Compensation for the interracial variance in the cutaneous synthesis of vitamin D.
We investigated the homeostatic compensation for the lower cutaneous synthesis of vitamin D in heavily melanized persons. Vitamin D2 (50,000 IU) was administered in a single oral dose to 24 young adults, 12 blacks and 12 whites, matched for age, gender, and socioeconomic status. We also included a group of eight healthy elderly white adults as representatives of a population with a nonracial mechanism for decreased cutaneous vitamin D synthesis. Plasma determinants were performed under basal conditions and at 6, 10, and 24 hours after vitamin D intake. Basal 25-hydroxyvitamin D (25-OH-D) levels were significantly lower in blacks (12.5 +/- 2.2 ng/ml (mean +/- SEM)) and in elderly whites (19.2 +/- 1.9 ng/ml), compared with young whites (30.2 +/- 3.0 ng/ml (p < 0.0001)); levels of basal 1,25-dihydroxyvitamin D (1,25(OH)2 -D) did not differ between groups. The vitamin D blood curve was similar between groups after the oral vitamin D2 load. Increases in 25-OH-D were 91.7 +/- 15.9% in blacks, 18.8 +/- 5.2% in young whites, and 28.6 +/- 6.9 in elderly whites; 1,25(OH)2-D levels increased slightly and did not differ between groups, although in blacks the change over time was significant (p < 0.05). As a whole, the study populations exhibited a strong relation between basal and peak 25-OH-D (r = -0.80; p < 0.001). Levels of intact parathyroid hormone and serum calcium of blacks and young whites did not differ within or between groups throughout the test.(ABSTRACT TRUNCATED AT 250 WORDS)
Matsuoka
L Y
LY
Department of Dermatology, Jefferson Medical College, Philadelphia, USA.
Wortsman
J
J
Chen
T C
TC
Holick
M F
MF
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People; D002112:Calcifediol / Q000097:blood; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood; D002762:Cholecalciferol / Q000097:blood; D004872:Ergocalciferols / Q000008:administration & dosage / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D012867:Skin / Q000378:metabolism*; D012880:Skin Pigmentation / Q000502:physiology*; D014807:Vitamin D / Q000096:biosynthesis* / Q000097:blood; D044465:White People
D004872:Ergocalciferols; D010281:Parathyroid Hormone; D014807:Vitamin D; D002762:Cholecalciferol; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium