Relationship Between Vitamin D Status From Childhood to Early Adulthood With Body Composition in Young Australian Adults

Kun Zhu; Wendy H. Oddy; Patrick Holt; Wendy Chan She Ping-Delfos; Joanne McVeigh; Leon Straker; Trevor A. Mori; Stephen Lye; Craig Pennell; John P. Walsh

Disclosures

J Endo Soc. 2019;3(3):563-576. 

In This Article

Abstract and Introduction

Abstract

Context: Vitamin D plays a role in the differentiation and metabolism of skeletal muscle and, possibly, adipose tissue; however, the relationship between vitamin D status during growth and body composition in early adulthood is unclear.

Objective: We examined associations between vitamin D status in childhood, adolescence, and early adulthood with body composition at age 20 years.

Design, Setting, Participants: We studied 821 offspring (385 females) of the Western Australian Pregnancy Cohort Study who had ≥3 serum 25-hydroxyvitamin D [25(OH)D] at age 6, 14, 17, and 20 years and body composition assessed at age 20 using dual-energy x-ray absorptiometry. The participants were grouped into four vitamin D status trajectories: consistently lower, decreasing, increasing, and consistently higher.

Results: The mean serum 25(OH)D at the study visits was 72.7 to 86.8 nmol/L. In males, serum 25(OH)D at 17 and 20 years was positively associated with lean body mass (LBM), and 25(OH)D at age 20 correlated negatively with fat body mass (FBM). Males with a consistently higher 25(OH)D trajectory had a 2.3- to 3.7-kg greater LBM and 4.1- to 6.0-kg lower FBM at 20 years compared with those with consistently lower or decreasing trajectories (P < 0.05 for all). In females, 25(OH)D at 14, 17, and 20 years was negatively associated with FBM. Females with increasing or consistently higher 25(OH)D trajectories had a 5.2- to 6.8-kg lower FBM at age 20 compared with those with a consistently lower trajectory (P < 0.05 for all).

Conclusions: In the present predominantly white, relatively vitamin D-replete cohort, a higher vitamin D status trajectory from childhood to early adulthood was associated with a greater LBM in males and lower FBM in both sexes at age 20.

Introduction

Vitamin D has well-established physiological roles in calcium homeostasis and bone metabolism, and considerable evidence has supported its importance in the differentiation and metabolism of skeletal muscle cells.[1] Despite this, studies examining the relationship between vitamin D status and lean body mass (LBM) in adults have yielded inconsistent results, with some showing positive associations,[2,3] and others showing null associations with muscle mass[4] or area.[5] It has been hypothesized that during growth, vitamin D might have a positive influence on the accumulation of lean mass and that this might partly mediate the positive effect of vitamin D on bone mineral accretion.[1] However, no prospective studies have examined the relationship between vitamin D status during the developmental years and LBM in young adults.

Individuals who are obese tend to have lower vitamin D levels than those who are lean, and an inverse relationship between the body mass index (BMI) and serum 25-hydroxyvitamin D [25(OH)D] is well-established.[6–8] The proposed mechanisms for this have included reduced subcutaneous synthesis of vitamin D owing to less time spent outdoors, sequestration of 25(OH)D in adipose tissue,[9] and volumetric dilution.[10] It is also possible that a low vitamin D status increases the risk of developing obesity, although the evidence has been conflicting. In the HUNT study (Nord-Trøndelag Health Study), participants with serum 25(OH)D <50 nmol/L at baseline had a substantially increased odds ratio for new-onset obesity during 10 years of follow-up.[11] In contrast, in an intervention study, cholecalciferol supplementation in overweight and obese adults for 1 year did not substantially affect body weight or body fat percentage compared with placebo; however, the mean serum 25(OH)D concentration was >50 nmol/L at baseline.[12] A Mendelian randomization analysis of vitamin D and obesity concluded that a higher BMI could lead to a lower 25(OH)D but that any effects of a lower 25(OH)D in increasing the BMI were likely to be small.[13] However, BMI has well-recognized limitations as a measure of body fatness, and it remains possible that vitamin D status affects body composition (i.e., the proportion of LBM and FBM) without altering the body weight or BMI. In support of this, in a 12-week randomized controlled trial of 77 healthy, premenopausal overweight and obese women with a serum 25(OH)D concentration <50 nmol/L, supplementation with vitamin D3 at 1000 IU daily substantially reduced the FBM, without substantial effects on body mass or BMI.[14] In young women, vitamin D insufficiency has been associated with a greater total FBM measured using DXA, with visceral and subcutaneous fat measured using computed tomography.[15] Data are lacking on whether the vitamin D status during childhood, adolescence, and early adulthood is associated with the body composition in young adults.

We previously reported that in the offspring (generation 2) of the Western Australia Pregnancy Cohort (Raine) study, a higher vitamin D status during childhood and adolescence was associated with substantially greater bone mass at age 20 years in men but not in women.[16] Because of the negative health consequences associated with a low muscle mass and high body fat in later life, in the present study, we examined the relationships between vitamin D status during growth and development with LBM, ALM (a surrogate of muscle mass), FBM, and trunk/limb fat mass ratio (a surrogate of visceral fat)[17] in young adults.

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