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

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28 OLSON MEMORIAL LECTURE – CARIG WORKSHOP 2011Cord plasma retinol [μmol/l]figure 3: Relationship between calculated and measuredamounts of vitamin A (μmol /g wet weight) in the livers of 11generally healthy human adults. The solid line is the line ofidentity (1:1 correspondence). From Furr et al. 161.21.00.80.60.40.200 0.1 0.2 0.3 0.4 0.5 0.6Measured liver vitamin A [μmol/g]“The first study in human subjectsto directly compare measuredliver vitamin A content with thepredictions of isotope dilution wasperformed in the laboratory ofProf James Olson”Applications of isotope dilution assessmentRibaya-Mercado et al 20 showed that the isotope dilution techniquecould indeed detect changes in total body stores of vitaminA in elderly subjects in Guatemala. Haskell et al 21 foundthat the isotope dilution technique could detect changes in totalvitamin A body stores in male adult subjects in Bangladesh,subsequent to long-term consumption of different amounts ofvitamin A. These two studies provided early corroboration of thetechnique. The improvement in vitamin A status in Nicaraguanschoolchildren after a sugar fortification program was evaluatedby Ribaya-Mercado et al. 22The kinetics of an oral dose of tracer vitamin A was examinedin preschool children in Peru. 23 There was also an apparent correlationbetween serum tracer/tracee ratio at three days afterdosing with the total body stores, as estimated from the ratio atlonger times of mixing.Conversion of carotenoids to vitamin Aand estimates of bioequivalencyTang et al 24,25 were the first to use isotope dilution to demonstratethat carotenoids from green and yellow vegetables canmaintain liver vitamin A stores, from a study in Chinese children.Lin et al 26 used double-label techniques (tracer retinol labeledwith ²H₆, and ²H₆-β-carotene which yielded ²H₃-retinol on cleavage)to verify that the extent of conversion of β-carotene to vitaminA is quite variable among human subjects, a finding corroboratedby Wang et al. 27 Ribaya-Mercado et al 28 subsequentlyfound that the extent of conversion of provitamin A-carotenoidsto vitamin A varies inversely with vitamin A stores as determinedby isotope-dilution, but is independent of serum retinolconcentration. Tang et al 29 used the double-label approach toshow that β-carotene can be cleaved to vitamin A in tissues afterabsorption. And Ribaya-Mercado et al 30 showed an increase invitamin A pools in Filipino children after dietary consumption ofcarotene-rich foods.Haskell et al 31 determined the bioequivalence of β-carotenefrom sweet potato (13:1) and Indian spinach (10:1), comparedwith that from isolated β-carotene in capsules (6:1). You et al 32did not estimate vitamin A status, but did use labeled retinolto estimate the intestinal absorption and conversion of an oraldose of carotenoids from red palm oil. Wang et al 33 measureda conversion factor of 4.5 for spirulina β-carotene in Chineseadults. The vitamin A equivalency of labeled β-carotene in capsuleswas determined to be approximately 3.36, whether administeredin an oil matrix or a vegetable diet, but the absorptionefficiency of β-carotene was much greater from the oil than fromthe vegetables. 34Estimation of human dietary requirements of vitamin AThe dietary intake of vitamin A (preformed plus provitamin A-carotenoids) was correlated with vitamin A stores by Ribaya-Mercado et al 35 in an elderly Filipino population. They calculatedthat a daily intake of 400 μg RAE for women, or 500 μgRAE for men, is sufficient to maintain adequate vitamin A stores.(This may be compared with estimates of 567 μg RAE for women,707 μg RAE for men, calculated by Olson from other considerations).36 Recently, Haskell et al 37 used isotope-dilution estimatesof vitamin A pool size to calculate an estimated averagerequirement of approximately 350 μg RAE per day to maintain aliver pool of 0.047 μmol/g for Bangladeshi men of small stature;maintaining a higher vitamin A pool would, of course, requirea greater intake. Clearly, this approach is useful for estimatingRecommended Dietary Intakes for vitamin A.
