In a recent study published in the journal Nutrients, researchers implemented a blueberry intervention using quartile divisions to define interindividual responses in vascular and cognitive endpoints after a specific dietary intervention. did.
study: Interindividual responses to the blueberry intervention across multiple endpoints.. Image credit: Bukhta Yulii/Shutterstock.com
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Improving individual health outcomes requires understanding interindividual heterogeneity in food responses and endpoints associated with vascular disease and cognitive impairment. Absorption, metabolism, tissue distribution, bioavailability, and nutritional function influence the differences.
Blueberries are considered a “superfruit” due to their high polyphenol content and antioxidant properties, and are associated with reduced risk of obesity, cardiovascular disease, type 2 diabetes, maintenance of cognitive function, and neuroprotection.
A recent meta-analysis by the authors of the current study demonstrated variability in response to fruit in cardioprotection and cognition across a variety of clinical outcomes.
The results showed a 4.0% increase in systolic blood pressure, a 15% increase in total cholesterol, a 9.0% increase in memory, and a 10% increase in executive function. However, there are no data to support consistency or inconsistency.
About research
In this study, researchers conducted urinary metabolomic analysis to compare individual differences after ingesting blueberries in whole fruit and powder form to identify response predictors.
In a 1-week, single-blind, crossover, randomized controlled trial (RCT) in healthy people, researchers tested two types of blueberries: whole fresh blueberries (160 g), and freeze-dried blueberries. powder (20 g), and blueberry placebo control (microcrystalline cellulose).
They calculated the intervention response for each endpoint as percent change (±%) from baseline.
Researchers instructed participants to take one tablespoon of the powder mixed with water once a day, ideally before lunch. They also listed polyphenol-rich foods to avoid and a food diary to measure blueberry intake.
The researchers measured seven cognitive endpoints and nine vascular function endpoints. Vascular function endpoints included systolic and diastolic blood pressure (SBP and DBP) and carotid and radial artery pulse wave velocity (crPWV).
They measured heart rhythm using electrocardiogram (ECG) pads. They collected serum samples from participants and assessed blood sugar levels and lipid profiles. [total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides] We then monitored the NO metabolite nitrite (NO2-) by chemiluminescence.
Cognitive endpoints included working memory assessed using 3-s and 7-s tasks. Episodic memory is assessed by word recognition tasks and delayed and immediate word recall. Attention is assessed based on mood (alertness, calmness, contentment) and finger vigilance. Mental fatigue is assessed using a visual analog scale.
On each study day, the researchers administered a computerized cognitive test that lasted approximately 30 minutes. They used ultra-high pressure liquid chromatography (UHPLC) to test urine samples submitted by participants.
They used untargeted profiling techniques and ROC analysis to investigate the potential of urinary metabolite biomarkers in response to vascular and cognitive endpoints.
result
The study involved 40 people with an average age of 26 years and a body mass index (BMI) of 23 kg/m2. After the intervention, participants showed significant individual differences in vascular health indicators and cognitive domains.
For all endpoints investigated, there were no consistent responses within and within subjects after the two treatments. Supervised multivariate analysis revealed no significant potential to differentiate urinary metabolites between treatments.
Treatment had no effect on SBP, DBP, or PWV levels after controlling for baseline covariances and serum triglycerides, total cholesterol, LDL, HDL, nitrite, and glucose.
Consuming whole blueberries or their powder caused nitrite levels to be higher than baseline (+69% and +4.30%, respectively), but decreased (9.10%) when taking a placebo. However, the effect was not statistically significant.
Treatment did not affect cognitive measures, but there was variation in both cognitive and vascular endpoints, with participants responding randomly to intervention and placebo control.
Consistency of response across cognitive and vascular endpoints was limited for any intervention, including the same blueberry treatment. There was no correlation between gender, BMI, visit order, and response.
Urine metabolite profiling of baseline samples revealed predictors of response with an area under the curve (AUC) value of 0.7 and a predictive accuracy of 61%.
conclusion
A study of blueberry therapy found that there were no predictive biomarkers to distinguish between responders, and responses varied by outcome.
This finding highlights the need for further techniques to characterize responses in human intervention studies and data combined with metabolomic, genotypic, and lifestyle behavioral feedback.
Identifying healthy foods and dietary categories requires a unique approach. The study also found individual differences in clinical outcomes, with 31% to 71% of subjects reporting a better response and 29% to 66% reporting a worse response.
Cerebral blood flow patterns, neurological correlates, genetics, physical and social environment, and personality may contribute to these differences.
