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?
Aged 50-80 years
General healthy status
Body Mass Index (BMI)18.5-35 kg/m2
Taking anti-inflammatory drugs (e.g., aspirin, warfarin, ibuprofen)
Having sign of infections or acute inflammation (e.g., fever, chills, sore throat, nasal congestion, moderate-severe pain, swelling-redness)
Received antibiotics within the past 3 months
Taking dietary supplements (e.g., vitamins, minerals) at high doses (e.g., more than 200% of the UK's reference nutrient intakes)
Crossover
Black rice (Intervention)
Other intervention210 g of cooked black rice
Brown rice (Control)
Other intervention210 g of cooked brown rice
Rey Auditory Verbal Learning (RAVLT)
This task consists of 5 consecutive free recalls of the same 15 nouns presented as a first auditory list (list A), followed by recall of a further 15 nouns presented as an interference list (list B) which is recalled only once. After 15 words had been presented, participants will be asked to say aloud each word as many as they can recall in any order (approximately a minute). The session will be occurred five times. Then, the participants listen an auditory list of 15 words (list B) and will be asked to say aloud each word as many as they can recall in any order. The number of correct words will be counted and averaged of five trials (list A). Measurements: at baseline (Day 0), acute intervention (2hrs), 7 days short-term intervention (Day 7) and acute on short-term intervention (Day7-2hrs)
Digit span Forward and Backward tasks
In this task, the series of digits (numbers) of varying length (spans of 2-9 for forward and 2-8 for backward). It consists of 8 items of forward and 7 items of backward tasks and has 2 trials for each item. The forward and backward digit span tasks, the number will be presented on computer screen an increasingly longer series of digits at a rate of 1 digit/s. The participants will be asked to repeat the number by pressing number on the keyboard. The score will be the maximum of digits of correct both trials, prior to failing two consecutive trials at any one span size. Measurements: at baseline (Day 0), acute intervention (2hrs), 7 days short-term intervention (Day 7) and acute on short-term intervention (Day7-2hrs)
Stroop task
The participants were presented with the words 'GREEN', 'BLUE', 'RED' and 'YELLOW', which were displayed either in the same colour ink as the meaning of the word (congruent trials) or in a colour inconsistent with the meaning of the word (incongruent trials). The participant will be instructed to respond to the colour in which the word is presented rather than the meaning of the word, by pressing a corresponding key on the keyboard. There were 96 trials in total and the task lasted for approximately four minutes. The primary dependent variable was reaction time for correct responses. Measurements: at baseline (Day 0), acute intervention (2hrs), 7 days short-term intervention (Day 7) and acute on short-term intervention (Day7-2hrs)
The Digit Symbol-Substitution Task (DSST)
Participants are given a table pairing the digits 1 through 9 with nine distinct symbols. Below the table, there is four rows of 25 boxes, each containing a number from one to nine with a blank box underneath. The numbered boxes will be in a random order. Starting at the beginning of the first row and working from left to right down the page, participants will be asked to fill the correct symbol in the blank box using the key at the top of the page. Participants were given 90 seconds to fill in as many boxes as possible in sequential order and the total number of correctly completed boxes will be used to indicate processing speed. Measurements: at baseline (Day 0), acute intervention (2hrs), 7 days short-term intervention (Day 7) and acute on short-term intervention (Day7-2hrs)
High sensitive C reactive protein (hs-CRP)
Serum hs-CRP (mg/L) will be analyzed by automated Enzyme immunoassays (ELISA).
Serum inflammatory markers
All serum inflammatory markers including, IL-6 (pg/ml), IL-1β (pg/ml), and TNF-α (pg/ml) will be analyzed by automated Enzyme immunoassays (ELISA).
Laser Doppler imaging (LDI)
The microvascular blood flow will be measured by LDI technique which assesses the changing of skin blood flow in response to acetylcholine and sodium nitroprusside by iontophoresis.
Blood pressure (BP)
BP (mmHg) will be measeured by Omron BP monitor.
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