Chennai nephrologist warns vitamin D overdose can harm your kidneys, shares 6 symptoms to watch out for

Vitamin D is important for healthy bones, teeth, and the immune system, but too much of it can be harmful — and may even damage the kidneys beyond repair. In an interview with HT Lifestyle, Dr Navinath M, consultant nephrologist and renal transplant physician at Asian Institute of Nephrology and Urology, Nungambakkam, Chennai, shared that many people take vitamin D supplements ‘to make up for a lack of sunlight or to improve health, but overdose is becoming more common with the growing popularity of these supplements’. Also read | AIIMS-trained doctor shares how to get enough vitamin D without any supplements

He said, “Vitamin D is good for health, but too much can destroy the kidneys and hurt other organs too. It is crucial to use vitamin D supplements with care and always under professional guidance — because in health, sometimes less is more.”

How much vitamin D do you need?

“The human body needs only a small amount of vitamin D each day — usually 400 to 1,000 IU for most adults. When a person regularly takes more than 4,000 IU per day, especially high doses like 8,000–12,000 IU over months or years, vitamin D levels become excessive,” Dr Navinath said.

According to him, another common cause for high vitamin D levels is inadvertent intake of high doses of Vitamin D 60000 IU capsules meant for weekly intake, daily by mistake. “Excessive vitamin D makes the blood hold on to too much calcium — a problem called hypercalcemia—and that excess calcium must be filtered out by the kidneys,” Dr Navinath said.

How does too much vitamin D harm the kidneys?

When the kidneys are forced to filter large amounts of calcium for a long time, Dr Navinath explained that the calcium starts to build up in the kidney tissue. “Over time, this can form kidney stones or even cause permanent calcium deposits called nephrocalcinosis. This overload can damage the kidneys’ delicate filtering units, leading to acute kidney injury or, in some cases, irreversible kidney failure,” he said.

Symptoms to watch out for

Vitamin D overdose does not always cause symptoms right away. When symptoms do appear, Dr Navinath said they may include:

⦿ Nausea and vomiting

⦿ Feeling thirsty all the time

⦿ Frequent urination

⦿ Muscle weakness

⦿ Confusion or tiredness

⦿ Pain in the lower back or sides (kidney pain)

Dr Navinath said, “If too much damage has occurred, the person may develop symptoms of kidney failure, like swelling in the legs, tiredness, and trouble breathing.”

Preventing vitamin D overdose

Dr Navinath said, “Overdose happens most often when people use supplements without medical advice, take multiple products with vitamin D, or use high-dose injections that are not properly regulated.”

To stay safe, he suggested:

⦿ Only take vitamin D if a healthcare provider recommends it.

⦿ Do not exceed prescribed doses, even if ‘more’ sounds better.

⦿ Get blood tests to check vitamin D and calcium if on supplements long-term.

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.