Expatriates may already be aware that too little vitamin D could be dangerous for them, leaving them susceptible to diseases and illnesses that need treatment on international health insurance policies.
However, recent research from the University of Copenhagen, which was published in the Journal of Clinical Endocrinology and Metabolism, found too much of this compound can have harmful effects as well.
Investigators analysed blood samples from 247,574 Copenhagers and found elevated risks of mortality among those with both low and high levels of vitamin D.
Those with less than 10 nanomol (nmol) of the compound in every litre of serum have a mortality rate 2.31 times greater than those with the lowest mortality rate, which was seen in those with 50 nmol of the substance per litre.
People with more than 140 nmol of the vitamin in one litre of serum have a risk of death 1.42 times higher than the ideal group.
Research has shown the compound can combat certain cancer types, depression and cardiac disease.
It also plays an instrumental part in transporting calcium to a human's bones, which reduces the risk of a person having to make an international healthcare claim due to broken hips or limbs.
Researchers stated it was only possible to conduct this wide-ranging study – believed to be the largest investigation of its kind – because of the civil registration system of Denmark.
All of the blood samples were sourced from the Copenhagen General Practitioners Laboratory and covered a wide age range.
"We can draw a graph showing that perhaps it is harmful with too little and too much vitamin D," deputy chairman of the PhD committee at the Faculty of Pharmaceutical Sciences Darshana Durup remarked.
"It is important to conduct further studies in order to understand the relationship," she added.
Vitamin D is produced when sunlight hits the skin and it is not naturally present in many foods. However, it can be purchased as a dietary supplement.