Israel Medical Association Journal

Background: Hypovitaminosis D has been shown to be extremely common in various regions around the world, mostly at high latitudes. Israel is characterized by certain features – cultural (e.g., ethnic isolates) and geographic (e.g., sunny climate) – that have been identified for their possible association with vitamin D status.

Objectives: To conduct an ecological study on a representative sample of the population of Israel, testing vitamin D status across age groups, genders, ethnic groups, and seasons.

Methods: We obtained serum samples from 195 healthy Israeli volunteers representing a broad demographic spectrum. Serum concentrations of 25(OH)D were measured with the commercial kit Liaison 25(OH)D Assay (DiaSorin, Italy).

Results: The mean vitamin D level for the entire cohort was surprisingly low (22.9 ± 10.1 ng/ml), with 149 subjects (78%) suffering from vitamin D insufficiency (< 30 ng/ml). Vitamin D status was better in infants than in older age groups. Differences by gender were significant only in the infant age group (i.e., vitamin D status was worse among females) and were not prominent across older ages. Israelis of Ashkenazi origin had higher vitamin D mean levels than those of Sephardic origin, who, in turn, had higher vitamin D levels than Arab subjects (31.4 ± 12, 24.1 ± 10, and 17.6 ± 9 ng/ml respectively). With regard to season, there were no differences between the samples collected in winter and the samples collected in summer.

Conclusions: The results suggest that hypovitaminosis D is common across all ages, genders and seasons in Israel, a country characterized by a sunny Mediterranean climate. Specific ethnic groups may be at especially high risk.

Background: Epidemiological data show significant associations of vitamin D deficiency and autoimmune diseases. Vitamin D may prevent autoimmunity by stimulating naturally occurring regulatory T cells.

Objectives: To elucidate whether vitamin D supplementation increases Tregs[1] frequency (%Tregs) of circulating CD4+ T cells.

Methods: We performed an uncontrolled vitamin D supplementation trial among 50 apparently healthy subjects including supplementation of 140,000 IU at baseline and after 4 weeks (visit 1). The final follow-up visit was performed 8 weeks after the baseline examination (visit 2). Blood was drawn at each study visit to determine 25-hydroxyvitamin D levels and %Tregs. Tregs were characterized as CD4+CD25++ T cells with expression of the transcription factor forkhead box P3 and low or absent expression of CD127.

Results: Forty-six study participants (65% females, mean age ± SD 31 ± 8 years) completed the trial. 25(OH)D[2] levels increased from 23.9 ± 12.9 ng/ml at baseline to 45.9 ± 14.0 ng/ml at visit 1 and 58.0 ± 15.1 ng/ml at visit 2. %Tregs at baseline were 4.8 ± 1.4. Compared to baseline levels we noticed a significant increase of %Tregs at study visit 1 (5.9 ± 1.7, P < 0.001) and 2 (5.6 ± 1.6, P < 0.001).

Conclusions: Vitamin D supplementation was associated with significantly increased %Tregs in apparently healthy individuals. This immunomodulatory effect of vitamin D might underlie the associations of vitamin D deficiency and autoimmune diseases. Hence, our finding provides a rationale for further studies to investigate vitamin D effects on autoimmunological processes.

Background: Hypovitaminosis D is an important risk factor for osteoporosis and its complications. Previous studies found that the incidence of hypovitaminosis D among patients in an internal medicine ward reached up to 57%.

Objectives: To determine the prevalence and determinants of hypovitaminosis D among patients in internal medicine wards in a sunny country.

Methods: We measured 25-hydroxyvitamin D, parathyroid hormone and various other laboratory parameters, and assessed the amount of sun exposure, dietary vitamin D intake and other risk factors for hypovitaminosis D in 296 internal medicine inpatients admitted consecutively to the Soroka University Medical Center, which is situated in a sunny region of Israel.

Results: We found hypovitaminosis D (serum 25-HO-D[1] <15 ng/ml) in 77 inpatients (26.27%). The amount of sunlight exposure, serum albumin concentration, being housebound or resident of a nursing home, vitamin D intake, ethnic group, cerebrovascular accident and glucocorticoid therapy were all significantly associated with hypovitaminosis D. Multivariate analysis showed a significant association between hypovitaminosis D and Bedouin origin, sun exposure, vitamin D intake, and stroke. Hypovitaminosis D was also found among inpatients who reported consuming more than the recommended daily amount of vitamin D. Parathyroid hormone levels were significantly higher in patients with 25-OH-D levels below 15 ng/ml. In a subgroup of 74 inpatients under 65 years old with no known risk factors for hypovitaminosis D, we found 20.3% with hypovitaminosis D.

