Effects of clarified açai (Euterpe oleracea Mart) supplementation on oxidative stress markers in hemodialysis patients: A randomized, controlled pilot study

Citation: Da Silva Martins ICV, Mafra D, Rogez H, Nascimento Pinheiro MC, Martins Nascimento JL, et al. (2020) Effects of clarified açai (Euterpe oleracea Mart) supplementation on oxidative stress markers in hemodialysis patients: A randomized, controlled pilot study. J Food Sci Nutr The 6(1): 032-037. DOI: https://dx.doi.org/10.17352/jfsnt.000024 https://dx.doi.org/10.17352/jfsnt DOI: 2641-3043 ISSN: L IF E S C IE N C E S G R O U P


Introduction
Oxidative stress is a very common complication in Chronic Kidney Disease (CKD) patients and becomes more severe in the late stage of the disease, which is exacerbated by the Haemodialysis (HD) procedure [1][2][3].
Several nutritional strategies have focused on reducing oxidative stress in CKD patients. Among these interventions are the consumption of antioxidants naturally present in some foods whose range of physiological intake is considered safe and can be achieved through food intake [4,5].
Açai (Euterpe oleracea Mart), a typical fruit from the Eastern Amazon basin in Brazil, where is consumed daily by the general population of the northern region of Brazil, has expanded to other regions of the country, especially in recent years for its export to various countries [6,7].
In previous clinical trials with healthy individuals, açai pulp improved lipid profi le, lipid peroxidation and free radicals balance, as well as increased levels of antioxidant enzymes [16,17]. Thus, our hypothesis is that açai supplementation in CKD patients may mitigate the oxidative stress, thus leading to clinical improvement. Therefore, the aim of this study is to evaluate the effects of two months of oral açai supplementation on oxidative stress markers in patients with CKD on Hemodialysis (HD).

Participants
Twenty-three HD patients (açai group: 11 patients and control group: 12 patients) from a hemodialysis Center in Belém, Pará, Brazil were eligible for the randomized controlled trial. Six patients in the açai group and four in the control group withdrew from the study. Therefore, completed the intervention eight patients comprised the açai group and ten the control group ( Figure 1).
Patients with access via arteriovenous fi stula in an upper extremity; a dialysis duration of 3-4 hours per session three times weekly on a blood fl ow rate of 350 mL/min to 400 mL/ min; and at least a six month history of hemodialysis were included. Patients with autoimmune and infectious diseases, cancer or AIDS; with serum levels of phosphorus and potassium above 5.5 mg/dL; or who used catabolic drugs, antioxidant vitamin supplements or açai were excluded.

Abstract
Introduction: Patients with Chronic Kidney Disease (CKD) on Hemodialysis (HD) present a reduction of antioxidant enzymes levels and increased production of free radicals. Nutritional strategies have been used to mitigate the this exacerbatedoxidative stress in these patients and supplementation with açai (Amazon fruit Euterpe oleracea) can be a good candidate to exert a protective effect against oxidative stress. The aim of this pilot study was to evaluate the effects of açai supplementation on oxidative stress markers in patients with CKD on HD.
Methods: Eighteen patients were randomized to receive 20 mL of clarifi ed açai pulp juice three times a week for eight weeks (8 patients, 55.5 ± 4.9 years; BMI, 24.8 ± 2.5 Kg/m 2 ) and to be the control group who did not receive any supplementation (10 patients, 56.1 ± 3.4 years, BMI, 25.2 ± 0.7 Kg/m 2 ). Oxidative stress markers plasma levels such as Malondialdehyde (MDA), nitrite, Total Glutathione (TG), Catalase (CAT) and Glutathione Peroxidase (GPx) were evaluated before and after supplementation.
Results: MDA plasma levels were signifi cant reduced from 6.8 ± 1.2 to 5.8 ± 0.9 nmol/mL in açai group (p= 0.037), compared to no signifi cant change in control group. The GSH total level presented slight increase after supplementation in açai group (320.7 ± 59.2 to 492.7 ± 84.8 nmol/mL, p=0.085). For Nitrite, CAT and GPx activity after eight weeks of supplementation with clarifi ed açai (Euterpe oleracea Mart.) pulp there was no change.

Conclusion:
The consumption of clarifi ed açai for eight weeks improved lipid peroxidation in HD patients. This result suggests the promising application of açai as an antioxidant food to patients with CKD on HD.

Experimental design
The patients were manually allocated with a simple randomization method to the experimental group or the

Clarifi ed açai (Euterpe oleracea Mart) pulp juice
The samples of the açai pulp juice with fresh fruits were lyophilized and pasteurized. The açai pulp juice were clarifi ed by a patented process licensed (PI 1003060-3). This process consists of the partial purifi cation of the gross aqueous extract produced by the adsorption technique on macroporous resins that resulted an açai pulp juice higher purity antioxidant extract with absence of lipids, proteins and fi bers [18,19].
The phytochemical composition to evaluate metabolites with antioxidant activity was performed to measure total polyphenols determined by the Folin-Ciocalteu method and total anthocyanins by a pH differential method [18].
Potassium mineral determination was quantifi ed using an atomic absorption spectrophotometer (Thermo, ICE3000) and expressed in mg/L.

