Dietary Reference Intakes (DRIs)

Population/ group applications of the DRI's

- use EAR - estimated average intake

AI

-Adequate Intakes -In the absence of adequate information to establish an RDA, AI is assigned -also meets 98% of population needed -Based on estimates of intakes that appear to maintain nutrition status in certain population -AI is based on "best guess" studies when studies are not as strong -Set for some vitamins, choline, some minerals, essential fatty acids, fiber -Set for children under the age of 1

How is RDA determined?

-Assuming the nutrient required follows a normal distribution.. 1. find Estimated Average Requirement = the level at which half the population would meet their need. 2. Increase requirement above mean by adding 2 standard deviations (this accounts for variability in the population). 3. RDA set at 97-98% of population.

EER

-Estimate Energy Requirements -Ave. energy needs for various age/gender groups -More conservative than individual nutrient recommendations to promote reduction in overweight and obesity -Maintenance of healthy wt is best guideline -amount of energy required to meet 50% of population needs in order *to maintain body weight*

EAR

-Estimated Average Requirement -*based on studies* that found the average of the population -meets needs of 50% of individuals in an age/gender group -Uses a measurable functional marker -Adjusts for digestibility -Used to evaluate adequacy of diets of a group

More uses of the DRI's

-Food planning and procurement -Food programs -Evaluating dietary survey data -Guides for food selection -Food and nutrition info and education -Food labeling -Food fortification -Developing new or modified food products -Clinical dietetics (not best due to "healthy" definition) -Nutrient supplements and special dietary foods

Uses of DRIs

-Guide for procuring food supplies for groups of healthy persons -Basis for planning meals for groups -Reference point for evaluating the -dietary intake of population subgroups -Component of food and nutrition education programs -Reference point for the nutrition labeling of food and dietary supplements

Goal of 1st - 10th editions

-Prevent nutrient deficiency (Not chronic disease) -Plan nutritional adequacy of groups (Not individuals)

RDA

-Recommended Dietary Allowances -Nutrient intake that is sufficient to meet needs of 97 - 98% of individuals in an age/gender group -EAR x 1.2 -Can only be set if EAR established -Accounts for nutrients' ability to prevent disease in addition to preventing deficiency -both EAR and RDA are based on studies

Establishing RDA

-Reference values that are quantitative estimates of nutrient intakes to be used for planning and assessing diets for healthy people. -Applies to US and Canadian populations.

Does AI bear a consistent relationship to the EAR or the RDA?

-The Adequate Intake (AI) *does not* bear a consistent relationship to the EAR or the RDA because it is set without being able to estimate the average requirement. It is assumed that the AI is at or above the RDA if one could be calculated.

UL

-Tolerable Upper Intake Levels -Maximum level of daily intake unlikely to cause adverse health effects -Chronic daily use -Set to protect even most susceptible individuals -Not a goal, but a ceiling -Not enough information to set UL for all nutrients

Subcommittees:

-Upper Reference Levels Subcommittee - Uses of DRIs Subcommittee

Individual applications of the DRI's

-Use RDA- use as a goal for optimal intake. (AI = adequate intake) -for nutrients with RDAs if < EAR, then probability of inadequacy is 50% or less -if between EAR > < RDA, diet needs improvement. ~ 67% or less would meet their needs. -typically if you're between 50-67%, you're okay

Depletion-repletion studies

-Vitamins -They *cause* a deficiency and then add back in a little at a time -Subject low or without a specific nutrient in the diet -Measure changes in biochemical or physical parameters -Replete at various levels until the lowest intake level normalizes biochemical or physical parameters

Nutrient balance studies

-energy, protein, and minerals -Balance = intake - output -just when intake equals output is considered to meet requirement -Minerals always involve looking at fecal matter

Expert Panels

-experts on a specific nutrient 1. Review scientific literature 2. Consider roles of nutrients in decreasing risk of chronic diseases, and other diseases and conditions 3. Interpret current data on intakes in North Americans

Biochemical measures of people

-that assess the degree of tissue saturation or adequacy of function and its link to dietary intake. -Examples include: -Vitamin C in white blood cells -Iron storage in serum ferritin -Red blood cell's glutathione reductase for riboflavin

Diet surveys of healthy populations

-what is the intake? -Breastfed babies - what is in breastmilk? -Does a marginal population's intake of a supplement (or diet) result in a healthy nutritional status

EAR risk of inadequacy

0.5 (50%) to an individual

Types of studies the DRI values are based on...

1. Depletion-repletion studies 2. Nutrient balance studies 3. Biochemical measures of people 4. Diet surveys of healthy populations 5. Extrapolation for animal studies

Current goals of the DRIs

1. Prevention of classical deficiency 2. Prevention of physiological important signs of deficiency 3. Maintenance of nutritional status quo 4. Maximum reduction for disease with at least partial nutrition etiology (chronic diseases)

Subcommittee on uses and interpretation

Assist the Panels and DRI Committee in development of practical info and guidance on using DRIs appropriately

DRI

Daily Reference Intake - it is the umbrella term where RDAs (Recommended Dietary Allowances) were placed along with new values that were added -EAR -RDA -AI -EER -UL

What is used to calculate RDA?

Estimated Average Requirement (EAR)

Subcommittee on Upper Reference Levels

Estimates levels of nutrients that may increase risk of toxicity or adverse effects and advises the Panels

Example of Users of DRIs:

Government-industry-academia-health services

When plotting nutrient needs, you will typically see the development ...

of a bell-shaped curve - Individuals needed less of a particular nutrient will be closer to the y-axis. Individuals that need more of a particular nutrient will be further away from the y-axis. (Establishing the RDA)

DRI Committee

oversees and conducts the project

RDA risk of inadequacy

risk of inadequacy is very small—only 0.02 to 0.03 (2 to 3%)