NFS284 Lecture 3. How much of a nutrient is required to maintain health? Types and amounts of foods to maintain health

Transcription

1 NFS284 Lecture 3 Chapter 2: Nutritin: Guidelines: Applying the Science f Nutritin 2.1 Nutritin Recmmendatin fr the Canadian Diet Nutrient-based apprach Hw much f a nutrient is required t maintain health? Fd-based apprach Dietary pattern Types and amunts f fds t maintain health Recmmendatins are regularly updated Nutrient-based apprach Histry First recmmendatins in Canada 1939, 1943 Recmmended Nutrient Intakes (RNI) Tday Dietary Reference Intake (DRIs) Determined by the Institute f Medicine (IOM) by Canadian and American scientists beginning in the 1990 s and cntinuing tday Canada s Official Fd Rules 1942: Fig 2.2 Fd-based apprach 2.2 Dietary Reference Intakes (DRIs) Fr planning and assessing diets f healthy individuals Values fr different life stages/males r females Infants Children Teens Yung, middle, lder adults Pregnancy/lactatin

2 Energy Estimated Energy Requirement (EER) Macrnutrients Acceptable Macrnutrient Distributin Range (AMDR) Other Nutrients Estimated Average Requirement (EAR) Recmmended Dietary Allwance (RDA) Adequate Intake (AI) Tlerable Upper Intake Level (UL) Knw terms and abbreviatins Statistics Distributin curve Median = 50% abve, 50% belw Measure f range r variance -> diff. frm lwest level t highest level Median is the same, standard deviatin (r variance) is different Frequency: # f individuals Lk at areas under curve -> lk at prbability Shaded area under the curve -> prbability f adequate r inadequate nutrient intake 50% f the curve is shaded -> 50% prbability f adequate r inadequate nutrient intake Estimated Average Requirement (EAR) Definitin: nutrient intake that meets the requirement f 50% f individuals in a grup (ie. Sex; age) Hw is it used T estimate the prbability that an individual s usual intake is meeting his/her requirement

3 T estimate what prprtin f a grup is meeting their requirements Used by individual and ppulatin Hw is it determined? Determine a bichemical criterin that allws yu t determine the intake at which an individual s requirement is being met Determine the requirement distributin frm a sample f the ppulatin Nutrient basis Can measure criterin; using this, can measure requirement fr each individual Establishing EARs CONSIDER: Hypthetical Vitamin X Physilgical criteria: Vitamin X requirement is met when the level f Vitamin H in serum reaches saturatin IMPORTANT: nt universal criterin fr all nutrients Cnduct a depletin-repletin experiment n a ppulatin f healthy adults Knw when smene has reached nutrient requirement when reached saturatin Depletin Fed a vitamin X-free diet Levels f vitamin X in bld are tracked Eventually levels decline until n vitamin X is detected (ie. The individual is deficient) Then repletin Repletin

4 Begin refeeding vitamin X What happens? Bld levels f vitamin X begin t rise Eventually each individual reaches an intake at which there is n crrespnding rise in bld levels, ie. Bld is saturated with vitamin X That vitamin X intake is the individual s vitamin X requirement Start w/ lw levels, eventually reach plateau Intake f Vit X t saturatin level is requirement f Vit X Will the requirement be the same fr each individual? At end, wuld knw each individual requirement Requirement Distributin fr Vit X (39 subjects) Start w/ 39 subjects; get 39 different requirements, get nrmal distributin Middle line crrespnds w/ intake f 100 s EAR = 100 mg; if smene intakes 100 mg, 50% making requirement EAR = middle pint f distributin T understand hw requirement distributins are used, it is imprtant t distinguish between REQUIREMENT and INTAKE Nutritin Requirement Experimentally determined requirement fr a nutrient Amunt required t maintain health Nutrient Intake Amunt f nutrient cnsumed Determined by the cmpsitin f the diet EAR (Estimated Average Requirement) Frm the Vit X requirement distributin the EAR can be determined

5 EAR represents the average daily nutrient intake that meets the requirements f half the healthy individuals in a given grp If an individual s nutrient intake is equal t the EAR then there is a 50:50 chance the individual is meeting his/her requirement EAR = median line May r may nt be meeting requirement; 50% chance Determining the prbability f meeting requirements frm the requirement distributin f a nutrient What is the prbability that A is meeting his requirement? Gray area represents 12% f the ttal area under the curve Individual A has 12% f meeting requirement Cnsuming less than EAR What is the prbability that B is meeting his requirement? Gray area represents 80% f the ttal area under the curve Intake greater than EAR Higher the intake the higher the prbability f meeting requirement Recmmendatins depend n prbabilities 2.2 Dietary Reference Intakes: Hw is the RDA used? As a gal fr an individual s usual intake, because it is almst certainly adequate RDA = EAR + 2 Standard Deviatins If g ut 2 SDs ut frm median n nrmal distributin, cver 98% f curve Theretically curve ges n frever s can t have 100% Recmmended dietary allwance (RDA) Target intake that increase prbability f meeting requirement If cnsume level f RDA

