16 intrauterine programming of ncd 24 olson memori... - DSM

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48 OPINION 1Opinion 1: Vitamin D Status and TuberculosisHenrik FriisDepartment of Human Nutrition, Faculty of LifeSciences, University of Copenhagen, DenmarkResearch in vitamin D has increased dramatically, mainly dueto the discovery that vitamin D is important not just for bonehealth, but also for a range of body functions, and in terms ofthe risk of chronic and infectious diseases. While some of theresearch is basic science, much is based on observational epidemiology,linking low serum concentrations of 25-hydroxyvitaminD (25(OH)D) to various diseases. Since the validity of mostmarkers of micronutrient status is affected by an acute phaseresponse, the review of the validity of 25(OH)D by Dr Thurnhamin this issue is timely.The main source of vitamin D is sunlight, yet deficiencyseems to be a problem in Asia and Africa, and even in equatorialcountries. 1 The burden of infectious diseases is high in lowincome populations, even among apparently healthy individuals.If, indeed, an acute phase response reduces 25(OH)D independentof vitamin D status, this will lead to an overestimation of theprevalence of deficiency, and probably confound the estimatesof association between 25(OH)D and the various outcomes.Vitamin D and tuberculosisAn area of research that illustrates the implications of poor validityof 25(OH)D in the presence of an acute phase responseis the role of vitamin D for the risk of pulmonary tuberculosis(TB). It is biologically plausible that vitamin D – given its importancefor the immune system – is a determinant of TB. 2 However,most research has been based on case-control studies, inwhich 25(OH)D is determined, as a measure of vitamin D status,in new cases with TB and in controls. Since TB patients have ahuge acute phase response, any negative effect on 25(OH)D will,hence, either lead to overestimation of a true or create a falsenegative association.Not surprisingly, a review of seven studies found that low25(OH)D was associated with the risk of TB. 3 The authors rightlyconclude that there is a need for prospective studies, but arguethat, given the evidence for the role of vitamin D in immunity,the association is likely to be due to an effect of vitamin D deficiencyon risk of TB. But what is the evidence for the opposite?Well, other protein-bound vitamins are affected during the acutephase response, since most proteins behave as negative acutephase proteins. And, as Dr Thurnham points out, not only therecent paper by Reid 4 but also an older study 5 suggest that theacute phase response affects the validity of 25(OH)D as a vitaminD marker. However, several other studies failed to demonstratesuch an effect. 1,6 Yet the absence of evidence is not evidenceof absence, and the issue should have been much betterresearched.So, what is the way forward? Intervention trials are importantbut expensive, and research funding is scarce. Thus, observationalstudies are needed to justify and prioritize trials, andto guide the design. There is a need for a better understandingof vitamin D metabolism, better markers of vitamin D status, andways to adjust for the acute phase response, as has been suggestedfor other nutrients. 7,8 Finally, when vitamin D trials areconducted, this provides an opportunity to study the effects onvarious metabolites that should not be missed.Correspondence: Henrik Friis, Department of Human Nutrition,University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C,Denmark E-mail: hfr@life.ku.dk“Observational studiesare needed to justifyand prioritize trials, andto guide the design”References01. Friis H, Range N, Pedersen ML et al. Hypovitaminosis D is commonamong pulmonary tuberculosis patients in Tanzania but is not explainedby the acute phase response. J Nutr 2008;138:2474-2480.02. Liu PT, Stenger S, Tang DH et al. Cutting edge: vitamin D-mediatedhuman antimicrobial activity against Mycobacterium tuberculosisis dependent on the induction of cathelicidin. J Immunol2007;179:2060-2063.
