Prevention is a proactive pursuit. Whether we are talking about teaching our children to look both ways when crossing the street, or taking aspirin to avoid a heart attack, the process is the same: we implement an active strategy to avert a possible disaster.

For the last decade I have shifted my practice from the world of interventions-angioplasties, stents, and electrophysiologic procedures-to at times, the more trying task of understanding risks that lead to myocardial infarction and sudden cardiac death. Exercise, dietary adjustments, stress modification, lipid management, omega-3 fatty acids, and appropriate medications have become the cornerstones of a well-constructed program to avoid heart disease. Although cardiovascular disease remains the leading cause of death in the western world, preventive strategies have successfully made a sizable dent in its impact.

 So what does all this heart disease talk have to do with chronic kidney disease?

Because Stage 5 CKD is a disease that carries a terrible prognosis, the life expectancy of chronic dialysis patients is reduced 20 to 25 years, giving the typical dialysis patient a 20% annual mortality. Putting this in perspective, of the approximately 400,000 chronic hemodialysis patients in the United States, we can expect that nearly 80,000 will die each year.

Chronic hemodialysis increases the risk of cardiovascular death ten-fold and greater than half of all ESRD deaths are the direct consequence of heart disease. In fact, in many circles CKD-like diabetes and peripheral vascular disease-is considered to be a cardiovascular risk equivalent. In other words, from a cardiologist's perspective, a patient with CKD is the same as one with known significant coronary artery disease. The logical consequence of this realization is for us to approach CKD patients with very much the same preventive tactics that we use for heart patients. With inflammation likely one of the salient links between heart and kidney disease, it makes sense to focus on methods to limit inflammation in these patient populations.

Understanding the value of omega-3
The omega-3 fatty acids have become popular in both the medical and lay press. The omega-3s are polyunsaturated fatty acids (PUFAs), meaning they contain more than one double bond. The "3" refers to the location of the first double bond, counting from the terminal end of the molecule. The "essential" omega-3 (cannot be made by the body) is alpha linolenic acid (ALA), an 18-carbon molecule containing 3 double bonds. It is found in many nuts and oils. ALA can be converted to the far more biologically active 20-carbon omega-3 eicosapentaenoic acid (EPA). Even more active than EPA is the 22-carbon fatty acid, docosahexaenoic acid (DHA). Unfortunately DHA cannot be manufactured to any significant degree and so we must rely upon our diet-predominantly fish-and supplements to provide what we need in order to maintain optimal health. Both EPA and DHA confer the health benefits we will be discussing.

On a biochemical basis the benefit of the omega-3s can be best understood when looking at their relationship to another class of fatty acids, the omega-6s. These fats, which are overrepresented in the typical western diet, compete with omega-3s for crucial enzymes. Linoleic acid (LA), the 18-carbon "essential" omega-6 competes with ALA, while arachidonic acid, the 20-carbon product of LA, competes with EPA. As a fair generalization, the more omega-6s we have, the more inflammation and thrombosis, while a preponderance of omega-3s result in opposite effects, anti-inflammation and anti-thrombosis. Since both heart disease and kidney disease are now understood to be states of increased inflammation, the omega-3s clearly weigh in on the side of enhanced health when it comes to managing these common disorders.

EPA and DHA have been extensively evaluated in medical literature. Although benefit is yet to be confirmed in all of these disorders, the current areas of interest include colitis, dementia, macular degeneration, weight loss, heart attacks, stroke, arthritis, dry eyes, depression, atrial fibrillation and other arrhythmias. What is clear already is that omega-3s decrease triglyceride levels by about 8% for every 1,000 mg of combined EPA and DHA taken daily. It is also known that EPA and DHA decrease the incidence of sudden cardiac death and decrease cardiovascular events, such as heart attacks, arrhythmias, and the need for angioplasties, stents, and coronary artery bypass surgery. Direct receptor mediated processes account for the electrical effects of the omega-3s, but the lion's share of benefits are felt to be a product of the powerful anti-inflammatory effects of not only EPA and DHA, but their recently discovered byproducts-resolvins and protectins-as well. While EPA and DHA help defend against the initiation of an inflammatory response, resolvins and protectins actually abort inflammation and terminate the destructive cycle that would otherwise ensue.

