Higher levels of abdominal fat may predict vitamin D deficiency

Rachida Rafiq

In an analysis of several adiposity measures, abdominal fat was the mostly strongly associated with vitamin D concentration in men and women, according to study findings presented at the European Congress of Endocrinology annual meeting.

“Although we did not measure vitamin D deficiency in our study, the strong relationship between increasing amounts of abdominal fat and lower levels of vitamin D suggests that individuals with larger waistlines are at a greater risk for developing deficiency, and should consider having their vitamin D levels checked,” Rachida Rafiq, MD, a doctoral student at the department of internal medicine and endocrinology at VU University Medical Center in Amsterdam, said in a press release.

In a cross-sectional study, Rafiq and colleagues analyzed baseline data from men and women participating in the Netherlands Epidemiology of Obesity study, a population-based study of adults aged 45 to 65 years (mean age, 56 years; mean vitamin D concentration, 70.8 nmol/L). Researchers used linear regression analyses to examine the associations of total body fat, abdominal subcutaneous adipose tissue and visceral adipose tissue (n = 2,441) and hepatic fat (n = 1,980) with serum 25-hydroxyvitamin D concentrations. Researchers used standardized values to compare across adiposity measures, and adjusted for age, race, education, chronic diseases, smoking status, alcohol consumption and physical activity.

Among men and women, visceral adipose tissue was associated with vitamin D status, with a 1-cm² greater visceral adipose tissue associated with a 0.05-nmol/L lower 25-(OH)D status in men (95% CI, –0.09 to –0.02) , and a 0.06-nmol/L lower 25-(OH)D concentration in women (95% CI, –0.1 to –0.01).

Researchers also found that total body fat was inversely associated with 25-(OH)D concentrations in women only, with a 1% higher total body fat associated with a 0.4-nmol/L lower 25-(OH)D value (95% CI, –0.67 to –0.13). Hepatic fat concentration was associated with 25-(OH)D values in men only, with a 10-fold increase in hepatic fat associated with a 6.21-nmol/L lower 25-(OH)D value (95% CI, –10.7 to –1.73).

There was no observed association between subcutaneous adipose tissue and vitamin D status, according to researchers.

The researchers noted that the findings suggest a more important role for abdominal fat in the relationship between adiposity and vitamin D, and a target for future studies.

“A higher amount of visceral adipose tissue is related to lower levels of vitamin D concentrations. This implies that specific attention for vitamin D deficiency should be given to individuals with a high amount of visceral adipose tissue. Future studies should focus on the underlying mechanisms that explain the specific relationship of visceral adipose tissue with vitamin D,” Rafiq told Endocrine Today.

“Due to the observational nature of this study, we cannot draw a conclusion on the direction or cause of the association between obesity and vitamin D levels,” Rafiq said. “However, this strong association may point to a possible role for vitamin D in abdominal fat storage and function.” – by Regina Schaffer

For more information:

Rachida Rafiq, MD, can be reached at VU University Medical Center, Department of Internal Medicine and Endocrinology, De Boelelaan 1118,1081 HV Amsterdam, Netherlands; email: ra.rafiq@vumc.nl.

Reference:

Rafiq R, et al. Abstract OC6.5. Presented at: European Congress of Endocrinology; May 19-22, 2018; Barcelona, Spain.

Disclosure: Endocrine Today could not confirm relevant financial disclosures at the time of publication.