Low Vitamin D if low UV (Pregnant Japanese, 2012)

High frequency of vitamin D deficiency in current pregnant Japanese women associated with UV avoidance and hypo-vitamin D diet

PLOS x, March 4, 2019 https://doi.org/10.1371/journal.pone.0213264

Kumiko T. Kanatani , Takeo Nakayama, Yuichi Adachi, Kei Hamazaki, Kazunari Onishi, Yukuo Konishi, Yasuyuki Kawanishi, Tohshin Go, Keiko Sato, Youichi Kurozawa, Hidekuni Inadera, Ikuo Konishi, Satoshi Sasaki, Hiroshi Oyama, Japan Environment and Children's Study Group

Blood samples were taken generally in 1st trimester during 2011-2013Only a single woman took 600 IU of Vitamin D (none >600 IU)Note: Japanese Vitamin D Levels have increased a lot since then* Need 460 IU of vitamin D to get half of young Japanese women to even 20 ng level – Nov 2017* Japanese need at least 30 ng of Vitamin D, test costs are now reimbursed – Nov 2016* Vitamin D levels increasing 7 percent per year, bones denser in Japan (probably supplementation) - June 2015Note: Many women want whiter, not darker skin so avoid the sun (including the use of parasols)* Japanese women 20X more likely to be vitamin D deficient than men, etc. – Many 2013* Senior Korean women have much less vitamin D than men (possible reasons) Jan 2014* If you can get UVB without UVA you will get Vitamin D perhaps without any tanning * Vitamin D from low-cost UVB lamps * You can assemble your own Vitamin D lamp for < $50* It has about 50X less UVA than sunlight (thus not darken skin)* Items in both categories Pregnancy and UV are listed here: {category}

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Amount of time in sun (anytime of the day) vs season

Background

As a consequence of indoor occupations and reduced exposure to sunlight, concerns have been raised that vitamin D deficiency is widespread in developed countries. Vitamin D is known to be associated with increased risks of morbidity and mortality in various diseases.

Objective

To investigate the serum vitamin D status and its relation with life-style factors in pregnant Japanese women.

Methods

Among a cohort for 3,327 pregnant women who participated in an the adjunct study of the Japan Environment and Children's Study during 2011–2013, in which data were obtained on various life-style factors, including both dietary intake of vitamin D and frequency of UV exposure, this study consisted of 1,592 pregnant women, from whom 2,030 serum samples were drawn in Jan, Apr, Jul, and Oct, and the association between serum 25(OH)D level and life-style factors were analyzed using linear mixed models.

Results

Serum 25(OH)D levels were less than 20ng/mL in 1,486 of 2,030 samples (73.2%). There was an obvious seasonal change, with serum 25(OH)D levels of less than 20 ng/mL in 89.8% and 47.8% of samples in spring (April) and autumn (October), respectively. Both the frequency spent under sunlight and dietary intake of vitamin D were significantly associated with serum 25(OH)D level. An increase in sunlight exposure of more than 15 min for 1 to 2 days per week in non-winter, or dietary intake of 2 μg/day of vitamin D resulted in an elevation of 1 ng/mL in serum 25(OH)D levels.

Conclusion

These findings indicate that vitamin D deficiency is very severe in Japanese pregnant women, especially those rarely exposed to sunlight. The benefits of UV rays should also be informed of when its risk is alerted, and clinicians should propose the adequate UV exposure level.