Hypovitaminosis D in elderly people living in an overpopulated city : Buenos Aires, Argentina

PLANTALECH L; A BAGUR; J FASSI; H SALERNI; MJ POZZO; M ERCOLANO; LADIZESKY M; CASCO C; SN ZENI; J SOMOZA; B OLIVERI

Focus in Nutrition

Nova Publishers Inc.

Lugar: New York; Año: 2006; p. 1 - 15

Abstract                 Background:Elderly people are susceptible to hypovitaminosis D. Bone loss and fractures have been associated with Vitamin D deficiency. Urban populations are prone to suffering Hypovitaminosis D due to the type of housing (large apartment buildings), lack of green spaces, and indoor lifestyle. In addition, low-income elderly subjects have been reported to be a risk population. The aim of this study was to determine winter 25OHD serum levels of the non-institutionalized elderly population of a large overpopulated city, and to analyze their determining factors. Population and Methods: A population of healthy people aged 71.5 ± 5.4 years (X ± SE) (113 women and 56 men) living in the city of Buenos Aires (34° SL), was studied at the end of winter. None of the subjects were receiving treatment with Vitamin D supplements. Exposure to sunlight, housing, type of clothing worn in summer, Vitamin D rich food (D food) intake and socioeconomic status, were assessed using specific questionnaires. Calcium,Parathyroid hormone (PTH), bone turn-over markers and 25OHD were measured. Results: Mean 25OHD circulating levels were 17.9 ± 0.64 ng/ml. Only 51 % of subjects had sunlight exposure; 63 % consumed D food. 25OHD levels were higher in men (19.8 ± 0.2 vs 17.0 ± 0.1ng/ml p < 0.04) and in subjects who had more than 3.5 hrs /week of sun exposure (21.4 ± 1.5 vs 16.6 ± 0.6 ng/ml; p < 0.0001), ate D food three times /week or more (21.6 ± 0.2 vs 16.4 ± 0.1ng/ml; p < 0.0001), lived in a house (19.5 0.1 vs 17.1 ± 0.1 ng/ml; p < 0.018), and wore light clothes in summer (20.9 ± 2.3 vs 18.0 ± 2.7 ng/ml; p< 0.006). A multivariable regression linear model showed that gender, (Beta coefficient 2.44, CI 95% (0.25-5.15), p<0.076) sunlight exposure (Beta coefficient 0.96, CI 95% (0.45-1.46), p<0.0001) and D food intake (Beta coefficient 5.03, CI 95% (2.0-8.1), p<0.001), with adjusted R squared 0.22; p<0.0001, were predictors of 25OHD serum levels. Subjects with low income were found to have less time/week of sunlight exposure (Low: 1.9 ± 05 Middle: 2.9 ± 0.6, High Income: 5.8  ± 1.6 hours /week; p< 0.004), and poor D food intake (60%, 22.9% and 18.8% respectively; p < 0.002). Low-income subjects also showed increased PTH levels and bone turn over. 25OHD serum levels were similar in all three socioeconomic levels, although high-income subjects tended to have better Vitamin D status. Conclusions: Hypovitaminosis D is common in elderly people living in a big city, as is the case of Buenos Aires, during winter; it is related to low sunlight exposure and poor intake of Vitamin D rich foods, which counteract seasonal changes in Vitamin D synthesis. Subjects with low income are most vulnerable. Key Words: Hypovitaminosis D, elderly, urban population, sun exposure, vitamin D-rich foods.