Methionine
Methionine is the essential amino acid that starts every protein and supplies the sulfur for cysteine. With cysteine, adults need about 15 mg per kilogram of body weight a day.
15 mg per kg of body weight a day, with cysteine
1.05 g a day for a 70 kg adult
Upper limit · none set, for lack of studies
- Most per 100 g 1.1g Brazil nuts
- In protein 22mg/g with cysteine, the WHO pattern
- Main sources Fish, meat and eggs then seeds, grains and nuts
- Low in Beans and lentils relative to their other amino acids
Daily requirement: WHO, FAO and UNU 2007. Food figures per 100 g from USDA FoodData Central, only for foods with a Caltide calorie page.
Foods High in Methionine
Ranked per 100 g, with what a usual portion gives, limited to 3 foods per category. Foods with a Caltide calorie page link to it.
B
Brazil nuts
1.1g / 100 g
B
Bacon
Nutrition facts
1g / 100 g
S
Sesame seeds
1.1 g in 1 cup
0.88g / 100 g
C
Cube steak
0.26 g in 1 piece/slice
0.85g / 100 g
B
Beef roast
0.5 g in 1 regular/thin slice
0.84g / 100 g
R
Rotisserie chicken breast
0.5 g in 1 medium slice
0.83g / 100 g
G
Gruyère
0.82g / 100 g
B
Beef sirloin steak
0.24 g in 1 piece/slice
0.79g / 100 g
T
Turkey mince
0.47 g in 1 patty
0.79g / 100 g
R
Rotisserie chicken drumstick
0.39 g in 1 drumstick
0.77g / 100 g
T
Trout
0.69 g in 1 small/regular fillet
0.77g / 100 g
R
Rotisserie chicken
0.45 g in 1 slice
0.75g / 100 g
What Is Methionine?
Methionine is one of the nine essential amino acids and one of two that contain sulfur; the other, cysteine, the body can make from it. That is why requirements are set for the pair: whatever cysteine food does not supply, methionine has to cover.
The First Amino Acid of Every Protein
When a cell reads a gene to build a protein, the start signal in the genetic code stands for methionine, so every new protein chain begins with it. Many proteins trim it off afterwards, but none can be started without it.
Methionine and the Methyl Cycle
Methionine's other job is chemical. The body joins it to ATP to make S-adenosylmethionine (SAMe), which hands a small methyl group to DNA, to brain messengers, to creatine and to many other molecules. What is left after the handover is homocysteine.
Homocysteine then goes one of two ways. Folate and vitamin B12 recycle it back into methionine, or vitamin B6 helps turn it into cysteine, which goes on to make taurine and the antioxidant glutathione. A shortage of any of those three vitamins lets homocysteine build up in the blood, which is why a high homocysteine result often leads to a check of B vitamins rather than of methionine.
Methionine in Beans and Grains
Legumes are the plant world's lysine source but are low in methionine. A 180 g cup of cooked lentils in the Caltide food library gives about 1.2 g of leucine and only about 0.14 g of methionine. Grains and seeds lean the other way: oats and chia seeds are rich in both sulfur amino acids, which is why a mixed plant diet covers the pair without trouble.
Methionine in a Day of Vegan Meals
One ordinary plant-only day from the Caltide food library, in usual portions, with no supplements. The column shows methionine; cysteine comes on top.
| Meal | Food | Amount | Methionine |
|---|---|---|---|
| Breakfast | Oats | 40g | 0.083g |
| Breakfast | Chia seeds | 12g | 0.071g |
| Lunch | Lentils | 180g | 0.14g |
| Lunch | Quinoa | 185g | 0.18g |
| Snack | Peanut butter | 32g | 0.085g |
| Dinner | Tofu | 125g | 0.1g |
| Dinner | Pasta | 140g | 0.09g |
| Dinner | Broccoli | 90g | 0.034g |
| Total | 0.78g |
The same foods also bring about 0.93 g of cystine, the form cysteine takes in food, for 1.7 g of sulfur amino acids in all. Against 1.05 g for a 70 kg adult, that is 163%.
Common Methionine Mistakes
Judging a vegan diet by methionine alone. Grains and seeds are rich in cystine, and cystine spares methionine. Read the two together, as the requirement does.
Blaming methionine for high homocysteine. Low folate or vitamin B12 and kidney disease are common causes of a raised level, which is why those are checked first.
Methionine Supplements
Supplements are a source of methionine too, on its own or as SAMe, and the two are not interchangeable.
L-Methionine
Sold as capsules and found in essential amino acid blends and protein powders. A healthy person eating enough protein has no need for extra. A large single dose raises blood homocysteine within hours, the basis of the methionine loading test used in research.
SAMe
- What the evidence saysstudied for depression and osteoarthritis; the NCCIH rates the evidence as limited and uncertain
- Safetymay interact with antidepressants, and people with bipolar disorder should not take it without a doctor
Sources are listed at the end of this page. Not medical advice.
Tracking Methionine in Caltide
- Logged automaticallyCaltide adds up methionine and cystine from the foods you log and the supplements you tick off, as two rows in the Nutrition tab.
- Why there is no percentageThe WHO requirement is set for methionine and cysteine together, so Caltide shows the amounts without a daily target for either one alone.
Methionine Sources and References
The figures and claims on this page are checked against these sources. Food amounts come from USDA FoodData Central.
Questions About Methionine
The WHO, FAO and UNU 2007 report gives methionine and cysteine together: 15 mg per kilogram of body weight a day, about 1.05 g for a 70 kg adult. The body makes cysteine from methionine, so the two share one requirement.
In the Caltide food library, brazil nuts: 1.1 g per 100 g. Bacon (1 g) and Sesame seeds (0.88 g) come next.
Yes, compared with their other amino acids. Cooked lentils have 0.077 g of methionine per 100 g but several times as much leucine. Grains, nuts and seeds fill the gap: oats have 0.21 g and chia seeds 0.59 g.
It starts every new protein the body makes, and it is turned into SAMe, the compound that hands methyl groups to DNA, hormones and other molecules. Its sulfur also ends up in cysteine, taurine and the antioxidant glutathione.
Homocysteine is made each time methionine gives up a methyl group. Folate and vitamin B12 recycle it back to methionine and vitamin B6 helps turn it into cysteine; when those vitamins run low, homocysteine can build up in the blood.
No. SAMe (S-adenosyl-L-methionine) is made from methionine in the body and is also sold as a supplement. The NCCIH says studies for depression and osteoarthritis are limited and their results uncertain.
Healthy people eating enough protein have no need to. Large doses of methionine raise blood homocysteine within hours, which is why doctors once used a methionine dose as a test.
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