Evidence Trace, complete trial record

In plain terms

In plain terms: Luteolin has not yet been tested in a human trial designed to measure the outcome relevant here. The available human research does not yet answer the question.

Luteolin

D Not shown: no human trial shows benefit

Route 1 — no qualifying human trial has been conducted

Category Supplements

Evidence Combination RCT only; luteolin alone untested (D Route 1)

Reviewed July 2026

PMIDs 35450527 · 33802381 · 38861957 · 37380908

The endpoint this grade is based on: Objectively measured functional outcome, Olfactory recovery after COVID-19, tested only inside a palmitoylethanolamide combination: luteolin alone is untested (D Route 1). The one trial of luteolin alone, in Gulf War illness symptoms, was null (D Route 2).

The evidence as the record states it

Evidence record

PMID 35450527 PMID 33802381 PMID 38861957 PMID 37380908

Di Stadio et al. (Current Neuropharmacology, 2022; PMID 35450527): randomized trial of co-ultramicronized palmitoylethanolamide plus luteolin with olfactory training for olfactory recovery after COVID-19. The trial does not isolate luteolin; the product is a fixed combination, allocation was unbalanced (130 against 55) and the comparator arms differ in training, not in luteolin. Even for the combination the picture is mixed: Gellrich et al. (ORL, 2024; PMID 38861957), an independent Dresden trial of 50 patients, found no difference in clinically meaningful olfactory improvement over training alone, and in Di Stadio et al. (Eur Arch Otorhinolaryngol, 2023; PMID 37380908), 202 patients in four arms, the combination without olfactory training did no better than training with placebo. Grade D on Route 1: no randomized trial of luteolin alone has tested an olfactory, cognitive or neuro-inflammatory outcome. A PubMed search in October 2026 for randomized trials naming luteolin returned 14 records, every one a combination or mixture product except one: the luteolin-alone arm of a placebo-controlled pseudo-randomized crossover of botanical agents in 21 veterans with Gulf War illness (Hodgin et al., Int J Environ Res Public Health, 2021; PMID 33802381), in which luteolin did not reduce symptom severity at either dose while resveratrol did. That is a tested null in a different population, graded on its own row.

PMID 35450527 PMID 33802381 PMID 38861957 PMID 37380908

Evidence by specific use

Olfactory recovery after COVID-19, luteolin alone

Grade D

No randomized trial has given luteolin alone for olfactory recovery. Every olfactory trial tested a fixed palmitoylethanolamide plus luteolin combination with or without olfactory training (Di Stadio et al., 2022; PMID 35450527; Di Stadio et al., 2023; PMID 37380908; Gellrich et al., 2024; PMID 38861957), and a combination does not grade a single ingredient. Even the combination's evidence is mixed: the independent Dresden trial found no difference in clinically meaningful improvement, and the combination without training did no better than training with placebo. Smell tests are measured performance, so the endpoint type is functional. Route 1: untested.

PMID 35450527 PMID 38861957 PMID 37380908

Symptom severity in Gulf War illness, luteolin alone

Grade D

Hodgin et al. (Int J Environ Res Public Health, 2021; PMID 33802381): the only placebo-controlled trial of luteolin alone found. Luteolin did not reduce symptom severity at either dose; resveratrol in the same screening study did. Tested and no benefit, on a small self-report crossover: D on Route 2.

PMID 33802381

Animal lifespan data and mechanistic plausibility are excluded from EBL grades by rule. They inform the scientific rationale but do not carry the letter.

Why Grade D Route 1 and not Grade C

Grade D Route 1 applies when no qualifying human randomized trial has tested this compound or intervention against the relevant endpoint. Absence confirmed: luteolin[Title] AND randomized controlled trial[pt] AND (olfactory[tiab] OR smell[tiab] OR anosmia[tiab] OR cognit*[tiab] OR neuroinflamm*[tiab]) NOT palmitoylethanolamide[tiab] (PubMed, October 2026)

The first qualifying human RCT with a meaningful endpoint would move this to Grade C or higher, depending on what it shows.

What would move this grade

The first qualifying randomized controlled trial in humans, testing this intervention against a meaningful aging-relevant endpoint, would initiate grading. Depending on the result, it could land at any grade from A to D.

How to track whether this is working HsCRP and IL-6 at baseline and 8 weeks for anti-inflammatory applications. For cognitive applications, use a validated brief cognitive battery at baseline and 12 weeks. Luteolin bioavailability is low in standard forms: formulations using liposomal delivery or quercetin co-administration, which improve absorption.