Human bioavailability of curcumin and cocoa polyphenols by microencapsulated ingredients

INTRODUCTION: Polyphenols have been receiving increasing interest from food industry due to their several documented biological properties. However instability under food processing and storage conditions, as well as unpleasant taste and the low bioavailability of most polyphenols may limit their use as food ingredients. Encapsulation technology may overcome these physico-chemical and nutritional drawbacks. OBJECTIVES: To evaluate the effect of microencapsulation on human bioavailability of curcumin and cocoa polyphenols from new enriched foods. METHODS: A new type of bread containing 1% of curcumin in free form (FCB) or encapsulated with cellulose derivatives (ECB), and a nut cream enriched with 1.5% of a polyphenol-rich cocoa extract, in free form (FCC) or encapsulated with high amylose corn starch (ECC), were formulated and produced in laboratory scale. Twelve healthy subjects were enrolled and randomized between two protocols, with a cross-over design. After a 3-day polyphenol-free diet, fasted subjects consumed the experimental foods. Blood, urine and feces at baseline and at different time points over 24 h were collected. Parental compounds and metabolites of curcumin and cocoa polyphenols were quantified in biological samples by HPLC/MS/MS. RESULTS: ECB consumption determined a four-fold increase of curcumin bioavailability vs FCB (serum AUC0-24 of curcuminoids being 2.24 nmol/L•h vs 0.46 nmol/L•h, respectively, p<0.05) without variation of urinary excretion (urine AUC0-24 of curcuminoids being 0.09 nmol/L•h vs 0.10 nmol/L•h, p=n.s.). On the contrary ECC consumption determined a lower absorption of cocoa polyphenols vs FCC (serum AUC0-24 of cocoa polyphenols being 0.89 µmol/L•h and 15.44 µmol/L•h, respectively, p<0.05), and an increased fecal excretion (114.3%, p