The dangers of having too little vitamin D, also known as the sunshine vitamin because levels can be boosted by exposure to sunlight, are well known and have contributed to a rise in the number of people taking vitamin D supplements.
But a study by scientists at the University of Copenhagen, believed to be the biggest of its kind, has highlighted the connection between high levels of vitamin D and cardiovascular death.
Vitamin D is made by the skin in reaction to sunlight and can also be found in oily fish, eggs, fortified cereals and spreads or supplements. It helps to regulate the amount of calcium and phosphate in the body, keeping bones and teeth healthy.
A deficiency can lead to bone deformities such as rickets or bone pain and tenderness as a result of a condition called osteomalacia in adults.
But people who are taking too many vitamin D supplements over a long period of time can cause more calcium to be absorbed than can be excreted. The excess can be deposited in and damage the kidneys.
Excessive vitamin D can also lead to calcium being removed from bones, which can soften and weaken them.