A Quora user recently asked, “What are the potential risks of taking high-dose vitamin D supplements for an extended period of time? How long can one safely take high-dose vitamin D before experiencing negative side effects?” It’s a relevant question, especially in India, where vitamin D deficiency is rampant and self-supplementation is common. To clear the confusion, we spoke to Dr Vyankatesh Shivane, Consultant Diabetologist and Metabolic Physician, Department of Endocrinology, Jaslok Hospital & Research Centre, Mumbai, and Dr Vimal Pahuja, Associate Director, Internal Medicine and Metabolic Physician, Dr LH Hiranandani Hospital, Powai.DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.What counts as a “high dose” and when does it become toxic?“Vitamin D is also called the Sunshine Vitamin, as it is available in abundance in sunlight. India, in spite of being a sunny country, most of the Indian population is either Vitamin D insufficient or deficient,” says Dr Pahuja.“Normally, a level of Vitamin D more than 30 ng/mL is considered a sufficient level, as at this level, the level of Parathyroid hormone is stable without causing any harm to the bones.”He explains that vitamin D levels above 100–150 ng/mL are considered harmful to the body. “At these levels, more calcium is excreted in the urine, making someone at risk of kidney stones. Vitamin D supplements of more than 50,000 IU per day for many weeks are considered to be toxic,” he says.According to Dr Shivane, “In India, vitamin D deficiency is widespread, but excess supplementation has become a new concern.” He notes that the Endocrine Society of India (ESI) and ICMR-NIN recommend 600–800 IU/day for adults, with an upper safe limit of 4,000 IU/day. “For optimal bone and muscle health, the adequate serum 25(OH)D range is 20–40 ng/mL. Levels above 40 ng/mL provide no added benefit and may raise calcium levels.”What are the risks of taking high-dose vitamin D long-term? Testing is advised before starting supplements (Image: Unsplash)“High-dose, long-term use can cause hypercalcaemia, kidney stones, vascular calcification, and even cardiac arrhythmias,” warns Dr Shivane. “Since vitamin D is fat-soluble, toxicity develops gradually and presents with nausea, thirst, muscle weakness, and confusion.”Story continues below this adDr Pahuja agrees, adding that toxicity often happens unintentionally. “It is not always the case, but inadvertently, a few patients keep on taking daily supplements rather than weekly. Or they may continue it for a longer duration than prescribed, as they may feel ‘better’ with supplements.”Also Read | ‘How can someone differentiate between normal dehydration and the excessive thirst associated with diabetes?’How long can one safely take high-dose vitamin D?“One should take Vitamin D supplements only as per their Doctor’s advice. Do not continue these supplements for longer than as advised,” says Dr Pahuja. “Once low levels of Vitamin D has been normalised, ask the doctor for regular maintenance dose of Vitamin D. Usually in India we need 1000 IU to 1500 IU per day as maintenance dose for Vitamin D.”What are the early signs of vitamin D toxicity?“As stated above increase frequency of urine, increase thirst, pain in abdomen, Bone and body pains may the early signs of toxic levels of vitamin D,” says Dr Pahuja. “One should check and confirm these levels at earliest and in some cases concomitant tests of Blood Calcium and Phosphorous are required to detect excess of calcium in the blood.”Story continues below this adHow often should vitamin D levels be tested?Dr Shivane recommends, “Testing is advised before starting supplements and again after 8–12 weeks; once stable, annual monitoring is adequate.” Dr Pahuja adds that after initial correction with weekly 60,000 IU doses for 10–12 weeks, one can continue with a maintenance dose and “Annually you can check whether these supplements are optimum enough to maintain your Vitamin D in normal ranges.”He also highlights the role of sunlight: “Daily sunlight exposure of 45–60 minutes between 10 am to 12 pm may be helpful. Sunlight should be available to maximum body surface area like both hands below elbows, both legs below knee, neck and face etc. It is advised not to apply sunscreen or lotions on these parts to get maximum benefit of sunlight.”DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.