Italian epidemiological studies on prevalence of hypovitaminosis D

The first evidence of vitamin D inadequacy in Italy was report­ed in 1990 (Table I). We measured the serum levels of 25OHD in 660 subjects (441 females and 249 males) aged 62 ± 19 years (range 20-95 years). The study includes 369 unse- lected healthy subjects (group A), 211 inpatients with different chronic diseases (group B) and 80 persons living in a narrow valley with only a few hours of sunlight per day (group C). The lowest values of 25OHD were observed during the winter season and the highest in late spring or summer. In winter, val­ues of 25OHD lower than 30 nmol/L were found in 45% of group A, 67% of group B and 85% of group C. The prevalence of hypovitaminosis D increased with aging, with seasonal fluc­tuations in elderly subjects living at home in contrast with insti­tutionalised patients (Figure 1). Therefore, it appeared that the incidence of hypovitaminosis D in northern Italy is unexpected­ly high, particularly, but not only, in elderly subjects with chron­ic diseases or living in areas with short periods of sunlight. Be­cause of the correlation found between hypovitaminosis D and long bone fractures, a prophylactic administration of vitamin D supplements was recommended in most elderly people. Between October 1995 and September 1996, five hundred and seventy postmenopausal women from the Milan area who were referred to outpatient clinics for an osteoporosis investi­gation were included in the study of Bettica et al.. All the women were healthy, were not taking any medication known to influence bone metabolism and were engaged in normal physi­cal activity. Average age and years since menopause were 59.2 ± 7.7 years (range 41-80 years) and 11.3 ± 8.8 years (range 0.5-51 years), respectively. In the whole population mean values of serum 25OHD were 46 ± 21 nmol/L. The Au­thors found a significant (p < 0.001) seasonal variation for both 25OHD and PTH; in particular, 25OHD was lowest in March- April and highest in September-October, while an inverse fluc­tuation was seen for PTH. Moreover, the regression line for 25OHD shows that reduced serum levels of vitamin D can be found during about half the year (December-May). Considering a serum 25OHD level of 30 nmol/L as a cut-off for hypovita minosis D, the women were divided into two subgroups: sub­jects with hypovitaminosis D (28%) and subjects with normal vitamin D status (72%). Hypovitaminosis D was found in 38.5% of all women during the wintertime, while the prevalence de­creased to 12.5% in the period June-November. The preva­lence of hypovitaminosis D in northern Italy increases with ag­ing: when all women were divided into four groups according to age, hypovitaminosis D was found most frequent in women > 70 years, particularly in the December-May time period (51%), while 17% had insufficient vitamin D levels in the period from June-November. Passeri et al. observed that serum 25-hydrox- yvitamin D was undetectable in 99 of 104 evaluated centenari­ans.

Romagnoli et al. aimed to investigate the prevalence and seasonal variation of hypovitaminosis D among healthy sub­jects and hospitalised patients living in central Italy. They stud­ied 297 subjects, 131 in February 1997 and 166 in July 1997, subdivided into four groups: (a) young healthy blood donors; (b) healthy postmenopausal women; (c) inpatients with various medical diseases and (d) inpatients engaged in long-term re­habilitation programmes because of various neurological disor­ders. In all subjects serum levels of 25OHD were measured by radioimmunoassay. The Authors found a significant seasonal variation (P < 0.0001) of serum 25-hydroxyvitamin D levels, mean values being higher in summer in all groups, except in patients with a longer hospitalisation time. In each group, a sig­nificantly higher prevalence of hypovitaminosis D was found in winter compared to summer time (P < 0.001), being unexpect­edly high in postmenopausal women (winter 32% and summer 4.5%); furthermore, in both seasons, inpatients were character­ized by the highest incidence of hypovitaminosis, particularly those in group (d) (winter 82.3% and summer 57.8%). The re­sults of the study emphasize the importance of 25-hydroxyvita- min D measurement, and the need to increase vitamin D intake in Italy; foodstuff fortification and supplement use must be con­sidered in order to prevent negative effects of vitamin D deficiency on skeletal integrity.