When advising our patients which omega-3 fish oil products to purchase, there are three points to clarify. First, be sure that the label is being appropriately interpreted-we are searching specifically for 1,000 mg of combined EPA and DHA per day (not 1,000 mg of fish oil). Look at the number of soft gels per serving size and the amount of combined EPA and DHA per soft gel. The number of pills needed can range anywhere from one to five a day, so this is an important exercise. Second, if patients have trouble with the common side effect of a fishy burp, have them take an enteric-coated product. Finally, if patients are concerned about the quality of their fish oil, direct them to an independent organization such as consumerlab.com where their recently completed evaluation of 49 commonly utilized omega-3 fish oil products can be reviewed.

Protein and ESRD
So now that we've added a healthful fat to the diets of our patients with CKD, let's turn our attention to another macronutrient: protein. We all understand that protein is essential for building muscles, but many do not appreciate the ubiquitous needs of protein. Protein plays a pivotal role in building and repairing lean body tissues, including muscles, tendons, the circulatory system, brain, immune system, skin and other organs. Protein is not just for athletes; it is required by every single cell in our body. When it comes to CKD and ESRD in particular, protein takes on an even more critical role. Let's first evaluate the impact that dialysis has upon our protein stores.

Chronic hemodialysis produces a severely catabolic state. During a typical dialysis session, three grams of protein and eight grams of amino acids can be lost. Protein synthesis is decreased, body stores of protein are broken down, and there is an increase in protein excretion as well. Unfortunately, whole body catabolism persists for two hours following hemodialysis. To compound this metabolic downward spiral, dialysis patients are often plagued by an altered sense of taste and an aversion to the very foods that would improve their protein stores - meat, chicken, and even fish. The net effect is a state of uremic malnutrition, one that afflicts between 20% and 50% of ESRD patients. As a result, not only does muscle mass decrease, but albumin, the most important plasma protein, declines as well. Because albumin has such diverse benefits, the adverse consequences of low albumin are legion. Albumin maintains osmotic pressure, functions as a powerful antioxidant, and carries hormones, vitamins E, C, and the antioxidant enzyme, glutathione. Albumin even serves as a sort of sacrificial lamb, placing itself in fatal jeopardy in order to break the chain of an out-of-control free radical spiral. Low albumin levels also result in a vicious cycle of malnutrition and inflammation wherein low albumin leads to inflammation which leads to anorexia-lowering albumin levels, which leads to more inflammation. When albumin levels fall, there is a hefty price to pay.

Rating protein quality
There are a number of methods of rating protein quality as well as a number of potential sources of protein. The Biological Value (BV) of protein was previously the preferred method of rating proteins. It provides a measure of the amount of nitrogen retained by the body for a given protein load. Recently the Protein Digestibility Corrected Amino Acid Score (PDCAAS) supplanted this methodology. The PDCAAS takes into consideration not just how much protein is retained by our bodies, but whether or not the protein provides an appropriately balanced allotment of all the essential amino acids. A PDCAAS score of one is optimal and is shared by whey, milk, casein, and egg. When repleting our malnourished ESRD patients, we should be sure to provide optimal protein quality as well as optimal protein density. Our goal is to give these individuals a large amount of top-quality protein in a delectable form that engenders continued use of the protein source.

Conclusion
 It is usually necessary to make certain minor sacrifices in order to accomplish the more consequential goal of reversing uremic malnutrition. Some of these sacrifices will include extra calcium and/or phosphorus (which are invariably associated with good protein sources such as chicken, fish, and beef), potassium and even sodium. It is well worth it though, as patients' higher albumin levels should translate into fewer hospitalizations, a better quality of life, and a lower incidence of life-threatening ailments.


