Reduced plasma half-life of radio-labelled 25-hydroxyvitamin D₃in subjects receiving a high-fibre diet

Abstract

I . The plasma disappearance of 3H-labelled 25-hydroxyvitamin D, (25(OH)D3) was studied in healthy volunteers on normal and high-fibre diets, using ,H-labelled tracer doses given intravenously.2. The mean ( +SEM) plasma half-life in the high-fibre-diet group was 19.2f 1.7 d, which was significantly shorter than in the group on normal diets (27.5f2.1 d, P < 0.02).3. This finding suggests that a high-fibre diet leads to enhanced elimination of 25(OH)D3 by an action within the intestinal lumen. This may involve interference with an enterohepatic circulation of the metabolite, perhaps by binding of 25(OH)D3 to dietary fibre. We have examined the possibility that a high-fibre diet may increase loss of endogenous 25(OH)D, by measuring the plasma disappearance of radio-labelled 25(OH)D, in healthy volunteers, taking either a normal or a high-fibre diet. METHODSThirteen healthy Caucasian subjects were studied, twelve male and one female, with a mean age of 32.5 years (range 28-44 years). The project received the approval of the hospital ethical committee and all subjects gave their informed consent.The subjects were allocated to either normal (n 6) or high-fibre (n 7) diets. The high-fibre group took 20 g fine bran (Allinson's Bran Plus) three times daily (equivalent to approximately 20 g dietary fibre/d) in addition to their normal diet, while the only restriction placed on the other group was that they should avoid high-extraction breakfast cereals, wholemeal bread and bran. The diets were started 24 h before the injection of radio-labelled 25(OH)D, and continued for 30 d.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

“…The estimated half-life of 25OHD in infants is 2-3 wk (717), similar to values in adults (59,62,189,344,449), which means that a higher cord blood 25OHD will only influence neonatal levels over about the first 6 wk. Randomized intervention studies indicate that typical maternal vitamin D doses of 400-1,000 IU/day do not consistently increase breast milk content of vitamin D or 25OHD, whereas with maternal vitamin D doses of 2,000 -4,000 IU/day, an increase in milk content of vitamin D and 25OHD and neonatal 25OHD can be demonstrated (13,14,402,780).…”

Should We Be Concerned about the Vitamin D Status of Athletes?

“…Concerning dietary practices, vitamin D intake appears to be lower in some vegetarians (Davey et al) and vegans (Outila et al) and in those who consume few dairy products or fortified foods Whiting & Calvo, 2005b). The high phytate and fiber content of vegetarian diets might also decrease vitamin D absorption or increase vitamin D loss by impairing interhepatic vitamin D circulation (Batchelor & Compston, 1983). In contrast, consuming fish at least four times per week achieved mean vitamin D concentrations of 65 nmol/L (Nakamura, Nashimoto, Hori, & Yamamoto, 2000).…”

Vitamin D Deficiency and Seasonal and Inter-day Variation in Circulating 25-hydroxyvitamin D and Parathyroid Hormone Levels in Indoor Daytime Workers: A Longitudinal Study

“…Hiroaki ITOH 1 * , Ippei MORI 1, 2 , Yuki MATSUMOTO 1 , Syou MAKI 1 and Yasutaka OGAWA 1 25-Hydroxyvitamin D (25OHD), a major component of circulating vitamin D metabolites whose biological half-life in blood (2-5 wk in normal subjects) [10][11][12][13][14] is substantially longer than that of vitamin D itself (24 h) 10) , is commonly used as an indicator of individuals' vitamin D status 15) . Exposure to solar ultraviolet (UV) B irradiation changes 7-dehydrocholesterol to previtamin D by photosynthesis in the skin.…”