DRIs: Dietary Reference Intakes PDF

# DRI Process - North American Initiative from Institute of Medicine and Health Canada. - Introduced in 1967. - Intended to replace 1989 RDAs and 1990 RNIs. ## What are Dietary Reference Intakes - Dietary Reference Intakes (DRIs) comprise a set of nutrient-based reference values, each of which ha...

# DRI Process - North American Initiative from Institute of Medicine and Health Canada. - Introduced in 1967. - Intended to replace 1989 RDAs and 1990 RNIs. ## What are Dietary Reference Intakes - Dietary Reference Intakes (DRIs) comprise a set of nutrient-based reference values, each of which has special uses. ## Components of the DRIs 1. EAR: Estimated Average Requirement 2. RDA: Recommended Dietary Allowance 3. AI: Adequate Intake 4. UL: Tolerable Upper Intake Level 5. AMDR: Acceptable Macronutrient Distribution Ranges The image shows a graph with: - **x-axis**: Observed Level of Intake - **y-axis**: Risk of Inadequacy and Risk of Adverse Effects - **vertical lines**: EAR, RDA, and UL ## 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 the population has their requirement met. - Resulting value is RDA. - **RDA = EAR + 2 SD**. The image shows two bell curves describing the distribution of intake of a nutrient. - The first curve shows the distribution of the intake of a nutrient in 120 people, from 20 to 70 units, representing a small, average, and large intake. - The second curve demonstrates how RDA covers 98% of the population. ## Use of DRIs - Apply to healthy people. - RDA is generous: covers 98% of the population. - Compare to usual (average) intake, not intake on any given day - RDA is a goal for an individual. - EAR used to assess groups. ## RDA - 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 gender and life stage group (life stage considers age and, when applicable, pregnancy or lactation). - The RDA for a nutrient is a value to be used as a goal for dietary intake by healthy individuals. - The RDA is not intended to be used to assess the diets of either individuals or groups or to plan diets for groups. ## Adequate Intake - Nutrients Without an EAR - Do Not Have RDA. Need scientific studies to determine EAR. - The AI is based on observed or experimentally determined estimates of nutrient intake by a group (or groups) of healthy people. - The main intended use of the AI is as a goal for the nutrient intake of individuals. - Calcium, Vitamin D, Fluoride, Biotin, Pantothenic acid (and all infant values). ## Tolerable Upper Intake Level - For nutrients recognized as toxic. - Often based on case reports, not studies. - ULs are useful because of the increased interest in and availability of fortified foods and the increased use of dietary supplements. ## 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 - In cells enzyme cofactor for collagen synthesis. - Involved in synthesis of hormones, neurotransmitters. - Now recognized as important anti-oxidant. - Increases Fe absorption. - **← → plasma → urine excretion**. ## EAR and RDA for Vitamin C - **EAR = 75mg for adult men, 60mg for women**. - Based on the following study: - 7 healthy men lived in for 6 months. - Fed low C diet (5mg/d) until depleted. - Given graded doses until steady state reached. - Measured serum, neutrophil, and urine ascorbate. ## EAR for Vitamin C - At 100mg, neutrophils were saturated with ascorbate in 4/7 subjects, but urine excretion was high (25% of dose). - At 60mg, neutrophils were not quite saturated, but urine excretion 0%. - Panel chose value between 60 and 100 => 75mg, as level of "adequate" vitamin C levels in WBCs. ## RDA for Vitamin C - Use RDA as a goal for an individual. - RDA = EAR + 2 SD - **Men:** RDA = 75 + 2(7.5) = 90mg. - **Women:** RDA = 60 + 2 (6) = 75mg (rounded). - **Smokers - need more.** - Add 35mg to RDA. ## Toxicity of Vitamin C - 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 B12. - 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 >3g. - 3g = LOAEL - Since UL is set so no risk of adverse effects, then UL = 3/1.5 = 2g (~ NOAEL). # Thank You - Dr CSN Vittal