Food for Thought: Assessing the effect of diet and dietary advice on cognitive function in older people at risk

(1) High anthocyanin diet ('purple diet') for 6 months; or (2) Freeze dried product derived from blackcurrants for 6 months; or To minimise potential barriers to participation and to maximise participant retention in the study, we sought the feedback of a consumer advisory group which comprised one older male carer of a person with dementia, a female hospital dietitian who mainly supported older patients and who had an interest in dementia risk reduction, and a female PhD student who cared for an elderly parent with MCI. The group reviewed the entire protocol as part of a 2 hour online discussion group, and provided valuable advice to enhance planned recruitment strategies, to promote perceived benefits to participants and to enhance support especially for those involved in the ‘purple diet’ arm. Intervention arm 1 will receive intensive dietary counselling by nutrition professionals to consume a “purple diet” that includes foods that are rich in anthocyanin content that are convenient, tasty, and affordable - to provide daily intakes of ~250mg of anthocyanins per day. Dietary advice will consist of face-to-face counselling at the baseline and 3-month visits, as well as follow-up phone calls and emails to participants during the 6 months of intervention. At baseline, participants will receive the ‘Purple Food Guide’ a supermarket friendly guide, as well as the ‘Purple Food for Thought’ cookbook to support their consumption of readily available anthocyanin rich foods. Participants will be asked to consume a minimum of 2 servings of ‘low anthocyanins’ foods or 1 serving of a ‘high anthocyanins’ food daily, either from the recipes provided or from lists of ‘low’ (<100mg/100g serve) and ‘high’ (=100mg/100g serve) anthocyanin foods. Serves are derived from the portion size guide in the Australian Guide to Healthy Eating. Seasonal anthocyanin-rich fresh produce will be discussed during phone calls and with hand-outs throughout the duration of the trial. The individual phone calls scripts will be developed by dietitians and administered by the researchers. If requested or necessary, participants may be referred to one of the dietitians in the research team for the individual phone consultations. During individual phone calls, participants will be encouraged to ask any questions about the material and information provided. Additional material will be sent to participants in follow-up emails, such as seasonal recipes and food purchasing tips. Suggestions from the consumer advisory group included: exploring options to lower costs and promote access to low-cost purple foods/ingredients; promoting opportunities for support to improve cooking and preparation skills and motivation; and also exploring options within the study to support social connections between participants . These suggestions were incorporated into the final participant resources and an AU$100 gift voucher was provided to participants in this arm to assist with food-related costs. Intervention arm 2 will receive 6 g of freeze-dried product derived from New Zealand grown blackcurrants (Neuroberries™; Arepa Pty Ltd., Auckland, providing ~250 mg anthocyanins/day, comprising approximately equal quantities of delphinidin and cyanidin subclasses). We have conducted preliminary investigations to evaluate the acceptance of this product among older adult consumers. This product can be consumed in various ways, including as a beverage added to water or in other foods, such as smoothies and yoghurt. Participants in this intervention arm will be guided to maintain their usual diet throughout the study.