A man developed kidney failure after taking 12 times the recommended amount of vitamin D every day.
The unnamed 54-year-old, from Canada, had been taking the bumper dose drops for two-and-a-half-years after being advised it by a naturopath.
But his health took a turn for the worse when he took a two week holiday and spent eight hours a day sunbathing – exposure to the sun helps the body to produce vitamin D.
Medical tests showed his blood creatinine levels were climbing, which is a sign the kidneys are struggling to work.
Doctors then found a dangerous build-up of vitamin D and calcium in his blood had impaired the function of his kidneys.
A 54-year-old man from Canada developed kidney failure after taking 12 times the recommended dose of a vitamin D supplement
It took a year to get the patient back to health – but he has been left with chronic kidney disease and may need dialysis in later life.
The patient, who did not have a history of bone loss or vitamin D deficiency, took a total of 8,000-12,000IU a day.
The recommended amount for people in Canada is a maximum 1,000IU – four times lower than guidelines for people in Britain.
Doctors, led by Bourne Auguste, a nephrologist at Toronto General Hospital, said they were concerned other people would make the same mistake.
Mr Auguste told Global News: ‘He thought that vitamins are harmless.
‘And his logic, which one can understand looking back, is that the more vitamin D I take, the stronger the bones will be.’
For unknown reasons, the patient said he was seeing a naturopathic, a specialist that suggests alternative methods such as homeopathy to try and treat illnesses.
She advised the man take eight drops of a brand daily which contained 500IU per drop, according to the report in the Canadian Medical Association Journal.
This would have come to 4,000IU – the maximum that is recommended a day in the UK by the NHS before it could become harmful.
But, unknowingly, the man bought another vitamin D product that contained 1,000IU per drop.
After returning home from a two-week trip to Southeast Asia, he went to his doctor. However, it is unclear why he attended.
His creatinine level had increased from his baseline of 100 μmol/L before the trip, to 132 μmol/L.
His doctor thought he could be suffering from dehydration or heat stroke, and told him to stop taking his high blood pressure and diuretic medication.
But after four weeks, his creatinine level had risen to 376 μmol/L despite having no obvious illness. He was then referred to a kidney specialist.
It was then that the man was quizzed about his health background and told to stop taking supplements and eating calcium rich foods.
The patient was given medication and counselled on how to reduce the toxicity to his kidneys.
Almost one year after diagnosis, his calcium and vitamin D levels have returned to normal, but he has stage 3B chronic kidney disease.
The kidneys have an important role in making vitamin D useful to the body by converting the source into the active form of vitamin D that is needed by the body to help absorb calcium and phosphorous.
Vitamin D toxicity is rare but its widespread availability in various over-the-counter products could be risky for people who are uninformed, the authors said.
There’s no risk of your body making too much vitamin D from sun exposure or food choices.
The doctors wrote: ‘Our experience informs us that patients and clinicians should be better informed about the risks regarding the unfettered use of vitamin D.
‘Given new findings from the US Preventive Services Task Force, current Canadian guidelines regarding its use in low-risk individuals should be revisited.’
The authors said that a dose greater than 10,000IU per day for several months is not recommended to anyone.
It’s not known exactly how much time is needed in the sun to make enough vitamin D to meet the body’s requirements.