For adults over 50, excess abdominal fat and low vitamin D may form a particularly dangerous combination. A study of more than 5,500 people found that participants with both conditions had a 123% higher risk of death over the study period than those with neither — more than double the risk.
The findings, published in the journal Diabetes, Obesity and Metabolism, come from an analysis of 5,520 adults aged 50 and older who took part in the English Longitudinal Study of Ageing (ELSA), one of the world's largest studies of aging, and were followed for six years. The project was coordinated by Tiago Silva Alexandre, a professor in the Department of Gerontology at the Federal University of São Carlos (UFSCar) in Brazil, in collaboration with University College London and with funding from FAPESP.
The researchers first examined the two conditions separately. Abdominal obesity — defined as a waist circumference greater than 102 centimeters in men or 88 centimeters in women — was linked to a 47% higher risk of death. Vitamin D deficiency, defined as a blood level below 30 nanomoles per liter, was associated with a risk increase of up to 91%. When both conditions were present together, the associated risk of death rose by 123%.
The two conditions appear to reinforce each other in a vicious cycle. Abdominal fat can "sequester" vitamin D circulating through the body, storing it in fat cells and reducing the amount available in the bloodstream; people with obesity also produce lower levels of the enzymes needed to metabolize the vitamin. "Abdominal obesity is a well-known risk factor because it's associated with inflammation and metabolic problems. Vitamin D, on the other hand, is a hormone that acts on various organs," Alexandre explained. "When these two conditions occur together, one amplifies the effects of the other, further increasing the risk of death."
Aging adds another layer: older adults naturally experience "inflammaging," a persistent low-grade inflammation, and vitamin D normally acts as an immune-system regulator that keeps it in check. The authors stress that monitoring vitamin D levels and treating excess abdominal fat are essential measures to prevent premature death, especially after age 50.
