This article was downloaded by: [Michigan State University] On: 05 March 2015, At: 14:29 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Nutrition and Cancer Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/hnuc20
Increased Risk of Prostate Cancer: Vitamin D Deficiency or Low Serum Calcium Levels? a
a
Parvane Saneei & Ahmad Esmaillzadeh a
Food Security Research Center, Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran Published online: 12 May 2014.
Click for updates To cite this article: Parvane Saneei & Ahmad Esmaillzadeh (2014) Increased Risk of Prostate Cancer: Vitamin D Deficiency or Low Serum Calcium Levels?, Nutrition and Cancer, 66:5, 914-914, DOI: 10.1080/01635581.2014.904910 To link to this article: http://dx.doi.org/10.1080/01635581.2014.904910
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Nutrition and Cancer, 66(5), 914 C 2014, Taylor & Francis Group, LLC Copyright ISSN: 0163-5581 print / 1532-7914 online DOI: 10.1080/01635581.2014.904910
LETTER TO EDITOR
Increased Risk of Prostate Cancer: Vitamin D Deficiency or Low Serum Calcium Levels? Parvane Saneei and Ahmad Esmaillzadeh
Downloaded by [Michigan State University] at 14:29 05 March 2015
Food Security Research Center, Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran
DEAR SIR: In a recent issue of Nutrition and Cancer, Salem et al. (1) described the results of an interesting observational study on the association between serum calcium concentrations and prostate cancer in 194 newly diagnosed cases of prostate cancer and 317 healthy controls. They came to the conclusion that serum total and ionized concentrations of calcium were inversely associated with the risk of prostate cancer. Although the results are of great importance, several points need to be considered in the interpretation of these findings. First, as we all know, serum calcium concentrations cannot thoroughly reflect individual’s calcium status (2). Unlike serum levels of other minerals, like magnesium (2), that are quite straightforward, serum calcium levels are complicated. Low or high serum levels of calcium do not necessarily reflect peoples’ low or high intakes of dietary calcium. Serum calcium levels are believed to be under strict homeostatic control and cannot be easily influenced by the dietary intakes of calcium (2). Serum calcium concentrations were only affected in pathological conditions, such as the presence of tumors, osteoporosis, or severe malnutrition. Vitamin D deficiency, which is highly prevalent among Iranians (3), has earlier been shown to result in lower serum calcium levels. Given the previous reports on the association between vitamin D deficiency and risk of prostate cancer (4), we believe that the associations Salem et al. reported in their study between serum calcium levels and risk of prostate cancer could be explained by vitamin D status of cases and controls. Therefore, the association between serum calcium levels and risk of prostate cancer reported in their study can be misleading, has no take-home message, and must be interpreted
along with vitamin D status. However, assessment of the association between long-term dietary intakes of calcium (instead of serum calcium levels), along with serum vitamin D levels, and risk of prostate cancer is of interest and further studies are required to examine this association. Second, several contributing factors, including diet, to the risk of prostate cancer have earlier been known; most have not been taken into account in this article. For instance, dietary intakes of β-carotene, flavonoids, black tea, total fat, tomato and its products, and garlic are associated with prostate cancer (5,6). In addition, because prospective studies did not support the protective associations of high serum calcium levels with prostate cancer (7), the case-control design of the study should also be kept in mind. Identifying the association between nutritional status of vitamins and minerals and risk of prostate cancer is definitely important; however, careful methodological, epidemiological, and statistical methods should be adopted to avoid any incorrect conclusions. REFERENCES
Submitted 4 October 2013; accepted in final form 10 March 2014. Address correspondence to Ahmad Esmaillzadeh, Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, PO Box 81745-151, Isfahan, Iran. Phone: +98-311-7922720. Fax: +98-311-6681378. E-mail: [email protected]
914
1. Salem S, Hosseini M, Allameh F, Babakoohi S, Mehrsai A, et al.: Serum calcium concentration and prostate cancer risk: A multicenter study. Nutr Cancer 65, 961–968, 2013. [Epub ahead of print] 2. Willett WC: Nutritional Epidemiology, 2nd ed. New York, NY: Oxford University Press, 1998. 3. Hovsepian S, Amini M, Aminorroaya A, Amini P, and Iraj B: Prevalence of vitamin D deficiency among adult population of Isfahan City, Iran. J Health Popul Nutr 29, 149–155, 2011. 4. Li H, Stampfer MJ, Hollis JB, Mucci LA, Gaziano JM, et al.. A prospective study of plasma vitamin D metabolites, vitamin D receptor polymorphisms, and prostate cancer. PLoS Med 4, e103, 2007. 5. Geybels MS, Verhage BA, Arts IC, van Schooten FJ, Goldbohm RA, et al.: Dietary flavonoid intake, black tea consumption, and risk of overall and advanced stage prostate cancer. Am J Epidemiol 177, 1388–1398, 2013. 6. Salem S, Salahi M, Mohseni M, Ahmadi H, Mehrsai A, et al.: Major dietary factors and prostate cancer risk: a prospective multicenter casecontrol study. Nutr Cancer 63, 21–27, 2011. 7. Skinner HG and Schwartz GG: A prospective study of total and ionized serum calcium and fatal prostate cancer. Cancer Epidemiol Biomarkers Prev 18, 575–578, 2009.
