Impact of short-term dietary modification on postprandial oxidative stress

<p>Abstract</p> <p>Background</p> <p>We have recently reported that short-term (21-day) dietary modification in accordance with a stringent vegan diet (i.e., a Daniel Fast) lowers blood lipids as well as biomarkers of oxidative stress. However, this work only involved measurements obtained in a fasted state. In the present study, we determined the postprandial response to a high-fat milkshake with regards to blood triglycerides (TAG), biomarkers of oxidative stress, and hemodynamic variables before and following a 21-day Daniel Fast.</p> <p>Methods</p> <p>Twenty-two subjects (10 men and 12 women; aged 35 ± 3 years) completed a 21-day Daniel Fast. To induce oxidative stress, a milkshake (fat = 0.8 g·kg^-1; carbohydrate = 1.0 g·kg^-1; protein = 0.25 g·kg^-1) was consumed by subjects on day one and day 22 in a rested and 12-hour fasted state. Before and at 2 and 4 h after consumption of the milkshake, heart rate (HR) and blood pressure were measured. Blood samples were also collected at these times and analyzed for TAG, malondialdehyde (MDA), hydrogen peroxide (H₂O₂), advanced oxidation protein products (AOPP), nitrate/nitrite (NOx), and Trolox Equivalent Antioxidant Capacity (TEAC).</p> <p>Results</p> <p>A time effect was noted for HR (<it>p </it>= 0.006), with values higher at 2 hr post intake of the milkshake as compared to pre intake (<it>p </it>< 0.05). Diastolic blood pressure was lower post fast as compared to pre fast (<it>p </it>= 0.02), and a trend for lower systolic blood pressure was noted (<it>p </it>= 0.07). Time effects were noted for TAG (<it>p </it>= 0.001), MDA (<it>p </it>< 0.0001), H₂O₂(<it>p </it>< 0.0001), AOPP (<it>p </it>< 0.0001), and TEAC (<it>p </it>< 0.0001); all concentrations were higher at 2 h and 4 h post intake compared to pre intake, except for TEAC, which was lower at these times (<it>p </it>< 0.05). A condition effect was noted for NOx (<it>p </it>= 0.02), which was higher post fast as compared to pre fast. No pre/post fast × time interactions were noted (<it>p </it>> 0.05), with the area under the curve from pre to post fast reduced only slightly for TAG (11%), MDA (11%), H₂O₂(8%), and AOPP (12%), with a 37% increase noted for NOx.</p> <p>Conclusion</p> <p>Partaking in a 21-day Daniel Fast does not result in a statistically significant reduction in postprandial oxidative stress. It is possible that a longer time course of adherence to the Daniel Fast eating plan may be needed to observe significant findings.</p