LA

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

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

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).

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

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.==

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)

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

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

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