Vitamin B12 (Cobalamin)
Overview
Vitamin B12 (cobalamin) is an essential water-soluble vitamin used by methionine synthase in one-carbon metabolism and by methylmalonyl-CoA mutase in propionate and odd-chain-fatty-acid metabolism. These roles connect B12 status to homocysteine remethylation, myelin maintenance and neurological function [1,4]. Within BRAIN, B12 is treated as a required nutrient and PM substrate/cofactor relationship, not as a general cognitive enhancer.
Deficiency can produce haematological and neurological consequences, but deficiency treatment, ordinary dietary adequacy and supplementation in replete people are different evidence contexts [4]. Homocysteine-lowering studies have generally tested supplemental B vitamins, sometimes alongside omega-3 status, rather than whole B12-containing foods [1–3].
Methylcobalamin
Methylcobalamin is one coenzyme form of cobalamin. The methionine-synthase role on this page is that cobalamin function. A food vitamin B12 value is not a separate methylcobalamin assay, and a supplemental form is not the same exposure as the vitamin in a meal [1,4].
Dietary Context
Vitamin B12 occurs directly in animal-derived foods including shellfish, fish, meat, eggs and dairy, and in fortified foods. This is the ordinary relationship Food → contains → Vitamin B12; it does not require a microbial-formation or dietary-precursor module.
Some algae and fermented products contain corrinoids, but analytical detection alone does not establish human-active cobalamin. Chlorella has evidence for bioavailable B12 forms, whereas spirulina can be dominated by inactive analogues [5]. People who exclude animal foods generally require reliable fortified-food or supplemental sources.
Research Spotlights & Evidence Checks
Foods
19 foods
Beef
High creatine, CoQ10, and bioavailable heme iron
Cheddar Cheese
Hard cow’s-milk cheese rich in protein, calcium, and vitamin B12
Chicken
Niacin, zinc, and tryptophan
Chlorella
Algae with bioavailable true vitamin B12 and antioxidant support
Clams
High taurine and B12 content
Cockles
Bivalve shellfish providing B12, iron, zinc, selenium, and marine taurine
Crab
Lean shellfish providing complete protein, zinc, selenium, and vitamin B12
Fortified Plant Milks
Plant-based milks fortified with B12, D, and sometimes iodine
Liver
Nutrient-dense organ meat with bioavailable B12, retinol, iron, and CoQ10
Milk
Dairy drink providing complete protein and calcium
Mussels
Nutrient-dense bivalve providing phospholipid-bound omega-3s; accepted by some vegans (ostroveganism)
Nori
Red seaweed providing iodine and amino acid precursors for creatine synthesis
Nutritional Yeast
Fortified yeast providing B12, B6, and NAD+ precursors
Oysters
Highest zinc content among common foods; unique source of phospholipid-bound omega-3s; accepted by some vegans (ostroveganism)
Salmon
Oily fish rich in EPA/DHA, protein, and B vitamins
Salmon Roe
Premium salmon (ikura) eggs — phospholipid-bound EPA/DHA and choline
Sardines
Small oily fish rich in EPA/DHA, CoQ10, and calcium
Scallops
Lean shellfish rich in creatine, taurine, and vitamin B12
Turkey
High tryptophan and niacin for serotonin synthesis and NAD+ production
Recipes
6 recipes containing this substance
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.
Neuroeshot (Roe, Lemon, Hot Sauce)
A small savory shot of roe, lemon juice, and fermented hot sauce for concentrated omega-3s and choline.
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.
Turkey Wing Stew
A collagen-rich, glycine-heavy slow-cooked stew made from affordable turkey wings — rich in protein, tryptophan, and B vitamins.
Turmeric Milk
A warming drink combining turmeric (curcumin) with milk/fat for enhanced curcumin absorption
Biological Regulatory Systems
| Biological Regulatory System | Evidence-qualified relationship | Evidence |
|---|---|---|
| Methylation & One-Carbon Metabolism (BRS2) | B12 is a methionine-synthase cofactor in folate-dependent homocysteine remethylation; the canonical PM lists B12 as a direct dietary requirement | [1,2] |
| Neurotransmitter Regulation (BRS1) | Neurological relevance is strongest in B12 deficiency and myelin/one-carbon biology; it is not evidence of cognitive enhancement in replete people | [4] |
| Mitochondrial Function & Bioenergetics (BRS4) | B12 is required for methylmalonyl-CoA mutase and conversion to succinyl-CoA | [4] |
References
[1] Homocysteine Lowering Trialists' Collaboration (1998). Lowering blood homocysteine with folic acid based supplements: meta-analysis of randomised trials. Establishes the supplemental B-vitamin context for homocysteine lowering and the additional biochemical contribution of B12.
[2] Huang et al. (2015). Effect of omega-3 fatty acids supplementation on plasma homocysteine levels: a meta-analysis of randomized controlled trials. Supports interaction between supplemental B12 and omega-3 interventions while remaining combination-exposure evidence.
[3] Oulhaj et al. (2016). Omega-3 fatty acid status enhances the prevention of cognitive decline by B vitamins in mild cognitive impairment. Illustrates nutrient-status interaction in a B-vitamin intervention rather than a whole-food or isolated-B12 effect.
[4] Pawlak et al. (2013). How prevalent is vitamin B12 deficiency among vegetarians?. Supports dietary-risk and deficiency context for B12 while distinguishing deficiency consequences from enhancement claims.
[5] Watanabe et al. (2002). Characterization and bioavailability of vitamin B12-compounds from edible algae. Distinguishes bioavailable cobalamin from inactive corrinoid analogues in non-animal candidate sources.