Almond intake alters the acute plasma dihydroxy-octadecenoic acid (DiHOME) response to eccentric exercise

Abstract

Introduction: This investigation determined if 4-weeks ingestion of nutrient-dense almonds mitigated post-exercise inflammation and muscle soreness and damage.

Methods: An acute 90-min of eccentric exercise (90-EE) was used to induce muscle damage in 64 non-obese adults not engaging in regular resistance training (ages 30-65 years, BMI < 30 kg/m²). Using a parallel group design, participants were randomized to almond (AL) (57 g/d) or cereal bar (CB) (calorie matched) treatment groups for a 4-week period prior to the 90-EE (17 exercises). Blood and 24-h urine samples were collected before and after supplementation, with additional blood samples collected immediately post-90-EE, and then daily during 4 additional days of recovery. Changes in plasma oxylipins, urinary gut-derived phenolics, plasma cytokines, muscle damage biomarkers, mood states, and exercise performance were assessed.

Results: The 90-EE protocol induced significant muscle damage, delayed onset of muscle soreness (DOMS), inflammation, reduced strength and power performance, and mood disturbance. Interaction effects (2 group × 7 time points) supported that AL vs. CB was associated with reduced post-exercise fatigue and tension (p = 0.051, 0.033, respectively) and higher levels of leg-back strength (p = 0.029). No group differences were found for post-90-EE increases in DOMS and six cytokines. AL was associated with lower levels of serum creatine kinase immediately- and 1-day post-exercise (p = 0.034 and 0.013, respectively). The 90-EE bout increased plasma levels immediately post-exercise for 13 oxylipins. Interaction effects revealed significantly higher levels for AL vs. CB for 12,13-DiHOME (p < 0.001) and lower levels for 9,10-DiHOME (p < 0.001). Urine levels increased in AL vs. CB for seven gut-derived phenolics including 5-(3',4'-dihydroxyphenyl)-γ-valerolactone that was inversely related to changes in plasma 9,10-DiHOME (r = -0.029, p = 0.021).

Discussion: These data support some positive effects of almond intake in improving mood state, retaining strength, decreasing muscle damage, increasing the generation of gut-derived phenolic metabolites, and altering the plasma oxylipin DiHOME response to unaccustomed eccentric exercise in untrained adults. The elevated post-exercise plasma levels of 12,13-DiHOME with almond intake support positive metabolic outcomes for adults engaging in unaccustomed eccentric exercise bouts.

Keywords: (poly)phenols; almonds; cytokines; exercise; inflammation; metabolites; oxylipins.

FIGURE 1

CONSORT subject flow diagram.

FIGURE 2

Pre-study and 4-week supplementation data for the composite variable of six urine gut-derived phenolics (interaction effect p-value = 0.0013; q-value = 0.1258). *Group contrast of the increase relative to pre-supplementation, P = 0.0013. Sum of: 5-(3′,4′-Dihydroxyphenyl)- γ-valerolactone; hydroxybenzoic acid-sulfate* (2 isomers of unknown structural configuration); 3-(3-hydroxyphenyl)propanoic acid-5-sulfate; benzoic acid-4-sulfate; 3-(3-hydroxyphenyl)propanoic acid-5-O-glucuronide; 3-(4-methoxyphenyl)propanoic acid-sulfate.

FIGURE 3

Immediate-post-exercise increases (post-/pre-exercise ratios) in 13 plasma oxylipins for all subjects combined in response to the 90-min eccentric exercise bout. All q-values <0.10 after correction for multiple paired t-tests.

FIGURE 4

Plasma 9,10-DiHOME data before and after 4-weeks supplementation, and immediately post 90 min eccentric exercise and in an overnight fasted state during 4 days of recovery (AL = almond, n = 33; CB = cereal bar, n = 31) (means ± SE). Time effect, p < 0.001, interaction effect, p < 0.001, q < 0.10. *p-value = 0.0013, group contrast of the increase relative to pre-supplementation. Suppl, supplementation; PostEx, post-90 min eccentric exercise bout.

FIGURE 5

Plasma 12,13-DiHOME data before and after 4-weeks supplementation, and immediately post 90 min eccentric exercise and in an overnight fasted state during 4 days of recovery (AL = almond, n = 33; CB = cereal bar, n = 31) (means ± SE). Time effect, p < 0.001, interaction effect, p < 0.001, q < 0.10. *p = 0.000013, group contrast of the increase relative to pre-supplementation. Suppl, supplementation; PostEx, post-90 min eccentric exercise bout.

FIGURE 6

Pearson correlation scatterplot between the change in urine 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone (pre- and post-4-weeks supplementation with almonds or cereal bars) and the post-exercise change in plasma 9,10-DiHOME (r = –0.288, p = 0.021).