Supplementation of docosahexaenoic acid (DHA), vitamin D3 and uridine in combination with six weeks of cognitive and motor training in prepubescent children: a pilot study

Abstract

Background: Learning and memory have been shown to be influenced by combination of dietary supplements and exercise in animal models, but there is little available evidence from human subjects. The aim of this pilot study was to investigate the effect of combining a motor- and cognitive exercise program with dietary supplementation consisting of 500 mg docosahexaenoic acid (DHA), 10 μg vitamin D3 and 1000 mg uridine (DDU-supplement) in 16 prepubescent children (age 8-11 years).

Methods: We designed a randomized, placebo-controlled, double-blinded study lasting 6 weeks in which DDU-supplement or placebo was ingested daily. During the intervention period, all children trained approximately 30 min 3 days/week using an internet-based cognitive and motor training program (Mitii). Prior to and post the intervention period dietary record, blood sampling, physical exercise tests and motor and cognitive tests were performed.

Results: Fourteen of the 16 children completed the intervention and ingested the supplement as required. 6 weeks DDU-supplementation resulted in a significant increase in the blood concentration of vitamin D2+3 and DHA (p = 0.023 and p < 0.001, respectively). Power calculation based on one of the cognitive tasks revealed a proper sample size of 26 children.

Conclusion: All children showed improved performance in the trained motor- and cognitive tasks, but it was not possible to demonstrate any significant effects on the cognitive tests from the dietary supplementation. However, DDU-supplementation did result in increased blood concentration of DHA and vitamin D2+3.

Trial registration: Clinical registration ID: NCT02426554 (clinical Trial.gov). January 2015 retrospectively registered.

Keywords: Blood samples; Children; DHA; Nutritional supplement; Pilot study; Training; Uridine; Vitamin D.

© The Author(s). 2017.

Figures

Fig. 1

Study design. The children completed dietary registration during four representative days two weeks prior to the pre-test. During the intervention two children dropped out of the study, which resulted in 6 children in the DDU group and 8 children in the Placebo group

Fig. 2

Individual dietary intake of mono- and polyunsaturated fatty acids and vitamin D. 1–4 represents girls and 5–11 represents boys. Bold line represents daily minimum recommended levels of intake monounsaturated fatty acid intake (E%) (a), black horizontal line indicates recommended level at 10–15 E% [37]. Polyunsaturated fatty acid intake (E%) (b), black horizontal line indicates recommended level at 5–10 E% [37]. Vitamin D (μg) intake (c) with (grey bars) and without (black bars) vitamin supplement (7 out of 11), black horizontal line indicates recommended daily intake at 10 μg [37]. d Correlation between dietary intake of vitamin D incl. dietary supplement and plasma 25(OH)D2+3 (vitamin D2+3) concentration in blood. Pearson product moment correlation is presented on the graph

Fig. 3

Plasma concentrations of vitamin D2 + 3, docosahexaenoic acid (DHA) and brain-derived neurotrophic factor (BDNF). Vitamin D2+3 plasma concentration (a) DHA plasma content (b), and BDNF plasma concentration (c) before and after DDU- and placebo supplement. Right upper corner: Delta concentrations of vitamin D2+3 (a), DHA (b) and BDNF (c) in relation to interventions. Data are mean ± SEM

Fig. 4

Performance in two Mitii modules. Mathematics (a) and Memory (b) during the intervention periods when children received DDU-supplement (closed circles) or placebo (open circles). The mathematic task is given by an average increase in percentage of correct responses each possible training day (note: nobody from the placebo group trained day 18 therefore no results are provided). The memory task is given by an average decrease in percentage of errors during each possible training day. The error bars indicate SEM for each group

Fig. 5

Performance in a Cogstate task. Reaction time before and after DDU- and placebo supplement in the One Back Task. A lower reaction time indicates better performance. Individual scores (left side of the figure) and mean score values (right upper corner) are displayed. The SEM is given