6 If cnsume level f RDA, have 98% chance f meeting requirement Assess intake based n hw clse t RDA Recmmended Dietary Allwance RDA: meets the requirements f 98% f individuals: 140mg 1 persn utside Using the EAR t Determine the Prevalence f Adequate Intake within a Grup T estimate what prprtin f a grup is meeting their requirements EAR cut pint methd intake distributin (results f a survey f nutrient intakes) EAR represents median; 50% prbability RDA = target; increase prbability EAR Cutpint Methd Intake distributin 90% has intake less than EAR, nt meeting requirement; bad EAR cutpint methd prprtin f the ppulatin whse intake is less than the EAR = Prprtin f the ppulatin that is NOT meeting its requirement Can t identify which individuals, but can calculate hw well GROUP ding Befre answer Q, intake distributin r requirement Plt intakes based n dietary survey Shape f curve nt nrmal; have high lw end, almst never have 0 mg b/c nutrients s widespread 78% nt meeting requirement; median intake lw (tp graph) Median intake high (bttm graph) 10% f ppulatin nt meeting requirement 2 intake distributins when median intakes

7 QUESTION: If the median intake is equal t the RDA des that mean that 98% f the ppulatin is meeting its requirement? ANSWER: It depends Cnsider these tw intake distributins This distributin is typically what is seen in real wrld data, i.e. when median intake = RDA mre than 2% f ppulatin is nt meeting its requirements Hw well a ppulatin is ding with respect t nutrient intake depends n bth the median intake and the standard deviatin f the intake distributin, therefre use EAR cutpint methd fr assessment Median intake same; in this case, = RDA but variance different EAR cutpint prduces diff results Diff prprtin even thugh same median Can t make assessments based n median intake; need EAR cutpint Depends n variance 2% and 12% nt meeting requirement Hw is the EAR cutpint methd used: Health Canada: Cnsiders a ppulatin t have an adequate intake if the prprtin f the ppulatin whse intake is belw the EAR is 10% r less (remember this number) Canadian Cmmunity Health Survey: Measured nutrient intake and used the EAR cutpint methd t determine the adequacy f nutrient intake Adequate Intake Insufficient data t calculate an EAR Mre research is needed

8 Usually based n an estimate f average nutrient intake by a healthy ppulatin Example: recmmendatins fr calcium intake fr yung infants 0-6 mnths f age = 200mg Adequate intake f 200 mg The average calcium intakes f exclusively breast-fed infants If yur intake > AI, then intake is OK AI is gd persnal target If intake < AI yur intake may r may nt be OK Dn t have requirement distributin AI is persnal; targeting Tlerable Upper Intake Level (UL) The highest level f habitual nutrient intake that is unlikely t pse a risk f adverse effects UL is nt a recmmended level f intake N additinal benefit abve RDA Because f the ppular use f supplements adverse effects are pssible Sme UL are based nly n the amunt f nutrient cnsumed in supplement frm But it s OK frm natural fd surces Main surce f nutrients frm fd, but created UL fr supplement DIETARY REFERENCE INTAKES (DRI) Energy Estimated Energy Requirement (EER) Macrnutrients Acceptable Macrnutrient Distributin Range (AMDR)

9 Other Nutrients Estimated Average Requirement (EAR) Recmmended Dietary Allwance (RDA) Adequate Intake (AI) Tlerable Upper Intake Level (UL) Knw terms and abbreviatins Energy Balance Energy cntent (kcal) f fd cnsumed = energy cntent expended fr metablism and physical activity weight is unchanged, i.e. energy balance Energy cntent (kcal) f fd cnsumed > energy cntent expended fr metablism and physical activity weight gain, i.e. psitive energy balance Energy cntent (kcal) f fd cnsumed < energy cntent expended fr metablism and physical activity weight lss, i.e. negative energy balance Fr us, try t maintain weight Estimated energy requirements (EER) Equatins (determined by experiment) are used t estimate the average energy needs f adults Men: EER = 662 (9.53 X age [y]) + PA x (15.91 x weight [kg] x height [m]) Wmen: EER = 354 (6.91 X age [y]) + PA x (9.36 x weight [kg] x height [m]) PA (physical activity term) = 1.00 (sedentary) 1.48 (very active) Dn t memrize equatins, but knw the variables invlved See als sectin 7.3: Estimating Energy Needs pg 274 Definitins f activity levels

