Polyunsaturated fatty acids of the n-3 class in chronic dialysis

Mitochondria: a new therapeutic target in chronic kidney disease

Cellular metabolic changes during chronic kidney disease (CKD) may induce higher production of oxygen radicals that play a significant role in the progression of renal damage and in the onset of important comorbidities. This condition seems to be in part related to dysfunctional mitochondria that cause an increased electron "leakage" from the respiratory chain during oxidative phosphorylation with a consequent generation of reactive oxygen species (ROS). ROS are highly active molecules that may oxidize proteins, lipids and nucleic acids with a consequent damage of cells and tissues. To mitigate this mitochondria-related functional impairment, a variety of agents (including endogenous and food derived antioxidants, natural plants extracts, mitochondria-targeted molecules) combined with conventional therapies could be employed. However, although the anti-oxidant properties of these substances are well known, their use in clinical practice has been only partially investigated. Additionally, for their correct utilization is extremely important to understand their effects, to identify the correct target of intervention and to minimize adverse effects. Therefore, in this manuscript, we reviewed the characteristics of the available mitochondria-targeted anti-oxidant compounds that could be employed routinely in our nephrology, internal medicine and renal transplant centers. Nevertheless, large clinical trials are needed to provide more definitive information about their use and to assess their overall efficacy or toxicity.

Review of the Effects of Omega-3 Supplementation in Dialysis Patients

Chronic dialysis patients experience a host of conditions that limit quality and length of life, and recent therapeutic strategies have had only modest success in ameliorating many of these problems. By mediating cell membrane function and structure and the synthesis of lipid mediators such as eicosanoids, omega-3 fatty acids may offer dialysis patients a host of therapeutic benefits. Omega-3 fatty acids are derived primarily from dietary sources, and cold-water fish is the main source of eicosapentanoic and docosahexanoic acids, the two major bioactive omega-3 fatty acids. Studies of omega-3 supplementation in dialysis patients describe salutary effects on triglyceride levels, dialysis access patency, and perhaps uremic pruritus and oxidative stress. In contrast, the putative hematologic, antihypertensive, anti-inflammatory, and antiarrhythmic effects are not as well documented. Adverse effects generally have been limited to gastrointestinal complaints. Unfortunately, the preponderance of published studies are characterized by suboptimal study design, small sample sizes, supraphysiologic omega-3 doses that may be difficult to consume for extended periods, little long-term follow-up, and a lack of confirmation of compliance. Not surprising, the 2005 National Kidney Foundation Kidney Disease Outcomes Quality Initiative Clinical Practice Guidelines for Cardiovascular Disease in Dialysis Patients recommend further research in this field. In summary, although preliminary data suggest that omega-3 fatty acids may have clinical benefits, formal recommendations encouraging omega-3 supplementation of dialysis patients are premature until long-term and adverse effects are better defined.

Benefits of fish oil supplementation for hemodialysis patients

A literature review on fish oil supplementation in the population undergoing chronic hemodialysis therapy suggests that supplementation may be beneficial for various challenges to health and well-being prevalent in this population. One study indicated that pruritus symptoms improved with fish oil supplementation, but not with supplementation with two other oils. In a study designed to determine whether fish oils could prevent vascular access graft thrombosis, graft patency rates were approximately 76% in the fish oil and approximately 15% in the placebo group (P>.03). In a pilot study, subjects given fish oil required 16% less erythropoietin and experienced a 3.6% increase in serum albumin levels. Some studies suggest that fish oil supplementation in hemodialysis patients is cardioprotective, with one study finding that "fish eaters" are half as likely to die as "non-fish eaters." Potential risks of supplementation include gastrointestinal distress, prolonged bleeding, and vitamin A toxicity, although the likelihood of serious side effects is probably low. Dietitians are in a position to advise physicians and/or patients regarding appropriate dosages and ways to minimize risks when supplementation seems warranted. Future research could compare the benefits of fish consumption with those of fish oil supplementation and explore the benefits of other n-3 fatty acid sources, such as flaxseed.