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Fiber-rich diet with brown rice improves endothelial function in type 2 diabetes mellitus: A randomized controlled trial.

  • 2017-06-29
  • PloS one 12(6)
    • Keiko Kondo
    • Katsutaro Morino
    • Yoshihiko Nishio
    • Atsushi Ishikado
    • Hisatomi Arima
    • Keiko Nakao
    • Fumiyuki Nakagawa
    • Fumio Nikami
    • Osamu Sekine
    • Ken-Ichi Nemoto
    • Makoto Suwa
    • Motonobu Matsumoto
    • Katsuyuki Miura
    • Taketoshi Makino
    • Satoshi Ugi
    • Hiroshi Maegawa

Study Design

Type
Randomized Controlled Trial (RCT)
Sample size
n = 14
Population
28 patients with type 2 diabetes mellitus
Methods
Randomized, 8 weeks of brown rice vs white rice diet
Blinding
Open-label
Duration
8 weeks
Funding
Unclear

Background & aims

A fiber-rich diet has a cardioprotective effect, but the mechanism for this remains unclear. We hypothesized that a fiber-rich diet with brown rice improves endothelial function in patients with type 2 diabetes mellitus.

Methods

Twenty-eight patients with type 2 diabetes mellitus at a single general hospital in Japan were randomly assigned to a brown rice (n = 14) or white rice (n = 14) diet and were followed for 8 weeks. The primary outcome was changes in endothelial function determined from flow debt repayment by reactive hyperemia using strain-gauge plethysmography in the fasting state. Secondary outcomes were changes in HbA1c, postprandial glucose excursions, and markers of oxidative stress and inflammation. The area under the curve for glucose after ingesting 250 kcal of assigned rice was compared between baseline (T0) and at the end of the intervention (T1) to estimate glucose excursions in each group.

Results

Improvement in endothelial function, assessed by fasting flow debt repayment (20.4% vs. -5.8%, p = 0.004), was significantly greater in the brown rice diet group than the white rice diet group, although the between-group difference in change of fiber intake was small (5.6 g/day vs. -1.2 g/day, p<0.0001). Changes in total, HDL-, and LDL-cholesterol, and urine 8-isoprostane levels did not differ between the two groups. The high-sensitivity C-reactive protein level tended to improve in the brown rice diet group compared with the white rice diet group (0.01 μg/L vs. -0.04 μg/L, p = 0.063). The area under the curve for glucose was subtly but consistently lower in the brown rice diet group (T0: 21.4 mmol/L*h vs. 24.0 mmol/L*h, p = 0.043, T1: 20.4 mmol/L*h vs. 23.3 mmol/L*h, p = 0.046) without changes in HbA1c.

Conclusions

Intervention with a fiber-rich diet with brown rice effectively improved endothelial function, without changes in HbA1c levels, possibly through reducing glucose excursions.

Research Insights

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