P.8.b.002 The effect of dietary intake of vitamin B6 on sleep quality and insomnia

Abstract

Purpose: There is increased notion that daily diet has an important impact on health and disease. In this context, the relationship between nutrition and sleep is gaining increased research interest, particularly focusing on tryptophan, niacin and Vitamin B6. Vitamin B6 has an important role in the synthesis of several neurotransmitters (i.e. 5-HT, melatonin, norepinephrine and dopamine) crucial for CNS functioning. Melatonin and its precursor 5-HT are crucial in sleep regulation; however, although several foods contain 5-HT, dietary 5-HT cannot pass the blood-brain barrier. The system is therefore dependent on the 5-HT precursor tryptophan to be utilized for synthesis in the presence of a coenzyme derived from vitamin B6. Both tryptophan and vitamin B6 must be obtained from the diet [1]. The purpose of this study was to investigate the link between dietary vitamin B6 intake and sleep. Methods: A survey was conducted among university students in Utrecht, the Netherlands. Dietary intake of vitamin B6 was assessed with a short semi-quantitative food group questionnaire [2]. From past-week food consumption, the daily intake of Vitamin B6 could be estimated. Insomnia, sleep quality (0-10 score) and total sleep time (TST) were assessed using the SLEEP-50 questionnaire [3]. The insomnia scale consists of 9 nine items, scored on a 4-point-scale: 1 (not at all), 2 (somewhat), 3 (rather much), and 4 (very much). The sum score of the items was computed. A sum score ≥ 19 corresponds to a positive screen for insomnia (sensitivity = 71%, specificity = 75%). Daily intake of vitamin B6 was associated with insomnia scores, sleep quality and TST using nonparametric (Spearman) correlations. Statistical analyses were conducted for the total population, and men and women separately. Results: A total of N= 509 healthy subjects completed the survey (28.1% of them were men). Their mean (SD) age was 20.8 (2.4) years old. Overall, scores of dietary intake of vitamin B6 (mean = 1.3 mg, SD = 1.2), insomnia (mean = 14.6, SD = 4.3), sleep quality (mean = 7.3, SD = 1.2) and TST (mean = 6.7 h, SD = 0.9) were all within normal ranges. The daily dietary intake of Vitamin B6 was significantly correlated with insomnia (r = -0.134, p = 0.001) and sleep quality (r = 0.123, p = 0.009). No significant correlation was found between TST and vitamin B6 (r = 0.010), p = 0.832). In men (N = 143), dietary intake of vitamin B6 correlated significantly with insomnia (r = -0.204, p = 0.029) and sleep quality (r = 0.218, p = 0.018). In women, vitamin B6 dietary intake was significantly associated with insomnia (r = -0.152, p = 0.006) but not with sleep quality (r = 0.098, p = 0.075). Conclusion: Daily dietary intake of vitamin B6 was significantly, albeit modest, associated with insomnia and sleep quality.