Short-term vitamin E supplementation before marathon running: A placebo-controlled trial

Gastrointestinal complaints and occult bleeding have been commonly describe d in marathon runners. We hypothesized that these complaints may arise from intestinal ischemia caused by the shunting of blood away from the splanchn ic circulation during endurance racing followed by reperfusion injury. Stud ies in animal models have suggested prophylactic vitamin E supplementation may prevent this type of injury. We sought to determine if prerace vitamin E supplementation would prevent intestinal ischemia/reperfusion injury in h umans. Forty subjects who planned to complete the 1996 Houston-Tennaco Mara thon were randomized to receive vitamin E (1000 IU daily) or placebo (soya lecithin) for 2 wk before the race in a double-blinded trial. Inclusion cri teria included no use of non-steroidal anti-inflammatory drugs (NSAIDs) wit hin 24 d of the race or vitamin or mineral supplements containing vitamins C or E or selenium within 30 d of the race. Subjects were studied 2 wk befo re the race and immediately following the race. Blood was obtained for seru m vitamin E and: total lipid and salicylate concentrations. A solution of l actulose (5 g) and mannitol (2 g) was consumed and urine was collected for 6 h. ALiquots were assayed for lactulose and mannitol concentration. Stool samples were tested for occult blood and following the race subjects rated their nausea, abdominal pain, and cramping on a 1-5 scale. Twenty-six subje cts (24 male, 2 female) completed the marathon. Finish times ranged between 2 h 43 min and 5 h 28 min. All subjects had heme-negative stool prerace- a nd four developed heme-positive stool postrace, with no difference between vitamin E and placebo groups (Fisher's exact = 0.63). All had non-detectabl e salicylate concentrations pre- and postrace. Serum vitamin E concentratio n increased in both groups (1.56 +/- 0.27 to 3.46 +/- 1.25 mg/dL, P = 0.02 in the vitamin E group and 1.45 +/- 0.40 to 1.66 +/- 0.48 mg/dL in the plac ebo group, P = 0.02). However, the serum vitamin E: total lipid ratio incre ased significantly in the vitamin E-supplemented group (0.0022 +/- 0.0002 t o 0.0051 +/- 0.0015, P = 0.02), but not in the placebo group (P = 0.25). Ov erall, the urinary lactulose:mannitol ratio increased from 0.03 +/- 0.02 to 0.06 +/- 0.08 postrace (P = 0.06) without difference between vitamin E or placebo groups. Intestinal permeability increased significantly more in tho se who developed occult bleeding. More subjects in the placebo group develo ped abdominal cramping (Fisher's exact = 0.04) and abdominal pain (Fisher' s exact = 0.06), although there was no difference in severity between group s. There was no difference in the incidence of nausea and no diarrhea was r eported by any subject. Intestinal permeability tends to increase and occul t gastrointestinal bleeding occurs during endurance running, suggesting the occurrence of intestinal ischemia/reperfusion injury. Prerace supplementat ion with the antioxidant vitamin E had no effect on performance, intestinal injury, occult bleeding, or the severity of postrace gastrointestinal comp laints. Vitamin E supplementation was associated with a decreased incidence of these complaints but had no effect on their severity. Nutrition 1999;15 :278-283. (C) Elsevier Science Inc. 1999.