Todays Topics Dietary Reference Intakes Energy Balance DRI

Today’s Topics Dietary Reference Intakes Energy Balance

DRI Process • • • North American Initiative Institute of Medicine and Health Canada Each panel has at least 1 Canadians review draft document Intended to replace 1989 RDAs and 1990 RNIs • Not just traditional nutrients

Dietary Reference Intakes (DRIs) • DRIs are a set of nutrient reference values • For vitamins, minerals, macronutrients and energy • Used modelling to develop the eating pattern • Examined different combinations of amounts and types of food to find an eating pattern that would meet nutrient needs • Used DRI nutrient reference values and assessment methods to determine if the eating pattern was satisfactory 4

Components of the DRIs • Four values instead of one • These are: – EAR: Estimated Average Requirement – RDA: Recommended Dietary Allowance – AI: Adequate Intake – UL: Tolerable Upper Intake Level • How derived? How Interpreted?

Components of the DRIs Also have • estimated average energy requirement • acceptable macronutrient distribution range

Dietary Reference Intakes (DRIs) Vitamins and minerals • Assessed against Estimated Average Requirement (EAR) when available or Adequate Intake (AI) 7

Components of the DRIs Estimated Average Requirement (EAR) • The EAR is the median daily intake value that is estimated to meet the requirement of half the healthy individuals in a life-stage and gender group. At this level of intake, the other half of the individuals in the specified group would not have their needs met. • The EAR is based on a specific criterion of adequacy, derived from a careful review of the literature. Reduction of disease risk is considered along with many other health parameters in the selection of that criterion. • The EAR is used to calculate the RDA. It is also used to assess the adequacy of nutrient intakes, and can be used to plan the intake of groups. • Recommended Dietary Allowance (RDA) • The RDA is the average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (97 to 98 percent) healthy individuals in a particular life-stage and gender group. • The RDA is the goal for usual intake by an individual.

Components of the DRIs Recommended Dietary allowance (RDA) • The RDA is the average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (97 to 98 percent) healthy individuals in a particular life-stage and gender group. – The RDA is the goal for usual intake by an individual.

EAR and RDA values • EAR – obtain scientific data to estimate the average requirement for a nutrient – Add 2 SD to this value so that 98% of popn has their requirement met – Resulting value is RDA • RDA = EAR + 2 SD

Use of DRIs • Apply to healthy people • RDA is generous: covers 98% of popn • Compare to usual (average) intake, not intake on any given day • RDA is goal for an individual • EAR used to assess groups

EAR and RDA (cont) • In preceding diagram, EAR set at 45 units • RDA is 63 units • Therefore, RDA = EAR +2(9) • MOST nutrients: RDA = EAR + 2(10%) • Can be written as RDA = EAR x 1. 2

Components of the DRIs • Adequate Intake (AI) • If sufficient scientific evidence is not available to establish an EAR on which to base an RDA, an AI is derived instead. • The AI is the recommended average daily nutrient intake level based on observed or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people who are assumed to be maintaining an adequate nutritional state. • The AI is expected to meet or exceed the needs of most individuals in a specific life-stage and gender group. • When an RDA is not available for a nutrient, the AI can be used as the goal for usual intake by an individual. The AI is not equivalent to an RDA. • Relative body weight (i. e. loss, stable, gain) is the

Components of the DRIs Tolerable Upper Intake Level (UL) • The UL is the highest average daily nutrient intake level likely to pose no risk of adverse health effects to almost all individuals in a given life-stage and gender group. • The UL is not a recommended level of intake • As intake increases above the UL, the potential risk of adverse effects increases.

Nutrients Recognized as Toxic • • UL value assigned to many nutrients Often based on case reports, not studies Value at UL has no risk Risk increases with higher intake – sustained intake not a single dose (except Mg)

Dietary Reference Intakes (DRIs) • Energy – Assessed median energy content of diets against Estimated Energy Requirement (EER) for reference individuals – To avoid overestimation of energy requirements, a sedentary level of activity was considered in the EER formula

Components of the DRIs Estimated average energy requirement (EER) • An EER is defined as the average dietary energy intake that is predicted to maintain energy balance in healthy, normal weight individuals of a defined age, gender, weight, height, and level of physical activity consistent with good health. In children and pregnant and lactating women, the EER includes the needs associated with growth or secretion of milk at rates consistent with good health.

