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Open Access Research article

Serum concentrations of 25-hydroxyvitamin D and immunoglobulins in an older Swiss cohort: results of the Senior Labor Study

Benjamin Sakem1, Cristina Nock2, Zeno Stanga34, Pedro Medina1, Urs E Nydegger1, Martin Risch5 and Lorenz Risch167*

Author Affiliations

1 Division of Clinical Chemistry, Labormedizinisches Zentrum Dr. Risch, Waldeggstrasse 37, CH-3097, Liebefeld bei Bern, Switzerland

2 Private Medical Office, Grundgasse 2, CH-6460, Altdorf, Switzerland

3 Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital, Bern, Switzerland

4 Division of General Internal Medicine, University Hospital, Bern, Switzerland

5 Central Laboratory, Kantonsspital Graubünden, Chur, Switzerland

6 Private University of the Principality of Liechtenstein, Triesen, Principality of Liechtenstein

7 Division of Clinical Biochemistry Medical University Innsbruck, Innsbruck, Austria

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BMC Medicine 2013, 11:176  doi:10.1186/1741-7015-11-176

Published: 1 August 2013

Abstract

Background

Vitamin D and the components of humoral immunity play important roles in human health. Older people have lower 25-hydroxyvitamin D (25(OH)D) serum levels than younger adults. We aimed to determine the levels of 25(OH)D serum concentrations in healthy senior citizens and to study their relationship to the levels of components of humoral immunity.

Methods

A total of 1,470 healthy Swiss men and women, 60 years or older, were recruited for this study. A total of 179 subjects dropped out of the study because of elevated serum concentrations of C-reactive protein. Fasting blood sera were analyzed for 25(OH)D with the high-performance liquid chromatography (HPLC) and for parathyroid hormone (PTH), immunoglobulins and complement C4 and C3 concentrations with immunoassays. The percentage of participants in each of the four 25(OH)D deficiency groups - severely deficient (<10 ng/ml), deficient (10 to 20), insufficient (21 to 29 ng/ml) and normal (>=30 ng/ml) - were statistically compared. The relationship of the major components of the humoral system and age with 25(OH)D levels was also assessed.

Results

About 66% of the subjects had insufficient levels of 25(OH)D. Normal levels of 25(OH)D were found in 26.1% of the subjects of which 21% were males and 30.5% were females (total study population). Severely deficient levels of 25(OH)D were found in 7.98% of the total study population. Low levels of 25(OH)D were positively associated with IgG2 (P = 0.01) and with C4 (P = 0.02), yet were inversely related to levels of IgG1 and IgA (P < 0.05) and C3 (P = 0.01). Serum levels of total IgA, IgG, IgG2 and IgG4 peaked together with 25(OH)D during late summer.

Conclusions

Approximately two-thirds of the healthy, older Swiss population presented with Vitamin D insufficiency. The incremental shift in IgA and C3 levels might not necessarily reflect a deranged humoral immune defense; however, given the high prevalence of vitamin D deficiency, the importance of this condition in humoral immunity will be worth looking at more closely. This study supports the role of vitamin D in the competent immune system.

Keywords:
25(OH)D; Immunoglobulins; IgA; Complement; Humoral immunity; Sunlight exposure; Older people