Nutrition overview

Nutrition: the biochemical and physiological process by which an organism uses food to support its life

• the process of nourishing the body

Nutrients: the constituents of food necessary to sustain the normal functions of the body.

• some provide energy
• most help to build cells and tissues, and/or regulate body processes
• no single food supplies all the nutrients the body needs to function

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Diet: the customary amount and kind of food and drink a person takes in day to day.

All energy is provided by the three classes of macro-nutrients (intake needed is larger):

• fats
• carbohydrates
• protein

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Nutrients needed in lesser amounts are called micro-nutrients

They include:

• vitamins
• minerals
• essential fatty acids
• essential amino acids

Calorie: unit of energy, the amount of heat necessary to raise the temperature of 1kg of water 1°C

^^Fats^^: 9 cal/g

^^Carbohydrate and protein:^^ 4 cal/g

Dietary Reference Intakes

Dietary Reference Intakes (DRI): estimates of the amounts of nutrients required to prevent deficiencies and maintain optimal health and growth.

• Th DRI establishes upper limit on the consumption of some nutrients, unlike the Recommended Dietary Allowances (RDA).

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Definition

The DRI consists of ^^4 dietary reference standards^^ for the intake of nutrients designated for ==specific age groups, gender, and physiologic states.==

1. Estimated Average Requirement
2. Recommended Dietary Allowance
3. Adequate Intake
4. Tolerable Upper Intake Level

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Estimated Average Requirement (EAR)

The average daily nutrient intake level estimated to meet the requirement of ==one half of the healthy individuals in a particular life stage (age) and gender group.==

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Recommended Dietary Allowance (RDC)

The average daily nutrient intake level that is sufficient to meet the requirement of ==nearly all (97% - 98%) individuals in a particular life stage and gender group.==

• RDC is not the minimal requirement for healthy individuals, but rather it provides a margin of safety for most individuals
• the EAR serves as the foundation for setting the RDA
• %%RDA = EAR + 2 SD%% (standard deviation)

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Adequate Intake (AI)

An Adequate Intake (AI) is set instead of an RDA if there is ==insufficient scientific evidence== available to calculate an EAR of RDA.

• based on estimates of nutrient intake by a group/s of apparently healthy people

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Tolerable Upper Intake Level (UL or TUL)

The ==highest== average daily intake level that is likely to pose no risk of adverse health effects to almost all individuals in the general population.

• as intake increases above the UL, the potential risk of adverse effects may increase
• useful because of the increased availability of fortified foods and the increased use of dietary supplements
• for some nutrients, there may be insufficient data on which to develop a UL

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Using the Dietary Reference Intakes

• most nutrients have a set DRI

• usually a nutrient has an EAR and a corresponding RDA

• most are set by %%age%% and %%gender%%, and are influenced by special factors (e.g. %%pregnancy and lactation%% in women)

• when data are not sufficient to estimate an EAR (or RDA), and AI is designed

• intakes at or above the RDA can be considered adequate

• intakes above the AI can be considered adequate

• intakes between the UL and the RDA can be considered to have no risk for adverse effects

• intakes over the UL show risk for adverse effects

• the DRI does not include any special needs of the sick, it is designed to meet the nutritional needs of the healthy

  

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