Nutrition Introdution Flashcards
Define nutrition
Nutrition is utilization of foods by living organisms for growth, reproduction and maintenane of health.
Define nutrients.
Nutrients are substances and qualities of food that are required for life, and for growth, maintenance, and repair of body tissues.
Nutrients are divided into two broad groups known as
Organic compounds and inorganic compounds
Some nutrients are classes of substances, give examples of five:
Fiber, energy, omega-3 fatty acids, vitamin E, vitamin A
Define fiber as a nutrient
Many subtanes that are variably water soluble and fermentable.
Define energy as a nutrient
Chemical bond energy in organic susbtances
omega-3 fatty acids include:
Eicosapentaenoic acid (EPA), docosahexaneoic acid DHA
nutrients classified under Vitamin E include:
tocopherols and tocotrienols
Describe nutrients classified under vitamin A:
substances with retinol-like activity in animals (ex. carotene)
What are the two general functions of nutrients?
- Supply energy for metabolic processes
2. Substrate for body structural and functional substances
Define an essential nutrient.
An essential nutrient is a substance that is required and cannot be synthesized or synthesized in amounts sufficient to meet animal needs.
Define a conditionally-essential nutrient.
A substance that is essential under certain conitions, such as a physioligcal stage (choline for growth) or a disease stage (vitamin C during liver insufficiency)
List the essential nutrients for most animals.
- Water - greatest mass of daily intake
- Energy - derived from protein, fat, and carbs
- Amino acids - 20 in diet, about half are essential
- Minerals - macrominerls and trace- or micro-minerals
- Vitamins - fat soluble and water soluble
- Fatty acids - omeg-6 and omega-3 series
Vitamins
Organic compounds of low concentration that are variably provided in foods
Nutrients must be provided in ________ and _______ relative to one another.
Nutrients must be provided in proper amounts and proper proportions relative to one another.
Nutrient disproportion is known as a _______.
Malnutrition
Amount and proportions of nutrients needed vary with physiological state and disease. List 4 physiological states.
- Growth
- Maintenance
- Gestation
- Lactation
Define optimal nutrition.
A concept of animal response to nutrient exposure. Nutrients are provided in amounts and proportions that optimize a physiological or economically important response.
Define deficiency in regards to a nutrient-animal response relationship graph.
When response variable increases with increasing nutrient concentration.This condition indicates diet has too little nutrient, and that diet is not meeting the animal’s requirement for the nutrient.
Define suboptimal in regards to a nutrient-animal response relationship graph.
The response variable increases with increasing nutrient amount but diminishing returns occurs with further increases in nutrient amount.
Define optimal in regards to a nutrient-animal response relationship graph.
The animal response does not change with increasing nutrient amount. This condition is usually desired.
Define “excess” in regards to a nutrient-animal response relationship graph.
The response decreases with increasing nutrient amount. More nutrient is not always better, a nutrient may become toxic. Excess of a nutrient may cause deficiency of another nutrient. Amount excess that toxicity varies among species.
Determining “optimal” nutrient concentration.
- For each nutrient there is more than one response variable that may be used to determine the optimal nutrient amount.
- Body reserves of nutrient will affect the response to dietary concentration (i.e. a deficiency may not be observed for a long time because of body reserves. An apparently optimal concentration found in a short-term trial may actually be inadequate over long-term.
Define nutrient requirement.
Nutrient requirement is the minimum dietary amount of a highly bioavailable nutrient that optimizes a response important to a physiological feature.
Define bioavailable.
Readily obtained from diet for use in tissues. (efficiently digested and absorbed, also needs to be available to tissues)
A nutrient requirement varies with the _____.
A nutrient requirement varies with the physiological state.
Define nutrient allowance.
Nutrient allowance is the minimum dietary amount of a nutrient that should be present in a practical formulation (ex. a commercial diet) that will maintain health.
How does a nutrient allowance differ from a nutrient requirement?
- A nutrient allowance is for ‘health’ not a single response variable.
- A nutrient allowance is typically greater than its corresponding nutrient requirement.
What is a ‘safety factor’ in regards to a nutrient allowance?
A nutrient allowance typically is a nutrient requirement plus an agreed upon added amount, known as a safety factor.
Why are safety factors used?
- Bioavailability of a nutrient is typically less than 100%
- Nutrient content in dietary ingredients may unpredictably vary
- Nutrient requirements are often extrapolated from other species
What are the shortfalls of nutrient allowances?
- Safety factors are sometimes arbitrarily agreed to.
- Safety factors may be based on incorrect assumptions about nutrient bioavailability, and/or nutrient contents in dietary ingredients.
- Safety factors do not account for unrecognized interactions of dietary factors that may substantially affect bioavailability.
Is there a ‘best diet’ for an animal species?
No, there is no one best diet or food for any animal species!
Is it easy to know determine dietary nutrient composition?
No, knowing nutrient composition of any diet with complete certainty is difficult because individual nutrient assays are not readily available and are expensive. Also, standard tables of nutrient composition of dietary ingredients are useful but limited.
List three useful estimates of dietary nutrient composition.
- Proximate analysis
- Guaranteed analysis
- “average nutrient content” determined from diet samplings
Proximate analysis is also known as?
Wende analysis
Define a proximate analysis.
A very crude estimation of dietary nutritional value. It is an analysis of 6 physical-chemical characteristics:
- Moisture - good estimate of water content of a diet
- Crude fat
- Crude fiber
- Ash - weight of diet after drying and burning off all organic mater. “Crude” estimate of dietary mineral content.
- Crude protein
- Nitrogen free extract - crude estimate of the digestible carbohydrate content of a diet
Define guaranteed analysis.
A listing of proximate analysis results and other assay results “guaranteed” by the manufacture to be packaged in feed or food.
Why is the guaranteed analysis of limited value?
Because results of the “analysis” are:
- either minimums or maximums
- Often an incomplete listing of proximate analysis of contents
Facts about average nutrient content.
Rarely are results for all nutrients given. Better than proximate and guaranteed analysis for assessing nutritional adequacy. Value is limited because bioavailability of nutrients is unknown.
