This review considers the bioavailability of health-protective anthocyanin pigments from foods, in light of the multiple molecular structures and complicated traffic patterns taken by anthocyanins both as flavonoid metabolites and as phenolic acid metabolites within the body. Anthocyanins have generally been considered to have notoriously poor bioavailability, based on the very low levels typically detected in routine human blood draws after ingestion. Although some investigations have assessed anthocyanin bioavailability solely based on the measurement of parent anthocyanins or phenolic acid breakdown products, more recent research has increasingly revealed the presence, qualitative diversity, relatively high concentrations, and tenacity of molecular intermediates of anthocyanins that retain the unique flavonoid C6-C3-C6 backbone structure. We argue that the persistence of anthocyanin metabolites suggests enterohepatic recycling, leading to prolonged residence time, and supports the notion that anthocyanins are far more bioavailable than previously suggested.
There is increasing evidence that the postprandial state is an important contributing factor to chronic disease. The role of fruit phenolic compounds to protect health and lower disease risk through their actions in mitigating fed-state metabolic and oxidative stressors is of interest and the topic of the present paper. Two main questions are posed: first, what is the role of plant foods, specifically fruits rich in complex and simple phenolic compounds in postprandial metabolic management; and second, does the evidence support consuming these fruits with meals as a practical strategy to preserve health and lower risk for disease? This review provides an overview of the postprandial literature, specifically on the effect of fruits and their inherent phenolic compounds in human subjects on postprandial lipaemia, glycaemia/insulinaemia and associated events, such as oxidative stress and inflammation. Among the identified well-controlled human trials using a postprandial paradigm, >50 % of the trials used wine or wine components and the remaining used various berries. Notwithstanding the need for more research, the collected data suggest that consuming phenolic-rich fruits increases the antioxidant capacity of the blood, and when they are consumed with high fat and carbohydrate ‘pro-oxidant and pro-inflammatory’ meals, they may counterbalance their negative effects. Given the content and availability of fat and carbohydrate in the Western diet, regular consumption of phenolic-rich foods, particularly in conjunction with meals, appears to be a prudent strategy to maintain oxidative balance and health.
1 February 2010 in Journal of the American College of Nutrition
Background: Elevated levels of lipids, such as total cholesterol (TC), low-density lipoprotein cholesterol (LDL), and triglycerides (TG), are widely recognized as risk factors for cardiovascular disease (CVD). Oxidized LDL (OxLDL) is an emerging risk factor considered relevant in oxidative stress and endothelial dysfunction, which is implicated in the progression of CVD. Consumption of a diet rich in polyphenols may be cardioprotective through its impact on oxidative stress and protecting LDL from oxidation. Objectives: This study was designed to test the ability of strawberry phenolic compounds to mitigate the postprandial effects of a high-fat meal on OxLDL as well as investigate the effects of phenolic compounds on lipid metabolism. Methods: Twenty-four hyperlipidemic men and women (14 women, 10 men; mean age 50.9 ± SD 15 years) were recruited to participate in this randomized, single-blind, placebo-controlled, 12-wk crossover trial. After a 10-day run-in period, subjects consumed either an active strawberry beverage (Str; containing 10 g freeze-dried fruit) or a placebo (Pbo) beverage matched in energy and macronutrient composition for 6 weeks. Twice before randomization and once at the 6-week crossover point, subjects received either Str or Pbo with a high-fat challenge meal (HFM). TC, LDL, high-density lipoprotein cholesterol, TG, and OxLDL were measured at defined intervals for 6 h before and after HFM challenge. Fasting concentrations of blood variables at 0, 6, and 12 weeks were compared to assess chronic intake of Str or Pbo. Results: After the HFM during the run-in period, TG and OxLDL were lower after Str than Pbo (p = 0.005, p = 0.01, and p = 0.0008, respectively). HFM responses after 6 weeks of Str versus Pbo resulted in decreased lipid levels and a sex by treatment interaction for OxLDL (p = < 0.0001, and p = 0.0002). Conclusion: The present results support a role for strawberry in mitigating fed-state oxidative stressors that may contribute to atherogenesis.