In general, nutrients are classified as either macronutrients (needed in large quantities) or micronutrients (needed in smaller quantities). Vitamins and minerals are micronutrients, while macronutrients are familiarly known as proteins, fats, and carbohydrates. Each macronutrient provides energy in the form of calories and plays an important role in the body as well.
For instance, protein is required for repair and growth, while fat is needed to form cell membranes and absorb certain micronutrients. Carbohydrates, although recently given a bad rap in the weight loss world, contribute to a number of processes including a healthy immune system. In addition to protein, fat, and carbohydrates, both fiber and water are technically considered to be macronutrients. Just like vitamins and minerals, the body requires them even though they technically do not provide energy in the form of calories.
When your kidneys are not functioning optimally specific nutrients become more of a concern than others. They include protein, potassium, sodium, and phosphorous. Let’s examine these important aspects of nutrition as they relate to chronic kidney disease.
Protein: Protein is made from chains of amino acids, called “the building blocks of life.” There are 20 amino acids which combine in different ways to form a variety of proteins the body uses to create cells, hormones and enzymes. Eleven of these 20 amino acids are manufactured in the body by the liver. The other nine, called “essential” amino acids, can only be obtained through diet. The average healthy person needs between 40 to 65 grams of protein each day, exact amounts primarily based on body size, weight, and any extenuating health issues.
Most people with chronic kidney disease who are not on dialysis are told to limit their protein intake. This is because protein and animal protein in particular is very hard on the kidneys that must filter out the resulting waste products into the urine. When compromised, the kidneys cannot adequately do this filtering job and there may be a buildup of waste products in the blood. Blood tests that measure protein waste include blood urea nitrogen (BUN) and creatinine. These tests help your doctor assess how much the kidneys are working.
Reducing the amount of protein you consume can clearly reduce the burden that the kidneys face. The amount by which you may need to reduce your protein intake is based upon the stage of your kidney function (Stages 1 through 4). If kidney failure is reached (Stage 5) and dialysis becomes necessary, additional amino acid supplementation may be necessary due to a number of essential amino acids present in protein are eliminated during dialysis, supplementation of amino acids (the building blocks of protein) ensures that your body is receiving what it needs.
Potassium: Potassium is a mineral that controls nerve and muscle function and is particularly important for maintaining a normal heart rhythm. In addition, potassium is necessary for maintaining fluid and electrolyte balance, as well as pH level. In order to perform these functions, potassium blood levels must be kept between 3.5 and 5.5 mEq/L. It is the kidneys that help to do this and when the are not functioning adequately, excess potassium cannot be eliminated and levels can easily become too high.
We get potassium from the food we eat and some selections are higher in potassium than others. However, many of the fruits and vegetables that contain important anti-oxidants and vitamins that we need for good health sometimes will also contain higher levels of potassium. What to do? In this respect, moderation is key so be sure to vary your intake and include foods – fruits in particular – that are lower in potassium on as many occasions as possible. These would include but are not limited to apples, pears, berries, watermelon, and pineapple. Be sure to also incorporate the leaching technique described in the upcoming section on kitchen tips that will assist in reducing the potassium content of many vegetables.
Sodium: Sodium is one of the body’s three major electrolytes (potassium and chloride are the other two). Electrolytes control the fluids going in and out of the body’s tissues and cells. Salt – the kind we consume in the food we eat – contains both sodium and chloride so it is a major source of electrolytes. Sodium also plays a major role in regulating blood pressure and blood volume, as well as the acid-alkaline balance of blood and body fluids. Generally speaking, the recommended intake of sodium for most healthy people is 2,400 milligrams or less each day. This equals the amount of sodium in one teaspoon of salt.
Although sodium is an essential nutrient, too much sodium can be harmful for people with chronic kidney disease. This is because (as is the case with potassium) the kidneys cannot eliminate excess sodium and fluid from your body when they are compromised. As sodium and fluid build up in the tissues and bloodstream, blood pressure increases and this is a particularly dangerous situation for kidney disease. High blood pressure can cause even more damage to unhealthy kidneys that in turn reduces kidney function further, resulting in more fluid and waste build up in the body.
Restricting sodium intake depends upon your blood pressure and stage of kidney disease, but for the most part it is a necessary step and one, which is recommended in my full program “The Kidney Disease Solution”. Watch for hidden sources of sodium, particularly in prepared prepackaged foods including frozen and canned selections that may use sodium as a preservative as well as a taste enhancer. The best way to enjoy salt in small doses is by adding your own small pinches here and there to food that is labeled salt-free or at least low-sodium. This gives you the control you need to be sure you are meeting the intake guidelines set for your specific situation. Remember also that salt substitutes, although containing less sodium, will usually have increased amounts of potassium and perhaps added chemicals. As a general rule, the use of salt substitutes in cooking is discouraged.
Phosphorous: Most people are unaware of the mineral phosphorous as a nutrient, but next to calcium, it is the most abundant mineral in the body. Required for a number of functions, phosphorous is essential in healthy bone and teeth formation as well as enabling the body to change macronutrients into energy and to maintain proper pH balance.
Again, when the kidneys are compromised in their ability to eliminate excess minerals and waste, phosphorous can build up to unwanted levels that, among other things, will decrease calcium absorption and may lead to renal osteodystrophy – a weakening of the bones due to chronic kidney disease. Reducing the amount of phosphorous consumed in the diet is normally recommended. Unfortunately, it is often difficult to know the phosphorous content of foods because it is not generally listed on nutritional labels. In addition, phosphorous is contained in so many different foods that it is also difficult to vigilantly avoid. Because of this, physicians may prescribe phosphorous binders that help with excess elimination.
In general, dairy products, meat, and eggs contain relatively high amounts of phosphorous but if you are reducing protein, you will be reducing this source as well. Other sources include cola drinks, chocolate, peanuts, beer, and a number of nuts and seeds. Numerous food additives also contain phosphorous so by drastically reducing your intake of processed foods and relying more on your own food preparation, you can reduce the amount of phosphorous you consume.