Elsevier

Nutrition

Volume 24, Issue 5, May 2008, Pages 414-420
Nutrition

Applied nutritional investigation
Seemingly paradoxical seasonal influences on vitamin D status in nursing-home elderly people from a Mediterranean area

https://doi.org/10.1016/j.nut.2008.01.006Get rights and content

Abstract

Objective

We investigated vitamin D status in institutionalized elderly subjects by measuring serum 25-hydroxyvitamin D (25[OH]D) and its association with season and other factors: age, gender, nutritional status, cognitive function, functional ability, dietary intake, vitamin D supplement consumption, and disease.

Methods

The cross-sectional study included 86 subjects, 65–94 y of age (29 men and 57 women), who lived in three nursing homes in Murcia, a Spanish Mediterranean area. The Mini Nutritional Assessment, Short Portable Mental Status Questionnaire, and BI were used to evaluate nutritional status, functional ability, and cognitive function, respectively. Serum 25(OH)D concentrations were used to assess vitamin D status. The thresholds of inadequacy were considered to be <25 nmol/L (vitamin D deficiency) and <50 nmol/L (vitamin D insufficiency).

Results

Body mass index was 28.8 ± 5.8 kg/m2 (mean ± SD). Vitamin D dietary intake was very much below the recommended dietary intake. The Mini Nutritional Assessment was 23.6 ± 4.0, cognitive function was 7.8 ± 1.9, and functional ability 82.9 ± 23.1. The percentages of subjects with inadequate serum 25(OH)D concentrations were 58.2% and 32.6%, taking into consideration cutoffs of 50 and 25 nmol/L, respectively. Vitamin D deficiency was more common in women (40.3%) than in men (20.7%). Serum 25(OH)D concentrations varied significantly with the season in which the samples were taken, but not with the other factors analyzed.

Conclusion

In this Mediterranean area, a substantial percentage of institutionalized subjects showed an inadequate vitamin D status, which could be remedied by the consumption of vitamin D–fortified foods and/or vitamin D supplements, especially during the summer months.

Introduction

Vitamin D deficiency has been found to be prevalent among elderly populations in many regions of the world [1], [2], [3], [4], [5], [6]. In community-dwelling elderly people, the prevalence of vitamin D deficiency is 5–25% and this is much greater (48–80%) in the institutionalized elderly population [7], [8], [9], [10].

Vitamin D is produced endogenously when the skin is exposed to sunlight (ultraviolet B 290–315 nm) and can be obtained exogenously from a few natural food sources and by food fortification and supplements. Several factors potentially affect vitamin D status. These include genetic factors, adiposity, and factors affecting the cutaneous synthesis of vitamin D such as skin pigmentation, age, season, latitude, melanin concentration, clothing, and use of sunscreens [11]. Elderly people are prone to vitamin D deficiency because of various risk factors including decreased dietary intake, diminished sunlight exposure, reduced skin thickness, impaired intestinal absorption, and impaired hydroxylation in the liver and kidneys [12], [13]. In addition, several studies carried out in elderly people have revealed a poorer vitamin D status during the autumn and winter because of the lower sunlight exposure during these months [2], [14], [15], [16], [17].

An inadequate vitamin D status is associated with increased bone turnover and bone loss, which increases fall and fracture risks. This condition is also related to muscle weakness and more recently to the risk of colorectal, breast, ovarian, and prostate cancers and type 1 diabetes and heart disease [18], [19], [20], [21], [22], [23]. Vitamin D and calcium supplementation has been shown to contribute to the prevention of hip and non-vertebral fractures in elderly women and men [14], [24], [25], [26], [27], [28].

It is well recognized that elevated serum parathyroid hormone concentrations and low 25-hydroxyvitamin D (25[OH]D) levels are common indicators of vitamin D deficiency. Serum or plasma 25(OH)D concentration is considered an appropriate measurement of vitamin D status [11], [29]. The limit for optimal 25(OH)D concentrations is still unclear, with levels ranging from 20 to 122 nmol/L to prevent secondary hyperparathyroidism [30], [31], [32], [33]. We chose to operate with limits of 25 nmol/L for vitamin D deficiency and 50 nmol/L for insufficiency, in agreement with previous studies [2].

The aim of the present study was to determine vitamin D status (assessed by measuring serum concentrations of 25[OH]D) in elderly nursing-home subjects from the province of Murcia, a Mediterranean area in southeast Spain, and the relation to season and other factors, namely age, gender, dietary intake, vitamin D supplements, nutritional status, functional ability, cognitive function, and disease.

Section snippets

Subjects

The cross-sectional study was carried out in the province of Murcia (southeast Spain) between May 2005 and October 2006. The age of the subjects ranged from 65 to 94 y and all lived in three public nursing homes from urban areas. Only subjects who had a normal diet were included (subjects who had enteral or parenteral nutrition or pureed foods were excluded). From a total of 464 subjects living in the three nursing homes studied, 143 (30.8%) consumed a normal diet and/or were not severely

Results

The mean characteristics of the subjects studied are summarized in Table 1. The number and age of the subjects were significantly higher for women than for men and proportional to the subjects living in the three nursing homes studied (data not shown).

The mean BMI value of the subjects (28.8 ± 5.8 kg/m2) was within the normal range for elderly populations (24–29 kg/m2).

The mean MNA score was 23.6 ± 4.0; according to the classification of the MNA test, our subjects were not malnourished or at

Discussion

The BMI for elderly populations should be 24–29 kg/m2[44]; in the present study, the mean BMI value of the subjects was within this range but at the highest values of normality (28.8 ± 5.8 kg/m2).

The median daily dietary intake of energy, proteins, and calcium exceeded the recommended dietary intake for Spanish elderly people [40].

The results concerning average daily dietary intake of energy, proteins, and calcium, in addition to BMI and MNA, suggest that the studied subjects can be considered

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    This study was supported by the Social Action Institute of Murcia, Murcia Region Government, Spain.

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