According to new research from the US, the risk of diseases, such as hip fractures, heart attacks and cancer, increases when the blood concentration of vitamin D falls below 20 ng/milliliter or 50 nmol/liter.
In order to investigate how much vitamin D needs to be circulating in the blood in to lower the risk of a major medical event, such as a heart attack, hip fracture, diagnosis of cancer, or death, researchers measured the 25-hydroxy-vitamin D concentrations in blood samples of 1,621 Caucasian adults aged 65
and older (1). Over a period of about 11 years, the researchers looked at the association between each individual’s 25(OH)D test results and the time that the first defined medical event occurred. Based on a statistical analysis, it was concluded that the risk of these disease events rose when the concentration of
25(OH)D fell below 20 nanogramms/milliliter or 50 nanomol/liter. The association of low 25(OH)D blood concentrations with the risk of major disease events varied with the season: the vitamin D levels ran highest in the summer and lowest in the winter; levels in autumn were generally higher than those in spring.
The researchers commented that these results provided support to the threshold level recently recommen-ded by the US Institute of Medicine. This target level for adults was considerably lower than those set by other expert panels. The vitamin D threshold amount has become controversial, as several scientific societies set different targets. Season-specific targets for 25(OH)D blood concentrations may be more appropriate than a static target when evaluating a patient’s health risk. Sun exposure presents a tricky situation because people have to protect themselves from skin cancer and other sun damage. Additional dietary vitamin D intake is therefore recommended to reach adequate blood levels, the scientists said.