Kidney Disease Education Center What Is Kidney Disease Stages of Kidney Disease Causes of Kidney Disease Scheduling a Kidney Screening Symptoms of Kidney Failure End Stage Renal Disease Diet with Renal Failure Choosing a Kidney Doctor Find a Kidney Doctor Choosing a Dialysis Provider Planning for a Vascular Access Online Diet Management Tools Meet Your Local Kidney Expert Register for a no-cost, 90-minute training session taught by a certified instructor. Please Enter Your ZIP Code: Vitamin D and Chronic Kidney Disease By DaVita® renal dietitians Helen Dorough and Sara Colman We get vitamin D from the ultraviolet (UV) rays of the sun, but not all sunlight is equal. The amount of UV rays absorbed depends on where you live, the time of day, the season, whether it’s cloudy and if you’re using sunscreen. People who live in sunny areas at lower latitudes typically get enough vitamin D compared to people living at higher latitudes , particularly during late fall and winter.
What foods give us vitamin D? Few foods are naturally good sources of vitamin D. The best food sources for vitamin D are fatty fish including salmon, sardines, cod, tuna and halibut. Many foods, such as some breakfast cereals and milk, are fortified with vitamin D. Milk must contain at least 100 IU of vitamin D per cup, according to federal regulations. The practice of fortifying milk with vitamin D began in the 1930s to prevent rickets, a bone disease that was common in children at the time. Other dairy products are not required to be fortified. Milk substitutes such as soy milk, rice milk and nondairy creamer may or may not have added vitamin D. Benefits of vitamin D Vitamin D is responsible for: Building and maintaining strong bones Keeping the right level of calcium and phosphorus in the blood Preventing bones from becoming weak or malformed Preventing rickets in children and osteomalacia in adults Too much vitamin D can be toxic. The recommended maximum intake is 25 mcg (1,000 IU) for infants and 50 mcg (2,000 IU) for children and adults with normal kidney function.
It’s not unusual for people with kidney failure to have low levels of vitamin D. Your doctor may check your vitamin D level and if it’s low, order a supplement. Your doctor can tell you if a supplement is a good choice for you and if you need it. Always check with your physician before starting an over-the-counter vitamin, mineral, diet supplement or medicine. These items may be harmful to people with chronic kidney disease (CKD) if not taken properly. The vitamin D, calcium, phosphorus and parathyroid hormone (PTH) connection Healthy kidneys are rich with vitamin D receptors and play a major role in turning vitamin D into its active form. This helps balance calcium and phosphorus in your body by controlling absorption of these minerals from the food you eat and regulates parathyroid hormone (PTH). When kidneys fail, their ability to activate vitamin D is lost. Without the activated vitamin D to control calcium and phosphorus levels in the blood, PTH will try to overcompensate and go out of range.
PTH is secreted by the parathyroid glands that are located in the neck near the thyroid glands. In kidney failure, the parathyroid glands may incorrectly sense that there is not enough calcium in the blood and produce excess parathyroid hormone which tells the body to pull calcium out of the bones and put it in the bloodstream. This excess of PTH can cause secondary hyperparathyroidism which can result in bone pain and weak bones that fracture easily. All patients with kidney failure are at risk for secondary hyperparathyroidism. For this reason, PTH levels are routinely monitored through lab work approximately every three months or more often if needed. There are significant problems that may result with excess calcium in the blood stream. Calcium can deposit in soft tissues leaving “little rocks” in the tissue. These deposits or calcifications will never go away. The consequences of calcification are serious. If the heart becomes calcified, blood flow may be reduced, which could cause a heart attack.
Calcification in the lungs can result in difficulty breathing. And, calcification in joints can cause extreme pain. Vitamin D medicines for dialysis patients When a person with CKD develops a high PTH, a physician may prescribe activated vitamin D to suppress PTH production. Hemodialysis patients will be given a prescription medicine intravenously during their dialysis treatment. Those not on dialysis or on peritoneal dialysis will be prescribed an oral form of activated vitamin D or generic calcitriol. PTH levels are checked regularly to make sure the dose of the medicine is correct and that PTH is adequately suppressed but not over-suppressed. It’s a fine line that the doctor, nurse and dietitian are monitoring. If a person has a high blood level of phosphorus or calcium, the physician will often choose not to treat the high PTH with activated vitamin D because there is an increased risk of calcium-phosphorus deposits in the soft tissues. It’s important for all kidney failure patients to keep phosphorus and calcium blood levels within a normal range.
