Study protocol: A randomised, double blinded, placebo-controlled clinical trial testing the effects of a vitamin D-enriched mushroom supplement on cognitive performance and mood in healthy elderly adults

Background: Cross-sectional evidence suggests a positive relationship between vitamin D status and cognitive performance and mood; however, interventional clinical evidence is lacking. Vitamin D deficiency is prevalent in the elderly. If justified, supplementation offers a potentially cost-effective approach for maintaining cognitiondependent quality of life in aging populations. Exposure to UV light elevates the vitamin D content of mushrooms, which represent a novel and convenient source of dietary vitamin D (D2). Here we present the protocol for a study to determine whether increasing vitamin D status improves cognitive function, mood and depressive symptoms in healthy older subjects.

Methods: The study is a double blind, placebo-controlled clinical trial with 400 healthy male and female subjects aged 60–90 years old. Subjects pre-screened for confounders of cognition but not vitamin D status, are randomised across four groups, receiving daily supplement treatments in parallel over six months; either: vitamin D2-enriched mushroom solids, vitamin D3 alone, standard mushroom solids, or placebo. Primary endpoints are: changes in serum 25-OH-D2 and 25-OH-D3 metabolites and general cognitive performance. Secondary endpoints include mood and depressive symptoms. Data analysis will adjust for covariate measures. Blood samples taken at the three clinic visits (baseline, 5 weeks and 6 months) will be stored.