Dear Food Speak: My mother's having trouble managing her blood pressure, and it's now affecting her kidneys. Her doctor suggested she learn the DASH diet. Is that a good call?

G.Y., Fairfield

High blood pressure is a leading cause of kidney disease. Elevated blood pressure makes the heart work harder and can damage blood vessels over time. If blood vessels in the kidneys are affected, the kidneys lose their ability to filter waste and extra fluid from the blood. That can raise blood pressure further, causing a vicious cycle. Having high blood pressure increases the chances that kidney disease will worsen.

People with high blood pressure, including those at risk for kidney disease, can benefit from the DASH diet (Dietary Approaches to Stopping Hypertension). This diet is rich in calcium, potassium and magnesium -- nutrients proven to lower blood pressure. Emphasis is on fruits, vegetables, low-fat dairy, lean protein such as fish and poultry, whole grains, legumes and nuts.

Usually in the later stages of kidney disease, nutrients such as potassium and phosphorous can build up in the blood, raising the risk of serious health problems. Since the DASH diet is high in potassium and phosphorous and provides more protein than some people's failing kidneys can handle, a person with kidney disease may require a modified version of the diet. Studies show that a protein-controlled diet may slow the progression of chronic kidney disease.

If your mom is experiencing early kidney disease, the DASH diet may be appropriate so long as her blood levels remain normal. Talk to your doctor about how advanced your mom's kidney disease is and what her latest lab values say about her diet needs. Blood work can be thrown off even by certain blood pressure medicines that cause the body to retain potassium.

Ask your mom's doctor to refer you to a registered dietitian who works with kidney disease. Meal planning support can be especially helpful for those individuals who have both kidney disease and co-morbid conditions like diabetes, cardiovascular disease and obesity. Also, nutritional needs can change a lot for people whose kidney disease progresses from decreased function to kidney failure.

Your mom's treatment plan for reducing her high blood pressure should also include: keeping to a healthy weight, exercise, stress management, taking medication(s) as prescribed, moderating alcohol and holding down dietary sodium to a limit of about 1500 milligrams daily. Your mom's doctor can set a target for her blood pressure and decide whether monitoring blood pressure between office visits is necessary.

Courtney Sansonetti is a medical nutrition therapist and certified diabetes educator for Rehabilitation Associates Inc. Her column appears monthly. Email questions to c.sansonetti@rehabassocinc.com.