Absorption and Bioavailability of Anthocyanins
Clinical trials with blackcurrants and other berries
Anthocyanins absorbed into the blood
Anthocyanins are understood to have many beneficial health properties. Therefore, the bioavailability of anthocyanins, including their absorption and excretion is viewed as an important issue. Several human studies have been completed to show the bioavailability of anthocyanins for use by the human body.
A.) In this study participants were given blackcurrants as either an extract powder, puree or drink. Blood plasma and urine sample were collected for analysis. Good evidence of anthocyanin absorption and bioavailability was gained from all blackcurrant formats.
Figure 1. Time-dependent concentration (nM) of anthocyanin cyanidin-3-rutinoside detected in plasma after ingesting blackcurrant fruit puree.
Anthocyanin species are calculated based on standards of malvidin-3-galactoside and are uncorrected for recovery. Results are the mean of 5 plasma samples. Error bars represent SD's and reflect the biological variance.
B.) In this study, using both rats and humans, four components of black currant anthocyanins, were found to be directly absorbed and distributed to the blood and excreted into urine. In a rat study, following oral administration of purified anthocyanins, the anthocyanins were detected in the blood.
In a human study, when a mixture of blackcurrant anthocyanins were consumed by eight volunteers, the four components of blackcurrant anthocyanins were detected in the blood and urine. The anthocyanin compounds detected in urine in the period 0-8 hours after ingestion was only 0.11 % of the dose ingested. These results indicate that 3-rutinoside anthocyanins were directly absorbed and distributed to the blood.
Abundance of Anthocyanin metabolites
The results of this clinical study showed that the products of metabolism (metabolites) of anthocyanins were abundant in human urine even after five days with no dietary intake of anthocyanins.
Volunteers consumed 250ml of blueberry juice after a five day period without consumption of anthocyanins. Parent anthocyanins (those present in the juice) were 4% of the urinary anthocyanins and 96% were anthocyanin metabolites, for the following 24 hours .i.e. in all the urine samples there was far greater concentration of anthocyanin metabolites than the parent anthocyanins.
While the concentration of the parent anthocyanins was significantly increased by consuming the juice, the intake of the blueberry juice had a relatively small effect on the anthocyanin metabolite concentration in the urine, as these metabolites were still present from sources other than the blueberry juice, consumed 5 days prior.The results of this study suggest that exposure to anthocyanin-based components is substantially greater than suggested by earlier research.
Bioavailability of the cyanidin -3- glucoside anthocyanin, and its metabolites.
This study used isotopically labelled cyanidin-3-glucoside using carbon 13 (13C) to trace the metabolism of C3G anthocyanins (one of the four major anthocyanins in blackcurrants) and their metabolites in the human body.
Overall the study indicated a much higher relative bioavailability and a greater diversity of metabolites for anthocyanins than has been previously reported. These metabolites are present in circulation for more than 48 hours after ingestion. Given that only 43.9% of the dose was recovered this may have implications for even greater bioavailability, if the study had taken samples for detection over a longer time period.
1. A joint project conducted between Plant & Food Research New Zealand Limited and The Institute of Food, Nutrition & Human Health, Massey University, New Zealand, 2008.
2. Hitoshi Matsumoto, Hiromi Inaba, Mitsuo Kishi, Shigeru Tominaga, Masao Hirayama, and Takanori Tsuda. Orally Administered Delphinidin 3-Rutinoside and Cyanidin 3-Rutinoside Are Directly Absorbed in Rats and Humans and appear in the Blood as the Intact Forms. JOURNAL OF AGRICULTURAL FOOD CHEMISTRY, 2001, 49, 1546-1551.
3. Wilhelmina Kalt, Yan Liu, Jane E. McDonald, Melinda R. Vinqvist-Tymchuk, and Sherry A. E. Fillmore. Anthocyanin Metabolites Are Abundant and Persistent in Human Urine. JOURNAL AGRICULTURAL AND FOOD CHEMISTRY, 2014, web only: Just accepted manuscript
4. Human metabolism and elimination of the anthocyanin, cyanadin-3-glucoside: a 13C tracer study. Czank, C., American Journal of Clinical Nutrition, 2013; 97:995-1003.