Relationships between circulating 25(OH) vitamin D, leptin levels and visceral adipose tissue volume: results from a 1-year lifestyle intervention program in men with visceral obesity.

BACKGROUND/OBJECTIVES: Obesity has been associated with elevated leptinemia and vitamin D deficiency. To date, whether there is an association between vitamin D and leptin levels independent from adiposity remains uncertain. Our objective was to investigate the associations between changes in 25(OH) vitamin D levels, changes in adiposity variables, and changes in leptin levels produced by a 1-year lifestyle intervention program. SUBJECTS/METHODS: Sedentary men (n = 113) with abdominal obesity, dyslipidemic, and non-vitamin D supplemented were involved in a 1-year lifestyle modification program. Subjects were individually counseled by a kinesiologist and a nutritionist once every 2 weeks during the first 4 months with subsequent monthly visits in order to elicit a 500 kcal daily energy deficit and to increase physical activity/exercise habits. Adiposity mapping by computed tomography and cardiometabolic biomarkers, as well as vitamin D measurements were performed at baseline and at the 1-year visit. RESULTS: The 1-year intervention resulted in a 26% decrease in visceral adipose tissue volume (from 1951 ± 481 to 1463 ± 566 cm3), a 27% decrease in leptin levels (from 12.0 ± 8.1 to 8.5 ± 7.8 ng/mL) and a 27% increase in plasma 25(OH) vitamin D concentrations (from 50 ± 18 to 60 ± 18 nmol/L, p < 0.0001). One-year increases in 25(OH) vitamin D levels were inversely correlated with 1-year changes in leptin levels (r = -0.41, p < 0.001). The association remained significant after adjustment for 1-year changes in various adiposity indices: visceral adipose tissue (r = -0.30, p = 0.0019), subcutaneous adipose tissue (r = -0.35, p = 0.0004), total abdominal adipose tissue (r = -0.31, p = 0.0015), and fat mass (r = -0.31, p = 0.001). CONCLUSIONS: In response to a 1-year lifestyle intervention, changes in 25(OH) vitamin D levels were independently associated with changes in leptinemia after adjustment for adiposity changes. This finding supports a possible physiological link between leptinemia and 25(OH) vitamin D levels independent from adiposity and underscores the role of lifestyle modifications leading to lowered leptinemia in the clinical management of vitamin D deficiency.

Dietary intake of branched-chain amino acids in a mouse model of Alzheimer's disease: Effects on survival, behavior, and neuropathology.

INTRODUCTION: High levels of plasmatic branched-chain amino acids (BCAA), commonly used as dietary supplements, are linked to metabolic risk factors for Alzheimer's disease (AD). BCAA directly influence amino acid transport to the brain and, therefore, neurotransmitter levels. We thus investigated the impact of BCAA on AD neuropathology in a mouse model. METHODS: 3xTg-AD mice were fed either a control diet or a high-fat diet from 6 to 18 months of age. For the last 2 months, dietary BCAA content was adjusted to high (+50%), normal (+0%), or low (-50%). RESULTS: Mice fed a BCAA-supplemented high-fat diet displayed higher tau neuropathology and only four out of 13 survived. Mice on the low-BCAA diet showed higher threonine and tryptophan cortical levels while performing better on the novel object recognition task. DISCUSSION: These preclinical data underscore a potential risk of combining high-fat and high BCAA consumption, and possible benefits from BCAA restriction in AD.

Changes in circulating vitamin D levels with loss of adipose tissue.

PURPOSE OF REVIEW: Low vitamin D levels have been extensively reported in obesity. Thus, the pandemic of obesity has been paralleled by a high prevalence of low vitamin D status. Given the well documented associations linking poor vitamin D status to adverse health outcomes (diabetes, cardiovascular disease, cancers, all-cause mortality), a proper understanding of the mechanisms linking excess adiposity to low vitamin D status is key to identify and implement effective interventions to replenish vitamin D levels in obese individuals. In this review, we will discuss recent literature investigating the effects of adipose tissue volume loss through energy restriction and/or physical activity on circulating 25-hydroxyvitamin D [25(OH)D] levels. RECENT FINDINGS: Improvements of circulating 25(OH)D levels with adiposity loss through lifestyle interventions without supplementation is being reported by a growing number of studies, including recent randomized controlled trials. SUMMARY: Low 25(OH)D is one of the metabolic disturbances associated with excess adiposity, particularly visceral adiposity. Recommendations for the treatment of obesity-related vitamin D deficiency should emphasize the role of visceral adiposity loss through healthy lifestyle habits, in conjunction with weight-adjusted vitamin D supplementation, not only to replenish 25(OH)D levels but also to address other visceral adiposity-related disturbances, such as insulin resistance, inflammation, hypertension, and dyslipidemia.