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Alkaline Diets and Kidney Disease

Many dangerous fad diets exist that purport to treat diseases such as cancer by manipulating the pH of blood with different foods. While there is no good evidence that acidic foods alter the body’s pH and promote disease, the hypothesis that “dietary acid load” relates to disease should not be completely dismissed. The kidney serves to regulate blood pH, but if kidney function declines and other tissues catabolize to maintain pH, then it is very plausible that manipulating the diet to reduce the acid load could spare tissues and improve outcomes in chronic kidney disease (CKD). After all, for example, the metabolism of amino acids yields hydrogen ions, whereas fruits and vegetables contain organic salts that generally reduce acid load when metabolized. Recently, a growing number of human studies that manipulate diet acid load using fruits and vegetables and sodium bicarbonate support this hypothesis. Let’s take a look at some of them.

The first randomized controlled trial on bicarbonate supplementation and CKD progression was published in 2009 by de Brito-Ashurst and colleagues. Bicarbonate is produced by the kidneys and serves to neutralize acid. Supplementation of bicarbonate for 1 year in CKD patients slowed the progression of kidney disease as suggested by creatinine clearance and reduced the need for dialysis. The next year, in 2010, a 5-year trial was published by Donald Wesson’s group that found a slowed kidney decline as measured by estimated glomerular filtration rate (eGFR) with bicarbonate supplementation. Several subsequent studies by his group have used bicarbonate or fruits and vegetables to achieve beneficial outcomes. Goraya et al. gave oral bicarbonate or enough fruits and vegetables that were estimated to reduce dietary acid load by 50% to CKD patients for 30 days and also observed a slowed reduction in eGFR in patients at moderate, but not mild, stages of the disease. In patients with more advanced stages of CKD, one year of bicarbonate or fruits and vegetables did not slow the decrease in eGFR, though several urinary markers of kidney injury were reduced. Their most recent trial tested if kidney function might be preserved through a reduction in angiotensin II in moderate stage CKD patients. Three years of bicarbonate or increased fruits and vegetables lessened the decline in eGFR and resulted in a corresponding decrease in the marker angiotensin II. Other studies using bicarbonate from six months to two years have provided strong evidence that reducing acid load consistently slows the decline of eGFR, and improves markers of bone health and muscle function.

Each of the studies described provided fruits and vegetables to patients free of charge to increase adherence. It will be important to test if adherence can be maintained through education alone. Additionally, it may be that “prescribing” fruits and vegetables is effective at improving outcomes and reducing health care costs more so than bicarbonate since they also reduce blood pressure. While “alkaline diets” in general should be viewed skeptically, there is accumulating evidence that fruits and vegetables as dietary alkali do indeed help in kidney disease.

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Living the Mediterranean Lifestyle

By Emily Roberts

The Mediterranean Diet is based on the eating patterns in the Mediterranean region and focuses on fruits, vegetables, fish, whole grains and healthy fats (1).  A diet not invented, but discovered, is now recognized as one of the healthiest dietary patterns (2). UNESO defines it as “a social practice based on all the “savoir-faire”, knowledge, traditions ranging from the landscape to the table and covering the Mediterranean Basin, cultures, harvesting, fishing, conservation, processing, preparation, cooking and in particular the way we consume” (3). The Mediterranean region is considered the Mediterranean Basin that borders the Mediterranean Sea and includes parts of seven countries: France, Portugal, Italy, Spain, Greece, Malta and Cyprus (4). There have been foreseen health benefits of consuming this diet, classifying it as “heart healthy” due to its likelihood to reduce the risk for heart disease (5,6). Living on the southern coast of France, I not only experience the Mediterranean lifestyle, but I have the opportunity to consume a Mediterranean Diet.

The Discovery

The Mediterranean Diet was discovered to have particular health benefits by Ancel Keys of the University of Minnesota in the 1950’s. He happened upon this discovery while studying the health of poor populations in Southern Italy in comparison to the wealthy in New York. He found the Italian populations had lower levels of cholesterol and a low rate of coronary heart disease (1).

Typical Foods

The diet is full of fresh foods including fruits, vegetables, herbs, fish, olive oil, breads, nuts and pastas (1). There is a very low consumption of red meats, poultry, butter, refined grains and processed foods. The diet is rich in fiber, monounsaturated fats and polyunsaturated fats, antioxidant compounds, and essential vitamins and minerals; conversely, it is very low in saturated fats. Given the diet’s composition of nutrient dense foods, strong adherence to this diet is associated with improved nutritional adequacy (2).

The Benefits

A strong adherence to the Mediterranean Diet enhances the chances of improving your health status. It has been found to reduce the risk for mortality, especially due to cardiovascular disease (7). There have been many cohort studies conducted in the Mediterranean Basin often showing good adherence to the diet and resulting in reduced incidence for cardiovascular events (6). The benefits of the diet are likely to improve with physical activity as well, such as decreased blood levels of LDL (1).

My observations

During my time in the south of France I have noticed the influence the agriculture and natural resources of the Mediterranean Basin has on the cuisine. This area is rich in olive groves, offering a plentiful supply of fresh olive products. The sea offers fresh fish, shellfish and other seafood, while local markets sell fresh fruits and vegetables. Cattle farms are not as populous in this area, so the consumption of red meat and butter is not as high as other European regions (such as Northern France). However, considering I am still residing in France, pastries, baguettes, and of course cheese are a typical part of the French dietary meal pattern. This differentiates my diet somewhat from other Mediterranean regions. Thankfully, walking as a means of transport is very common if not necessary, offering an efficient form of daily exercise. Fresh and homemade are the two words that best describe home cooking near the Mediterranean.  While residing with a local French family, I ate many freshly prepared meals. Everything made from scratch from salad dressings to whole grain bread.

The Mediterranean Diet is not an effort, rather a daily practice for many Europeans. As Americans, we may recommend it as a diet intervention or integrate it into our own eating habits for health reasons. This diet is seen to be successful by offering significant health benefits. This encourages me to try various diets from around the world that could potentially provide various health benefits for Americans, as well as a taste of a new culture.

1.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3684452/

3.La DiÈte MÉditerranÉenne 2010. Candidature transnationale en vue de l’inscription sur la Liste ReprÉsentative du Patrimoine Culturel ImmatÉriel de l’HumanitÉ. Espagne / GrÈce / Italie/Maroc, Version Informations Additionnelles.