Kidney Disease & Nutrition Intervention
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Kidney Disease & Nutrition Intervention
The kidneys are the body’s filtration and excretion system. Healthy kidneys excrete metabolites, waste and excess soluble nutrients through urine formation and tightly control the blood pH.
Over 200 million people worldwide (26 million in the United States alone) suffer from either chronic or acute kidney disease. There are several factors that can affect kidney function such as aging, drugs, toxins, extreme dieting and immune related conditions. However, the most probable cause of kidney dysfunction and deterioration is high blood pressure followed by diabetes type 1 and 2.
It is important to monitor kidney function in hypertensive and diabetic individuals to prevent or delay End-Stage Renal Disease (ESRD) which can lead to death. Kidneys are also considered to play an important role in the endocrine system since they make hormones that control hemoglobin synthesis and blood pressure regulation.
Humans can live with only one kidney however, maintaining the health of both kidneys are very important.
What causes kidney damage?
Kidneys are delicate organs and are susceptible to physical injury (e.g., accidents and sports injuries), chemical injury (e.g., toxins, poisons and allergic reactions to some medications) and inflammation (e.g., autoimmune diseases and immune complexes).
Drug induced– Kidneys can be stressed by overuse of pain killers such as; narcotics and OTC pain killers (aspirin, ibuprofen, and acetaminophen) in older individuals. In some cases acute renal failure has occurred in patients suffering from Lupus (an autoimmune disease) and chronic renal failure.
Other drug-induced kidney damage can occur by; allergic reactions to certain drugs like antibiotics, mixing of alcohol with large doses of Non-Steroidal Anti-inflammatory Drugs (NSAIDS), outdated medications and ingestion of or sniffing toxic chemicals.
Metabolic– Excess calcium, phosphorous, uric acid and cysteine in presence of certain body fluid pH can lead to formation of crystals referred to as kidney stone. Metabolic conditions such as; hyperparathyroidism which leads to release of calcium from bones and teeth can result in formation of calcium oxalate kidney stones. In addition, there are inherited conditions like cystinuria (too much of the amino acid cysteine), and hyperoxaluria (the body produces too much of the salt oxalate) which can also cause formation of kidney stones but, these conditions are rare.
Carcinomas (tumors) – Kidney tumors usually occur in middle aged individuals and are rare.
Kidney Perfusion– Several acute and chronic conditions like diabetes type 2, hemolysis of red blood cells, autoimmune disease and physiological shock can decrease renal blood flow and damage the kidneys and cause accumulation of urea and other toxic metabolites in blood.
Inflammation– Pyelonephritis (kidney infection), kidney stones, prostate enlargement or kidney tumor can also cause lower perfusion of the kidneys. Kidney infections and urinary tract infections (UTI) can occur through sepsis (blood infection), sexual contact, and kidney stone blockages can cause kidney damage. These conditions should be treated immediately to prevent more serious disease.
In patients with certain infectious diseases of the respiratory tract like tuberculosis or Streptococcal pyogenes infections, inflammatory cytokines can cause a localized inflammatory reaction in the kidney and cause permanent kidney damage.
How are kidney diseases treated?
Kidney disease treatment depends on the type of disorder and the underlying cause of the disease. Laboratory tests are performed in an attempt to determine the cause and to assess kidney function. Routinely used medications are; antibiotics (treat infections), diuretics (reduce fluid retention and edema), anti-hypertensive medications (reduce sodium absorption and protein excretion) and corticosteroids (to reduce inflammation).
Management of inflammation is very important since inflammatory cytokines cause increase protein excretion and further damage the kidney tubules. A medication called Pentoxifylline (Marketed under name brand Trental) is effective by improving red blood cell flexibility (rheology) hence, improving oxygen tension in capillaries. It also works by inhibiting an inflammatory cytokine named Tumor Necrosis Factor-alpha (TNF-alpha) which has been known to increase proteinuria in especially diabetic patients.
In more severe cases of renal failure (creatinine values of 1.9<) dialysis may be initiated. There 2 different types of dialysis; peritoneal and hemodialysis. Peritoneal dialysis is a more natural process of eliminating blood toxins however, it predisposes patients to infections and requires higher level of patient involvement. A catheter is placed in the peritoneal wall of the patient abdomen (see illustration 1) and a high osmotic fluid is infused into the peritoneal cavity and is left for a period of 3-4 hours (3-4 times daily) to pull the waste from blood into the peritoneal cavity. After that time the fluid containing the blood waste is drained and discarded. Hemodialysis is the other method for removing blood waste and it requires a machine that filters the blood waste and returns the filtered blood back into the patient’s blood vessel (see illustration 2). Hemodialysis is more commonly used and preferred by patients with better cardiac function.
Illustration 1 (Peritoneal Dialysis) Illustration 2 (Hemodialysis)
Kidney transplant is also an option for patients with kidney function of less than 15%. Transplant candidates must be free of certain viral infectious diseases however, it is more difficult to find a match and they must remain on immunosuppressive agents for the rest of their lives.
