Nutrient glossary
What is methionine?
Methionine starts the build of every protein and donates the methyl groups DNA regulation runs on.
Reviewed 20 July 2026. General information, not medical advice.
The short version
Every new protein your body makes begins with methionine. It also powers the methylation cycle, tagging DNA and recycling homocysteine with help from folate and B12, and it supplies sulphur for cysteine and glutathione, the cell’s main antioxidant.
Eggs, fish, meat and brazil nuts are dense in it; beans run lower, which grains balance out, the mirror image of lysine.
Daily reference
800 mg a day
The adult requirement is about 10.4 mg per kg of body weight a day for methionine itself, with cysteine covering the rest of the sulphur amino need.
This is the fixed adult reference used across these pages. In the app, your amount adjusts to your body and way of eating.
Best food sources of methionine
| Food | Per serving | Per 100g |
|---|---|---|
| Chicken Breast | 1.37 g | 806 mg |
| Sirloin Steak | 1.15 g | 766 mg |
| Ribeye Steak | 1.14 g | 758 mg |
| Roast Chicken | 1.12 g | 801 mg |
| Tuna Steak | 1.08 g | 827 mg |
| Halibut | 1.05 g | 748 mg |
| Duck Breast | 1.03 g | 737 mg |
| Salmon Fillet | 962 mg | 641 mg |
Common questions
- Is less methionine better for longevity?
- Restriction extends life in rodents, but human evidence is not there, and cutting it means cutting protein quality. Not an evidence-based strategy today.
- Which foods are high in methionine?
- Egg whites, fish, chicken, brazil nuts and sesame seeds rank highest relative to protein.