Dietary Quercetin and Kaempferol: Bioavailability and Potential Cardiovascular-Related Bioactivity in Humans

Abstract

Fruit and vegetable intake has been associated with a reduced risk of cardiovascular disease. Quercetin and kaempferol are among the most ubiquitous polyphenols in fruit and vegetables. Most of the quercetin and kaempferol in plants is attached to sugar moieties rather than in the free form. The types and attachments of sugars impact bioavailability, and thus bioactivity. This article aims to review the current literature on the bioavailability of quercetin and kaempferol from food sources and evaluate the potential cardiovascular effects in humans. Foods with the highest concentrations of quercetin and kaempferol in plants are not necessarily the most bioavailable sources. Glucoside conjugates which are found in onions appear to have the highest bioavailability in humans. The absorbed quercetin and kaempferol are rapidly metabolized in the liver and circulate as methyl, glucuronide, and sulfate metabolites. These metabolites can be measured in the blood and urine to assess bioactivity in human trials. The optimal effective dose of quercetin reported to have beneficial effect of lowering blood pressure and inflammation is 500 mg of the aglycone form. Few clinical studies have examined the potential cardiovascular effects of high intakes of quercetin- and kaempferol-rich plants. However, it is possible that a lower dosage from plant sources could be effective due to of its higher bioavailability compared to the aglycone form. Studies are needed to evaluate the potential cardiovascular benefits of plants rich in quercetin and kaempferol glycoside conjugates.

Phenolic Compounds Exerting Lipid-Regulatory, Anti-Inflammatory and Epigenetic Effects as Complementary Treatments in Cardiovascular Diseases

“…Another study conducted on stable angina patients receiving 120 mg/day quercetin for two months showed a statistically significant reduction of IL-1β levels and attenuated TNF-α and IL-10 levels in treated patients' plasma, and decreased transcriptional activity of NF-kB in PBMC [177]. Several studies were done to evaluate the safety of quercetin administration to humans [178]. The conclusion of these studies was that up to 5000 mg/day quercetin supplementation for four weeks does not cause adverse effects.…”

Thrombose-Preventive Influence of Quercetin in Rats on the Hyper-Coagulation Diet

“…Îòaeå, àíàë³ç îòðèìàíèõ ðåçóëüòàò³â ó ùóð³â ²² ãðóïè âêàçóº íà óïîâ³ëüíåííÿ çãîðòàííÿ êðîâ³, çîêðåìà çà ðàõóíîê óòâîðåííÿ çãóñòêó, çðîñòàííÿ àíòè-òðîìá³íîâî¿ àêòèâíîñò³ êðîâ³ òà â³äíîâëåííÿ àêòèâ-íîñò³ ïðîòå¿íó Ñ (â³äïîâ³äíî íà 39,5% òà 19,3%) òà ïîñèëåííÿ ô³áðèíîë³çó (íà 25%). Çðîñòàííÿ êîíöåí-òðàö³¿ ÐÔÌÊ òà çíèaeåííÿ ð³âíþ ô³áðèíîãåíó â³äîáðàaeຠïðîòèçàïàëüíèé åôåêò êâåðöåòèíó ïðè íèçüêîìó ðèçèêó êðîâîòå÷ çà óìîâ îäíî÷àñíîãî çàñòîñóâàííÿ ³ç àíòèêîàãóëÿíòàìè [6,9,12].…”

“…Îäíèì ç 䳺òîëîã³÷íèõ ï³äõîä³â ó öüîìó çâ'ÿçêó º çá³ëüøåííÿ ó ðàö³îí³ ê³ëüêîñò³ ôðóêò³â òà îâî÷³â. Êâåðöåòèí -îäèí ç íàéá³ëüø ïîøèðåíèõ ïîë³ôå-íîë³â â îâî÷àõ òà ôðóêòàõ [6]. Ìåõàí³çì éîãî 䳿 ïîâ'ÿçàíèé ³ç çäàòí³ñòþ ðåãóëþâàòè îêèñíî-â³äíîâëþâàëüíèé ñòàí òà ð³âåíü îêñèäó àçîòà, îòaeå, ïðè äîñòàòíüîìó âaeèâàíí³ ïîë³ôåíîë³â ³ç ïðîäóêòàìè õàð÷óâàííÿ ìîaeëèâå ïîïåðåäaeåííÿ ðîçâèòêó êàðä³-îëîã³÷íèõ çàõâîðþâàíü ÷åðåç êîðåêö³þ åíäîòåë³àëü-…”

Dietary Bioactive Compounds and Human Health and Disease

“…This is a very interesting work that shows that, regardless of the daizein consumed with the diet, the amount of bioactive compounds generated from it has a high inter-individual variation, which may be conditioned by the human intestinal microbiota. Finally, Dabeek et al extensively review the existing literature on the bioavailability and bioactivity of dietary quercetin and kaempferol, two of the most consumed polyphenols [4,5], assessing their possible impact on cardiovascular health in humans [4]. Together with phenolics, sulphur-containing compounds have also accumulated a large body of scientific evidence of their protective role against pathologies related to oxidative stress, inflammation, and the immune system, many of which are summarized by Rodrigues et al [6].At the metabolic level, in animal models, Lim et al find a decrease in insulin resistance, triglycerides and LDL and total cholesterol, white fat tissue weights, and leptin levels after supplementation with cyanidine-3-O-galactoside-enriched Aronia melanocarpa extract [7].…”

“…Mas-Capdevila et al raise interesting hypotheses about how the resistance of peptides to gastric digestion may modulate their antihypertensive effect [11], adding a novel approach to previous work about this topic [12,13]. At this point, factors such as bioavailability, synergistic effects between these compounds, or their interaction with other food components, are essential to deepening the knowledge of bioactive compounds on health [4]. In this regard, Mc Veay et al evaluate the synergic effect of lauric acid and L-tryptophan on fasting glucose, insulin, and glucagon in healthy men [14].…”