Purified black tea theaflavins and theaflavins/catechin supplements did not affect serum lipids in healthy individuals with mildly to moderately elevated cholesterol concentrations.

BACKGROUND: Ingestion of tea flavonoids found in both green and black tea is linked to cardiovascular health benefits such as lowering serum lipids. Evidence for a cholesterol-lowering benefit of green or black tea consumption from human intervention studies is, however, conflicting and active components responsible for the effect have not yet been clearly identified. AIM OF THE STUDY: In a randomized, double-blind, placebo-controlled, parallel design study the effects of ingesting a purified black tea theaflavins (TFs) powder alone or in combination with catechin (TFs/catechins) on lowering serum total (TC) and LDL-cholesterol (LDL-c) were assessed. METHODS: In total, 102 mildly to moderately hypercholesterolemic (TC and LDL-c: 5.70 +/- 0.74 and 3.97 +/- 0.61 mmol/L, respectively) subjects (67 men and 35 women) were randomly assigned to consume once daily one capsule of one of the 3 treatments: TFs (providing 77.5 mg), TFs/catechins (providing 75.0 mg TFs plus 150.0 mg catechins and 195.0 mg of other polyphenols), or placebo (cellulose). RESULTS: Serum TC and LDL-c concentrations did not differ significantly among the 3 treatments as assessed at 4, 8, and 11 weeks using analysis of covariance (p = 0.1187 and p = 0.1063, respectively). Although changes over time from baseline to week 11 were significant for TC and LDL-c (p = 0.0311 and p = 0.0269, respectively), this decrease over time was seen in the TFs and placebo groups. CONCLUSION: In this human intervention study, no statistically significant LDL-c lowering effect was seen with either TFs alone or the TFs/catechins combination as compared to placebo. Based on these findings it cannot be concluded that tea flavonoids such as theaflavins and catechins are responsible for a putative cholesterol-lowering effect of black tea, at least not with the daily dose applied in the present study.

Angiotensin converting enzyme inhibitory peptides from a lactotripeptide-enriched milk beverage are absorbed intact into the circulation.

Food products containing angiotensin converting enzyme (ACE) inhibitory peptides reportedly play a role in treatment of mild hypertension. The aim of this placebo-controlled crossover study was to assess the bioavailability of Ile-Pro-Pro and 7 other ACE-inhibiting peptides present in a lactotripeptide (LTP)-enriched yogurt beverage and whether meal intake affects Ile-Pro-Pro bioavailability. Six male and female subjects randomly consumed an LTP-enriched yogurt beverage or a placebo in the fasted state and an LTP-enriched yogurt beverage in the fed or fasted state. The area under the curve (AUC) of Ile-Pro-Pro after the LTP treatment in the fasted state was 2.1-fold of that after the placebo treatment (P < 0.001). The maximum peptide plasma concentration (C(max)) value was greater after consumption of the LTP-enriched beverage (897 +/- 157 pmol/L) than after the placebo treatment (555 +/- 0.09 pmol/L; P < 0.001) with a greater time after ingestion when reaching C(max) (T(max)) in the placebo treatment. Plasma concentrations of the peptides Leu-Trp, Phe-Tyr, Ile-Tyr, and Leu-Pro-Pro increased compared with baseline (P < 0.05) in the LTP-enriched and placebo treatment when consumed in the fasted state. However, DeltaC(max) values differed significantly between the placebo and LTP-enriched treatment only for Leu-Pro-Pro. Meal intake affected Ile-Pro-Pro concentrations. When the beverage was consumed after a meal, the AUC of Ile-Pro-Pro was 1.3-fold (P < 0.05) of the AUC derived from premeal intake. This was due to an increase in the plasma elimination half-life (P < 0.05); C(max) and T(max) were not affected by meal intake. In summary, this is the first demonstration, to our knowledge, that the tripeptide Ile-Pro-Pro selectively escapes from intestinal degradation and reaches the circulation undegraded.