Losing belly fat and cutting down on processed, phosphorus-laden foods may help reduce the risk of kidney disease, claim researchers from Johns Hopkins University in Baltimore, MD.

Previous studies have shown that it is not just how much fat you have, but where it is on your body that increases the risk of certain diseases. And the distribution of excess fat around the belly has been linked to cardiovascular diseases, type 2 diabetes and now, kidney disease.

The researchers from Johns Hopkins claim that reducing your waist circumference and cutting down on dietary phosphorus have been linked to lower levels of protein in the urine (albuminuria). The presence of this protein in urine is one of the first indicators of kidney disease.

The results are published in the American Journal of Kidney Diseases.

According to the Centers for Disease Control and Prevention (CDC), an estimated 26 million American adults suffer from chronic kidney disease (CKD). This is a silent condition, with many sufferers not aware that they have it until it is quite advanced.

Left untreated, the kidneys lose their ability to clean the blood of waste products that build up, causing damage to bones, increased risk of high blood pressure, anemia, nerve damage and poor nutritional health. It may eventually lead to kidney failure.

The latest figures the CDC published, for 2006, showed that CKD was responsible for 45,000 people’s deaths.

One of the advantages of the current study is that it highlights preventative measures that people can adopt before they have any symptoms of CKD.

Dr. Joseph Vassalotti, chief medical officer at the National Kidney Foundation, says:

Other studies have suggested that once diagnosed with kidney disease, weight loss may slow kidney disease progression, but this is the first research study to support losing belly fat and limiting phosphorus consumption as a possible way to prevent kidney disease from developing.”

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Study participants found that by decreasing their waist circumference and reducing how much processed food they ate, the levels of protein in their urine also dropped.

For the study, researchers led by Dr. Alex Chang examined data collected from 481 participants taking part in the PREMIER study.

The PREMIER study was a multicenter study testing the effect of behavioral interventions of blood pressure. Here, people with prehypertension or borderline hypertension were given counseling and advice about weight loss, healthy diet and exercise.

The 481 participants in Dr. Chang’s study were selected because they had normal kidney function and had provided adequate 24-hour urine collection at both the baseline and 6-month test.

The researchers found that after 6 months, participants had, on average, decreased their belly fat by 4.2 cm and that the amount of albuminurea had also dropped by 25%. In addition, the researchers noted that a 314 mg reduction in phosphorus excretion resulted in an 11% decrease in urine protein.

The study points out that although many natural animal and vegetable proteins contain phosphorus, in the US it is often added to processed foods to enhance the flavor and extend the shelf-life.

And because of its chemical composition, the phosphorus in processed foods – which accounts for about 30% of all the phosphorus consumed in the American diet – and animal proteins is more easily absorbed in the body than plant phosphorus. Plant-based phosphorus is harder for the body to break down.

The study shows that limiting dietary phosphorus may be a simple way to reduce the risks of kidney disease. But, as it has no taste or smell, it may not be as easy as that.

The National Kidney Foundation says to avoid ingredients with the letters “PHOS” at their root. And as it also occurs in many natural products, its presence may not be immediately obvious.

Dr. Vassalotti adds:

A good rule of thumb is that if the food comes in a package, it’s likely to be high in phosphorus. Approximately 90% of phosphorus additives are absorbed by the body. This study suggests limiting the amount of processed foods in your diet may be an easy way to reduce your risk of developing kidney disease.”

The National Kidney Foundation also lists the following as being the “bad boys” of the phosphorus world:

  • Dark colas
  • Flavored waters
  • Cereals
  • Dairy products, including cheese, milk, cream, yogurt and ice cream
  • Deli meats
  • Organ meats (offal)
  • Oysters
  • Sardines
  • Dried beans, lentils and peas
  • Nuts and seeds, including peanut and other nut butters
  • Cocoa, including chocolate-based drinks and desserts.

Medical News Today reported on the findings of two other studies in April this year: Dr. Chang’s study covered diet and kidney disease, while researchers from the Netherlands suggested that “apple-shaped” people were more at risk of getting the disease than “pear-shaped” people.