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Methionine

Overview

Methionine is an essential amino acid supplied in dietary protein. It plays a central role in methylation processes. A methionine figure is not a cysteine figure. It forms S-adenosylmethionine (SAMe), the universal methyl donor that fuels neurotransmitter synthesis (dopamine, norepinephrine, serotonin) and drives phospholipid methylation in neuronal membranes. Methionine is converted to SAMe through a process that involves B vitamins (B6, B2, folate, B12) as cofactors. After donating its methyl group, SAMe becomes S-adenosylhomocysteine, which is then converted to homocysteine, which can be remethylated back to methionine in a cycle that requires adequate B vitamin status.

Recipes

3 recipes containing this substance

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.

Foods

5 foods

Chicken

Niacin, zinc, and tryptophan

Eggs

Complete protein with choline, B vitamins, and phospholipids

Salmon

Oily fish rich in EPA/DHA, protein, and B vitamins

Sardines

Small oily fish rich in EPA/DHA, CoQ10, and calcium

Tuna

Fish providing omega-3, niacin, selenium, and complete protein

Biological Mechanisms and Implications

References

• Methionine is essential and forms SAMe, the universal methyl donor for neurotransmitter synthesis and membrane phospholipid methylation
• B vitamins, particularly B6, B2, folate (5-MTHF), and B12, are essential cofactors in remethylation of homocysteine to methionine, which is converted to SAMe

BRS matrix — individual KC inputs

BRS / PM	Relationship	Biological role and limitation
BRS2 · BRS2-FM2-PM5 BRS2(KC2)	Supported upstream supply	Methionine enters the methionine cycle, producing homocysteine that supplies the CBS reaction and carries sulfur into cysteine formation. Limitation: Supported upstream supply, not direct CBS substrate or established sulfur-pool limitation. Cysteine is the product of this PM and is not admitted as an additional supply input. Tissue allocation, compensation and benefit from extra methionine intake are not established. Lamers et al. (2011) [7]