Essential fatty acid deficiency in renal failure: can supplements really help?

Pathophysiological and clinical aspects of malnutrition in chronic renal failure

Kidney diseases are the ninth leading cause of death in the USA. In these patients cardiovascular mortality is greater than in the general population. This observation, not completely explained by the so-called 'traditional' cardiovascular risk factors, lead the authors to postulate other 'emerging' ones found in chronic renal failure patients. Among these new findings, nutritional status, considered as the balance existing between nutrient requirements and intakes, plays an important role for the development of cardiovascular diseases. In fact several nutritional parameters are widely known as pathophysiological determinants of cardiovascular disturbances, which are based on accelerated atherosclerosis, due especially to enhanced oxidative stress and endothelial dysfunction. Chronic renal failure is a clinical condition that from many points of view seems to be a chronic inflammatory state, and many studies confirm this observation. This influences nutritional status especially in dialysis patients. Malnutrition is related in turn to accelerated atherosclerosis thus leading to a postulated 'malnutrition, inflammation, atherosclerosis' (MIA) syndrome in which malnutrition, inflammation and atherosclerosis contribute to an elevated cardiovascular mortality rate. The present review explores this issue, first by describing epidemiological aspects of malnutrition in chronic renal failure patients and then by analysing the specific biochemical and metabolic features of these patients.

Efficacy of omega-3 fatty acids supplementation in treatment of uremic pruritus in hemodialysis patients: a double-blind randomized controlled trial

BACKGROUND

Uremic pruritus is a common and bothersome complaint among end-stage renal disease which affect between 25% and 60% of this population .But there is no decisive cure for treatment of it. In this study, the effects of omega-3 for treatment of pruritus were investigated in hemodialysis patients.

METHODS

A double-blind randomized study was carried out in the form of placebo-controlled crossover study in four dialysis centers in Tehran, Iran during 2008. At first, 22 hemodialysis patients suffering from pruritus with previous drug resistance were selected. Next, these patients were randomly allocated into two groups of omega-3-placebo (group A) and placebo-omega-3 (group B) .Patients in group A were treated with a 1-gram Fish oil capsule for 20 days, and subsequently, they were treated with placebo for 20 days after a 14-day wash-out period .But the reverse act was done in group B.The pruritus assessment was made quantitatively through Detailed Pruritus Score.

RESULTS

Pruritus was decreased up to 65% from score mean of 20.3 (95% CI: 16.7-23.8) to 6.4 (95% CI: 2.9-9.8) in omega-3 group and the decrease in the placebo group was 15% from score mean of 17.0 (95% CI: 12.4-21.6) to 14.4 (95% CI: 10.5-18.2).So the level of statistical difference was significant (P=0.0001).

DISCUSSION

Omega-3 fatty acids found to be more effective than placebo in decreasing of uremic pruritus. So it seems that Omega-3 fatty acids could be used as an efficient drug for treatment of pruritus in uremic patients.

Effect of n-3 fatty acids on nutritional status and inflammatory markers in haemodialysis patients

AIMS

Nutrition as an aetiological factor participates a great deal in premature atherosclerosis in haemodialysis (HD) patients. The basic mechanisms of end-stage renal disease and premature atherosclerosis are connected with changes in cell functions at the membrane level. We investigated the red cell membrane fatty acids and the effects of fish oil supplements on nutritional status and inflammatory markers in HD patients.

METHODS

We examined 42 HD patients (mean age 55 +/- 8 years). The control group consisted of 16 healthy subjects of similar age and sex to the tested group. HD patients were administered supplements with 2.4 g of n-3 polyunsaturated fatty acids per day for 2 months. Before and after supplementation, we examined plasma lipids, cell membrane erythrocyte phospholipids content, serum albumin, haemoglobin, interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-alpha).

