“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 Professor Jutta Dierkes at the Department of Clinical Medicine, UiB, which led the study.
The study followed as many as 4,000 patients with cardiovascular diseases from year 2000, for a period of 12 years. The average age of the participants was 62 years old at the start of the study (WENBIT).
The study showed that it is favorable to have blood values around 42 to 100 nmol/l. Higher or lower values may put people at greater risk of dying from cardiovascular disease.
According to Prof. Dierkes, it is difficult to give general a recommendation of how much vitamin D supplementation one 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,” she said.
For example, the Nordic countries recommend an intake of 10 mcg per day from all vitamin D sources, the U.S. recommends 15 mcg, and Germany 20 mcg.
“Even if Norwegians receive less sun then the Germans, the Norwegians have more fish in their diet. Fish and cod liver oil are important sources to vitamin D during the winter, in addition to physical activities outdoors during the summer,” Prof. Dierkes explained.
She advised all who have experienced cardiovascular diseases to measure their levels of vitamin D, so that these can be better regulated, and the need for supplements assessed. This can usually be done by a local doctor.
“It is, however, important to take in account that the levels vary seasonally. A measurement in September will not show the same results as in January, in the Nordic countries.”
“The levels in January or February are often lower because of the lack of sunlight, which induces the skin form to vitamin D,” said Prof. Dierkes.