L-Methionine and blood vessels

What 2 graded rows on l-methionine agree on for blood vessels, and where they differ. Counted side by side, never averaged.

Consensus finder Rows from the L-Methionine page, reviewed Oct 21, 2026 How it decides

What the rows agree on

Each block and row is one graded row from the L-Methionine page, with its PubMed record.

Supplement

L-Methionine Choose another

2 rows · 40 people

Split. 1 row found a worse outcome and 1 had mixed results.

Mixed or worse

Improved

Each block is one evidence row, sized by how many people it enrolled, with its grade inside. Red: a worse outcome. Outlined: mixed results.

From the rows

The best-graded row, grade D, is a crossover trial of 24 people (1998) and found a worse outcome.

The rows run from 16 to 24 people, published from 1998 to 1999: 2 single studies.

1 worse · 1 mixed

Grade DFlow-mediated dilation after a methionine load · Worse
Crossover RCT · n 24 · 1998 · Healthy adults
0.1 g per kg of body weight, once · Single dose, measured over 4 to 8 hours
Homocysteine rose from 7.9 to 23.1 µmol/L at 4 hours and flow-mediated brachial dilation fell from 0.12 to 0.06 mm (p < 0.05), mirroring the homocysteine curve.
Row on the L-Methionine page · PubMed 9799203 (opens PubMed)
Grade DBlood-vessel function and homocysteine · Mixed
Open-label trial · n 16 · 1999 · Healthy volunteers
250 mg once; 250 mg a day; 100 mg/kg a day · Single dose, 1 month (low dose) or 1 week (high dose)
Endothelium-dependent vasodilation did not change at any dose. Homocysteine did not change at 250 mg a day but rose significantly on 100 mg/kg a day.
Row on the L-Methionine page · PubMed 10465239 (opens PubMed)