Substituting white for brown rice has no metabolic impact
MedWire News: Substituting white rice (WR) with brown rice (BR) has no major impact on metabolic risk factors in middle-aged Chinese men and women with diabetes or at high risk for diabetes, study results show.
Subgroup analysis of the diabetes patients showed that BR reduced diastolic blood pressure relative to WR, but it was not sufficiently powered to draw definitive conclusions.
"Longer durations of follow-up, and different varieties of rice are needed to further investigate the effects of BR on diabetes risk," Xu Lin (Shanghai Institutes for Biological Sciences, China) and colleagues comment in the Journal of Nutrition.
As a staple food in Asian countries, WR has been associated with increased risk for diabetes and the metabolic syndrome. In the Shanghai Women's Health Study, women who consumed at least 300 g of WR per day or more had a 78% greater risk for developing Type 2 diabetes compared with women who consumed less than 200 g/day.
Fewer studies have looked at the impact of substituting WR with BR among diabetics, however.
To investigate, the researchers recruited 202 middle-aged adults with diabetes or a high risk for diabetes and randomly assigned them equally to consume WR or BR ad libitum for 16 weeks. Metabolic risk markers were measured before and after the intervention.
Over the course of the study, no significant between-group differences were found for any markers except serum low-density lipoprotein cholesterol concentration, which surprisingly decreased more in the WR group (-0.33 mmol/L) than the BR group (-0.05 mmol/L).
Subgroup analysis revealed that this was confined to patients with diabetes, and the researchers comment: "Because there was a higher prevalence of diabetes in the WR group than the BR group, this result may be affected by imbalance between the two groups at baseline and thus should be interpreted with caution."
Subgroup analysis also revealed a greater reduction in diastolic blood pressure in the BR group compared with the WR group, but again they urge caution in interpretation due to lack of study power.
"In conclusion, substituting BR for WR was not associated with a substantial improvement in metabolic risk factors among people with diabetes or at high risk for diabetes," Lin et al comment.
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By Andrew Czyzewski