In addition to an increased prevalence of VDD, the deficient male population studied also showed higher fat mass and HbA1c levels.
Yet, the ‘Nutrients’ published report notes that the anti-inflammatory markers of interleukin-6 and interleukin-1 beta did not increase with vitamin D levels.
“These results suggest that VDD is associated with higher HbA1c levels, BMI, and TNF-α concentrations in women; thereby emphasizing the significance of maintaining sufficient vitamin D levels, particularly in women, to improve these clinical parameters,” the Korean researchers emphasise, highlighting the potential need for supplementation within this group.
The prevalence of VDD is rising following inadequate sunlight exposure and dietary intakes. Such deficiencies can have a significant impact on health, with well reported effects on bone health, as well as increasing evidence highlighting its influence on non-skeletal chronic health issue risk.
Recently, VDDs have been linked with metabolic diseases including diabetes, following an established inverse association between 25-hydroxyvitamin D (25[OH]D) levels and glucose. In addition, there has been an observed association between lower baseline levels of vitamin D in those with obesity.
Furthermore, it has been established that markers of inflammation are greatly increased in those suffering from metabolic conditions. Vitamin D supplementation has been linked with reduced inflammatory cytokines, whilst increasing anti-inflammatory types, including interleukin-1 beta (IL-1β). Thus, its potential as a treatment method within these patients has been hypothesised.
Following this, the present cohort study sought to investigate the link between vitamin D levels and glycated haemoglobin (HbA1c), BMI and inflammatory markers in those aged ≥50 years.
The cross-sectional study included the recruitment of 290 men and 125 women from the Veterans Health Service Medical Centre (VHSMC) sarcopenia cohort in Korea, consisting of individuals with and without sarcopenia. Those classified with VDD were those with serum 25(OH)D levels below 20 ng/mL.
It was reported that VDD was more prevalent in the men (64.5%), when compared to the women (35.2%) in the studied population.
Amongst the male population with VDD, it was observed that individuals had higher fat mass and HbA1c levels, whilst having a lower muscle strength and worse physical performance. Females with VDD were noted to have a higher BMI, HbA1c, TNF-α, and creatinine levels.
Following analysis, a significant inverse relationship was established between 25(OH)D levels and HbA1c, BMI, and TNF-α in women, one in which remained significant after correcting for potential confounders.
However, levels of interleukin-6 and interleukin-1 beta did not increase with vitamin D levels in both men and women.
“Vitamin D deficiency is linked to higher HbA1c, BMI, and inflammatory markers in older Korean women, thus warranting the maintenance of sufficient vitamin D levels for overall health,” the report concludes.
The researchers explain that several mechanisms may explain this potential connection between vitamin D and glucose metabolism, which can largely be attributed to the vast distribution of vitamin D receptors within the pancreas, muscles, and adipocytes which can influence insulin section and glucose uptake.
They add: “The activation of VDRs within pancreatic β cells directly influences the secretion of insulin, while in skeletal muscle, it enhances glucose uptake through the SIRT1/IRS1/GLUT4 axis.
“Furthermore, vitamin D has been found to impede adipocyte differentiation and adipogenesis and decrease peroxisome proliferator-activated receptor-γ expression. These actions contribute to the reduction in peripheral insulin resistance, which can be beneficial for individuals with obesity and disorders of metabolism.”
Despite the findings, the researchers emphasise the need for RCTs to be conducted to prove a cause and effect relationship.
“Association between Vitamin D Deficiency and Clinical Parameters in Men and Women Aged 50 Years or Older: A Cross-Sectional Cohort Study”
by Ji Hyun Lee, Ye An Kim, Young Sik Kim, Young Lee and Je Hyun Seo