Benefits
Cardiovascular Risk Reduction (Epidemiological)
A dose-response meta-analysis showed kaempferol intake is linearly associated with lower risk of cardiovascular disease, and quercetin showed a similar inverse association with coronary heart disease. Cohort evidence is not consistent, however. In the Nurses' Health Study (66,360 women, 12 years, 938 non-fatal myocardial infarctions and 324 coronary deaths) there was no association between flavonol or flavone intake and non-fatal myocardial infarction or fatal coronary heart disease; the only signal was a weak reduction in coronary death in the highest kaempferol quintile (relative risk 0.66, 95% CI 0.48-0.93, p for trend 0.04), which the authors attributed largely to broccoli consumption rather than to kaempferol itself. All of this measures kaempferol eaten in food, not kaempferol taken as a supplement. The only randomised trial to measure cardiovascular numbers directly was a 4-week safety study of 50 mg/day in 48 healthy adults, in which blood pressure, total, HDL and LDL cholesterol and triglycerides did not improve (Akiyama 2023, PMID 37701215). No trial has measured endothelial function or any cardiovascular event.
Growth-Signaling Effects in Cultured Cells
In cultured cell lines kaempferol alters several growth-signaling pathways, including PI3K/AKT, and changes the expression of adhesion and matrix proteins such as matrix metallopeptidase 2. These experiments use micromolar concentrations; the mean peak plasma concentration in people after a 9 mg oral dose is about 0.1 micromolar (DuPont 2004, PMID 15164116), so the laboratory concentrations are roughly 100 to 1,000 times higher than anything oral kaempferol produces in the body. Nothing here has been shown to happen in a person. Kaempferol is not a treatment for any disease. The population data do not support a preventive role either: in the Women's Health Study (38,408 women, 11.5 years, 3,234 incident cancers) intake of kaempferol and the other quantified flavonols showed no association with total cancer or with breast, colorectal, lung, endometrial or ovarian cancer, and the authors concluded their results do not support a major role for these compounds in cancer prevention.
Anti-inflammatory Activity
Kaempferol inhibits NF-κB and AP-1 signaling, MAPK pathways, and pro-inflammatory cytokine production in vitro. Reduces iNOS and COX-2 expression. All of this is cell-culture work at concentrations well above what oral kaempferol reaches in human plasma. The only human trial to measure an inflammatory marker was a 4-week safety study of 50 mg/day in 48 healthy adults, in which C-reactive protein did not fall (Akiyama 2023, PMID 37701215); no trial has measured IL-6, TNF-alpha or any other inflammatory marker. An anti-inflammatory effect in people has not been demonstrated.
Glucose Metabolism in Animal Models
Animal studies show kaempferol suppresses IKK/NF-κB hepatic signaling, IRS-1 phosphorylation, and significantly enhances insulin secretion and synthesis. Improves insulin sensitivity in rodent models. No human trial has tested kaempferol for blood-sugar control. The only trial to measure glucose and HbA1c at all was a 4-week safety study of 50 mg/day in healthy adults, in which neither improved (Akiyama 2023, PMID 37701215); insulin was not measured. None of the rodent findings has been shown to occur in people, and kaempferol should not be used in place of diabetes care.
Antioxidant Activity
Like other flavonols, kaempferol scavenges free radicals and induces endogenous antioxidant systems via Nrf2 activation. Antioxidant capacity is comparable to other major flavonoids (quercetin, myricetin) in chemical assays. Those are test-tube measurements. No randomised or clinical trial of kaempferol has reported oxidative-stress markers such as malondialdehyde or F2-isoprostanes in people, so antioxidant activity inside the human body has not been demonstrated.
Mechanism of action
NF-κB and AP-1 Pathway Inhibition
Kaempferol inhibits IκB kinase (IKK), preventing NF-κB activation. Also suppresses AP-1 transcription factor activity. In cell culture this reduces expression of inflammatory cytokines and proliferation-related genes. It is the proposed explanation for kaempferol's laboratory anti-inflammatory activity. Whether it occurs at all at the concentrations oral kaempferol reaches in human tissue is unknown.
PI3K/AKT/mTOR Pathway Modulation
In cancer cells, kaempferol downregulates PI3K/AKT signaling — reducing pro-survival signaling and inducing apoptosis. The same pathway is speculatively linked to insulin signalling, but this has not been shown in humans.
