The Effect of the Timing of Banana Intake on Postprandial Glucose Spike: Randomized Parallel-Group Comparison Study
Mitsuko Itoh and Hiroyoshi Inoue
Objective: To elucidate the effects of the timing of banana intake on postprandial glucose spike and
glucose metabolism.
Methods: This randomized parallel-group comparison study was designed to randomize 54 adults aged
41- 60 years into three groups. The first group consumed 120 g of banana at breakfast daily for 2 weeks,
the second group consumed 120 g of banana after dinner daily for 2 weeks, and the third consumed
no banana or banana-containing food for 2 weeks. The participants in each group wore a continuous
glucose monitor on their arms for 2 weeks to measure their blood glucose trend. Body composition and
serum biomarkers were evaluated before and after intervention.
Results: There were 16 participants in the banana-at-breakfast group, 16 in the banana-after-dinner
group, and 15 in the control group. We defined a postprandial blood glucose increase of >140 mg/dL
as a “glucose spike.” When comparing the glucose spike incidence ratio (incidence of glucose spikes
divided by number of times measured), the point estimate of the incidence ratio of banana-at-breakfast
group at dinner compared with breakfast was 1.55 (point estimate. 95% confidence interval: 1.09-
2.20), that of banana-after dinner group 1.83 (point estimate. 95% confidence interval: 1.28-2.61), and
control group 2.03 (point estimate. 95% confidence interval: 1.36-3.04). In addition, the banana-afterdinner and control groups showed a higher incidence ratio, compared with the banana-at-breakfast
group. Glycoalbumin decreased significantly in the banana-at- breakfast group compared with the other
groups.
Conclusions: The results showed that glucose spikes were less generated when consuming bananas
at breakfast than when consuming them after dinner or not consuming them at all. The level of
glycoalbumin, an index for average blood glucose, was lower in the banana-at-breakfast group than in
the banana-after-dinner and control groups within 2 weeks.
Clinical Trial Registry: UMIN 000050025
