Vitamin D toxicity: what are the side effects of taking too many supplements?
A lack of vitamin D can lead to bone pain and deformities - but did you know that too much vitamin D can also have negative health implications?
Vitamin D helps regulate the amount of calcium and phosphate in the body, and these nutrients are needed to keep muscle, teeth and bones healthy.
Where is vitamin D found?
The body creates vitamin D from direct sunlight on the skin when outdoors, but vitamin D is also found in a small number of foods, including:
- oily fish – such as salmon, sardines, herring and mackerel
- red meat
- egg yolks
- fortified foods – such as most fat spreads and some breakfast cereals
Another source of vitamin D is dietary supplements.
How much vitamin D do I need?
According to the NHS, babies up to the age of one year need 8.5 to 10 micrograms of vitamin D a day.
Children from the age of one year and adults need 10 micrograms of vitamin D a day, which includes pregnant and breastfeeding women, and people at risk of vitamin D deficiency.
What happens if I take too much vitamin D?
Taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body.
This is known as hypercalcaemia. This can potentially weaken the bones and damage the kidneys and the heart.
According to Mayo Clinic, hypercalcemia can cause:
-Nausea and vomiting
- Frequent urination
Symptoms may also progress to bone pain and kidney problems, such as the formation of calcium stones.
“Vitamin D toxicity, also called hypervitaminosis D, is a rare but potentially serious condition that occurs when you have excessive amounts of vitamin D in your body,” adds Mayo Clinic.
“Vitamin D toxicity is usually caused by megadoses of vitamin D supplements — not by diet or sun exposure.”
How many vitamin D supplements should I take?
“If you choose to take vitamin D supplements, 10 micrograms a day will be enough for most people,” notes the NHS.
“Don't take more than 100 micrograms of vitamin D a day as it could be harmful. This applies to adults, including pregnant and breastfeeding women and the elderly, and children aged 11 to 17 years.”
Children aged one to 10 years shouldn't have more than 50 micrograms a day and infants under 12 months shouldn't have more than 25 micrograms a day.
However, the NHS adds: “Some people have medical conditions that mean they may not be able to safely take as much. If in doubt, you should consult your doctor.
“If your doctor has recommended you take a different amount of vitamin D, you should follow their advice.”