The researchers analyzed data from nearly 2,500 participants enrolled in the Finnish Vitamin D Trial (FIND) to understand how vitamin D affected long-term disease risk. Participants were assigned to either take 40 or 80 micrograms of vitamin D3 every day, or they were given a placebo. All of the participants were in good health at the start of the study, and the team tracked their outcomes over the course of five years.
After analyzing blood samples, there were very slight differences among participants’ vitamin D levels in all three groups after one year; the placebo group had vitamin D concentration levels at 73 nmol/L, the group taking 40 micrograms had levels averaging 100 nmol/L, and the group taking 80 micrograms reached an average of 120 nmol/L. For reference, low vitamin D levels would be at or below 50 nmol/L.
Ultimately, there were no protective benefits – in terms of cardiovascular disease, cancer, or the mortality rate for either condition – associated with taking vitamin D supplements on a daily basis. The researchers learned that participants in the placebo group and those taking the vitamin D supplements had similar health outcomes.
However, the study showed that all but 9% of the participants had healthy vitamin D levels at the start of the study. The researchers explained that this could be why the supplements didn’t lead to any significant changes to long-term health.
For consumers looking to protect their health, the researchers recommend monitoring vitamin D levels before starting a supplement regimen. In addition to taking supplements, making dietary changes, including eating more fish or liquid dairy products, can help boost vitamin D levels.