Energy RDA =EAR

Components of the DRIs Acceptable Macronutrient Distribution Range (AMDR) • The AMDR is a range of intake for a particular energy source (protein, fat, or carbohydrate), expressed as a percentage of total energy (kcal), that is associated with reduced risk of chronic disease while providing adequate intakes of essential nutrients.

Components of the DRIs

Nutrients Without an EAR – Do Not Have RDA • Need scientific studies to determine EAR • Nutrients without EAR do not have an RDA • Instead: given an AI – Used as goal for individual (~ RDA) – We cannot assess groups using an AI • Calcium, Vitamin D, Fluoride, Biotin, Pantothenic acid (and all infant values)

Examples to Illustrate DRIs • • • Vitamin C Has an EAR Has an RDA Has a UL Important yet not much is known • • • Calcium No EAR Has an AI Has a UL Important but controversial

Vitamin C • Many functions: – Enzyme cofactor for collagen synthesis – Involved in synthesis of hormones, neurotransmittors – Now recognized as important anti-oxidant – Increases Fe absorption • In cells plasma urine excretion • in specialized tissues: WBCs

EAR and RDA for Vitamin C • EAR = 75 mg for adult men 60 mg for women • Based on following study: – 7 healthy men lived in for 6 months – Fed low C diet (5 mg/d) until depleted – Given graded doses until steady state reached – Measured serum, neutrophil, and urine ascorbate

EAR for Vitamin C • At 100 mg, neutrophils were saturated with acorbate in 4/7 subjects, but urine excretion was high (25% of dose) • At 60 mg, neutrophils were not quite saturated, but urine excretion 0 % • Panel chose value between 60 and 100 => 75 mg, as level of “adequate” vitamin C levels in WBCs

How do we assess Vitamin C adequacy? • Find usual intake of vitamin C in population • The percent of the pop’n whose intakes are below EAR = % at risk for inadequacy • In following figure, North Americans have some risk of inadequacy: – ~ 10 -20% ingesting too little

Vitamin C RDA • • • Use RDA as a goal for an individual RDA = EAR + 2 SD Men: RDA = 75 + 2(7. 5) = 90 mg Women: RDA = 60 + 2 (6) = 75 mg (rounded) Smokers – need more – Add 35 mg to RDA

Vitamin Toxicity • Many “problems” attributed to vitamin C – Excess urinary oxalate excretion, increased uric acid excretion in urine kidney stones – Pro-oxidant – Fe absorption iron overload – serum B 12 – Rebound scurvy • DRI panel found no evidence for anything except GI disturbances (osmotic diarrhea)

UL for Vitamin C • Uncontrolled cases and several controlled studies show that some people get GI disturbances at >3 g • 3 g = LOAEL • Since UL is set so no risk of adverse effects, Then UL = 3/1. 5 = 2 g (~ NOAEL)

Calcium • Panel chose “desirable daily calcium retention” as criterion for setting AI • Retention is classically measured as calcium balance (Intake – Losses); assume what is retained is in bones • Now, can directly measure bone mineral content BMC ~ mineral in bone

AI for Calcium • Age 19 -30: retain 10 -50 mg/day, estimate 957 mg intake from old balance studies • “Judge” 1000 mg to be appropriate • At older ages (50+): clinical trial data shows less bone loss at intakes > 1000 mg • Account for less absorption at 50+ • Value set at 1200 mg

UL for Calcium • Whiting and Wood compiled case reports of “milk-alkali syndrome” in 1995 (NR ’ 97) • Other problems of excess Ca = kidney stones, iron absorption, Zn retention • LOAEL = 5 g (in otherwise healthy) • UL = 5 g/2 = 2. 5 g

ENERGY BALANCE

Introduction to energy (nrg) balance As far as energy in the body goes it is a case of constant spend (catabolism or breakdown of energy yielding nutrients) and refill (anabolism or build up of energy yielding nutrients; dietary intake of energy yielding nutrients is also important in refill process) Not all excess energy in is stored-some extra energy is used for maintaining extra body weight Slow weight loss desirable –otherwise get the yo-yo effect - diet and exercise is the key to proper weight management

