Evaluation of the antioxidant capacity of a milk protein matrix in vitro and in vivo in women aged 50-70 years.

Bovine milk proteins have emerged as a novel, dairy-based source of dietary antioxidants and a component of a nutritional strategy to maintain muscle mass during ageing. The aim of this study was to characterise the in vitro antioxidant capacity (AOC) of a milk-based protein matrix (MPM) before and after simulated gastrointestinal digestion (SGID) and determine whether plasma AOC was similarly modified in vivo following acute ingestion of the MPM in healthy 50-70 years old women. To achieve this, the AOC of the MPM was measured by the oxygen radical absorbance capacity (ORAC) assay prior to and following SGID. In parallel, plasma obtained from women prior to and for 3 h following ingestion of the MPM was analysed ex vivo for change in AOC to evaluate the translation in vivo. SGID of the MPM increased AOC by ∼ 35% (27,365 ± 2152 versus 42,592 ± 2299 µmol TE/100 g dw; p < 0.05). Sampled ex vivo, ingestion of the MPM increased fasting plasma AOC by ∼ 23% (10,952 ± 751 to 13,519 ± 800 µmol TE/L; p < 0.05). These data provide preliminary evidence of an association between the change in the ORAC-based measurement of AOC of an MPM subjected to simulated digest in vitro and the change in plasma AOC following ingestion of the MPM sampled ex vivo from healthy elderly women.