Menopause. 2018 Apr 9. doi: 10.1097/GME.0000000000001103. [Epub ahead of print]
Vallejo MS1, Blümel JE2, Lavín P3, Torres C1, Araos A1, Sciaraffia C1.
Santiago Women (33 degrees Latitude)
|Age||Summer: % <20 ng||Winter: % < 20ng|
|20-39||5 %||49 %|
|40-59||27 %||51 %|
|>60||40 %||40 %|
Seems logical for 3 reasons
- Amount of vitamin D absorbed by the skin decreases with age
- Amount of time spent outdoors( near noon) probably decreases with age
- Amount of skin exposed when outdoors probably decreases with age
Most Vitamin D studies “adjust” vitamin D measurements with season
Do the studies vary the amount of adjustment with age?
- Search VitaminDWiki for "SEASONALLY ADJUSTED" 33 studies as of April 2018
The aim was to study whether the seasonal variation of vitamin D [25(OH)-D or calcidiol] is similar or different in younger and older women living in a southern country.
Measurement of serum 25(OH)-D concentration in 739 Chilean women aged 20 to 87 years, residents of Santiago (latitude: 33.4° South) who, during a routine gynaecological checkup, agreed to be evaluated.
The mean serum concentration of 25(OH)-D for the group was 24.1 ± 10.5 ng/mL. In women 20 to 39 years, the mean was significantly different from the mean of the ≥60 years old group (25.8 ± 10.6 ng/mL vs 23.9 ± 11.1 ng/mL; P < 0.02). Globally, 38.4% of participants had vitamin D deficiency and 36.1% insufficiency. A deficiency was present in 28.4% of the 20 to 39 years old, and in 43.9% in the ≥60 years old group (P < 0.004). In the whole group, a lower proportion (P < 0.0001) of vitamin D deficiency cases in the youngest women occurred during the summer (23.7%) in comparison to the winter (47.7%).
It was observed that the proportion of participants in the 20 to 39 years old group with vitamin D deficiency fell from 48.9% in winter to 4.9% in summer (P = 0.0001).
In the older groups, this change (less deficiency) is progressively smaller, 51.2% to 27.6% (P = 0.0020) in women 40 to 59 years old,
and it does not happen in women ≥60 years (40% with vitamin D deficiency).
Serum vitamin D deficiency [25(OH)-D or calcidiol] is highly prevalent in Santiago, especially in older women (≥60 y) throughout the year. In contrast, in younger women (<40 y), the vitamin D deficiency tends to disappear during summer. More epidemiological studies and targeted prevention actions on vitamin D deficiency are warranted.
PMID: 29634637 DOI: 10.1097/GME.0000000000001103