Seasonal variation in the serum 25-hydroxyvitamin D levels of young and elderly active and inactive adults in São Paulo, Brazil

Abstract

Objective: To evaluate the 25-hydroxyvitamin D [25(OH)D] concentrations in individuals in the city of São Paulo belonging to different age groups and exhibiting specific behavioral characteristics and to correlate the 25(OH)D concentration with the level of UV radiation (UVR). Patients and Methods: A total of 591 individuals were included, distributed as follows: 177 were living in institutions (NURSING, 76.2 ± 9.0 y old), 243 were part of the community elderly (COMMUNITY, 79.6 ± 5.3 y old), 99 were enrolled in a physical activity program targeting the elderly (ACTIVE, 67.6 ± 5.4 y old) and 72 were young (YOUNG, 23.9 ± 2.8 y old). Blood samples from all individuals were collected throughout the year. UVR measurements were taken by an official meteorology institution. Results: The UVR values varied throughout the year, following a sinusoidal-like pattern. Because of the Earth’s orbit, we hypothesized that there would be cyclic patterns for the 25(OH)D and UVR values that repeat every 12 mo. The general formula is represented by the equation P1+P2⋅sin(−2⋅π12⋅(t−P3)) The mean 25(OH)D concentration and the amplitude of the variation were significantly higher for the YOUNG and ACTIVE groups than for the COMMUNITY and NURSING groups. The nadir for UVR was in June, whereas the nadir for the 25(OH)D concentration was in the spring, corresponding to a delay of one season. Conclusions: There was seasonal variation in the 25(OH)D concentration for all the groups studied; however, the amplitude of the variation was higher for the groups of young and physically active people, possibly due to the higher level of sunlight exposure for these groups. The lowest 25(OH)D concentration was detected in the spring.

Differences in the prevalence of vitamin D deficiency and hip fractures in nursing home residents and independently living elderly

“…Moreover, the difference persisted irrespective of the mobility level of the residents. The lower sun exposure in residents has been linked also to a flatter all-year vitamin D curve (19). The sun exposure of our subjects was limited by the typically cold winter weather.…”

“…Maeda and cols. for instance measured similar winter levels and difference between community-dwelling elderly and nursing home residents (19). Their study was carried in Brazil, at latitude of 23° S. The locations included in our study lie between 42°40' and 43°50' N and much lower UVB should be expected.…”

Is there an association between vitamin D and liver fibrosis in patients with chronic hepatitis C?

“…It should be questioned if vitamin D deficiency increases with age and the patients included in the present study should be quite young to assess this relationship. Vitamin D concentration was evaluated in individuals in the city of São Paulo belonging to different age groups (15) . A total of 591 individuals were included.…”

Vitamin D Insufficiency in Adolescents: Results of Year-Round Screening in Moscow

“…ш. [5], синтез холекальциферола значительно ниже, и, соот-ветственно, выше частота встречаемости дефицита или авитаминоза D. Самые низкие концентрации кальцидиола у жителей северного полушария обнаруживаются в весен-ние месяцы года, когда полностью истощаются запасы витамина D, синтезированного предыдущим летом [8]. При обследовании 118 взрослых молодых женщин и мужчин, проживающих в Турции, выявлено, что средний сыворо-точный уровень 25(OH)D составляет 28,4 ± 10,4 нг/мл в августе и 13,8 ± 6,6 нг/мл в феврале [9].…”