Kaempferol

Q: Does kaempferol help sleep?

One 2-week crossover trial in 33 office workers found better sleep quality on a wearable device. It has not been repeated.

Q: Is kaempferol from food as good as a supplement?

No trial has compared them. The trials used 10 mg capsules of kaempferol aglycone; from endive, 9 mg of kaempferol reached a peak blood level of 0.1 µM after about 6 hours in 8 adults.

Q: Is kaempferol safe?

A 4-week placebo-controlled trial of 50 mg/day in 48 healthy adults found no changes in blood or urine tests and no adverse events. Longer use is untested.

Q: Does kaempferol interact with medicines?

No human interaction studies exist, and the 4-week safety trial did not test medicines. The 50 mg safety dose is about five times estimated dietary intake, so the 10 mg trial dose is close to normal dietary amounts.

Q: What does kaempferol do?

In small company-run trials, 10 mg lowered heart rate and oxygen use during exercise and raised daily steps. It did not make athletes run faster.

Q: Who studied kaempferol in people?

Almost all trials come from researchers at Otsuka Pharmaceutical, which limits independence.

Also called kaempferol aglycone, kaempferol glycosides, KMP, quinoa kaempferol.

Best grade D across 4 graded outcomes Other Last checked Oct 21, 2026

The short answer

From 8 sources

Kaempferol is a dietary flavonoid. Nearly all human trials come from one company, Otsuka Pharmaceutical, using 10 mg doses. Small crossover trials found lower oxygen use and heart rate during exercise and more daily steps, but 400-m race times did not improve. A 4-week trial of 50 mg/day found no safety problems.

Every graded outcome on this page

4 rows · line = participants

Grade DWeather-related headache and discomfortWeather-related painn 387
Grade DDaily steps, heart rate and sleep qualitySleep and activityn 33
Grade DOxygen uptake and endurance during cyclingEndurancen 16
Grade DRace times and physiological load in repeated 400-m runsSprint performancen 13

Key facts

Exercise oxygen use: A single 10 mg dose lowered oxygen uptake during submaximal cycling and lengthened time to exhaustion at 100% VO2max vs placebo in 16 trained athletes¹
Race times: In 13 male athletes running two 400-m races, 10 mg did not change race times but lowered heart and breathing rates and muscle-damage markers in the second run²
Daily activity and sleep: Over 2 weeks, 10 mg/day raised daily steps and lowered heart rate vs placebo in 33 office workers, and device-measured sleep quality improved³
Safety: 50 mg/day, about five times estimated dietary intake, caused no changes in blood, urine or blood pressure and no adverse events over 4 weeks in 48 adults⁴
Absorption from food: In 8 adults eating endive with 9 mg of kaempferol, blood levels peaked at a mean 0.1 µM after 5.8 hours and 1.9% of the dose reached the urine in 24 hours⁷
Who funds it: Every trial on this page lists Otsuka Pharmaceutical employees as authors^1,2,3,4,5

What it is

Kaempferol is a flavonol found in kale, beans, tea, broccoli and quinoa, sold as a purified supplement.

How it works

Proposed

In cell studies by the same group, kaempferol increased mitochondrial ATP production under low oxygen. Trial authors propose that this improves oxygen use during exercise and shifts the nervous system toward rest (lower heart rate, higher heart rate variability). These ideas are not confirmed.^1,3

Forms, side by side

2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.

Kaempferol forms compared

2 forms

Kaempferol forms compared: 2 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
2 forms	Aglycone capsules	From foods
Absorption in people	Not reported in the trial abstracts.^4,1,3	In 8 adults eating endive (9 mg kaempferol), plasma kaempferol peaked at a mean 0.1 µM after 5.8 hours and 1.9% of the dose was excreted in urine within 24 hours, mostly as kaempferol-3-glucuronide.⁷
GI tolerance	No adverse events at 50 mg/day for 4 weeks.^4,1,3	Part of normal diets.⁶
Studied for	Exercise, activity, sleep, safety	Absorption (pharmacokinetic study); population studies of diet

Kaempferol aglycone capsules
Absorption in people
Not reported in the trial abstracts.^4,1,3
GI tolerance
No adverse events at 50 mg/day for 4 weeks.^4,1,3
Studied for
Exercise, activity, sleep, safety
Kaempferol from foods
Absorption in people
In 8 adults eating endive (9 mg kaempferol), plasma kaempferol peaked at a mean 0.1 µM after 5.8 hours and 1.9% of the dose was excreted in urine within 24 hours, mostly as kaempferol-3-glucuronide.⁷
GI tolerance
Part of normal diets.⁶
Studied for
Absorption (pharmacokinetic study); population studies of diet

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

4 graded outcomes, largest study first

4 graded outcomes: 3 improved, 1 mixed. The largest, a 2025 open-label trial of 387 people on Weather-related headache and discomfort, found an improvement.

