Serum 25-hydroxyvitamin D trajectory from childhood through early adulthood was associated with lean body mass in men and fat body mass in both men and women, according to findings from a longitudinal birth-cohort study.
“Optimal vitamin D status from childhood to early adulthood may be of public health relevance for the prevention of loss of muscle and obesity-related diseases in later life,” Kun Zhu, PhD, adjunct associate professor in the department of endocrinology and diabetes at Sir Charles Gairdner Hospital, Nedlands, Western Australia, told Endocrine Today. “Higher vitamin D status from childhood to early adulthood was associated with greater muscle mass in males and reduced body fatness in both sexes in early adulthood.”Zhu and colleagues analyzed data from 821 offspring (385 females) from the Raine study, a cohort of pregnant women recruited between May 1989 and November 1991 in Australia. Participants underwent serum 25-(OH)D measurements at age 6, 14, 17 and 20 years, as well as DXA measurements to assess body composition. Researchers stratified participants into four vitamin D status trajectories: consistently lower (n = 136), decreasing (n = 62), increasing (n = 64) and consistently higher (n = 174).
At study visits from childhood through adulthood, mean serum 25-(OH)D ranged from 72.7 nmol/L to 86.8 nmol/L.
Vitamin D, body composition
In men, vitamin D concentration at age 17 and 20 years was positively associated with lean body mass and appendicular lean mass at age 20 years. Researchers observed that, at age 17 years, each additional 25 nmol/L of 25-(OH)D in men was associated with an additional 0.91 kg in lean body mass and an additional 0.43 kg in appendicular lean mass. At age 20 years, each additional 25 nmol/L of 25-(OH)D in men was associated with an additional 2.12 kg in lean body mass and an additional 1.01 kg in appendicular lean mass. Additionally, serum 25-(OH)D at age 20 years was negatively associated with fat mass in men, with each additional 25 nmol/L associated with 3.15 kg less fat body mass and a 0.07 lower trunk-to-limb fat mass ratio, according to researchers.
In women, the researchers noted that serum 25-(OH)D levels measured at age 6, 14, 17 and 20 years were not a significant predictor of lean body mass at age 20 years; however, vitamin D measurements at age 14, 17 and 20 years were negatively associated with BMI and fat body mass at age 20 years. In women, each additional 25 nmol/L of serum 25-(OH)D was associated with a 0.77 kg/m² at age 20 years, as well as a 2.31 kg lower fat body mass. Vitamin D level at age 17 and 20 years was also negatively associated with body weight and weight-to-height ratio at age 20 years in women, whereas vitamin D level at age 17 years only was associated with lower trunk-to-limb fat mass ratio, according to researchers.
Vitamin D trajectory findings
After adjustment for covariates, men in the consistently higher vitamin D trajectory group had a higher lean body mass (by 2.3-3.7 kg) and lower fat body mass (by 4.1-6 kg) when compared with men in the consistently lower and decreasing trajectories at age 20 years. In women, there were no between-group differences with respect to fat body mass, weight-to-height ratio and BMI, although researchers observed a trend of lower body weight among women in the consistently higher trajectory group vs. the consistently lower trajectory (P = .07).
“The findings of our study suggest that consistently higher vitamin D status from childhood to early adulthood is associated with better muscle development in males and less fat accumulation in both sexes,” the researchers wrote. “However, since body composition was only assessed at [age] 20 years, the results could be explained by reverse causation; ie, that lower fat mass during growth and development led to higher vitamin D status, rather than the other way around.”
The researchers noted that, in the higher vitamin D trajectory group, there was evidence of greater participation in organized sports and less TV watching; however, those factors did not change any observed associations. – by Regina Schaffer
For more information:
Kun Zhu, PhD, can be reached at Sir Charles Gairdner Hospital, Department of Endocrinology and Diabetes, Nedlands, WA 6009, Australia; email: firstname.lastname@example.org.
Disclosures: The authors report no relevant financial disclosures.