Anthropometric parameters and dietary intake
For the anthropometric evaluation, the body mass index (BMI) was calculated as weight divided by height squared, and then the nutritional status was classifi ed according to the World Health Organization [20].

Determination of thiobarbituric acid-reactive substances (TBARS)
This test indicates estimated by the presence of products derived from lipid peroxidation, mainly malonaldehyde (MDA) using the Ohkawa et al (1979) method [21]. The absorbance was measured in a spectrophotometer at 532 nm (BIO-RAD Model 450 Microplate Reader, Hercules, CA, USA).

Nitrite quantifi cation
Plasma nitrite, fi nal product of nitric oxide (NO), was evaluated by the Griess Reagent method [22].

Statistical analysis
Data were expressed as the mean and Standard Deviation (SD). The normal distribution of the data was verifi ed by the Shapiro-Wilk test. The majority of the variables were normally distributed, except for the kinetic index of dialysis adequacy (Kt/V), parathyroid hormone and CAT activity.
The F test was used on independent parametric variables, and since all tests showed similar variations among the groups, the nonmatched Student's t-test was applied. The Mann-Whitney test was used for independent nonparametric and ordinal variables, and the chi-squared test was applied to independent and dichotomous variables. The tests were performed using the statistical package Stata with the confi dence values set to 95% (p<0.05).

Results
The clarifi ed açai pulp juice offered had total polyphenol content was 1013.  Table 1 shows demographic and biochemical parameters in Açai group (3 males) and Control group (9 males) at baseline moment and Table 2 shows the food intake profi le in both groups. Table 3 shows the effects of supplementation with clarifi ed açai (Euterpe oleracea Mart.) pulp juice on the MDA, nitrite and GSH total level, CAT and GPx activity before and after 2 months in HD patients. The results showed a signifi cant reduction in plasma MDA levels and a slight increase in the total GSH levels after supplementation.

Discussion
During the last decade, açai has been studied because of its richness in bioactive compounds that exert effects on the balance of oxidative stress 8 . In hemodialysis patients, antioxidant-rich foods seem to have a protective effect on oxidative stress and cardiovascular damage, which is responsible for the high mortality of this group [25][26][27]. We found with the supplementation of clarifi ed açai pulp juice for two months, a decrease in plasma MDA levels in HD patients, which may have benefi ts in improving oxidative stress. This study is the fi rst work describing the effects of intervention with clarifi ed açai (ideal model to evaluate the impact of isolated phenolic components and with high antioxidant capacity detected by the DPPH method) in patients with CKD on HD 10 .
A pilot clinical study randomized, double-blind, placebocontrolled of phase I in healthy individuals, showed that the ingestion of 120 mL juice containing a mixture of fruits and berries including predominantly açai, increased signifi cantly the serum antioxidant capacity at one hour and two hours after consumption as well as reduced the lipid peroxidation [31].
To evaluate oxidative stress, MDA was used as a lipid peroxidation marker, whose reduced plasma levels is associated with progression of CKD stages [32]. Our pioneering study showed, even as a pilot study, results similar to those found with supplementation of red fruit juice with a slightly larger sample size of 21 patients on HD and shorter intervention time for two months [33]. Similar result was found with supplementation pomegranate juice intake in 101 HD patients for one year [34]. In animal model of renovascular hypertension, the extract of açai around 200 mg/kg, was also able to prevent lipid peroxidation [35]. The mechanism involved appears to be related to the anthocyanins that have an important role on protection in the cells of oxidative damage, this probably involves its action as a reduction in ROS produced in polymorphonuclear cells, and reduced of migration of pro-infl ammatories [31]. However, it is still uncertain if lipid peroxidation may not only be the cause, but also the result of cell damage, since progression of CKD stages is associated with the value of MDA and increased consumption of antioxidant enzymes [36,37]. Data are presented as the mean ± SD or as median and confi dence interval The p value is representative of the intergroup analysis. Data are presented as the mean ± SD. Furthermore, it is inaccurate to assume a dose-time effect due to the low bioavailability of anthocyanins in organisms and the associated absorption factors that lead to synergistic açai components and metabolite effects because they induce intestinal microbiota modifi cation [38].
Our work suggests that supplementation with açai may be benefi cial in protecting against damage caused by oxidative stress. Moreover, quantifying açai recommendations is still needed because dietary and pharmacological interaction factors are unknown [38].
As limiting factor of this work, the small size of the sample, the absence of the evaluation of the antioxidant capacity and the total phenolic compounds plasma levels. However, this was the fi rst randomized pilot trial that obtained time-response association between clarifi ed açai juice and reduction in lipid peroxidation in HD patients.

Conclusion
In conclusion, despite our study having a small sample size, the consumption of clarifi ed açai for eight weeks it seems improved lipid peroxidation in HD patients. This result indicates the promising application of açai as an antioxidant action in patients with CKD. Thus, it is desirable outcomes that polyphenol-rich interventions may inhibit or slow down oxidative stress in hemodialysis patients. From this fi nding, future studies in larger populations are needed to verify how much the açai is able to assist in combating the sequelae of free radicals.