RESULTS

Baseline values in the tested group confirmed the presence of essential fatty acids deficiency. A statistically significant negative correlation between TNF-alpha and eicosapentaenoic acid (EPA) (r = -0.497; P < 0.05) and IL-6 and EPA (r = -468; P = 0.03) was found in HD patients before supplementation. There was a significant increase in docosahexaenoic acids, high density lipoprotein cholesterol, plasma albumin, haemoglobin levels in HD patients after supplementation (P = 0.0001). There was a significant increase in EPA (P = 0.01) after treatment, and there was a significant decrease in inflammatory markers (IL-6 and TNF-alpha, P = 0.0001) after supplementation in the tested group.

CONCLUSION

A dietary regime with fish oil could be used in dialysis patients to slow down the development of atherosclerosis and improve nutritional parameters.

Plasma and erythrocyte phospholipid fatty acids composition in Serbian hemodialyzed patients

Dyslipidemia is one of the possible risk factors for advanced atherosclerosis in patients with chronic renal failure. Abnormal phospholipid metabolism may play an important role in the progression of atherosclerosis in patients with renal failure. The aim of this study was to determine specific characteristics of plasma and erythrocyte phospholipid content and fatty acid composition in 37 patients with chronic renal failure on hemodialysis (HD). The results were compared with the characteristics of healthy subjects. Briefly, plasma triglyceride (p < 0.001), total cholesterol (p < 0.05), and total phospholipids (p < 0.01) levels were significantly higher and HDL-cholesterol level significantly lower (p < 0.01) in HD patients. Plasma phosphatidylcholine and phosphatidylethanolamine concentration were significantly higher (p < 0.001) in HD patients. The plasma phospholipid fatty acids composition indicated significantly (p < 0.01) higher level of oleic (18:1 n-9) and lower levels of eicopentaenoic (20:5 n-3 EPA) and docosahexaenoic (22:6 n-3 DHA) acids (p < 0.05). However, in HD patients, the relative concentration of plasma phospholipid n-6 polyunsaturated fatty acid (PUFA) was significantly lower (p < 0.05). The fatty acid composition of erythrocyte phospholipid in HD patients was modified with EPA and DHA levels significantly lowered (p < 0.05). Our results demonstrate an abnormal phospholipid metabolism and deficiency of n-3 PUFA in plasma and erythrocyte phospholipids in hemodialyzed patients.

EFA supplementation in children with inattention, hyperactivity, and other disruptive behaviors

This pilot study evaluated the effects of supplementation with PUFA on blood FA composition and behavior in children with Attention-Deficit/Hyperactivity Disorder (AD/HD)-like symptoms also reporting thirst and skin problems. Fifty children were randomized to treatment groups receiving either a PUFA supplement providing a daily dose of 480 mg DHA, 80 mg EPA, 40 mg arachidonic acid (AA), 96 mg GLA, and 24 mg alpha-tocopheryl acetate, or an olive oil placebo for 4 mon of double-blind parallel treatment. Supplementation with the PUFA led to a substantial increase in the proportions of EPA, DHA, and alpha-tocopherol in the plasma phospholipids and red blood cell (RBC) total lipids, but an increase was noted in the plasma phospholipid proportions of 18:3n-3 with olive oil as well. Significant improvements in multiple outcomes (as rated by parents) were noted in both groups, but a clear benefit from PUFA supplementation for all behaviors characteristic of AD/HD was not observed. For most outcomes, improvement of the PUFA group was consistently nominally better than that of the olive oil group; but the treatment difference was significant, by secondary intent-to-treat analysis, on only 2 out of 16 outcome measures: conduct problems rated by parents (-42.7 vs. -9.9%, n = 47, P = 0.05), and attention symptoms rated by teachers (-14.8 vs. +3.4%, n = 47, P = 0.03). PUFA supplementation led to a greater number of participants showing improvement in oppositional defiant behavior from a clinical to a nonclinical range compared with olive oil supplementation (8 out of 12 vs. 3 out of 11, n = 33, P = 0.02). Also, significant correlations were observed when comparing the magnitude of change between increasing proportions of EPA in the RBC and decreasing disruptive behavior as assessed by the Abbreviated Symptom Questionnaire (ASQ) for parents (r = -0.38, n = 31, P < 0.05), and for EPA and DHA in the RBC and the teachers' Disruptive Behavior Disorders (DBD) Rating Scale for Attention (r = -0.49, n = 24, P < 0.05). Interestingly, significant correlations were observed between the magnitude of increase in alpha-tocopherol concentrations in the RBC and a decrease in scores for all four subscales of the teachers' DBD (Hyperactivity, r = -0.45; Attention, r= -0.60; Conduct, r = -0.41; Oppositional/Defiant Disorder, r = -0.54; n = 24, P < 0.05) as well as the ASQ for teachers (r = -0.51, n = 24, P < 0.05). Thus, the results of this pilot study suggest the need for further research with both n-3 FA and vitamin E in children with behavioral disorders.