SIGHT AND LIFE | VOL. 25 (2) | 2011 OLSON MEMORIAL LECTURE – CARIG WORKSHOP 2011 2929Alternative isotope dilution calculationsA practical problem with the Olson equation is the impliedneed for a lengthy mixing period between administration oftracer and collection of a blood sample for determination ofisotope ratio. From the human studies by Bausch and Rietz 12and Sauberlich et al, 18 it was concluded that 21 days were necessaryfor complete mixing. However, tracer:tracee ratios atthree and six days after dosing were shown by Ribaya-Mercadoet al to correlate well to those at 21 days. 20 Three-day predictiveequations were determined by Tang et al, 38 Haskell et al 23and Ribaya-Mercado et al. 39 Although these equations differ inform, happily they give similar results.Duncan et al 40 developed empirical two-component exponentialregression equations to correlate rat liver vitamin Astores with plasma isotope dilution data for 4, 4.4, 5 and 5.4days for rats given tracer intravenously. Similarly, Adams andGreen 41 developed empirical biexponential regression equationsto correlate rat liver vitamin A stores with plasma isotopedilution data at 3 days, 4, 4.4, 5, 5.4, and 6 days after oral administrationof tracer dose. An extension of this approach forapplication to humans has been developed (Duca and Green,personal communication).Further research needs for application of isotopedilution to assess human vitamin A statusThe kinetics of vitamin A metabolism in children has been examinedin only one study, among 12–24 month children. 23 Sofar, the Olson equation as determined for adults has been usedwithout verification. Although such studies pose ethical concerns,further data on vitamin A metabolism in young humansare essential for developing suitable prediction equations to allowthe extension of this technique to children.Further development of short-term prediction equations willfacilitate the use of the isotope-dilution procedure. Mathematicalmodels of human vitamin A kinetics show promise for thedevelopment of general prediction equations which are applicableto a wide range of sampling times (Green MH and Furr HC,unpublished work).“Further data on vitamin Ametabolism in young humans areessential for developing suitableprediction equations to allowthe extension of this techniqueto children”ReviewsAmong the generally available reviews of isotope dilution for assessmentof vitamin A status are those of Wasantwisut, 42 Tanumihardjoet al, 43 Furr et al, 44 Haskell et al 45 and Furr et al. 46AcknowledgmentsThe author happily acknowledges the support of Prof JamesOlson in helping understand and implement the application ofisotope dilution for assessment of human vitamin A status, andis also grateful for collaborations with many colleagues.Correspondence: Harold C Furr, 115 West Rainbow Drive,Bridgewater, VA 22812-1735 USA E-mail: hfurr581@yahoo.comReferences01. Moore T. Vitamin A. Amsterdam: Elsevier, 1957.02. Olson JA. New approaches to methods for the assessment of nutritionalstatus of the individual. Am J Clin Nutr 1982;35:1166-1168.03. Burri BJ, Jacob RA. Vitamin A analogs as tests for liver vitamin Astatus in the rat. Am J Clin Nutr 1988; 47:458-462.04. Tanumihardjo SA, Furr HC, Erdman JW Jr et al. Use of the modifiedrelative dose response (MRDR) assay in rats and its applicationto humans for the measurement of vitamin A status. Eur J ClinNutr 1990;44:219-224.05. Fonseca de Moura F, Burri BJ, Clifford AJ. Accelerator massspectrometry in the study of vitamins and mineral metabolism inhumans. In: Zempleni J, Rucker RB, McCormick D B, Suttie JW, eds.Handbook of Vitamins. Boca Raton FL: CRC Press,2007: pp545-557.06. Tanumihardjo SA.Vitamin A status assessment in rats with 13C4-retinyl acetate and gas chromatography/combustion/isotope ratiomass spectrometry. J Nutr 2000;130:2844-2849.07. van Lieshout M. Bioavailability and bioefficacy of β-carotenemeasured using 13C-labeled β-carotene and retinol: studies inIndonesian children. Wageningen, Netherlands: WageningenUniversity, 2001.08. Aklamati EK, Mulenga M, Dueker SR et al. Accelerator mass spectrometrycan be used to assess vitamin A metabolism quantitativelyin boys in a community setting. J Nutr 2010;140:1588-1594.09. Rietz P, Vuilleumier JP, Weber F et al. Determination of thevitamin A bodypool of rats by an isotopic dilution method.Experientia 1973;29:168-170.⇢
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Page 5 and 6: WelcomeThe risk of doing nothing
Page 7 and 8: The Sight and Life editorial board
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Page 32 and 33: 32 THE LINK BETWEEN NUTRITION, DISE
Page 38 and 39: 38 VITAMIN D AND INFLAMMATIONPlasma
Page 40 and 41: 40 VITAMIN D AND INFLAMMATIONfigure
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 48 and 49: 48 OPINION 1Opinion 1: Vitamin D St
Page 50 and 51: 50 OPINION 2variety of medications,
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Page 58 and 59: 58 FEIKE SIJBESMA: A VISION OF LIFE
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