The impact of chronic carbohydrate manipulation on mucosal immunity in elite endurance athletes

Sep 13, 2018Journal of sports sciences

How long-term changes in carbohydrate intake affect gut immune defense in top endurance athletes

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Abstract

Resting salivary immunoglobulin A (s-IgA) secretion rate increased approximately two-fold post-intervention across all dietary approaches.

Elite race walkers (n = 26) followed either a high carbohydrate diet, a periodized carbohydrate approach, or a low carbohydrate/high fat diet for three weeks.
Resting s-IgA levels significantly increased in all dietary groups, but no substantial differences were found between the diets.
Post-exercise, all dietary treatments showed substantial increases in s-IgA concentration ranging from 20% to 130%.
There were also 43-64% reductions in saliva flow rate after exercise across all groups, with trivial differences between dietary approaches.
High volume training may diminish the impact of carbohydrate availability on mucosal immunity in elite athletes.

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Carbohydrate (CHO) availability could alter mucosal immune responses to exercise. This study compared the effect of three dietary approaches to CHO availability on resting and post-exercise s-IgA levels. Elite race walkers (n = 26) adhered to a high CHO diet (HCHO), periodised CHO availability (PCHO) or a low CHO/high fat diet (LCHF) for 3 weeks while completing an intensified training program. HCHO and PCHO groups consumed 8.0-8.5 g.kgCHO daily, with timing of ingestion manipulated to alter CHO availability around key training sessions. The LCHF diet comprised 80% fat and restricted CHO to < 50 g.day. A race walk test protocol (19 km females, 25 km males) was completed at baseline, after adaptation, and following CHO restoration. On each occasion, saliva samples were obtained pre- and post-exercise to quantify s-IgA levels. Resting s-IgA secretion rate substantially increased ~ two-fold post-intervention in all groups (HCHO: 2.2 ± 2.2, PCHO: 2.8 ± 3.2, LCHF: 1.6 ± 1.6; fold-change± 95% confidence limits), however, no substantial differences between dietary treatments were evident. Post-exercise, substantial 20-130% increases in s-IgA concentration and 43-64% reductions in flow rate occurred in all dietary treatments, with trivial differences evident between groups. It appears that high volume training overrides any effect of manipulating CHO availability on mucosal immunity in elite athletes. -1 -1

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