Older women do not have seasonal variations of vitamin D levels: a study from a southern country - April 2018
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?
OBJECTIVE:
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.
METHODS:
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.
RESULTS:
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).
CONCLUSIONS:
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
No seasonal change in Vitamin D levels for Frail Older Hospitalized Patients - May 2018
Seasonal Variation in Vitamin D Status among Frail Older Hospitalized Patients.
J Frailty Aging. 2018;7(2):95-99. doi: 10.14283/jfa.2018.10.
Pourhassan M1, Wirth R.
BACKGROUND AND OBJECTIVES:
Seasonal variation in 25-hydroxyvitamin D [25(OH)D] levels is the result of sunlight dependent skin synthesis of vitamin D. However, its presence is not studied in frail older hospitalized patients. We sought to investigate whether seasonal variation in 25(OH)D levels is evident among these patients.
DESIGN AND SETTING:
This study investigated older participants who were consecutively admitted between February 2015 and December 2016 to the geriatric acute care ward. Results of routine measurements of 25(OH)D at hospital admission were retrospectively analyzed and stratified according to months and seasons. Previous intake of vitamin D supplementation was derived from the patients' medical records.
RESULTS:
The study group comprised 679 participants (mean age 82.1±8.2; 457 females), of which 78% had vitamin D deficiency. Older individuals not taking vitamin D supplements had a lower mean serum 25(OH)D than those receiving supplements. Of those patients with no vitamin D supplementation, 87.0% were vitamin D deficient and only 5% showing sufficient vitamin 25(OH)D. Further, there were neither monthly nor seasonal variations in vitamin 25(OH)D levels among these patients and their vitamin D levels stayed far below the recommended threshold of 20 ng/ml across the seasons.
CONCLUSION:
Vitamin D deficiency was very prevalent in the subgroup of older hospitalized patients without vitamin D supplementation, irrespective of season. Since no seasonal variations in mean 25(OH)D levels was observed, sunlight dependent skin synthesis is unlikely to contribute to vitamin D status in these patients. Supplementation seems to be necessary to maintain desirable vitamin D levels among this population throughout the year.