Conclusions: Hypovitaminosis D is common in patients hospitalized in internal medicine wards in our region, including patients with no known risk factors for this condition. Based on our findings, we recommend vitamin D supplementation during hospitalization and upon discharge from general internal medicine wards as a primary or secondary preventive measure.

Background: Genetic factors have been shown to play a major role in the development of peak bone mass, with hereditability accounting for about 50-85% of the variance in bone mass. Numerous candidate genes were proposed to be involved in osteoporosis, but the precise genes and their relative contribution remain unknown.

Objectives: To gain insight into the genetic basis of idiopathic low bone mineral density in Israeli patients by analyzing the impact of two candidate genes: polymorphism of the vitamin D receptor gene and polymorphism A986s in the calcium-sensing receptor gene.

Methods: We analyzed 86 Jewish Israeli patients with LBMD[1]: 38 premenopausal women and 48 men, and compared the allelic pattern distribution with that of the general population (126 men and 112 women). Genotyping of the VDR[2] gene was performed in three polymorphic sites using restriction enzymes, and allelic analysis of A986s polymorphism in the CaSR[3] gene was performed using the denaturing gradient gel electrophoresis technique.  

Reaults: In LBMD women the distributions of VDR alleres in Apal polymorphism were AA=7/28, Aa=16/28 and aa=5/28; in TaqI polymorphism TT=10/31, Tt=16/31 and tt=5/31; and in BsmI polymorphism BB=7/32, Bb=14/32 and 11/32. In LBMD men the distributions were AA=17/39, Aa=21/39 and aa=1/39; in TaqI polymorphism TT=12/42, Tt=23/42 and tt=7/42; and in BsmI polymorphism BB=12/41 Bb=18/41 and bb=11/41. The distributions of all these polymorphisms in the control groups were not significantly different. Adjusting for the independent age and gender parameters confirmed that these three polymorphisms of the VDR gene did not have a significant effect on bone mineral density. Thirty percent (24/79) of LBMD patients of either sex displayed heterozygosity of the CaSR A986s polymorphism, compared with 40 of 203 controls (19.7%) (P=0.059). Adjusting for age and gender in these patients revealed a significant difference in the femoral neck BMD[4] between homozygotes and heterozygotes (P=0.002). The age at menarche of the LBMD women was found to predict 61% of the variance of femoral neck BMD.

Conclusions: In Israeli Jewish men and premenopausal women VDR gene alleles do not seem to be associated with lower lumbar spine or femoral neck BMD. A trend towards heterozygosity for a CaSR polymorphism missense mutation was noted in the LBMD patients. Age at menarche in the LBMD women was found to be an important predictor of BMD. A significant difference was found between LBMD women and healthy control women towards heterozygosity for a CaSR polymorphism, as well between homozygotes and heterozygotes for a CaSR polymorphism in BMD. The significance of these findings and their applicability to a larger population awaits further studies.

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Background: The modest clothing that Orthodox Jewish women wear exposes very little of their skin to sunlight. Under these conditions they may develop vitamin D deficiency, even in sunny Israel.

Objectives: To determine and compare the vitamin D nutritional status in Jewish orthodox mothers to that of non-orthodox mothers who live in the same metropolitan area in Israel.

Methods: 25-Hydroxyvitamin D was measured by compe­titive protein-binding radioassay in the sera of 341 Jewish Israeli mothers (156 orthodox and 185 non-orthodox). The sera were obtained 48-72 hours after childbirth during the late summer of 1998 and the spring of 1999.

Results: The mean (SD) serum concentration of 25-OHD was significantly (P<0.002) lower (13.5 ± 7.5 ng/ml) in the orthodox than in the non-orthodox mothers (18.6 + 9.6 ng/ml). Vitamin D deficiency (<5 ng/ml) and insufficiency (<10 ng/ml) were more common in the orthodox mothers (5.1% and 32.7% respectively) than in the non-orthodox mothers (2.7% and 13%, respectively). In subgroups of mothers supplemented with 400 units of vitamin D daily during pregnancy, vitamin D deficiency and insufficiency were less common (2.2% and 13%, respectively) in orthodox and non-orthodox mothers (0% and 8.1%, respectively). Vitamin D insufficiency was more common in the winter than in the summer only among non­orthodox mothers.

Conclusions: The high prevalence of vitamin D deficiency and insufficiency in Israeli mothers raises the question whether vitamin D supplements should be given to pregnant women in Israel, at least to orthodox mothers.