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Kidney disease patients should avoid foods with high phosphorus

12/24/2010 18:54:00 admin

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Patients with chronic kidney disease or CKD may be better off eating a vegetarian diet, a new study in the Dec 2010 issue of Clinical Journal of the American Society of Nephrology suggests.

Comparing a vegetarian diet with a meat-based diet, researchers found phosphorous levels decreased in kidney disease patients when they avoided using meat products.

Patients with chronic kidney disease cannot adequately get rid of phosphorus, a mineral commonly found in all types of foods, particularly meat products. In processed meat, phosphates as food additives or testure modifiers are used to increase the water-holding capacity.

High levels of phosphorus in the body have been known to be associated with a number of diseases or conditions including heart disease and death in kidney disease patients.

For the study, Sharon Moe, MD of Indiana University School of Medicine and Roudebush Veterans' Affairs Medical Center and colleagues told eight patients to use a vegetarian or meat-based diet for one week, and then the other diet two to four weeks later.

Two diets contained equivalent protein and phosphorus concentrations. Patients had low phosphorus levels in the blood and the urine when then ate the vegetarian diet, compared with the meat-based diet.

The researchers did not know why eating a vegetarian diet resulted in low levels of phosphorus, but they speculated that phosphorus in plant-foods is not as readily bio-available as the mineral in meat products.

The study suggests patients with chronic kidney disease should not only limit their intake of phosphorus, but also may need to consider avoiding use of meat products.

"These results, if confirmed in longer studies, provide rationale for recommending a predominance of grain-based vegetarian sources of protein to patients with CKD. This diet would allow increased protein intake without adversely affecting phosphorus levels," Moe et al. wrote.

Phosphorus and diseases

A study in a 2008 issue of the same journal suggests higher levels of phosphorus in the blood of patients with moderate CKD may increase calcification of the major arteries and heart valves leading to higher risk of cardiovascular disease.

Coauthor of the study Bryan Kestenbaum, MD, of the University of Washington in Seattle, Washington said very high levels of phosphorus have been linked to elevated risk of cardiovascular disease and vascular calcification in dialysis patients.

Dr. Kestenbaum demonstrated even a mild increase in the blood phosphorus level can boost the risk of cardiovascular events in patients with CKD who are not on dialysis.

High levels of phosphorus are harmful to healthy people as well.

In the same issue of the journal, another study report says that high-normal phosphorus levels are linked to increased coronary artery calcium even in healthy adults without kidney disease.

High levels of phosphorus have been linked in previous studies to attention deficit disorder and attention-deficit hyperactivity disorder in children. Reducing intake of phosphorus in diet may help reduce ADD/ADHD risk.

How to reduce intake of phosphorus?

Phosphorus is a structural component of bone in the form of a calcium phosphate salt known as hydroxyapatite. The mineral in the form of phospholipids is present as major structural components in cell membranes. It is also present in molecules involved in energy production and responsible for the storage and transmission of genetic information.

According to phosadd.com, meat products are not the only foods that contain high levels of phosphorus. The following processed foods and beverages are found high in phosphates, cited in verbatim from phosadd.com.

Soft drinks, soda drinks, especially cola or coke and fizzy lemonade

Cordials/fruit syrup beverages

Chocolate, lollies, sweets, candy, sugar

Ice-cream

Skim milk powder (often added to processed foods)

Biscuits, cookies, cakes from the supermarket

Tomato ketchup

Mayonnaise

Fish fingers

Processed cheese, especially soft cheese spread

Frozen pizzas

Hot dogs

Processed meats

Baking powder and self-raising flour often contains phosphate aerator

All foods that list as an ingredient mineral salts, emulsifiers and lecithin

Phosphorus is found high in some natural foods. But as the current study showed, the mineral in plant-foods may not be as readily available as in meat based foods. The following natural foods contain high levels of phosphorus, cited in verbatim from phosadd.com:

Egg yolks

Milk

Nuts

Wheat germ

Soybeans and their by-products

Peas

Beans

Lentils

Corn

Mushrooms

Oats

Cocoa beans (chocolate)