A follow-up study of the chronic kidney disease patients treated with Brazil nut: focus on inflammation and oxidative stress.

Brazil nut is the richest known food source of selenium. The supplementation with Brazil nut during 3 months was effective in reducing oxidative stress and inflammation in hemodialysis (HD) patients. However, there are no available data on the antioxidant effect after that supplementation. The objective of this work was to determine if the beneficial effects of one Brazil nut supplementation per day during 3 months for the HD patients could be sustained after 12 months. Twenty-nine HD patients (58.6 % men, 51.0 ± 3.3 years) from RenalCor Clinic, Rio de Janeiro, Brazil, were followed up 12 months after the supplementation study had finished. The plasma levels of antioxidant substances as selenium, glutathione peroxidase (GPx), 8-isoprostane, 8-hydroxy-2-deoxyguanosine (8-OHdG) and cytokines (tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6)) were determined before, after 3 months of supplementation and after 12 months. After 3-months supplementation, cytokines, 8-OHdG and 8-isoprostane plasma levels have decreased and the activity of GPx and selenium plasma levels have increased significantly. Additionally, after 12 months, the values of 8-isoprostane, 8-OHdG and cytokines increased and the activity of GPx and selenium plasma levels decreased significantly. The levels of oxidative stress and inflammation biomarkers after 12 months increased compared to the basal levels. Consequently, it is necessary to motivate patients to adopt different dietary intake patterns.

Relationship between total ghrelin and inflammation in hemodialysis patients.

In hemodialysis (HD) patients studies have shown that plasma ghrelin is increased and it has been speculated that ghrelin levels might be related to systemic inflammation. The present study attempted to correlate the serum levels of total ghrelin with serum TNF-α and IL-6, and with nutritional status and body composition in HD patients. Forty-seven HD patients from a single dialysis unit (18 women, mean age 55.3±12.2 yr; BMI 24.4±4.2kg/m(2); % body fat 29.4±7.4%) were studied and compared to 21 healthy subjects (12 women, 50.7±15.7 yr and BMI 25.6±4.0kg/m(2); % body fat 30.0±5.7%). Biochemical data, serum total ghrelin, TNF-α and IL-6 levels were measured. The body composition was evaluated by dual energy X-ray absortiometry (DEXA) and energy and protein intake were evaluated. Patients showed elevated plasma ghrelin levels when compared to healthy subjects (1.14±1.0ng/mL vs 0.58±0.4; p<0.001). There was a positive correlation between ghrelin levels and TNF-α (r=0.25; p<0.04), IL-6 (r=0.42; p<0.02), and a negative correlation between TNF-α and protein intake (r=-0.28; p<0.03), and energy intake (r=-0.34; p<0.01). No correlation was observed with any aspect of body composition. Plasma ghrelin levels are elevated in HD patients and associated with the state of systemic inflammation. We suggest that the inflammatory state may affect ghrelin bioactivity and metabolism in hemodialysis patients.

Effect of Brazil nut supplementation on the blood levels of selenium and glutathione peroxidase in hemodialysis patients.

OBJECTIVE: In patients who have undergone hemodialysis, large amounts of reactive oxygen species (ROS) are produced and, at higher concentrations, ROS are thought to be involved in the pathogenesis of cardiovascular disease. It has been proposed that selenium (Se) may exert an antiatherogenic influence by reducing oxidative stress. The richest known food source of selenium is the Brazil nut (Bertholletia excelsa, family Lecythidaceae), found in the Amazon region. We evaluated the effect of Brazil nut supplementation on blood levels of Se and glutathione peroxidase (GSH-Px) activity in patients on hemodialysis. METHODS: A total of 81 patients on hemodialysis (52.0±15.2 y old, average time on dialysis 82.3±91.4 mo, body mass index 24.9±4.4 kg/m(2)) from the RenalCor and RenalVida Clinics in Rio de Janeiro, Brazil, were studied. All patients received one nut (around 5 g, averaging 58.1 µg Se/g) a day for 3 mo. The Se concentrations in the nuts and in plasma and erythrocytes were determined by atomic absorption spectrophotometry with hydride generation (Hitachi, Z-500). GSH-Px levels were measured using Randox commercial kits. RESULTS: Plasma Se (18.8±17.4 µg/L) and erythrocyte (72.4±37.9 µg/L) levels were below the normal range before nut supplementation. After supplementation, the plasma level increased to 104.0±65.0 µg/L and erythrocytes to 244.1±119.5 µg/L (P<0.0001). The activity of GSH-Px also increased after supplementation, from 46.6±14.9 to 55.9±23.6 U/g of hemoglobin (P<0.0001). Before supplementation, 11% of patients had GSH-Px activity below the normal range (27.5-73.6 U/g of hemoglobin). After supplementation, all patients showed GSH-Px activity within the normal range. CONCLUSION: The data revealed that the investigated patients presented Se deficiency and that the consumption of only one Brazil nut a day (5 g) during 3 mo was effective to increase the Se concentration and GSH-Px activity in these patients, thus improving their antioxidant status.