Depression constitutes a major public health problem with significant personal, social and economic costs. One plausible route for the prevention of mood disorders is through diet. Higher intake of fruits and vegetables is associated with lower incidence of mood disorders over the lifespan and it has been proposed that the high concentrations of flavonoids present in these foods could account for these benefits. We recently reported that a single intervention of wild blueberries (WB) could improve short-term positive affect in both children and young adults, 2 hours after consumption (Khalid et al, 2017). Further follow-up work in adolescents randomly assigned to WB or a matched placebo drink for 4 weeks showed there was a significant decrease in self-reported depression symptoms in participants who were supplemented with WB intervention but not for those who received the placebo. This studentship will explore the effects of long-term WB treatment on mood in healthy volunteers and those with persistent low mood. Using a parallel-groups, double-blind, randomised trial design, this proposal will examine the effectiveness of 12 weeks WB (or matched placebo) treatment for reducing negative mood in healthy and low-mood participants. Outcome measures for mood, cognitive performance and stress responsivity will be assessed at 0, 6 and 12 weeks, and a further 6 weeks after the end of the intervention period to assess prolonged effects of treatment. We hypothesise that there will be a cumulative effect of WB intervention on cognitive functioning (increased executive function) over several weeks, and that cognitive change will be associated with reductions in low mood in participants who had elevated levels of symptoms at baseline. We will also assess the effect of our intervention on peripheral psychophysiology (heart rate variability and blood pressure) to determine if WB can specifically influence stress responsivity. Further explorations of the short-term effects of WB will run alongside the objectives outlined above to further investigate the robustness of the immediate elevation in mood seen in our previous work. For example, we will examine the duration of our beneficial response from a single dose or will perform a dose-ranging study to examine the lowest dose of WB to elicit benefits to mood.
Jointly funded by the Wild Blueberry Association of North America & the University of Reading
Khalid et al (2017), Nutrients, 9, 158; Khalid, Williams & Reynolds (2017), British Journal of Nutrition, 116, 2097-2108.