Human metabolism and elimination of the anthocyanin, cyanidin-3-glucoside: a (13)C-tracer study

Evidence suggests that the consumption of anthocyanin-rich foods beneficially affects cardiovascular health; however, the absorption, distribution, metabolism, and elimination (ADME) of anthocyanin-rich foods are relatively unknown.

We investigated the ADME of a (13)C5-labeled anthocyanin in humans.

Eight male participants consumed 500 mg isotopically labeled cyanidin-3-glucoside (6,8,10,3',5'-(13)C5-C3G). Biological samples were collected over 48 h, and (13)C and (13)C-labeled metabolite concentrations were measured by using isotope-ratio mass spectrometry and liquid chromatography-tandem mass spectrometry.

The mean ± SE percentage of (13)C recovered in urine, breath, and feces was 43.9 ± 25.9% (range: 15.1-99.3% across participants). The relative bioavailability was 12.38 ± 1.38% (5.37 ± 0.67% excreted in urine and 6.91 ± 1.59% in breath). Maximum rates of (13)C elimination were achieved 30 min after ingestion (32.53 ± 14.24 microg(13)C/h), whereas (13)C-labeled metabolites peaked (maximum serum concentration: 5.97 ± 2.14 micromol/L) at 10.25 ± 4.14 h. The half-life for (13)C-labeled metabolites ranged between 12.44 ± 4.22 and 51.62 ± 22.55 h. (13)C elimination was greatest between 0 and 1 h for urine (90.30 ± 15.28 microg/h), at 6 h for breath (132.87 ± 32.23 microg/h), and between 6 and 24 h for feces (557.28 ± 247.88 microg/h), whereas the highest concentrations of (13)C-labeled metabolites were identified in urine (10.77 ± 4.52 micromol/L) and fecal samples (43.16 ± 18.00 micromol/L) collected between 6 and 24 h. Metabolites were identified as degradation products, phenolic, hippuric, phenylacetic, and phenylpropenoic acids.

Anthocyanins are more bioavailable than previously perceived, and their metabolites are present in the circulation for ≤48 h after ingestion. This trial was registered at clinicaltrials.gov as NCT01106729.