The Effect of Beetroot Juice Supplementation on Physiological Fatigue and Quality of Sleep in Male Athletes

Abstract

Sleep loss and low tolerance to fatigue are among reasons that decline the athletic performance. Thus, the aim of the study was to investigate the effect of beetroot juice on physiological fatigue (time to exhaustion and blood lactate levels) and quality of sleep among male athletes. 30 male athletes with mean age of 20.7±3.7 years participated in the study voluntarily and divided randomly into three groups of supplement; placebo and control. Subjects in groups of supplement and placebo received 100 cc beetroot juice and placebo for a week, 2 hours prior to competition. 24-h recall questionnaire was used to monitor the nutrition status of subjects. Blood lactate levels and time to exhaustion were measured before and after one session of high-intensive exercise. The Pittsburgh Sleep Quality Index was given to the subjects for filling up before and after intervention. ANOVA and dependent t-tests were used to analyze the data. The results suggested that supplement group had a significant improvement in quality of sleep compared to placebo and control groups (p=0.001) while no significant difference was found between in placebo and control groups (p=0.97). In addition, both physiological fatigue indices including time to exhaustion and blood lactate levels were significantly improved after study intervention in supplement group (p≤0.05). Athletes are highly recommended to take beetroots supplement for the aim of postponing lactate acid accumulation. On the other hand, hence, it can be considered as a noninvasive and effective strategy to counteract sleep loss induced fatigue.

Current Evidence on Common Dietary Supplements for Sleep Quality

“…The male athletes (n = 30, mean age 20.7 years) were randomized to one of three groups, 100 milliliters of beetroot juice, a placebo, or control. 5 There was a statistically significant improvement in sleep quality among the beetroot juice group, but not in the other groups and sleep quality scores in the placebo and control groups were similar. 5 The contradictory evidence available on nitrate supplementation yields limited clinical impact.…”

Nutritional Interventions to Improve Sleep in Team-Sport Athletes: A Narrative Review

“…Athlete studies were in mixed sport disciplines, two in cycling [ 21 , 22 ] and another in basketball [ 23 ]. One study did not specify the discipline the athletes participated in [ 24 ].…”

“…In comparison, the consumption of two kiwifruits 1 h before bedtime yielded a substantial increase in TST of 55 min, as well as a 2% increase in SE and decreased SOL (14 min) and WASO (6.1 min) [ 32 ]. In athletes, beetroot juice showed an improvement in subjective quality of sleep as measured by the PSQI [ 23 ]. In healthy adults, 3 g of glycine ingested an hour before bed decreased SOL and the onset latency of slow wave sleep [ 37 ].…”

Reply to Dunican, I.C.; Walsh, J.H. Comment on “Gratwicke et al. Nutritional Interventions to Improve Sleep in Team-Sport Athletes: A Narrative Review. Nutrients 2021, 13, 1586”

“…However, we respectfully disagree with the sentiments expressed by the correspondents regarding the quality of evidence provided by the studies. Of the 19 studies described by our review, only three [ 12 , 13 , 14 ] did not compare the relevant nutrient with a placebo or control condition, only two studies [ 12 , 14 ] used a non-randomised study design, only four did not clearly indicate use of single or double blinding [ 12 , 13 , 14 , 15 ], and only five did not use an objective measure of sleep [ 2 , 15 , 16 , 17 ]. Furthermore, for most specific nutrients or foods, there was at least one study that used a randomized design, included a control or placebo condition, and employed an objective measure of sleep.…”

“…Furthermore, for most specific nutrients or foods, there was at least one study that used a randomized design, included a control or placebo condition, and employed an objective measure of sleep. The only exception to these conditions was beetroot for which there was one study [ 15 ] that used a randomized controlled and placebo-controlled trial, but did not blind participants or researchers, and only included subjective measures of sleep. Accordingly, the strength of evidence for most nutrients is almost certainly not “weak”, and taken together, lends support to use of certain nutrients to promote sleep in sport settings.…”