Effets des contraceptifs féminins sur la vitamine D?

[Nutrimuscle-Conseils]

Effect of oral contraceptives on total and bioavailable 25-hydroxyvitamin D
Frank Z.Stanczyk The Journal of Steroid Biochemistry and Molecular Biology Volume 211, July 2021,


Highlights
• Vitamin D plays an important role in women’s health.
• Little is known about the effect of oral contraceptives (OCs) on vitamin D status.
• 25(OH)D is a marker of vitamin D status regulated by vitamin D binding protein.
• OC formulations differ in effects on total and bioavailable 25(OH)D and VDBP.
• VDBP is suppressed by the androgenic progestin levonorgestrel.


Studies show an increase in circulating levels of 25-hydroxyvitamin D [25(OH)D] in women using combined oral contraceptives (COCs). 25(OH)D is a quantitatively important metabolite and widely used clinical marker of vitamin D status and is regulated by vitamin D binding protein (VDBP). However, studies have not identified the type of formulations used by the women, and there are no data on the effect of progestins on 25(OH)D levels. Our study objective was to compare the effects of two COC formulations [ethinyl estradiol (EE)/norethindrone acetate (NETA) vs. EE/levonorgestrel (LNG)] as well as LNG alone on total and bioavailable (free plus albumin-bound) 25(OH)D levels in serum samples collected at baseline, mid treatment, and end of treatment. Total 25(OH)D and VDBP were measured by immunoassay, and bioavailable 25(OH)D was calculated.

The results show that with the EE/NETA formulation, total and bioavailable 25(OH)D and VDBP levels increased non-significantly by 7.4 %, 14.9 %, and 10 %, respectively, from baseline to end of treatment. In contrast, the corresponding changes with EE/LNG showed an increase of 4.4 % in total 25(OH)D but a significant decrease of 18.2 % in bioavailable 25(OH)D and increase of 19.1 % in VDBP. When LNG was administered alone, no significant changes were observed in total and bioavailable 25(OH)D or VDBP levels during the course of treatment. Our findings show considerably different effects on total and bioavailable 25(OH)D levels, as well as VDBP levels, with different oral contraceptive formulations. LNG may have a suppressive effect on VDBP, similar to its well-known androgenic effect on SHBG. Further studies are needed to determine the effect of hormonal contraceptive formulations on vitamin D status and its potential impact on women’s health.

[Nutrimuscle-Conseils]

Vitamin D3 levels in women and factors contributing to explain metabolic variations
A.Mena-Bravo The Journal of Steroid Biochemistry and Molecular Biology Volume 211, July 2021,

Highlights
• Several factors explain variations in the metabolism of vitamin D3 in women.
• Anthropometric parameters influence serum levels of vitamin D3 metabolites.
• Seasonal period and latitude also allow explaining variations in vitamin D3 levels.
• These factors do not affect the serum levels of 1,25-dihydroxyvitamin D3.
• Clinical studies based on vitamin D3 should control all these variability sources.

The elucidated metabolism of vitamin D3 in humans has been the support to explain the high involvement of this liposoluble vitamin in physiological functions. Clinical studies have associated levels of vitamin D3 metabolites with several disorders. Despite this knowledge, there is a controversy regarding the estimation of deficiency and the physiological and supraphysiological levels of vitamin D3 metabolites. The association between serum concentrations of vitamin D3 metabolites and several potentially influential factors (namely, age and anthropometric, seasonal, spatial and metabolic factors) is analyzed in this study. For this purpose, 558 women were recruited and interviewed in several Spanish provinces before blood sampling. Serum vitamin D3 and its metabolites were determined using an SPE–LC–MS/MS platform.

The concentration range for vitamin D3 was 1.7–21.1 nmol/L and was influenced by body mass index (BMI), waist-to-hip ratio (WHR) and seasonal period. 25-hydroxyvitamin D3 levels were within 4.8–147.2 nmol/L and were related to WHR, season, latitude and calcium intake. The range of 24,25-dihydroxyvitamin D3, 0.3–15.0 nmol/L, was associated to BMI, WHR, season, latitude and calcium intake. Finally, energy intake influenced the vitamin D 25-hydroxylase through the 25-hydroxyvitamin D3/vitamin D3 ratio, which regulates the synthesis of the circulating form. According to these results, it is worth emphasizing the relevance of all these factors to explain the variability in serum levels of vitamin D3 and its metabolites. All these factors should be considered in future studies assessing the alteration of vitamin D3 metabolism.