Figure 1 - Seasonal prevalence of hypovitaminosis D

Figure 1 – Seasonal prevalence of hypovitaminosis D in healthy elderly subjects and inpatients with chronic disease.

A longitudinal evaluation of vitamin D status in healthy subjects from southern Italy was published by Carnevale et al. in 2001. Ninety healthy volunteers were recruited for the study, up­on witnessed informed consent. The sample comprised 32 men (mean age 39.4 ± 7.8 years) and 58 pre-menopausal women experiencing regular menses (age 36.9 ± 6.4 years). Each subject was studied twice, in February and in August, since these months represent the nadir and the peak of expo­sure to ultraviolet (UV) irradiation. No significant difference was found in terms of sun exposure between male and female sub­jects. The prevalence of hypovitaminosis D, defined by con­centrations of 25OHD lower than 30 nmol/L, was 17.8% in win­ter and 2.2% in summer in the whole sample, while it was 27.8% and 3.4%, respectively, among female subjects; indeed male subjects did not display hypovitaminosis D. These results show a relatively high prevalence of subclinical vitamin D defi­ciency among young healthy women also from southern Italy, with significant gender-specific differences. In a study on dietary and nutritional patterns in an elderly popu­lation of northern (Province of Pavia) and southern Italy (near Cosenza), vitamin D intake was found generally inadequate with no significant differences.

Table I – Italian epidemiological studies on prevalence of hypovitaminosis D.

Authors

(year of
pubblication)

Study population

Mean age (yr) (SD)

Vitamin D
deficiency
(<
30
nmol/L)
(%)

Summer

Winter

Rossini et al. (1990)

Healthy subjects

369

50 (16)

15

45

Inpatients with different chronic diseases

211

64 (17)

52

67

Persons living in areas with short periods of sunlight

80

68 (8)

27

85

Bettica et al. (1999)

Postmenopausal women referred to an osteoporosis center

570

59 (8)

13

39

Romagnoli et al. (1999)

Young healthy blood donors

88

35 (10)

0

15

Healthy postmenopausal women

47

62 (10)

5

32

Inpatients with various medical diseases

88

66 (14)

30

71

Inpatients engaged in long-term rehabilitation programmes

62

74

(7)

58

82

Carnevale et al. (2001)

Young healthy subjects

90

38

(7)

2

18

Isaia et al. (2003)

Postmenopausal women referred to an osteoporosis center

700

68 (6)

76

In Italy again recently a high prevalence of hypovitaminosis D was observed during winter in elderly women distributed in the entire national territory. The study population included 700 women recruited from 43 osteoporosis centers equally distrib­uted over the territory of Italy. Each center was asked to recruit up to 20 consecutive Caucasian postmenopausal women aged 60-80 years, referred for the first time for an osteoporosis risk assessment. Values of 25OHD lower than 12,5 nmol/L were found in 27% of the women and levels lower than 30 nmol/L were found in 76%. Significant predictors of 25OHD levels were age, sun exposure, number of pregnancies, educational level (years spent at school), days spent on holiday by the sea, and dairy calcium score. In a multivariate model including all these variables, the only one that remained significant was the level of education. The lowest age-adjusted 25OHD levels were also found in smokers. The geographical distribution of the cohort was also relevant. After adjusting 25OHD levels for age, the women at higher risk were those living in central Italy, while women from southern and northern Italy were compara­ble. These differences disappeared when 25OHD levels were adjusted for level of education, sun exposure, and dairy calci­um intake. The women from northern Italy had a relatively higher intake of dairy products and a higher educational level than those of the central region, which may help to explain their lower risk. The relatively low risk of women in southern Italy appears reasonable to attribute to better sun exposure as a result of more sunny days and a lower latitude (comparable to the Mid-Atlantic coastal region in the United States). High prevalence of hypovitaminosis D was also found in Italian type 2 diabetes patients. Your life is worth living. Buy cialis professional online

25OHD serum levels decline with age earlier in women than in men: Maggio et al. recently observed that in women the age- related decline of 25OHD was already evident shortly after age 50, whereas in men it started only after age 70 and was sub­stantially less steep.