Vitamin D also called the sunshine vitamin, is best known for keeping bones healthy by promoting calcium absorption. It also helps regulate cell growth, immune and neuromuscular function, and glucose metabolism. People can obtain vitamin D through food, supplementation and sun exposure.
For the study, the team examined how low levels of vitamin D may contribute to all-cause and cause-specific mortality in a large cohort that covered all age groups. They found a strong association between vitamin D deficiency and increased mortality risk.
“This association is most pronounced in the younger and middle-aged groups and for causes of deaths other than cancer and cardiovascular disease, especially diabetes,” wrote the researchers.
Their findings were presented at the Annual Meeting of the European Association for the Study of Diabetes in Spain.
The researchers drew data from the records of more than 78,000 participants with a mean age of 51 years who had their vitamin D levels measured at the General Hospital of Vienna between 1991 and 2011. With this data in hand, they then combed through the Austrian national registry to look for cases of death, omitting those who died within the first three years of undergoing a vitamin D test. They then followed up on the participants for an average of 10.5 years.
In the study, participants with blood levels of vitamin D at 50 nanomoles per liter (nmol/L) were considered deficient in the vitamin. Meanwhile, low and high levels were considered at 10 nmol/L and 90 nmol/L, respectively.
Results showed that a person’s risk of death increased by two to three times with low levels of vitamin D. The association was strongest among participants aged 45 to 60 years. Meanwhile, all-cause mortality was reduced by 30 to 40 percent with high levels of the vitamin, with the association also strongest in participants aged 45 to 60 years. The team, however, observed no significant association between vitamin D levels and mortality among participants over 75 years old.
When it comes to cause-specific mortality, diabetes-related death drew the strongest association with vitamin D deficiency. Participants deficient in the vitamin had a 4.4 times greater risk of diabetes-related death compared to those with healthy levels of the vitamin. Again, the association was strongest among participants aged 45 to 60 years. This age group was also seen as the most susceptible to death caused by conditions other than cancer and cardiovascular disease.
The team added that having higher levels of vitamin D did not show a significant link to mortality risk resurgence, pacifying concerns raised by previous studies suggesting it poses a negative effect.
”Our findings strengthen the rationale for widespread vitamin D supplementation to prevent premature mortality,” wrote the researchers. (Related: Vitamin D reduces inflammation caused by Type 2 diabetes.)
More and more studies are linking vitamin D to Type 2 diabetes.
One such study, published in the European Journal of Endocrinology, examined the effect of consistent vitamin D3 supplementation on insulin sensitivity in people with newly-diagnosed Type 2 diabetes or at high risk of developing the disease.
They found that supplementation for six months improved peripheral insulin sensitivity and beta-cell function. Peripheral insulin sensitivity refers to how readily cells in the peripheral tissue absorb glucose. Beta cells in the pancreas, on the other hand, produce and secrete insulin.
Jennifer Smith, a registered nutritionist who was not part of the study, commented that vitamin D supplementation before, and soon after, diagnosis appeared to retain the ability of cells to respond to insulin.
“The other thing it appears to help with,” added Smith, “is allowing the beta cells in the pancreas that make insulin to stay healthy and functional.”
VitaminD.news has more on the link between vitamin D deficiency and diabetes.