Between Saturdays
This week: how pomegranate juice preserves memory, why avocado and pineapple fiber feed a healthier gut, and what green bananas can do for blood sugar and body composition.
The beauty of food science is in how familiar things — fruit, fiber, even resistant starch can quietly shape complex biology. Every week, new studies continue to link what grows from the earth with measurable effects on memory, metabolism, and the microbiome.
This week’s four studies explore how plant-based compounds and dietary fibers support both the brain and the gut, two systems increasingly recognized as deeply connected.
Caught My Eye…
Pomegranate Juice and Memory: A Year of Retention
A 12-month, double-blind, placebo-controlled trial published in the American Journal of Clinical Nutrition (2020) followed 261 adults aged 50–75 who drank 8 ounces (237 mL) of pomegranate juice daily or a flavor matched placebo. The results were subtle but important: those in the pomegranate group maintained their visual memory performance over the year, while the placebo group showed decline. The biggest differences appeared in the ability to learn and recall visual information across repeated trials, suggesting that pomegranate polyphenols may help sustain hippocampal function during mid-life and aging.
The authors note that pomegranate’s rich mix of ellagitannins and anthocyanins crosses the blood–brain barrier and may reduce oxidative stress in brain tissue. The same process believed to underlie age related cognitive decline. It’s not a “sharpness boost,” but rather a slowing of erosion, a preservation of how efficiently the brain retains new information.
Avocado and Gut Health
In a 12-week randomized controlled trial published in the Journal of Nutrition (2021), 163 adults with overweight or obesity were assigned to eat one meal daily with avocado (about 175 g for men, 140 g for women) or a calorie matched meal without it. After three months, the avocado group showed a higher gut-microbiome diversity more species richness and abundance of beneficial bacteria such as Faecalibacterium, Lachnospira, and Alistipes.
These participants also had higher short chain fatty acid production (which supports gut barrier integrity) and lower bile acid levels, a profile linked to lower inflammation and improved fat metabolism. Interestingly, calorie intake and body weight didn’t differ, showing that avocado’s benefits came from composition, not calories. The study supports a simple truth: healthy fats and fiber together nurture a more balanced gut ecosystem.
Pineapple Fiber and the Microbiome
A 2024 Frontiers in Nutrition study tested whether pineapple derived fiber powder (7.4 g powder = 5 g fiber/day) could alter gut health in just two weeks. Sixty healthy adults took either pineapple fiber or a placebo daily while researchers tracked microbiome profiles and digestive comfort.
After 14 days, the pineapple fiber group showed increased levels of beneficial bacteria such as Bifidobacterium spp., Bacteroides ovatus, and Ruminococcus inulinivorans, species known to ferment fiber into short chain fatty acids that protect intestinal cells. Participants also reported better bowel regularity and minimal bloating, suggesting the fiber was well tolerated.
Although short, the study adds to growing evidence that tropical fruit fibers often discarded in processing can serve as prebiotics, nourishing microbes that support digestion, immunity, and mood regulation.
Green Banana Resistant Starch and Metabolic Control
Sometimes, it’s not sweetness but resistance that heals. A 24-week randomized trial in the British Journal of Nutrition (2019) followed 113 adults with prediabetes or type 2 diabetes who received standard dietary counseling ± daily green-banana biomass providing ≈ 4.5 g resistant starch.
By the end of the study, the banana group showed significant reductions in HbA1c, fasting glucose, blood pressure, body weight, waist circumference, and fat mass, while also gaining lean body mass. Those who didn’t receive the banana starch improved only modestly on a few parameters.
Resistant starch works by feeding colon bacteria that ferment it into butyrate, a short chain fatty acid that improves insulin sensitivity and gut barrier function. The results suggest that everyday foods even something as humble as green bananas can help realign metabolism at a cellular level.
Detailed Readings
Randomized placebo controlled study of memory effects of pomegranate juice
Metabolic evaluation of the dietary guidelines
Effect of green banana and pineapple fibre powder consumption on host gut microbiome