SIGHT AND LIFE | VOL. 25 (2) | 2011 OPINION 1 / 2 494903. Nnoaham KE, Clarke A. Low serum vitamin D levels andtuberculosis: a systematic review and meta-analysis.Int J Epidemiol 2008;37:113-119.04. Reid D, Toole BJ, Knox S et al. The relation between acute changesin the systemic inflammatory response and plasma 25-hydroxyvitaminD concentrations after elective knee arthroplasty.Am J Clin Nutr 2011;93:1006-1011.05. Louw JA, Werbeck A, Louw ME et al. Blood vitamin concentrationsduring the acute-phase response. Crit Care Med 1992;20:934-941.06. Newens K, Filteau S, Tomkins A. Plasma 25-hydroxy-vitamin D doesnot vary over the course of a malarial infection. Trans R Soc TropMed Hyg 2006;100:41-44.07. Thurnham DI, Mburu ASW, Mwaniki DL et al. Using plasmaacute-phase protein concentrations to interpret nutritionalbiomarkers in apparently healthy HIV-1-seropositive Kenyan adults.Br J Nutr 2008;100:174-182.08. Friis H, Range N, Braendgaard Kristensen C et al. Acute-phaseresponse and iron status markers among pulmonary tuberculosispatients: a cross-sectional study in Mwanza, Tanzania.Br J Nutr 2009;102:310-317.Opinion 2: The D-Cline may be Dueto Drug-SXR InteractionMichael F HolickDepartment of Medicine, Section of Endocrinology,Nutrition, and Diabetes, Vitamin D, Skin and BoneResearch Laboratory, Boston University MedicalCenter, Boston, MA, USAThe dramatic 40% decline in serum 25-hydroxy-vitamin D(25(OH)D) levels recently reported by Reid et al 1 within 24 hoursof elective joint replacement surgery has important short- andlong-term consequences, especially during post-operative healingafter surgery. It has been suggested that this 40% decline is,in part, due to the uptake of 25(OH)D by the inflammatory cells.It has been known for more than 100 years that vitamin D deficiencywas associated with increased risk for upper respiratorytract infections, and that sun exposure was effective in helpingto treat patients with tuberculosis. 2The connection between vitamin D and the immune systemis nicely documented by Dr Thurnham. Activated macrophagesafter ingesting an infective agent like a tuberculous bacteriumimmediately begin preparation for its destruction by increasingtranscriptional activity to produce 1,25-dihydroxy-vitamin D(1,25 (OH)₂D), and to enhance its responsiveness to this hormoneby increasing the number of vitamin D receptors (VDR). 3 Once1,25 (OH)₂D is bound to the VDR and retinoic acid X receptor,this complex interacts with the gene that produces the defensenprotein, cathelicidin, which in turn binds to the tubercle, resultingin its demise. Therefore, one explanation for the observationof the marked decrease in circulating levels of 25(OH)D can beattributable to this mechanism.“Another mechanismcould also have adramatic influence onvitamin D statusduring and after surgicalintervention”The role of steroid and xenobiotic receptor (SXR)However, what is not appreciated is another mechanism thatcould also have a dramatic influence on vitamin D status duringand after surgical intervention. The steroid and xenobioticreceptor (SXR) is responsible for destroying foreign substancesthat enter the body. It accomplishes this by increasing theexpression of cytochrome P450 enzymes such as CYP 3A4 andCYP 2C8. It is believed that the association of taking a wide⇢
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Page 5 and 6: WelcomeThe risk of doing nothing
Page 7 and 8: The Sight and Life editorial board
Page 9 and 10: SIGHT AND LIFE | VOL. 25 (2) | 2011
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Page 14 and 15: 14NCDs-Silent Killersle “Non-Comm
Page 16 and 17: 16 INTRAUTERINE PROGRAMMING OF NCDI
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Page 20 and 21: 20 INTRAUTERINE PROGRAMMING OF NCDM
Page 22 and 23: 22 INTRAUTERINE PROGRAMMING OF NCDR
Page 24 and 25: 24 OLSON MEMORIAL LECTURE - CARIG W
Page 32 and 33: 32 THE LINK BETWEEN NUTRITION, DISE
Page 38 and 39: 38 VITAMIN D AND INFLAMMATIONPlasma
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Page 42 and 43: 42table 3: Factors influencing vita
Page 44 and 45: 44 VITAMIN D AND INFLAMMATION1,25(O
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Page 50 and 51: 50 OPINION 2variety of medications,
Page 52 and 53: 52 SYSTEMATIC DATA ANALYSIS IN QUAL
Page 58 and 59: 58 FEIKE SIJBESMA: A VISION OF LIFE
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Page 62 and 63: 62ewsThe Carotenoids ResearchIntera
Page 64 and 65: 64ewsTackling Iron DeficiencyTACKLI
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Page 72 and 73: 72 REPORT FROM THIKAGirls at Thika
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Page 76 and 77: 76REMEMBERING MICHAEL C LATHAMRemem
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98 PUBLICATIONSThe Fight forthe Rig
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