Dr. Baum is a cardiologist and founder and director of Clinical Development VitalRemedyMD, based in Boca Raton, Fla.


NIH conference looks at the health effects of vitamin D

 Peggy Harum, RD, LD

The National Institute of Health convened a panel of experts to review available data on the health effects of vitamin D. Major gaps in the evidence were found. Data is strongest in the area of bone health among elderly men and post-menopausal women, suggesting that increased vitamin D intake can improve bone health and prevent falls.

Less is known about the impact of vitamin D on other stages of the life cycle and in racial and ethnic groups.

Intriguing findings from research conducted in recent years have led to increased interest in vitamin D among health care providers, researchers, and the general public, including concern about possibly widespread deficiency, calls for supplementation, and even use of large doses of vitamin D as treatments for a variety of conditions.

"Given recent findings, it's easy to see why people are so enthusiastic about the potential power of vitamin D, but we must recognize the limitations of any study and exercise caution when making broad public health recommendations," said Mary Frances Picciano, PhD, a senior nutrition research scientist in the NIH Office of Dietary Supplements. "This is a very complex set of issues and there is still a lot we don't know about how vitamin D levels affect health, especially across different age groups and ethnic populations."

"It's tempting to think that an essential nutrient is safe at any level - that if some is good, more is better," said Paul M. Coates, PhD, director of the Office of Dietary Supplements. "We've learned that this isn't always true, and there are potential harms associated with high levels of many nutrients."

Findings from the NIH conference, "Vitamin D and Health in the 21st Century: An Update" are summarized in the August 2008 issue of the Journal of Clinical Nutrition.

Participants in the NIH conference identified a number of limitations of the existing evidence on vitamin D, including:

• Many studies failed to control for factors that could confuse study findings such as diet, baseline vitamin D status, age, disease, season (as relevant to sun exposure), body mass index, skin pigmentation and physical activity

• Few studies examined the effects of vitamin D independent of calcium

    or other nutrients

• Reliable data on the vitamin D content of foods is not available

• Existing lab tests used to measure vitamin D levels in blood vary widely

• Preliminary research findings suggest arole for vitamin D in preventing chronic diseases such as diabetes, immune function, and cancer, but further study is needed

• Research has not identified the vitamin D levels needed to achieve desired health outcomes in people at various life and reproductive stages and in dark skinned individuals

Vitamin D, an essential component in bone health that helps ensure that the body absorbs calcium, comes from three sources: sunlight, dietary supplements, and foods. Most people meet their vitamin D needs through exposure to sunlight, but questions remain about what amount of sun exposure would yield beneficial levels of vitamin D without unacceptably elevating skin cancer risk. Very few foods naturally contain vitamin D, so much of the vitamin D in Americans' diet comes from fortified foods such as milk and cereal. Small amounts of vitamin D are found in beef, liver, cheese, and egg yolks.

The Recommended Dietary Allowance (now being revised) will be known as Dietary Reference Intake (DRI) and is a collaborative effort between the United States and Canada. Until now the daily recommendation of vitamin D is 400 international units for children age 4 and up, as well as males and females to age 50 years.

Without sufficient vitamin D, bones can become thin, brittle or misshapen. Vitamin D deficiency can lead to rickets in children and osteomalacia in adults. Together with calcium, vitamin D also helps protect older adults from developing osteoporosis. However, excess vitamin D intake can also cause harmful side effects, including nausea, vomiting, diarrhea, constipation, and development of kidney stones.
 
A study published in the July 2008 issue of the Journal of Renal Nutrition found that ergocalciferol (vitamin D2) supplementation (50,000 IU/week x 24) was associated with significant improvements in serum 25 (OH) D in stage 5 chronic kidney disease patients. In the dialysis patient population, there is emerging clinical evidence that IV Vitamin D therapy is associated with a survival advantage as well as a decrease in mortality.