Issues To Be Resolved

Opinions differ on how and if these compounds enter the body. Glycosides could be cleaved at the intestinal brush border or by microbes, causing only aglycones to

TABLE 3.2

Potential Antimicrobial Applications for Vaccinium Products Condition Reference

Dental plaque Weiss et al. 1998

Stomach ulcer Burger et al., 2000

Diarrhea Folklore be absorbed. However, intact anthocyanins may be absorbed. Published studies of anthocyanin absorption have used pure compounds or extracts, not whole foods, from which extraction and absorption is presumably more difficult. V. myrtillus anthocyanins given to rats by either oral or intravenous routes were recovered from urine and bile (Lietti and Forni, 1976b). Ring fission products were isolated from the urine of rats fed either delphinidin or malvin (malvidin-3,5-diglucoside) (Griffiths and Smith, 1972).

Improved analytical techniques have enabled researchers to better identify phy-tochemicals in biological samples. Direct feeding of cyanidin-3-glucoside and cyani-din-3,5-diglucoside resulted in recovery of the compounds and their metabolites from both rat and human plasma (Miyazawa et al., 1999). In four healthy elderly women fed 12 g of elderberry extract, which contained 720 mg anthocyanins, peak plasma anthocyanins levels (97.4 nmol/L) were achieved 71 min after consumption (Cao et al., 2001). The estimated anthocyanin half-life was 132.6 min, and both glycosides and aglycones were identified in the women's urine. The fate of these compounds is not clear. Health effects persist long after the presumed clearance; perhaps these compounds adhere to capillaries and other tissues.

Even less is known about the absorption and metabolism of larger compounds such as the proanthocyanidins. Mice fed cranberry juice cocktail or isolated proanthocyanidins (50 or 500 mg/300mL water) excreted urine with E. coli anti-adherence activity in vitro (Howell et al., 2001). The researchers concluded that these compounds must be absorbed in order to have reached the urinary tract.

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