A renal dietitian regularly works with people on dialysis to ensure that they aren’t eating too many foods rich in phosphorus or calcium and to make sure phosphorus binders are taken correctly. Common Drugs Prescribed for Dialysis Patients The ABCs of Vitamins for Kidney Patients Get a free recipe collection from the DaVita® kitchen. 283,082 Enjoyed So Far! Register for a no-cost, 90-minute training session taught by a certified instructor in your neighborhood. Find a Class Near Me Find a Dialysis Center Call 1-800-424-6589 now to talk to one of our placement specialists. Learn which DaVita service may best fit your lifestyle. From 1985 to 1995 a group of doctors set out to test a theory—that high doses of beta-carotene and retinol, two A vitamins with cancer-fighting properties, could greatly reduce our risk of getting cancer. They put study participants on 30 milligrams of beta-carotene and 25,000 International Units (IU) of retinol each day.
But instead of turning their bodies into cancer-fighting machines, the vitamins actually caused some participants to get cancer. The doctors stopped the trial nearly two years early because of the results. "We should step back and ask ourselves whether there might be a lesson to take from this sad experience of actually causing cancer with high vitamin intake," says Tim Byers, MD, professor of epidemiology at the Colorado School of Public Health. Byers, one of the original researchers in the trial, recently led a forum at the American Association for Cancer Research reviewing this and other studies that all found increased cancer risk with vitamin overdose. "I think the lesson is one that says a little nutrient is good, a lot may not be better," he says. It's an easy lesson, but one many do not obey. At the first sign of a cold, we guzzle orange juice and vitamin C powders, take vitamin C tablets or suck on vitamin C infused cough drops—despite research that overloading your body with Vitamin C does nothing to get rid of your cold.
It usually doesn't cause any harm either, though, which may be why people continue to take it. Vitamin C is a water-soluble vitamin, meaning any extra hangs around in the water in your body until it's flushed out in your urine. So taking too much once in a while isn't really a problem. MORE: Do You Just End Up Peeing Out All The Vitamins You Take? But not all vitamins are water-soluble, and the ones that are lipid-soluble, meaning they like to hang around in your body's fat, don't get flushed out. Instead, if you take too much of a lipid-soluble vitamin over a few weeks to a month, they sit in the liver and can build up to toxic levels, causing problems ranging from weak bones to liver damage, according to Katherine Zeratsky, a registered dietician nutritionist at the Mayo Clinic. Scientists are still trying to figure out exactly how much of a vitamin is too much for our bodies to handle, but in the meantime the Institute of Medicine has a list of Upper Tolerable Intake Levels, which is the best bet given the research so far.
How much is too much: More than one a day. If you're a health-conscious person in the United States today, chances are you take a multivitamin. And one a day, even if you're already getting enough nutrients in food, won't hurt you. But more than one a day over a long period of time will. The most serious risk, according to the National Institute of Health, comes from multivitamins that include iron or calcium. Calcium toxicity can cause abdominal pain, weak bones, constipation, irregular heartbeat, and depression among other symptoms. Iron is one of the most dangerous minerals to overdose on, and can cause problems ranging from diarrhea and liver damage to low blood pressure and coma. How much is too much: 2000 mg. Since vitamin C is water-soluble, excess that your body doesn't need just gets flushed out in your urine. But, The Mayo Clinic warns, large doses of vitamin C can cause problems like diarrhea, nausea, vomiting, heartburn, cramps, headache, insomnia, and kidney stones.
The average person needs only 65 to 90 mg of vitamin C every day, which you can find in one large orange or a cup of chopped bell peppers. Let's Stay In Touch MORE: 4 Vitamins You're Probably Not Getting Enough Of Vitamin A: How much is too much: 3000 IU Vitamin A is fat-soluble, which means it gets processed through your liver. Too much vitamin A will stick around until it can get processed—and taking too much every day for a month can lead to toxic levels. Other than studies like the one above showing both the beta-carotene and retinol forms of vitamin A can cause cancer, too much retinol has been linked with birth defects, weak bones, and liver damage. How much is too much: 1100 IU This is another one that has been linked to cancer. Vitamin E is fat-soluble and easy to get in your diet from foods like meat, eggs, and vegetables—so it's rare for people to have vitamin E deficiency. The average person only needs 15 mg a day, but can tolerate much more.
Too much vitamin E can cause problems with blood clotting, and poses risk of hemorrhage. High doses have also been associated with both lung and prostate cancers. How much is too much: 4000 IU, according to the IOM, but recent evidence suggests we may actually need more than 8000 IU to avoid Vitamin D deficiency. Unlike vitamin E, vitamin D deficiency is common. Doctors estimate three out of every four people are vitamin D deficient; so taking a vitamin D supplement might not be a bad thing. But be careful not to overdo it. Taking 50,000 IU of vitamin D a day can lead to toxicity, according to the Mayo Clinic. Vitamin D toxicity builds calcium in your blood and lead to weak bones, kidney stones, nausea, kidney problems, and calcification of soft tissue. MORE: Is A Vitamin Deficiency Making You Gain Weight? How much is too much: 1 to 1.3 mg There are many different forms of vitamin B, but the Institute of Medicine only lists limits for folic acid (vitamin B9) and vitamin B6.