Side Effects Of Vitamin D
The side effects of vitamin D supplements include elevated blood calcium if the person is suffering from certain diseases.
Some experts argue they should never be taken by people with chronic inflammation or an autoimmune disease.
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There are two sets of circumstances where side effects of vitamin D supplements occur... or may occur. There is broad agreement that vitamin D supplements should be avoided by people with diseases that cause elevated blood calcium (hypercalcemia). But there is a more controversial argument that some autoimmune diseases and chronic inflammations are the cause (rather than the result) of vitamin D deficiency and that supplements may further suppress the immune system and make the disease worse.
Following are a variety of diseases for which the side effects of vitamin D supplements may occur.
DISEASES THAT CAUSE HYPERCALCEMIA
Hypercalcemia refers to abnormally high levels of calcium in the blood which could result in bone loss, kidney stones, and calcification of organs like the heart and kidneys if untreated over a long period of time.
Diseases such as primary hyperparathyroidism, sarcoidosis, tuberculosis, oat cell carcinoma of the lung and non-Hodgkin's lymphoma disrupt the kidney’s normal regulation of active vitamin D (calcitriol) and cause high blood calcium. People with these conditions should consult with a knowledgeable doctor before increasing their intake of vitamin D supplements.
The Vitamin D Council also advises against the use of prescription calcitriol or newer analogs of calcitriol which may cause hypercalcemia while failing to address the real problem of low stores of vitamin D.
In 2008, research conducted by Trevor Marshall, Ph.D. (professor at Australia's Murdoch University School of Biological Medicine and Biotechnology) found that side effects of vitamin D supplements may occur with autoimmune and suspected autoimmune diseases. His studies found that unlike vitamin D gained from the sunshine, even nominal doses of ingested vitamin D can suppress the proper operation of the immune system so that the body cannot fight the chronic infection or inflammation associated with some diseases. His findings are supported by J.C. Waterhouse (author of "Vitamin D Metabolism in Chronic Disease") but are challenged by other scientists who argue that he does not have adequate research to support his claims. Examples of autoimmune diseases include Type 1 diabetes, multiple sclerosis (MS),irritable bowel syndrome, Crohn's disease and rheumatoid arthritis (RA).
As maintaining sufficient vitamin D blood levels is essential for bone health, people who are suffering from these illnesses are often at risk of osteoporosis. Those living in northern regions who are unable to get adequate vitamin D from the sunshine may benefit from the use of a tanning bed to maintain the blood levels necessary to protect bone health.
INTERACTIONS WITH MEDICATIONS
Vitamin D supplements may interact with several types of medications. People taking these medications should discuss vitamin D intake with their health-care provider.
Corticosteroid medications such as prednisone, often prescribed to reduce inflammation, can both reduce calcium absorption and impair vitamin D metabolism. These effects can further contribute to bone loss and osteoporosis over the long-term.
Weight Loss, Cholesterol and Epilepsy Drugs
The weight-loss drug orlistat (brand names Xenical® and alli™) and the cholesterol-lowering drug cholestyramine (brand names Questran®, LoCholest®, and Prevalite®) can reduce the absorption of vitamin D. Both phenobarbital and phenytoin (brand name Dilantin®) used to prevent and control epileptic seizures, also affect the metabolism of vitamin D.
Diuretics increase the rate of urination and are commonly used to treat heart failure, liver cirrhosis, hypertension and certain kidney diseases. People with anorexia or bulimia may also abuse diuretics in an attempt to lose weight.
Thiazide diuretics decrease urinary calcium excretion, which could lead to hypercalcemia (excess blood calcium) if vitamin D supplements are taken concurrently. Patients should work closely with their doctor to monitor calcium levels if taking thiazides and vitamin D concurrently.