By sizeTable

1Weather-related headache and discomfort

Improved · Grade D · Open-label trial, 387 people, 2025

Adults with moderate weather-related symptoms (Japan); 387 of 458 analyzed

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Weather-related headache and discomfort	Improved	387	Grade D · Open-label trial, 2025	Adults with moderate weather-related symptoms (Japan); 387 of 458 analyzed
Daily steps, heart rate and sleep quality	Improved	33	Grade D · Crossover RCT, 2024	City office workers, 17 men and 16 women (Japan)
Oxygen uptake and endurance during cycling	Improved	16	Grade D · Crossover RCT, 2025	Well-trained male university athletes (Japan)
Race times and physiological load in repeated 400-m runs	Mixed	13	Grade D · Crossover RCT, 2024	Male university athletes (about 21 years old, Japan)

Every graded row

4 rows

Form tested

Showing 4 of 4 outcomes. Human trials only.

Grade DWeather-related headache and discomfortWeather-related painFewer headaches (uncontrolled)Open-label trial
n 387 · 2025

Improved Headache frequency (Cohen's d 0.61), duration and severity fell from the pre-intervention period; over 80% reported improvement.

Design: Open-label trial, n = 387, 2025
Population: Adults with moderate weather-related symptoms (Japan); 387 of 458 analyzed
Form: Kaempferol, no control group
Dose: 10 mg/day
Duration: 4 weeks
Source: Reference 5 · PubMed 40705051 (opens PubMed)

Grade DDaily steps, heart rate and sleep qualitySleep and activityMore steps, better sleep scoresCrossover RCT
n 33 · 2024

Improved Daily steps and distance rose, heart rate fell at each activity level, and sleep quality measured by a Fitbit improved during kaempferol intake vs placebo.

Design: Crossover RCT, n = 33, 2024
Population: City office workers, 17 men and 16 women (Japan)
Form: Kaempferol vs placebo
Dose: 10 mg/day
Duration: 2 weeks per period, 7-day washout
Source: Reference 3 · PubMed 39155930 (opens PubMed)

Grade DOxygen uptake and endurance during cyclingEnduranceLower oxygen costCrossover RCT
n 16 · 2025

Improved VO2 and breathing rate were lower at 25%, 50% and 75% VO2max, and exercise time at 100% VO2max was longer (p < 0.05 vs placebo); lactate and respiratory quotient did not rise.

Design: Crossover RCT, n = 16, 2025
Population: Well-trained male university athletes (Japan)
Form: Kaempferol vs placebo
Dose: 10 mg once
Duration: Single dose
Source: Reference 1 · PubMed 40346019 (opens PubMed)

Grade DRace times and physiological load in repeated 400-m runsSprint performanceNo faster race timesCrossover RCT
n 13 · 2024

Mixed Race times did not differ; heart rate, breathing rate, myoglobin and AST were lower after the second run (p < 0.05).

Design: Crossover RCT, n = 13, 2024
Population: Male university athletes (about 21 years old, Japan)
Form: Kaempferol vs placebo
Dose: 10 mg once
Duration: Single dose
Source: Reference 2 · PubMed 39619966 (opens PubMed)

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

One company's research program

All five human studies here involve Otsuka Pharmaceutical staff, and none has been repeated by an independent group.^1,2,3,4,5

Body signals, not results

Kaempferol changed heart rate, breathing and oxygen use, but the one trial with a real performance outcome (race time) found no difference.^1,2

Diet links are observational

In US national survey data, each extra 5 mg/day of dietary kaempferol was linked to 7% lower odds of kidney damage in adults with overweight or obesity; this cannot show cause and effect.⁶

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from a single 10 mg dose before exercise to 10 mg/day for 2-4 weeks; a safety trial used 50 mg/day for 4 weeks, about five times estimated dietary intake. These are research doses, not recommendations.^1,3,5,4

When trials measured an effect

3 outcomes

How long trials ran before effects were measured
Outcome	Measured at	Basis
Oxygen use and endurance during cycling	Same day, after a single 10 mg dose	Single-dose crossover trial in 16 trained athletes¹
Daily steps and sleep quality (wearable)	Within each 2-week intake period	10 mg/day crossover in 33 office workers, tracked by a Fitbit through each 2-week period³
Weather-related headache	Week 4 (end of an uncontrolled study)	Questionnaires before and after 4 weeks of 10 mg/day; no placebo group⁵

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

Interactions

0 agents

None found in our sources.

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Kaempferol and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Kaempferol.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Who should be careful

4 groups

Athletes expecting faster times: In the only race-performance trial, 10 mg did not change 400-m race times.²
Drug interactions: No published human drug-interaction studies were found; LiverTox and LactMed have no kaempferol entry, and the 4-week safety trial did not test medicines.⁴
Pregnancy and breastfeeding: No reliable data on supplements: none of the cited trials included pregnant or breastfeeding women. LactMed's ginkgo entry reports kaempferol from ordinary diets in the breast milk of 17 mothers at 7.8-71.4 nmol/L; supplement doses have not been studied.^4,8
Higher doses: Safety has been tested only up to 50 mg/day for 4 weeks in healthy adults.⁴

How to read the label

What to check on the Supplement Facts panel.

How to read the label

2 checks

Aglycone dose

The trials used kaempferol aglycone (the free form), at 10 mg in performance and sleep studies and 50 mg in the safety study.^4,1

Food comparison

The safety trial authors estimate that 50 mg is about five times typical dietary intake, so a 10 mg capsule is roughly a day of normal dietary kaempferol.⁴

Have the bottle? Photograph its Supplement Facts panel and see each line, kaempferol included, beside the doses and forms the trials used in Label X-Ray.

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

6 answers

Does kaempferol help sleep?

One 2-week crossover trial in 33 office workers found better sleep quality on a wearable device. It has not been repeated.³

Is kaempferol from food as good as a supplement?

No trial has compared them. The trials used 10 mg capsules of kaempferol aglycone; from endive, 9 mg of kaempferol reached a peak blood level of 0.1 µM after about 6 hours in 8 adults.^1,3,7

Is kaempferol safe?

A 4-week placebo-controlled trial of 50 mg/day in 48 healthy adults found no changes in blood or urine tests and no adverse events. Longer use is untested.⁴

Does kaempferol interact with medicines?

No human interaction studies exist, and the 4-week safety trial did not test medicines. The 50 mg safety dose is about five times estimated dietary intake, so the 10 mg trial dose is close to normal dietary amounts.⁴

What does kaempferol do?

In small company-run trials, 10 mg lowered heart rate and oxygen use during exercise and raised daily steps. It did not make athletes run faster.^1,2,3

Who studied kaempferol in people?

Almost all trials come from researchers at Otsuka Pharmaceutical, which limits independence.^1,3,4

Sources

8 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

8 sources

1Acute kaempferol ingestion lowers oxygen uptake during submaximal exercise and improves high-intensity exercise capacity in well-trained male athletes.Crossover RCT Physiol Rep, 2025 · PMID 40346019
2Kaempferol Reduces Cardiopulmonary Load and Muscular Damage in Repeated 400-m Sprints: A Double-Blind, Randomized, Placebo-Controlled Trial.Crossover RCT Food Sci Nutr, 2024 · PMID 39619966
3Effect of kaempferol ingestion on physical activity and sleep quality: a double-blind, placebo-controlled, randomized, crossover trial.Crossover RCT Front Nutr, 2024 · PMID 39155930
4A randomized, placebo-controlled trial evaluating the safety of excessive administration of kaempferol aglycone.RCT Food Sci Nutr, 2023 · PMID 37701215
5Effects of kaempferol on weather-related pain: an open-label pilot study of subjective headache and other discomforts in pre-intervention and intervention periods in Japan.Open-label trial Int J Biometeorol, 2025 · PMID 40705051
6Beneficial Impact of Kaempferol on Kidney Function and Long-Term Prognosis in Overweight or Obese Adults.Observational Food Sci Nutr, 2026 · PMID 41607644
7Absorption of kaempferol from endive, a source of kaempferol-3-glucuronide, in humans.PK study Eur J Clin Nutr, 2004 · PMID 15164116
8GinkgoDatabase LactMed (NCBI Bookshelf), 2025 · ncbi.nlm.nih.gov

What changed

Every dated change to this page: what changed, who made it and why.

Change log

3 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026key facts, forms, who should avoid, FAQ, questions, time to effect, related	Searched PubMed for kaempferol trials and meta-analyses through October 2026: no human trial newer than the 2025 rows exists (an August 2025 correction to the cycling trial fixes a figure and a table but not the reported results), so the evidence table is unchanged. Added a human absorption study (9 mg from endive; peak 0.1 µM at 5.8 h, 1.9% in urine) to the food form, key facts and FAQ, and LactMed's ginkgo entry (kaempferol from ordinary diets measured in breast milk) to a rewritten pregnancy and breastfeeding note. Interaction check: LiverTox and LactMed have no kaempferol entry and PubMed lists no human drug-interaction study; the list stays empty. Added FAQ items on interactions and food versus supplements, time-to-effect rows, page questions and a performance goal-hub link.	Writer: Kymata Health EditorialTrigger: A–Z audit against docs/supplements/AUDIT-STANDARD.md
Oct 14, 2026all	Initial editorial evidence review (first draft). Every PMID checked against NCBI E-utilities esummary (titles and years taken from the record, none retracted) and the abstract read for each cited row. Studied doses are reported as research doses, not dosing advice.	Writer: Kymata Health EditorialTrigger: new page
Oct 14, 2026evidence, safety	Adversarial review: single 33-person crossover (activity and sleep) regraded C to D per the methodology grade rules.	Writer: Kymata Health EditorialTrigger: adversarial review

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