Effects of high-pressure-processed rice intake during interval walking training on glycemic control and NFKB2 gene methylation in hyperglycemic older people.

Purpose: High-pressure-processed (HPP) rice is white rice that maintains some key functional food ingredients of brown rice, such as polyphenols. We examined whether HPP rice intake during interval walking training (IWT) improved glycemic control with enhanced methylation of the NFKB2 gene in hyperglycemic older subjects.

Methods: We recruited 51 people aged ~ 70 yr who had already performed IWT for ≥ 6 months, but had hyperglycemia (blood glucose concentration ([Glc]) > 110 mg/dl or HbA1c > 6.0% while fasting). Participants were randomly divided into control (CNT) or HPP rice (HPR) groups and instructed to perform IWT for an additional 4 months while ingesting 75 g dry weight of either white rice or HPP rice, respectively, at every breakfast and dinner. Before and after intervention, [Glc] was measured by continuous glucose monitoring for 5 days, with standardized breakfast on day 5. Methylation of NFKB2 was measured by pyrosequencing.

Results: After intervention, mean fasting [Glc] values for 180 min before breakfast over 4 days (days 2-5) marginally decreased in HPR but were not different from CNT (P = 0.17). However, the standard deviation during the period decreased more in HPR than in CNT (P = 0.013). Moreover, total area under the curve (tAUC) for 180 min after breakfast on day 5 decreased more in HPR than in CNT (P = 0.035). The change in tAUC on day 5 after the intervention was negatively correlated with that in NFKB2 gene methylation (P = 0.002).

Conclusion: HPP rice intake during IWT improved glycemic control with suppressed reduction in NFKB2 gene methylation in hyperglycemic older people.

Trial registration number and date of registration: UMIN000024390; October 13, 2016.