Does timing of phytonutrient intake influence the suppression of postprandial oxidative stress? A systematic literature review

Phytonutrients show potential to suppress the postprandial oxidative stress that occurs following typical Western-style meals. Due to the transience of phytonutrients in circulation, we hypothesise that timing of phytonutrient consumption, relative to the meal, may be important for oxidative stress suppression. Reviewed studies met the criteria: (1) healthy human adults; (2) phytonutrient consumed in solid form within 24 h of a challenge meal; (3) postprandial measurements of oxidative stress or antioxidants in blood; and (4) controlled study design. Compared with control, significant decreases in oxidative stress markers (lipid hydroperoxides, malondialdehyde, sNox2-dp, 8-iso-PGF2α, p47phox and Keap-1) were observed where the phytonutrient was consumed at the same time as the challenge meal (n = 4). Meanwhile, no effect on oxidative stress markers was observed where phytonutrients were consumed at the same time (n = 1), one hour before (n = 1), or the day before (>12 h) (n = 2) the challenge meal. While only a limited number of studies were included, oxidative stress suppression appeared effective when the phytonutrient was consumed at the same time as the challenge meal. Further research is required to confirm these observations and systematically optimise the effect of phytonutrient timing.