Black Rice Consumption on Cognitive Function, Inflammation and Microvascular Function in Older Adults

Overview

Cognitive (brain) function, especially memory, gradually declines during ageing, which may in part be caused by an increase in systemic inflammation as well as a reduction in vascular functions and cerebral blood flow. Blood inflammatory mediators such as c-reactive protein (CRP) and interleukin-6 (IL-6) found to be significantly higher among people over 65 years compared to younger age groups. Anthocyanins is water-soluble compounds giving blue, purple and red colours in fruits and vegetables. Anthocyanins have been demonstrated to improve cognitive function, inhibit inflammation, and protect cardiovascular health. Black rice contains high amounts of anthocyanins mainly cyanidin 3-glucoside and peonidin 3-glucoside as well as various nutritional compounds such as carbohydrate, vitamin B, vitamin E and fibre. Previous studies reported health benefits of black rice, including anti-inflammation, antioxidative stress, anti-diabetes, and improved cognitive function. However, the effect of black rice consumption on cognitive function related to inflammation has not been studied in humans. Therefore, this study aims evaluate the acute \& short-term effects of black rice consumption on the cognitive function, inflammation, and vascular function in older adults aged 50-80 years. The primary and secondary research questions of this study will address: 1. Do the acute and short-term anthocyanin-rich black rice intakes improve cognitive function in older adults aged 50-80 years? 2. Do the acute and short-term anthocyanin-rich black rice intakes modulate inflammatory status and microvascular function in older adults aged 50-80 years?

This study is a randomised controlled crossover design with a week wash-out period for investigating the acute (2 hrs), short-term (7 days), and acute on short-term (7 days, 2 hrs) effects of black rice consumption on the cognitiv function, inflammation, and vascular function in older adults aged 50-80 years. The cognitive function will be assessed using computer-based test via Gorilla platform. The inflammatory mediators will be measured in a blood sample. The vascular function will be tested by Laser Doppler imaging with iontophoresis (LDI), blood pressure (BP) and heart rate (HR). Eligible volunteers will be asked to attend the Hugh Sinclair Unit of Human Nutrition for 1 screening visit and 4 study visits. The enrolment, volunteers will be recruited by poster, E-mail, or telephone. If they are interested in the study and meet the criteria, volunteers will be provided with the participant information sheet explaining the nature and requirements of study. The volunteers who are interested in attending the study will be asked to fill out the health and lifestyle screening questionnaires online link. The potentially eligible volunteers will be invited to attend a screening visit at the Hugh Sinclair Unit of Human Nutrition. For screening visit (approximately 1-1.5 h), the researcher will explain all the details of the study to volunteers and confirm information in a screening questionnaire. The volunteers who meet the study criteria will be asked to sign the informed consent before partaking in the study. Height, weight, waist circumference, BP, and HR will be measured. Then, global cognitive performance (MMSE test) will be assessed. Inclusion/exclusion criteria will then be reviewed for participant eligibility. Then, they will be asked to perform the demo cognitive tests (30 min). The volunteers will be provided with the participant information booklet which contains the guidelines on what to do during the study and will be invited to attend the study in following week. the volunteers will be asked to fill out food frequency questionnaire prior to first visit. For study visit 1-4, the volunteers will be asked to fast 8 hours in advance. They will be asked to consume a low the polyphenol rich diet for 24 hours in advance of 1st and 3rd study visit. As soon as they arrive at the nutritional unit, the 15 ml of venous blood will be taken, followed by cognitive testing and BP, HR and LDI will be completed at baseline (35-40 min). After that, the volunteers will receive cooked black rice or control cooked brown rice in a random order served with omelette and 1 glass of water. The volunteers will be asked to eat tested meal within 20 minutes. Then, 2 hours after consumption, the cognitive function will be then assessed, followed by LDI, BP and HR measurements. For the short-term intervention (to be continued after 1st and 3rd study visit), the volunteers will be provided raw rice and a rice cooker for cooking at home for a further 7 days. The volunteers will be asked to have daily rice consumption (1 meal per day) with avoiding anthocyanin rich food but maintain habitual physical activity during study. In addition, they will be asked to do daily check list to confirm study compliance during trial. A power calculation based on three similar studies investigating the acute effect of anthocyanin-rich food consumption on cognitive function in middle aged-older adults which suggested that 24 participants (include 10% attribution rate) should provide the sufficient statistic power (Average Effect size=0.64, α=0.05, Power=0.8). the collected data will be anonymised by providing each participant with unique identification number. The key file will be stored securely in a password protection folder stored in the University-managed cloud. Following completion of the study, the data will be fully anonymised before being archived. Only the applicants named on this form will be digital access to the data and only the researchers directly related to the study will have physical access to keys to the filing cabinets where the paper forms will be stored.