Vitamin D toxicity: Excess levels can cause kidney stones, heart problems

Business Standard

3 hours ago

Vitamin D, often called the 'sunshine vitamin', is vital for bone strength, immunity, and overall health. According to a study by the Indian Council for Research on International Economic Relations (ICRIER), published earlier this year, one in five Indians is Vitamin-D deficient. While deficiency can cause its own set of problems, experts share that too much vitamin D can lead to dangerous effects on the kidneys and heart.
"Vitamin D is very important for health, but like many things in medicine, it can cause problems if too much is taken. I have had numerous patients who were simply taking more Vitamin D than their body required and ended up with significant heart and kidney problems," said Dr Syed Mustafa Ashraf, Senior Consultant internal Medicine, CARE Hospitals.
When vitamin D turns harmful
"You won't get toxic levels from sunlight or diet. The risk comes with taking too many supplements over time. In numbers, we usually start worrying when 25-hydroxyvitamin D levels go beyond about 100–150 ng/mL," informed Dr Anirban Chattopadhyay, critical care specialist at The Calcutta Medical Research Institute (CMRI).
"Repeated readings with levels greater than 100 ng/mL can increase the risk of hypercalcemia and related disease," added Dr Haresh Mehta, DNB (Cardiology), MD (Internal Medicine) at Lilavati Hospital, Mumbai
Self-prescribing mega-doses or taking potent capsules without testing is a common cause. Online products with inaccurate labelling can also lead to accidental overdose.
"People hear about the benefits, start high-dose tablets on their own, and keep going for months without checking their levels. It's even riskier if they're also on calcium tablets, or if they have kidney problems, because the kidneys can't clear the excess efficiently," explained Dr Chattopadhyay.
How excess vitamin D affects kidneys and heart
"Evidence suggests that dietary vitamin D may be carried by lipoprotein particles and enter artery wall cells and atherosclerotic plaque, and may be converted to its active form by monocycle-macrophages. The resulting active form raises the question of the role of vitamin D intake on atherosclerotic calcification (calcium deposits within the arterial walls) and whether it would raise cardiovascular risk with increased vascular calcification. Any excess vitamin D can also elevate blood calcium concentrations (hypercalcemia) and be arrhythmic to the heart," said Dr Sandeep Patil, Chief Intensivist at Fortis Hospital, Kalyan.
"In the case of excess calcium for the kidney, this means the kidneys need to filter the excess calcium, excrete it, and can lead to kidney stones, calcium accumulation in the kidney tissue (nephrocalcinosis), and acute kidney injury," he further added.
Signs you might have excessive vitamin D
The main driver of symptoms is hypercalcaemia, which means that there is excess calcium in the blood. This can trigger:
Nausea, vomiting, constipation, or abdominal pain
Extreme thirst and frequent urination
Confusion, headaches, or unusual tiredness
Muscle weakness and bone pain
Irregular heartbeat or high blood pressure
How much vitamin D is safe?
Vitamin D is a fat-soluble vitamin required for the regulation of calcium and phosphorus. "It allows for the mineralization of the bone, the functioning of muscles, immune function, and the conduction of nerves. Adequate levels prevent rickets in children and osteomalacia or osteoporosis in adults. It also plays a part in the inhibition of inflammation and the regulation of cell growth," explained Dr Mehta.
Dr Patil shared the recommended daily intake -
Age 19 to 50: 600 IU/day
Age 50 to 70: at least 600 IU/day
Over 70: at least 800 IU/day
The maximum suggested daily limit for healthy adults is 4,000 IU/day. However, toxicity can occur in susceptible individuals with as little as 2,000 IU/day.
Treatment and prevention
Dr Ashraf shared that the treatment for vitamin D toxicity usually involves:
Stopping all vitamin D and calcium supplements until advised.
Administering IV fluids to address dehydration.
Using medications like corticosteroids and bisphosphonates in severe cases to block bone resorption.
In rare instances with significant kidney damage, hemodialysis may be required.
Talking about the right way to take vitamin D supplements, Dr Mickey Mehta, global holistic health guru, said, 'Without magnesium, Vitamin D3 remains inactive. Magnesium-rich foods like nuts, seeds, and leafy greens, along with Vitamin K2 from fermented foods or ghee, create essential harmony for the nutrients to be absorbed optimally. K2 directs calcium to bones and away from arteries, preventing calcification. Magnesium, Vitamin D3, and K2 work synergistically, so isolated supplementation can cause imbalance.'
Knowing your safe limit, watching for warning signs, and getting medical advice before making major changes can protect both your heart and kidneys.