HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Boucher, B. Search for Related Content PubMed PubMed Citation Articles by Boucher, B. Agricola Articles by Boucher, B.

Calcium and vitamin D intakes and blood pressure

The Royal London Hospital Whitechapel London E1 1BB United Kingdom E-mail: bboucher{at}doctors.org

Dear Sir:

Jorde and Bønaa (1), in reporting a negative association between estimated calcium intake and blood pressure, commented on the lack of a discernible effect of vitamin D intake on blood pressure despite previous reports suggesting that increased vitamin D status leads to a reduction in blood pressure. In discussing the shortcomings of the study, they mentioned that although vitamin D status is determined by exposure to sunlight as well as by diet, this determinant of vitamin D status "was not evaluated." There are, however, 2 obvious markers of exposure to sunlight in a country such as Norway, as in the United Kingdom and other European countries, that could properly be used as surrogates for such exposure and that may be available.

First, physical activity was examined as a determinant of blood pressure. If the records allow identification of the duration of outdoor as opposed to indoor activity, then that data could be used in analysis (2). Second, the capacity of sunlight to induce vitamin D synthesis in the skin varies markedly with season of the year in northern Europe, as can the markers of bone turnover (3). Indeed, review of the literature shows that reduction in blood pressure in the summer in such countries has been used as evidence to support the suggestion that increased vitamin D status is associated with a reduction in blood pressure (4). If, therefore, the dates on which subjects had their blood pressure measured are available, then the authors should be able to examine their data for seasonal variation in blood pressure. The use of one, or ideally both, of these factors in appropriate multifactorial analyses is required before conclusions can be drawn about the relative roles of calcium intake and vitamin D status in the determination of blood pressure in healthy Norwegian subjects.

REFERENCES

1. Jorde R, Bønaa KH. Calcium from dairy products, vitamin D intake, and blood pressure: the Tromsø study. Am J Clin Nutr 2000;71: 1530–5.[Abstract/Free Full Text]
2. Baynes KCR, Boucher BJ, Feskens EJM, Kromhout D. Vitamin D, glucose tolerance and insulinaemia in elderly men. Diabetologia 1997;40:344–7.[Medline]
3. Woigte HW, Scheidt-Nave C, Kissling C, et al. Seasonal variation of biochemical indexes of bone turnover: results of a population-based study. J Clin Endocrinol Metab 1998;83:68–75.[Abstract/Free Full Text]
4. Boucher BJ. Inadequate vitamin D status: does it contribute to the disorders comprising syndrome ‘X’? Br J Nutr 1998;79:315–27.[Medline]

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Boucher, B. Search for Related Content PubMed PubMed Citation Articles by Boucher, B. Agricola Articles by Boucher, B.