Oxidative stress in humans during work at moderate altitude

Increased oxidative stress has been associated with work at high altitude; however, it is not known whether oxidative stress is a significant problem at moderate altitudes. The oxidative stress indicators, breath pentane (BP) , 8-hydroxydeoxyguanosine (8-OHdG), oxygen radical absorption capacity (ORA C), 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), and lipid peroxides (L PO) were measured in breath, blood and urine samples of U.S. Marines engage d in moderate altitude (similar to 3000 m) cold weather field training. The test subjects were divided into a placebo and four antioxidant supplement groups (n = 15/group) and received the following supplements for 28 d: 1) v itamin E, 440 alpha-tocopherol equivalents (alpha-TE); 2) vitamin A, 2000 r etinol equivalents (RE) of beta-carotene; 3) vitamin C, 500 mg ascorbic aci d; 4) a mixture of 440 alpha-TE, 2000 RE of beta-carotene, 500 mg ascorbic acid, 100 mu g selenium and 30 mg zinc daily. Strenuous work (similar to 23 MJ/d) in cold weather at moderate altitude was accompanied by increases in several indicators of oxidative stress that were not effectively controlle d by conventional antioxidant supplements. The group receiving the antioxid ant mixture exhibited lower BP (P < 0.05) compared with those receiving sin gle antioxidant supplements; however, not all markers of oxidative stress r esponded like BP. Because these markers did not respond in the same manner, it is important to include markers from more than one source to assess the effect of supplemental dietary antioxidants.