The proper time for antioxidant consumption

Abstract

Consuming food rich in antioxidants may help organisms to increase their antioxidant defences and avoid oxidative damage. Under the hypothesis that organisms actively consume food for its antioxidant properties, they would need to do so in view of other physiological requirements, such as energy requirements. Here, we observed that Gouldian finches (Erythrura gouldiae) consumed most seeds rich in antioxidants in the middle of the day, while their consumption of staple seeds more profitable in energy intake (and poor in antioxidants) was maximal in the morning and the evening. This consumption of seeds rich in antioxidants in the middle of the day may be explicable (1) because birds took advantage of a time window associated with relaxed energy requirements to ingest antioxidant resources, or (2) because birds consumed antioxidant resources as a response to the highest antioxidant requirements in the middle of the day. If the latter hypothesis holds true, having the possibility to ingest antioxidants should be most beneficial in terms of oxidative balance in the middle of the day. Even though feeding on seeds rich in antioxidants improved Gouldian finches' overall antioxidant capacity, we did not detect any diurnal effect of antioxidant intake on plasma oxidative markers (as measured by the d-ROM and the OXY-adsorbent tests). This indicates that the diurnal pattern of antioxidant intake that we observed was most likely constrained by the high consumption of staple food to replenish or build up body reserves in the morning and in the evening, and not primarily determined by elevated antioxidant requirements in the middle of the day. Consequently, animals appear to have the possibility to increase antioxidant defences by selecting food rich in antioxidants, only when energetic constraints are relaxed.