L-Histidine and fatigue

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

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

What the rows agree on

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

Supplement

L-Histidine Choose another

2 rows · 120 people

Split. 1 row found an improvement and 1 found no difference.

No difference

Improved

Each block is one evidence row, sized by how many people it enrolled, with its grade inside.

From the rows

Trial sizeWhen published

The best-graded row, grade D, is a randomized trial of 100 people (2026) and found no difference.

The row that found no difference was larger: 100 people, against 20 people for the row that found an improvement.

The row that found no difference is newer (2026) than the row that found an improvement (2015).

1 improved · 1 no difference

Grade DFeelings of fatigue, clear thinking and working-memory reaction time · Improved
Crossover RCT · n 20 · 2015 · Adults with high fatigue and sleep-disruption scores
1.65 g/day (dose reported in the full text and a 2020 review) · 2 weeks per period
Profile of Mood States fatigue scores fell, reaction time on a working-memory task shortened, and ratings of clear thinking and attentiveness rose versus placebo.
Row on the L-Histidine page · PubMed 25921948 (opens PubMed)
Grade DMental fatigue and vigor after a single dose · No difference
RCT · n 100 · 2026 · Healthy adults aged 30–60 who regularly felt fatigued and short of sleep
1.65 g, single dose · Single dose before a mental workload
No improvement versus placebo on any endpoint in all participants (prespecified analysis). In an exploratory subgroup with high fatigue scores, fatigue, confusion and depression scores fell and vigor rose versus placebo. No adverse events.
Row on the L-Histidine page · PubMed 41986440 (opens PubMed)