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Quercetin: Difference between revisions
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In red onions, higher concentrations of quercetin occur in the outermost rings and in the part closest to the root, the latter being the part of the plant with the highest concentration. | In red onions, higher concentrations of quercetin occur in the outermost rings and in the part closest to the root, the latter being the part of the plant with the highest concentration.{{#pmid:17997520|pmid17997520}} One study found that [[wikipedia:Organic_farming|organically grown]] [[wikipedia:Tomato|tomatoes]] had 79% more quercetin than non-organically grown fruit.{{#pmid:17590007|pmid17590007}} Quercetin is present in various kinds of [[wikipedia:Honey|honey]] from different plant sources. {{#pmid:21229237|pmid21229237}} | ||
=== Background Intake === | === Background Intake === | ||
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Quercetin's bioavailability is complex, influenced largely by its poor water solubility, which results in low absorption and extensive metabolism, hence reducing its availability to exert biological effects. It is predominantly found in foods as glycosides, bound to sugar molecules, which impacts its absorption and subsequent bioavailability. | Quercetin's bioavailability is complex, influenced largely by its poor water solubility, which results in low absorption and extensive metabolism, hence reducing its availability to exert biological effects. It is predominantly found in foods as glycosides, bound to sugar molecules, which impacts its absorption and subsequent bioavailability. | ||
In a clinical study with a different formulation of quercetin (Quercetin Phytosome) a ~20 fold relative bioavailability compared to standard quercetin was measured. Given that Quercetin Phytosome contains ~40% quercetin, one can assume that the total bioavailability of standard quercetin is less than 2%. | In a clinical study with a different formulation of quercetin (Quercetin Phytosome) a ~20 fold relative bioavailability compared to standard quercetin was measured. Given that Quercetin Phytosome contains ~40% quercetin, one can assume that the total bioavailability of standard quercetin is less than 2%. {{#pmid:30328058|pmid30328058}} | ||
Quercetin, when consumed, undergoes an absorption process primarily in the small intestine. The glycosidic form of quercetin needs to be hydrolyzed by β-glucosidase to its aglycone form before absorption. Once hydrolyzed, it is absorbed through enterocytes via passive diffusion or through active transport mechanisms. The overall absorption of quercetin is estimated to be relatively low, varying between individuals and dependent on dietary matrix and presence of other flavonoids. | Quercetin, when consumed, undergoes an absorption process primarily in the small intestine. The glycosidic form of quercetin needs to be hydrolyzed by β-glucosidase to its aglycone form before absorption. Once hydrolyzed, it is absorbed through enterocytes via passive diffusion or through active transport mechanisms. The overall absorption of quercetin is estimated to be relatively low, varying between individuals and dependent on dietary matrix and presence of other flavonoids. | ||
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Once absorbed, quercetin undergoes extensive first-pass metabolism in the liver and intestines, where it is converted into various metabolites through glucuronidation, sulfation, and methylation. The extensive metabolism significantly reduces the concentrations of free quercetin in the plasma, limiting its bioavailability. The metabolites, however, may retain some biological activity and contribute to the overall effects of quercetin in the body. | Once absorbed, quercetin undergoes extensive first-pass metabolism in the liver and intestines, where it is converted into various metabolites through glucuronidation, sulfation, and methylation. The extensive metabolism significantly reduces the concentrations of free quercetin in the plasma, limiting its bioavailability. The metabolites, however, may retain some biological activity and contribute to the overall effects of quercetin in the body. | ||
It is suggested that individuals with poor vitamin C status might absorb quercetin better than those with adequate vitamin C levels. This could indicate a compensatory mechanism where the body might try to absorb more of certain beneficial compounds, like quercetin, in the absence of others, like vitamin C. However, the exact mechanisms or reasons behind this would need to be further explored. | It is suggested that individuals with poor vitamin C status might absorb quercetin better than those with adequate vitamin C levels. This could indicate a compensatory mechanism where the body might try to absorb more of certain beneficial compounds, like quercetin, in the absence of others, like vitamin C. However, the exact mechanisms or reasons behind this would need to be further explored. {{#pmid:25280405|pmid25280405}} | ||
===Formulation of Enhanced Bioavailability=== | ===Formulation of Enhanced Bioavailability=== | ||
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===Quercetin Phytosome=== | ===Quercetin Phytosome=== | ||
[[File:Pharmacokinetic profile of quercetin.png|thumb|[[Pharmacokinetic]] profile of standard quercetin and quercetin phytosome in the clinical study. The plasma concentrations of quercetin obtained after single oral administration of the unformulated quercetin at 500 mg/tablet and after single oral administration of its corresponding lecithin formulation, Quercetin Phytosome, at a dose of either 500 or 250 mg are shown. | [[File:Pharmacokinetic profile of quercetin.png|thumb|[[Pharmacokinetic]] profile of standard quercetin and quercetin phytosome in the clinical study. The plasma concentrations of quercetin obtained after single oral administration of the unformulated quercetin at 500 mg/tablet and after single oral administration of its corresponding lecithin formulation, Quercetin Phytosome, at a dose of either 500 or 250 mg are shown. {{#pmid:30328058|pmid30328058}}]] | ||
Quercetin Phytosome is a formulation where quercetin is bound to phospholipids, typically derived from sunflower or soy lecithin, to enhance its bioavailability and absorption. The relevant clinical study used Quercetin Phytosome (QUERCEFIT™) consisting of quercetin and sunflower lecithin in a 1:1 weight ratio along with about a fifth part of food-grade excipients that are added to improve the physical state of the product and to standardize it to an HPLC-measured total quercetin content of about 40%. In the clinical study, a ~20-fold increase in bioavailability was measured compared to standard quercetin with equal doses. | Quercetin Phytosome is a formulation where quercetin is bound to phospholipids, typically derived from sunflower or soy lecithin, to enhance its bioavailability and absorption. The relevant clinical study used Quercetin Phytosome (QUERCEFIT™) consisting of quercetin and sunflower lecithin in a 1:1 weight ratio along with about a fifth part of food-grade excipients that are added to improve the physical state of the product and to standardize it to an HPLC-measured total quercetin content of about 40%. In the clinical study, a ~20-fold increase in bioavailability was measured compared to standard quercetin with equal doses. {{#pmid:30328058|pmid30328058}} | ||
{| class="wikitable" | {| class="wikitable" | ||
|+[[Pharmacokinetic]] parameters (noncompartmental model) | |+[[Pharmacokinetic]] parameters (noncompartmental model) {{#pmid:30328058|pmid30328058}} | ||
! | ! | ||
!Quercetin 500 mg | !Quercetin 500 mg | ||