10 Sedentary: Activities f daily living; less than 30 min f intentinal exercise/day Active: Walking 1 hur 45 minutes at 6.5 km per hur every day (+470 t 580 kcal) Lw Active: Walking 30 minutes at 6.5 km per hur every day (+135 t 165 kcal) Recmmended; brisk pace; spend extra kcal Very Active: Walking 4 hurs 15 minutes at 6.5 km per hur every day (+1145 t 1405 kcal) EER (Estimated Energy Requirement) and Age Female: 5 5, 125 lb, 20 yrs, Sedentary, BMI 21, 1950 kcal Female: 5 5, 125 lb, 50 yrs, Sedentary, BMI 21,? kcal = 1739 Female: 5 5, 125 lb, 80 yrs, Sedentary, BMI 21,? kcal = 1532 Eat lt less t meet requirement Estimates This ges dwn b/c dn t eat much Metablism slws dwn; hrmnes stimulate Use muscle mass; prtin f muscle mass diff. in lder and yunger cunterpart EER and Sex Female: 5 5, 125 lb, 20 yrs, Sedentary, BMI 21, 1950 kcal Typical female Male: 5 5, 125 lb, 20 yrs, Sedentary, BMI 21,? kcal = 2266 BMI higher b/c males have mre muscle Male: 5 10, 150 lb, 20 yrs, Sedentary, BMI 21,? kcal = 2516 Typical Men s intake better than wmen; higher prbability that will meet requirement

11 EER and Bdy Size Female: 5 5, 125 lb, 20 yrs, Sedentary, BMI 21, 1950 kcal Female: 5 5, 150 lb, 20 yrs, Sedentary, BMI 25,? kcal = 2053 Higher energy requirement Weight change f individual in negative energy balance Calric requirement: 2000kcal dailty (typical) Cnsumptin: 1500kcal daily during time perid shwn Lw calrie diet; start in beginning Trying t lse weight Decrease cnsumptin t 1500 kcal/day Weight decrease and plateaus b/c 500 kcal deficit; bdy getting smaller as lsing weight; energy requirement decreases s n lnger 500 kcal deficit; deficit shrinks; manage t lse enugh weight that energy is 1500 kcal, which balances intake, getting plateau, therefre weight lss difficult Smaller bdy, less energy requirement Nw, can either start eating less fd r increase PA t maintain weight Requirement decrease as bdy size decrease DIETARY REFERENCE INTAKES (DRI) Energy Estimated Energy Requirement (EER) Macrnutrients Acceptable Macrnutrient Distributin Range (AMDR) Other Nutrients Estimated Average Requirement (EAR) Recmmended Dietary Allwance (RDA) Adequate Intake (AI)

12 Tlerable Upper Intake Level (UL) Knw terms and abbreviatins DRIs fr Macrnutrients = AMDR Acceptable Macrnutrient Distributin Ranges Expressed as % f ttal Calries Carbhydrates: 45 65% Fat: 20 35% Undesirable Fats: Saturated fat: as lw as pssible: <10% kcal (Canada s Fd Guide) <7% kcal (in scientific literature) Trans Fat: <1% kcal Prbably mre in Canadian ppulatin Chlesterl: As lw as pssible: 300 mg Prtein: 10 35% Where d these numbers cme frm? Balance b/w diff nutrients t build prteins in bdy Chlesterl driven by LDL, determined by saturated fats in diet than direct chlesterl intake Decrease intake Vitamins and minerals usually expressed as weight Want t cnsume carbs as 45-65% f calries Dn t want t high r t lw b/c wn t have enugh f ther macrnutrients Even vegetable fats have sme saturated fats s can t get dwn t 0

13 Questin: What percentage f ttal calric intake fr the individual described belw cmes frm each macrnutrient? An individual cnsumes a diet that cntains: Carbhydrates: 300 gm [300gm x 4kcal/gm]/2100kcal x 100% = 57% Prtein: 90 gm [90gm x 9kcal/gm]/2100kcal x 100% = 38.57% Fat: 60 gm [60gm x 4kcal/gm]/2100kcal x 100% = 11.4% Ttal kcalries: 2100 kcal (see Ch 1 Slides) (standard) Cnfrm t AMDRs? Des cnfrm