrichment in female mice. Limitation: The response was conditional on sex and experimental context. Methyl-derived PC enrichment is not absolute PEMT flux; extra folate above adequacy is not established to enhance formation or cognition. Chew et al. (2011) [11] |