Nutrition and Cancer Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/hnuc20
Increased Risk of Prostate Cancer: Vitamin D Deficiency or Low Serum Calcium Levels? a
a
Parvane Saneei & Ahmad Esmaillzadeh a
Food Security Research Center, Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran Published online: 12 May 2014.
Click for updates To cite this article: Parvane Saneei & Ahmad Esmaillzadeh (2014) Increased Risk of Prostate Cancer: Vitamin D Deficiency or Low Serum Calcium Levels?, Nutrition and Cancer, 66:5, 914-914, DOI: 10.1080/01635581.2014.904910 To link to this article: http://dx.doi.org/10.1080/01635581.2014.904910
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Nutrition and Cancer, 66(5), 914 C 2014, Taylor & Francis Group, LLC Copyright ISSN: 0163-5581 print / 1532-7914 online DOI: 10.1080/01635581.2014.904910
LETTER TO EDITOR
Increased Risk of Prostate Cancer: Vitamin D Deficiency or Low Serum Calcium Levels? Parvane Saneei and Ahmad Esmaillzadeh
Downloaded by [Michigan State University] at 14:29 05 March 2015
Food Security Research Center, Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran
DEAR SIR: In a recent issue of Nutrition and Cancer, Salem et al. (1) described the results of an interesting observational study on the association between serum calcium concentrations and prostate cancer in 194 newly diagnosed cases of prostate cancer and 317 healthy controls. They came to the conclusion that serum total and ionized concentrations of calcium were inversely associated with the risk of prostate cancer. Although the results are of great importance, several points need to be considered in the interpretation of these findings. First, as we all know, serum calcium concentrations cannot thoroughly reflect individual’s calcium status (2). Unlike serum levels of other minerals, like magnesium (2), that are quite straightforward, serum calcium levels are complicated. Low or high serum levels of calcium do not necessarily reflect peoples’ low or high intakes of dietary calcium. Serum calcium levels are believed to be under strict homeostatic control and cannot be easily influenced by the dietary intakes of calcium (2). Serum calcium concentrations were only affected in pathological conditions, such as the presence of tumors, osteoporosis, or severe malnutrition. Vitamin D deficiency, which is highly prevalent among Iranians (3), has earlier been shown to result in lower serum calcium levels. Given the previous reports on the association between vitamin D deficiency and risk of prostate cancer (4), we believe that the associations Salem et al. reported in their study between serum calcium levels and risk of prostate cancer could be explained by vitamin D status of cases and controls. Therefore, the association between serum calcium levels and risk of prostate cancer reported in their study can be misleading, has no take-home message, and must be interpreted
along with vitamin D status. However, assessment of the association between long-term dietary intakes of calcium (instead of serum calcium levels), along with serum vitamin D levels, and risk of prostate cancer is of interest and further studies are required to examine this association. Second, several contributing factors, including diet, to the risk of prostate cancer have earlier been known; most have not been taken into account in this article. For instance, dietary intakes of β-carotene, flavonoids, black tea, total fat, tomato and its products, and garlic are associated with prostate cancer (5,6). In addition, because prospective studies did not support the protective associations of high serum calcium levels with prostate cancer (7), the case-control design of the study should also be kept in mind. Identifying the association between nutritional status of vitamins and minerals and risk of prostate cancer is definitely important; however, careful methodological, epidemiological, and statistical methods should be adopted to avoid any incorrect conclusions. REFERENCES
Submitted 4 October 2013; accepted in final form 10 March 2014. Address correspondence to Ahmad Esmaillzadeh, Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, PO Box 81745-151, Isfahan, Iran. Phone: +98-311-7922720. Fax: +98-311-6681378. E-mail: [email protected]
914
1. Salem S, Hosseini M, Allameh F, Babakoohi S, Mehrsai A, et al.: Serum calcium concentration and prostate cancer risk: A multicenter study. Nutr Cancer 65, 961–968, 2013. [Epub ahead of print] 2. Willett WC: Nutritional Epidemiology, 2nd ed. New York, NY: Oxford University Press, 1998. 3. Hovsepian S, Amini M, Aminorroaya A, Amini P, and Iraj B: Prevalence of vitamin D deficiency among adult population of Isfahan City, Iran. J Health Popul Nutr 29, 149–155, 2011. 4. Li H, Stampfer MJ, Hollis JB, Mucci LA, Gaziano JM, et al.. A prospective study of plasma vitamin D metabolites, vitamin D receptor polymorphisms, and prostate cancer. PLoS Med 4, e103, 2007. 5. Geybels MS, Verhage BA, Arts IC, van Schooten FJ, Goldbohm RA, et al.: Dietary flavonoid intake, black tea consumption, and risk of overall and advanced stage prostate cancer. Am J Epidemiol 177, 1388–1398, 2013. 6. Salem S, Salahi M, Mohseni M, Ahmadi H, Mehrsai A, et al.: Major dietary factors and prostate cancer risk: a prospective multicenter casecontrol study. Nutr Cancer 63, 21–27, 2011. 7. Skinner HG and Schwartz GG: A prospective study of total and ionized serum calcium and fatal prostate cancer. Cancer Epidemiol Biomarkers Prev 18, 575–578, 2009.
