During extreme exercise, athletes experience increased inflammation that is
similar to the acute phase response. Endurance athletes, distance runners in
particular, are also more susceptible to compromised iron stores. This study
evaluated inflammation, immune function and iron status in athletes completing a
50K ultramarathon. Twenty-two well-trained distance runners, 11 males and 11
females, were randomized in a double blind manner into--1) those who consumed
300 mg vitamin E and 1000 mg vitamin C (500 mg twice daily) or 2) placebos--for
six weeks before and one week following a 50K ultramarathon race. Blood
samples were obtained on 13 separate occasions throughout the study: before
supplementation, during supplementation, the day before the race, pre-race, mid-race,
immediately post-race, 2 hours following the race, and daily for six days
following the race. Plasma levels of ascorbic acid and ��-tocopherol were measured
by HPLC with electrochemical detection. Inflammatory cytokines, interleukin-6
(IL-6), tumor necrosis factor-�� (TNF-��), and interleukin-1�� (IL-1��) were measured
using standard clinical assays. Each subject recorded immune function in an
activity log and incidence of illness was tabulated as number of days ill. Ferritin
was measured by enzyme immunoassay. Hemoglobin, hematocrit, and total-iron
binding capacity (TIBC) and serum total iron were analyzed by standard
procedures.
Plasma concentrations of ascorbic acid and ��-tocopherol increased
significantly in supplemented subjects (p<0.0001). Although the ultramarathon
race elicited an inflammatory response, antioxidant supplementation did not alter
the responses of IL-6 and TNF-��, which both increased from pre-race to mid-race,
post- and post-2 h (Scheffe post-hoc analysis, p<0.0001) and returned to pre-race
concentrations by 1 day after the race. Male supplemented subjects had lower IL-1��
concentrations compared to females consuming the supplement or to males
consuming the placebo (ANCOVA, gender/time/treatment interaction; p<0.01) at
mid-race (p<0.05 females, p<0.005 males), post 1 and 2 days (all p<0.002).
Males had significantly higher ferritin levels than the female subjects (ANOVA, p<0.0001); supplementation resulted in lower ferritin concentrations at post-5 days
(p<0.02, ANCOVA treatment time interaction, p<0.005). Supplementation did
not reduce the days illness among those consuming antioxidants compared to those
consuming the placebos. Ferritin not only increases during inflammation, it also is a measure of iron
stores. Females had significantly lower levels of iron than the male subjects for
each of the iron parameters measured (hemoglobin and hematocrit both p<0.0001,
ferritin p<0.001, TIBC p<0.02) excluding serum total iron. The ferritin
concentrations measured in the women were indicative of depleted iron stores (<12
��g/l), and antioxidant supplementation increased hematocrit levels in the female
subjects (p<0.05). This investigation indicates that female distance runners need
to be aware of an increased susceptibility to iron depletion compared to their male
counterparts. Antioxidant supplementation improved hematocrit levels (p<0.05)
among female runners and may improve iron status among females with depleted
stores.
Although other investigations have suggested that antioxidant vitamins
decrease exercise induced inflammation, no profound benefit of supplementation
was found in this investigation though a response similar to the acute phase
response was elicited by the ultramarathon race. Improvements in IL-i and
ferritin in response to antioxidant supplementation may indicate that the
supplementation was beneficial, but more research is needed to draw definitive
conclusions. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/31532 |
| Date | 19 February 2003 |
| Creators | Hopkins, Dawn Marie Weseli |
| Contributors | Traber, Maret G. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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