Programmed Cell Death in Cultured Cell Lines
In cell-culture experiments kaempferol triggers apoptosis in immortalised cell lines, with relative sparing of normal cells in some studies. These experiments use micromolar concentrations that oral kaempferol does not reach in human blood - peak plasma is about 0.1 micromolar after a 9 mg dose (DuPont 2004, PMID 15164116). This is laboratory pharmacology only. Kaempferol is not a cancer treatment and has never been tested as one in people.
Cell-Adhesion and Migration Markers in Cell Culture
In cultured cells kaempferol changes expression of epithelial-mesenchymal transition markers (N-cadherin, E-cadherin, Slug, Snail) and of matrix metallopeptidase 2. This is descriptive cell biology at concentrations not achievable from oral intake, and it has no demonstrated consequence in humans.
Free Radical Scavenging and Nrf2 Activation
Direct ROS scavenging attributed mainly to the 3-hydroxyl group and the 4'-hydroxyl on the B ring. Indirect antioxidant effects via Nrf2-mediated induction of phase II detoxification enzymes (HO-1, NQO1, glutathione synthesis). These are proposed antioxidant mechanisms demonstrated in cells and animals. No human study has confirmed that oral kaempferol activates Nrf2 or changes any oxidative-stress marker in people.
Clinical trials
Randomised, double-blind, placebo-controlled crossover trial of a single 10 mg oral dose of kaempferol, with constant-load exercise tests at 25%, 50%, 75%, 100% and 125% of VO2max. (Okita K, Mizokami T, Yasuda O, Ikeda Y. Physiol Rep. 2025;13(9):e70369. PMID 40346019. Registered UMIN000049589. Two of the four authors are affiliated with Otsuka Pharmaceutical Co., Ltd.; the paper itself declares no conflict of interest.)
16 well-trained male university athletes (mean VO2max 57.5 mL/kg/min).
Kaempferol significantly reduced oxygen uptake and respiratory rate during submaximal exercise at 25%, 50% and 75% of VO2max compared with placebo, without raising the respiratory quotient or blood lactate, and significantly extended exercise duration at 100% of VO2max. Limits: one small acute-dose crossover study in trained young men, run by the company that sells the ingredient, with no independent replication; an erratum has since been published (Physiol Rep 2025;13(16):e70518). It measured no antioxidant, inflammatory or cardiovascular-risk endpoint.
Randomised, double-blind, placebo-controlled 4-week trial of 50 mg/day kaempferol aglycone capsules, roughly five times estimated dietary intake, against a cornstarch placebo. (Akiyama M, Mizokami T, Ito H, Ikeda Y. Food Sci Nutr. 2023;11(9):5427-5437. PMID 37701215. All four authors employed by Otsuka Pharmaceutical Co., Ltd.)
48 healthy adults, 24 receiving kaempferol and 24 placebo, for 4 weeks.
The safety panel covered blood pressure, body composition, haematology, liver and kidney chemistry, C-reactive protein, total, HDL and LDL cholesterol, triglycerides, glucose and HbA1c, plus urinalysis. Nothing improved relative to placebo, and no adverse events were attributable to kaempferol. That makes this card doubly important: it establishes short-term tolerability at 50 mg/day, and it is also the only human data in existence on kaempferol and CRP, blood pressure, cholesterol or blood sugar - none of which moved. It measured no oxidative-stress marker. It is also the highest dose of isolated kaempferol ever given to people in a trial, which is why capsules sold at 100-200 mg have no human safety data behind them.
Double-blind, placebo-controlled, randomised crossover trial of 10 mg/day kaempferol for 2 weeks with a 7-day washout, with activity, heart rate and heart-rate variability recorded continuously by wrist accelerometer. (Ikeda Y, Gotoh-Katoh A, Okada S, Handa S, Sato T, Mizokami T, Saito B. Front Nutr. 2024;11:1386389. PMID 39155930. Registered UMIN000042438. Three authors employed by Otsuka Pharmaceutical Co., Ltd.)
33 city workers (17 men, 16 women).
Heart rate fell at every activity level, mean daily step count and distance covered rose, and self-reported sleep quality improved during kaempferol compared with placebo. Limits: a small crossover trial run by a company with a commercial interest in kaempferol, with device-recorded activity and self-report as the outcomes. No blood pressure, lipid, inflammatory or oxidative-stress endpoint was measured, and the results have not been independently replicated.