Cytokine responses at high altitude: effects of exercise and antioxidants at 4300 m.
OBJECTIVE
This study tested the hypothesis that antioxidant supplementation would attenuate plasma cytokine (IL-6, tumor necrosis factor (TNF)-alpha), and C-reactive protein (CRP) concentrations at rest and in response to exercise at 4300-m elevation.


METHODS
A total of 17 recreationally trained men were matched and assigned to an antioxidant (N = 9) or placebo (N = 8) group in a double-blinded fashion. At sea level (SL), energy expenditure was controlled and subjects were weight stable. Then, 3 wk before and throughout high altitude (HA), an antioxidant supplement (10,000 IU beta-carotene, 200 IU alpha-tocopherol acetate, 250 mg ascorbic acid, 50 microg selenium, 15 mg zinc) or placebo was given twice daily. At HA, energy expenditure increased approximately 750 kcal.d(-1) and energy intake decreased approximately 550 kcal.d, resulting in a caloric deficit of approximately 1200-1500 kcal.d(-1). At SL and HA day 1 (HA1) and day HA13, subjects exercised at 55% of VO2peak until they expended approximately 1500 kcal. Blood samples were taken at rest, end of exercise, and 2, 4, and 20 h after exercise.


RESULTS
No differences were seen between groups in plasma IL-6, CRP, or TNF-alpha at rest or in response to exercise. For both groups, plasma IL-6 concentration was significantly higher at the end of exercise, 2, 4, and 20 h after exercise at HA1 compared with SL and HA13. Plasma CRP concentration was significantly elevated 20 h postexercise for both groups on HA1 compared to SL and HA13. TNF-alpha did not differ at rest or in response to exercise.


CONCLUSIONS
Plasma IL-6 and CRP concentrations were elevated following exercise at high altitude on day 1, and antioxidant supplementation did not attenuate the rise in plasma IL-6 and CRP concentrations associated with hypoxia, exercise, and caloric deficit.
Hagobian
Todd A
TA
Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304-1290, USA.
Jacobs
Kevin A
KA
Subudhi
Andrew W
AW
Fattor
Jill A
JA
Rock
Paul B
PB
Muza
Stephen R
SR
Fulco
Charles S
CS
Braun
Barry
B
Grediagin
Ann
A
Mazzeo
Robert S
RS
Cymerman
Allen
A
Friedlander
Anne L
AL
D000328:Adult; D000531:Altitude; D000704:Analysis of Variance; D000975:Antioxidants / Q000008:administration & dosage*; D001823:Body Composition; D002097:C-Reactive Protein / Q000378:metabolism*; D002395:Catecholamines / Q000097:blood; D004311:Double-Blind Method; D002149:Energy Intake; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D000975:Antioxidants; D002395:Catecholamines; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein