Anthocyanins in Strawberry Polyphenolic Extract Enhance the Beneficial Effects of Diets with Fructooligosaccharides in the Rat Cecal Environment

The administration of fructooligosaccharides (FOS) beneficially modulates gastrointestinal functions and may enhance the metabolism of polyphenols. However, different polyphenolic components in the diet may have different influences on the activities of the digestive enzymes and microbiota in the gastrointestinal tract. Therefore, a 4-week study of forty-eight male Wistar rats was conducted to investigate the physiological response of the rat cecal environment to diets without and with FOS that contained two different strawberry polyphenolic extracts, specifically EP (polyphenolic profile 60, 35, 5, and 0% ellagitannins, proanthocyanidins, flavonols, anthocyanins, respectively) and EPA (polyphenolic profile: 50, 35, 6, and 9%, respectively). When combined with FOS, both extracts beneficially enhanced the acidification of the cecal digesta (P≤0.05 vs the groups without extracts), but the dietary combination of EPA and FOS elicited the greatest reduction in putrefactive short-chain fatty acid production and the lowest fecal β-glucuronidase activity in the cecum (P≤0.05 vs group EP). Moreover, the addition of dietary FOS elevated the metabolism of the examined strawberry extracts in the cecum and thereby increased the concentrations of the metabolites in the cecal digesta and urine (P≤0.05 vs the group with cellulose). Overall, both strawberry extracts modulated the effects of FOS in the gastrointestinal tract; however, the combination with EPA extract that contained anthocyanins exhibited greater beneficial effects in the lower gut environment than the EP extract.