Energy in governed by a) and b) a) Food composition-calories in food b) Amount of food intake driven by: Hunger Satiation Satiety Overriding hunger and satiety signals

Energy in Food composition – the more carbohydrate, lipid and/or protein in food consumed the greater the amount of energy consumed O 2 helps to make energy from food and, in that sense, oxygen is a nutrient even though the oxygen in food does not contribute to metabolism of the carbohydrate, lipid and protein in food

Energy in Food intake governed in part by hunger -in part hunger depends on food content of stomach: -smaller stomach requires less food to fill it -larger stomach requires more food to fill it -stomach fullness of course stops hunger -hunger also depends on receptors in the gastrointestinal tract that determine whether nutrient intake has been high or low and this also signals whether one is still hungry

ENERGY INTAKE CONTINUED FOOD INTAKE ALSO CONTROLLED BY: Satiation and Satiety Satiation signal says-when to stop eating Satiety signal says-do not start eating again Overriding hunger and satiety signals due to: boredom, stress, time of day, availability of food sight, and/or taste of food all of which may cause us to continue to eat

Energy out Components of energy expenditure Basal metabolism Physical activity Thermic effect of food Adaptive thermogenesis

Basal metabolism Just to keep the doors open and the heat and lights on Body is in “idle” -table 8 -1 - page 236 in 12 th edition of Rolfes et al

ENERGY OUT CONTINUED Physical activity amount of energy expended depends on in direct proportion to body mass and activity (duration, frequency and intensity). Only 16% of adults (Clarke et al. , 2019) and 39% of children and youth (2016 -17 Canadian Health Measures Survey, Statistics Canada) meet national physical activity guidelines https: //www. health. harvard. edu/staying-healthy/calorie-counting-made-easy Thermic effect of food-energy utilised to digest, absorb and transport and store nutrients Adaptive thermogenesis- stressors such as physical conditioning, extreme cold, overfeeding, starvation, trauma or other types of stress requires adaptation to such stressors- such adaptation results in increased energy expenditure

GRAND TOTAL ENERGY OUT 2200 kcal/day for females 2900 kcal/day for males

Measures of body fat distribution BMI =kg/m 2 underweight <18. 5 correct 18. 5 -24. 9 overweight > 25 - 29. 9 obese > 30 BMI is not a good measure of body fat distribution in all persons until get to a BMI of > 30 then obesity is assumed

Measures of body fat distribution Waist circumference Europid Males > 94 cm - increased risk of heart disease, type 2 diabetes, stroke, cancer (including but not limited to colon, prostate, breast) Europid Females > 80 cm-risk - increased risk of heart disease, type 2 diabetes, stroke, cancer (including but not limited to colon, breast) Waist circumference is a good measure of body fat distribution-particularly good measure of the extent of visceral fat

Waist circumference Ethnic-specific values for waist circumference Country or ethnic group Central obesity as defined by WC Men - cm (inches) Women - cm (inches) European, Sub-Saharan African, Eastern Mediterranean and Middle Eastern (Arab) 94 (37. 6) or greater 80 (32) or greater South Asian, Chinese, Japanese, South and Central American 90 (36) or greater 80 (32) or greater

Health risks associated with body weight and body fat Health risks of underweight • Tougher to preserve lean tissue against wasting • Infertility • Giving birth to unhealthy infants Health risks of overweight • Atherosclerosis(heart attack and stroke) • Diabetes-type 2 diabetes already discussed • Cancer- weight and weight gain tied in herenot fully understood why- may be related to hormones

Supplements alleged to control body weight -all claims are false!! Ma Huang-herb containing ephedrine alleged to induce weight loss Chromium picolinate-alleged to burn fat Spirulina-powder from algae-alleged to suppress appetite Guar gum -alleged to suppress appetite by absorbing water and bloating stomach Gymnena Sylvestre plant-claimed to block sugar absorption

Energy control (diet) and exercise combined are the best way to control body weight and hence health. Energy control (diet) and exercise combined prevent excess body fat related diseases