Red blood cell fatty acid profile of chronic renal failure patients receiving maintenance haemodialysis treatment

The fatty acid profile of chronic renal failure (CRF) patients on maintenance haemodialysis treatment (MHT) is abnormal and results point towards an essential fatty acid (EFA) deficiency. However, controversies still exist as to which of the essential fatty acids (EFAs) or EFA-products are decreased. In this study, the results of a comprehensive analysis of the fatty acids, performed on the red blood cells of 14 CRF patients on MHT, are presented. The red blood cell membrane fatty acids determined in this study include a range of saturated fatty acids (SFAs), mono-unsaturated fatty acids (MUFAs) and poly-unsaturated fatty acids (PUFAs). Results confirmed the suggested presence of an essential fatty acid deficiency in CRF patients on MHT. It showed the total content of the n-6 fatty acids (31.66 +/- 3.21 vs 34.67 +/- 2.05), as well as the total content of the PUFAs (37.22 +/- 4.08 vs 40.93 +/- 2.35), to be significantly decreased. The total MUFA content was, in contrast, significantly increased (16.87 +/- 0.91 vs 15.49 +/- 1.18). The EFA deficiency profile seen in this study points towards that of a chronic inflammatory condition. This is borne out by the fact that all three precursors of the eicosanoids--the mediators of various inflammatory and immune responses--were reduced in the presence of an increase in MUFAs as well as SFAs. The possibility of the fatty acid profile of CRF patients on MHT being that of a chronic inflammatory condition is supported by the fact that continuous complement-dependent and complement-independent immune activation, due to bio-incompatibility between blood cells and the dialysis membranes, is known to occur during the dialysis process.

Association of fish intake and survival in a cohort of incident dialysis patients

Multiple studies in the general population have shown cardioprotective and survival benefits associated with dietary fish intake, but little is known about outcomes associated with dietary fish intake in patients with chronic renal failure. We investigated fish consumption and survival in 216 incident dialysis patients. Fish consumption was identified in a 24-hour dietary recall and a 3-day food diary collected at baseline (near treatment start) and a 3-day food diary collected 1 year later. Patients who reported fish intake had higher average serum albumin levels at baseline than patients who did not report fish intake. Patient survival was followed up for an average of 3 years from baseline. In univariate Cox regression models, younger age, black race, peritoneal dialysis rather than hemodialysis as initial treatment modality, absence of cardiovascular comorbidity, higher self-assessed physical functioning, and fish consumption were significantly associated with patient survival. A multivariable Cox proportional hazards regression analysis showed that dietary fish consumption independently predicted patient survival, controlling for all other variables in the model. In multivariable analysis, patients who were younger, black, and had higher mental health scores at baseline also had a significantly decreased mortality risk. Patients who reported fish consumption were approximately 50% less likely to die during the study interval. Health outcomes associated with fish consumption merit continued study in patients with chronic renal failure.