The study, published in The Journal of Clinical Endocrinology & Metabolism, followed more than 4,000 people with a history of cardiovascular disease for 12 years, and measured levels of vitamin D status biomarkers in blood known as 25-hydroxyvitamin D (c).
Led by Professor Jutta Dierkes from the Department of Clinical Medicine at University of Bergen, the research shows that people with healthy or normal intakes of vitamin D were at a reduced risk of mortality from their heart disease than those with lower levels.
"We discovered that the right amount of vitamin D reduces the risk of death substantially. However, too much or too little increase the risk," said Dierkes.
Indeed, the team noted that while a healthy status of between 42 to 100 nmol/l can slash the risk of death by 30% compared to those with the lowest intakes, people with very high status were also at an increased risk compared to those within the ‘normal’ range.
While the study suggests that it is favourable to have blood values of 25OHD at around 42 to 100 nmol/l, the team also note that it difficult to give general a recommendation of how much vitamin D supplementation people should take.
"The optimal amount of vitamin D-supplement varies from one person to another. It depends where you live, and what kind of diet you have," noted Dierkes – adding that for example, the Nordic countries recommend an intake of 10 microgram per day from all vitamin D-sources while the USA recommends 15 micrograms and Germany suggests 20.
"Even if Norwegians receive less sun then the Germans, the Norwegians have more fish in their diet,” she added. “Fish and cod liver oil are important sources to vitamin D during the winter, in addition to physical activities outdoors during the summer."
Source: The Journal of Clinical Endocrinology & Metabolism
Volume 103, Issue 3, Pages 1161–1170, doi: 10.1210/jc.2017-02328
“Plasma 25-Hydroxyvitamin D and Mortality in Patients With Suspected Stable Angina Pectoris”
Authors: Eirik Degerud, et al