In individuals with kidney disease certain dietary guidelines are recommended. Patients suffering from chronic renal failure (CRF) or ESRD might need to limit the following nutrients if they are receiving dialysis:
- Sodium (salt)
If a patient is receiving dialysis on a regular basis, they must consume adequate protein [usually about 1.2 –1.3 grams (g)/kilogram (kg) ideal body weight], because dialysis removes most low molecular weight protein from their blood.
In patients who experience weight loss it is important to consume enough calories each day to prevent drastic weight changes. Typically, it is recommended that dialysis patients consume 30–35 calories/kg ideal body weight. This varies based on dry weight (weight after excess fluid is removed) vs ideal weight, if a significant difference exists.
Additional facts that are important is that during fluid removal at dialysis, the following can occur if you have not limited your potassium, phosphorus, sodium (salt), and fluids:
- Muscle spasms
- Cardiac arrest
- Bone damage
- Swelling or fluid retention
A renal dietitian usually will teach the patient what foods to avoid and which foods are OK to eat. If an individual has other co-morbidities like diabetes or cancer their nutritional needs require additional diet modifications. The most important things are to learn what changes they should make and consult with their renal dietitian routinely to develop a plan for making these changes.
Vegetarians have diets that are naturally high in potassium and phosphorus; therefore, need good nutritional advice. If required to limit phosphorus, sodium, or protein, remember the following:
- Phosphorus is especially high in dairy products (eg, milk, cheese, ice cream), dried beans and peas, nuts and peanut butter, some salt substitutes, cocoa, beer, and cola soft drinks.
- Sodium is especially high in table salt, canned soup, processed cheese, snack foods, prepared and “fast foods,” pickles, olives, sauerkraut, and smoked and cured food (eg, ham, bacon, luncheon meat).
- Protein is especially high in food from animal sources (eg, poultry, meat, seafood, eggs, and dairy products). Protein is found in smaller amounts in food from plant sources (e.g., bread, cereal, grain, vegetables, and fruit).
However, a certain amount of phosphorus, sodium, and protein is necessary for good health. To keep healthy, it is important to learn to read labels and make better choices. For example, non-dairy creamers and milk substitutes are a good way to lower dietary phosphorus.
Avoid losing too much weight. It is important to maintain a good calorie intake because calories give you energy. If limiting protein, get more calories from other food sources including:
- Unsaturated fats from oils (e.g., grape seed oil, canola or olive oil).
- Simple carbohydrates (e.g., honey, jam, and jelly)
- Note: The recommendations for using sugar may not be appropriate for diabetics or overweight individuals. If you are diabetic, consult your physician or renal dietitian for alternative recommendations.
Dietary supplements are often recommended by physicians and renal and their recommendations are guided by monthly blood testing utilized to monitor kidney function. Patients should always consult with a physician or renal dietitian before using or adding any supplements or herbal products.
- Multivitamins. In addition to a diet containing appropriate nutrients and protein, a comprehensive multivitamin is often required to replace vitamins lost during dialysis treatments however, be aware of the magnesium level and other nutrients that require excretion through urine. The ideal multivitamin & mineral supplement must include; vitamins B6, B12, and folate (folic acid) are known for having many beneficial qualities in addition to vitamins C, D, E and minerals such as; Calcium, Iron (in larger doses to address anemia), Magnesium, Zinc.
- L-Carnitine which is an Amino Acid that has proven effective in providing cellular energy to both healthy individuals and those with chronic diseases. For patients in a predialysis stage, undergoing dialysis, or post-transplant, nutritional supplementation with L-Carnitine lost during dialysis may reduce the side effects of common renal problems (e.g., cardiomyopathy and blood platelet aggregation, muscle weakness) and may also help improve the patient’s perception of overall quality of life.
- Coenzyme Q10 is important because of tremendous blood flow and high concentration of metabolic toxins continuously circulating through the kidneys, they are the site of extraordinary oxidative stress, which is known to contribute to progressive kidney damage and its complications (e.g., high LDL and increased cardiovascular disease risk).
- Digestive Enzymes is an enzyme complex that can reduce inflammation and enhance tissue repair. Enzyme can also improve blood rheology and enhance circulation.
- Ginkgo biloba is already known for its antioxidant effects. It may also protect small blood vessels against loss of tone, prevent capillary fragility, inhibit atherosclerosis, and treat diabetic vascular disease.
- Alpha Lipoic Acid is another powerful antioxidant with few known side effects and is able to prevent drug-induced kidney damage.
- Green tea contains tannin which can decrease blood levels of urea nitrogen and creatinine and decrease urinary levels of protein and glucose which indicates a protective effect on the kidneys.
This article was contributed by:
Hengameh G. Allen-Schaal, Ph.D., MPH, MT(ASCP)
Disclaimer and Safety Information
This information (and any accompanying material) is not intended to replace the attention or advice of a physician or other qualified health care professional. Anyone who wishes to embark on any dietary, drug, exercise, or other lifestyle change intended to prevent or treat a specific disease or condition should first consult with and seek clearance from a physician or other qualified health care professional. Pregnant women in particular should seek the advice of a physician before using any dietary supplements.