Could vitamin D reduce obesity-associated inflammation? Observational and Mendelian randomization study

Area of Science:

• Nutritional Immunology
• Obesity Research
• Endocrinology

Background:

• Obesity is linked to chronic inflammation, a process where the role of vitamin D remains unclear.
• Understanding the interplay between vitamin D, body mass index (BMI), and inflammation is crucial for public health.

Purpose of the Study:

• To investigate associations between serum 25-hydroxyvitamin D [25(OH)D] levels, BMI, and 16 inflammatory biomarkers.
• To determine if vitamin D mediates the relationship between higher BMI and inflammation.

Main Methods:

• Analysis of Northern Finland Birth Cohort 1966 (NFBC1966) data from 3586 individuals.
• Utilized multivariable regression and Mendelian randomization (MR) analyses.
• Triangulated findings with a systematic literature review of vitamin D supplementation trials.

Main Results:

• Higher BMI was associated with increased levels of 9 inflammatory biomarkers and decreased 25(OH)D.
• 25(OH)D levels were inversely associated with specific inflammatory markers (sICAM-1, hs-CRP, AGP) that were positively linked to BMI.
• MR analyses confirmed a causal effect of BMI on these inflammatory markers, but found no evidence of vitamin D mediation.

Conclusions:

• Observational, Mendelian randomization, and randomized controlled trial data collectively suggest vitamin D supplementation does not benefit obesity-related inflammation.
• Current evidence does not support a role for vitamin D in mitigating inflammation associated with increased body mass index.