Date Published: January 12, 2017
Publisher: Public Library of Science
Author(s): Se Jin Lee, So Young Lee, Su Ah Sung, Ho Jun Chin, Sung Woo Lee, Petter Bjornstad.
Little is known about the risk factors of proteinuria in the Asian population. On the basis of the association between rice intake patterns and chronic diseases, we hypothesized that rice intake patterns are associated with proteinuria in the Asian population. Data, including data regarding rice intake frequency and dipstick urinalysis results, from the Korea National Health and Nutrition Examination Survey in 1998, 2001, 2005, and 2007 were analyzed. The study involved 19,824 participants who were older than 20 years of age. Low rice intake was defined as consumption of rice ≤ 1 time/day. Proteinuria was defined as dipstick urinalysis protein ≥ 1 positive. Among the 19,824 participants, the prevalence of low rice intake and proteinuria were 17.3% and 2.9%, respectively. The low rice intake group showed a higher rate of proteinuria than the non-low rice intake group did (3.8% vs. 2.7%, P < 0.001). In multivariate logistic regression analysis, the odds ratio (OR) of low rice intake for proteinuria was 1.54 (95% confidence interval (CI): 1.25–1.89; P < 0.001). Low rice intake was also independently associated with high blood pressure (OR: 1.43, 95% CI: 1.31–1.56; P < 0.001) and diabetes (OR: 1.43, 95% CI: 1.27–1.62; P < 0.001). In conclusion, low rice intake was found to be independently associated with proteinuria in the Asian population, which might have been affected by the associations of low rice intake with high blood pressure and diabetes. Future prospective studies are needed to confirm the results of this study.
Proteinuria is a marker of kidney damage . Since measuring proteinuria quantitatively in a large population is not always possible, many studies have measured proteinuria semi-quantitatively by using dipstick urinalysis. Proteinuria measured using dipstick urinalysis is also a well-known predictor of future end-stage renal disease (ESRD) [2, 3] and all-cause mortalities [4–6], including those due to cardiovascular diseases. Although proteinuria can be reduced by the inhibition of the renin-angiotensin-aldosterone system (RAAS) , administration of RAAS inhibitor to people with proteinuria, who are otherwise healthy, is not always possible. It has been debated  that Asians may be at an increased risk of proteinuria than people of other ethnicities [9, 10]. Therefore, it is important to identify modifiable risk factors for proteinuria, particularly in Asians.
Among the 19,824 participants, the prevalence of low rice intake and proteinuria were 17.3% and 2.9%, respectively. Baseline characteristics of the study population according to rice intake are summarized in Table 1. Younger age and lower participation by males was observed in the low rice intake group than in the non-low rice intake group. More people in the low rice intake group had high BP, diabetes, and renal hyperfiltration than in the non-low rice intake group. People in the low rice intake group were more likely to live in urban areas. They had lower incomes than those in the non-low rice intake group. People with low rice intake had meals more frequently with a more westernized food pattern. They ate more meat and snacks, but less fruits or vegetables, than did those with non-low rice consumption.
Asian people might have an increased risk for proteinuria. There are several effective medications to lower the rate of proteinuria. However, medication is not always useful. In this context, we identified modifiable risk factors of proteinuria, particularly in the Asian population. It has been debated that high rice intake might be associated with decreased risk of chronic diseases such as hypertension and diabetes. Therefore, we hypothesized that low rice intake was associated with proteinuria. To test our hypothesis, we performed this study by using the data from KNHANES and found that low rice intake was significantly associated with proteinuria. Elder people, women, and people without diabetes might be more sensitive in a subgroup for the association between rice intake and proteinuria. To the best of our knowledge, this is the first study that reports such an association.