Evidence that obesity does not influence the vitamin D-endocrine system in blacks

Abstract

As compared to nonobese white men and women, age-matched nonobese black subjects and obese white individuals show alterations in the vitamin D-endocrine system that are characterized by increases in mean serum immunoreactive parathyroid hormone (PTH), serum 1,25-dihydroxyvitamin D [1,25-(OH)2D], and urinary cyclic adenosine 3,5-monophosphate (cAMP) and by decreases in mean serum 25-hydroxyvitamin D (25 OHD) and in urinary calcium. Thus, both groups show secondary hyperparathyroidism which is associated with increased renal tubular reabsorption of calcium and increased renal synthesis of 1,25-(OH)2D. In view of these findings, studies were conducted in 10 obese black subjects (3 men and 7 women) and in 12 nonobese black individuals (7 men and 5 women), ranging in age from 20 to 35 yr, to determine whether obesity influences the vitamin D-endocrine system in blacks. Body weight averaged 99 +/- 4 kg in the obese and 73 +/- 3 kg in the nonobese subjects (p less than .001). All of them were hospitalized on a metabolic ward and were given a constant daily diet containing 400 mg of calcium, 900 mg of phosphorus, 110 meq of sodium, 65 meq of potassium, and 18 meq of magnesium.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium retention and hormone levels in black and white women on high- and low-calcium diets

“…Among blacks, weight does not seem to affect the vitamin D-endocrine system. (22) The distributions of age in the two groups differed somewhat, but we could identity no significant effect of age decade on the retention or hormone levels. The postmenopausal women in this study were fairly evenly distributed in the two racial groups.…”

Prevalence and correlates of vitamin D status in African American men

“…The lack of association between BMI and 25(OH)D concentrations in our sample differs from previous studies, conducted primarily in white populations, that have noted an inverse association between the two [ 31 ]. Other evidence exists to suggest that adiposity may not be as strong a predictor of low vitamin D status among African Americans as it is in whites [ 14 , 32 , 33 ].…”

Vitamin D status among patients visiting a tertiary care center in Riyadh, Saudi Arabia: a retrospective review of 3475 cases

“…Results of Al-Elq et al study found an inverse relationship between vitamin D and BMI in Saudi males but not in females which appears that obesity is protective against vitamin D deficiency [23]. While negative association was found in many studies [24-28], some observed no relationship [29,30]. The mechanism behind such an association is that elevated concentrations of 1-25-vit D stimulate lipogenesis and inhibit lipolysis in cultured human adipocytes, leading to accumulation of fat [31].…”