THE EFFECTS OF LOW-PROTEIN BROWN RICE ON THE CKD PROGRESSION-CLINICAL TRIAL-

CKD (chronic kidney disease) is increasingly recognized as a global health problem and more than a million people is suffering from this disease. One of the therapeutic strategies against CKD is diet therapy which consists of protein and salt restriction for aiming at reducing renal tissue damages and uremic symptoms. On the other and, some type of dietary patterns is recommended for CKD. Whole grains have gained attention as healthy diet for early prevention of various diseases. Lower intake of whole grains has been linked to an increased risk of CKD. Especially, CKD subjects are inclined to suffer from constipation or defection problems partly because of the deterioration of intestinal microbiota composition, which could be ameliorated by fiber-rich whole grain intake. In Asia, rice is a major staple food and the brown rice is an example of whole grain food, which is highly nutritious due to the presence of various bioactive compounds including dietary fibers. We recently have developed new low-protein brown rice (LPBR) by a two-step fermentation. This LPBR contains one tenth of protein half of phosphorus in usual white rice. It also contains dietary fiber, g-oryzanol, and antioxidant ability. In these backgrounds, we investigated the effect of LPB on CKD progression.

The clinical trial was designed as an open-label intervention trial - one-arm. Fifteen servings of LPFG retort rice were provided per week and continued for 3 months. The subjects had stage 3 or higher CKD. The primary outcomes were defecation status and renal function. Defecation was assessed using the Cleveland Clinic Constipation Scoring System. Cytokine and uremic toxin levels were also investigated.

Twenty-one subjects were included in this trial. Their age was and eGFR was 32.74±10.99 mL/min/1.73m2, and urinary protein excretion was 0.88±0.90 g/g creatinine on the average. Mean protein intake of participants were 53.04±19.1 g which corresponded with 0.89±0.27g/kg ideal body weight. Mean salt intake was 9.36±3.18g/day. They all suffered from defection problems and was most frequent complaint was where 14 of 21 participants were annoyed. In the baseline data, their constipation score was associated with p-cresyl sulfate concentration and their protein intake was associated with serum CRP concentration. Low-protein brown rice reduced the constipation score from 3 to 1, and most of the uncomfortable symptoms about defection were recovered with the intervention. Protein intake remained the same, but salt intake decreased. Serum creatinine levels decreased (1.89±0.29 vs. 1.81±0.28 mg/dL, p<0.01) and eGFR increased (32.73±10.9 vs. 34.94±3.14 mL/min/1.73m2), but urinary protein levels remained unchanged (0.88±0.21 vs. 0.89±0.24 g/g creat p=0.982). Serum CRP concentrations decreased (0.214±0.072 vs. 0.130±0.034) enteric-derived uremic toxins, p-cresyl sulfate decreased (8.76±1.29 vs. 5.46±1.08g mg/mL p<0.05). Regarding cytokine levels serum levels of IL-6 (4.66±1.16 vs. 2.76±0.23 pg/mL, p<0.05), while blood levels of TNFα did not change (12.16±0.79 vs. 11.59±0.664 pg/mL, p=0.4631). Nutritional parameters such as serum total protein, albumin, and BMI levels did not change, and liver function was not affected. 

Our results suggest that low-protein brown rice may improve renal function by improving defecation and reducing systemic inflammatory conditions without altering the nutritional status of CKD subjects.