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Whay are animal diets important in research? (2)
- Diet can influence most physiological measures
- One of the most neglected aspects of rodent (main animal model) studies.
- It is therefore essential that rodent (and other experimental animal diets be carefully considered and described in all studies
- Assurance of adequacy & safety (Fed Regulations around the content of research animal diets)
What are feeding protocols to consider? (5)
- 1. Ad libium
- 2. Meal feeding
- 3. Pair feeding
- 4. Dark and light cycle
- 5. Fasting a rodent
What types of animal diets are there (5)
- Natural product diets –Open or closed label diets
- Chow is not a control diet
- –20-24% energy is protein
- –8-10% of the energy is fat
- –70% of the energy is carbohydrate (mainly complex)
- Semi-purified diets
- Chemically defined diets
- Vitamin & mineral mixes
How are animal diets determined
- Nutritional needs of rodents are defined by the National Research Council (rodent requirements posted with lecture)
- Usually expressed on a per kg basis
- the nutrient needs are defined as the minimum requirement: they do not include a safety factor (i.e.. +2SD) and they change with energy density of the diet.
- –They have been determined mainly on assuring general health and growth
How are animal diets expressed?
What semi synthetic ingredients are listed in these diets?
- - w/w or g/kg
- - Corn oil, deextrose, corn startch, glutamine, inulin, celluolose
Calculate the caloric content of 100g of diet
Calculate the % energy from fat, protein & carbohydrate in the animal diet.
–How does the carbohydrate & fat proportions relate to human recommendations?
Calculate how much calcium is in the diet as a percent of energy?
–How does this relate to human requirements?
What are human research diets used for? (2) Why?
- 1)Controlled Feeding Studies
- 2) Behavioral Counseling Studies
- Both useful in determining the effects of diet on biological processes and/or risk factors for chronic diseases- both are used in controlled research trials.
What two important factors must be considered in dietary interventions? (2)
- Control over the composition of the diet
- Degree of compliance/adherence required
Degrees of Dietary control spectrum
Low ==> High
defn: free living and metabolic ward
- 1) free living/ seletcion of food
- 2)food provided, take out, free living
- 3) free living, food provided, eat in
- 4) live in, food provided, eat in
- 5) live in, formulat diet or defined whole food special products ( pudding, cookies, bars), eat in
What are the problems of diet interventions?
Behavior modification: Counseling of subjects to adhere to a specific dietary modification
- –Designing the diet recommendations
- –Documenting the intervention (?standardized)
- –Training others to counsel subjects
- –?control treatment
- –Adherence; ensuring & assessing
How are contrilled feeding trials done?
Subjects consume foods that have been precisely prepared & given to them
- Usually used in randomized controlled (?blinded) clinical trials
- Usually of shorter duration
- Controlled diet, strict/measured dietary compliance
- Can also be done in free living individuals.
Key Features of a Controlled Feeding study (2)
- Precise knowledge of diet composition
- –Chemical or detailed analysis of the diet and/or ingredient of interest
- Meet the energy needs of the subjects precisely
- –How can you determine that?
- –How can you monitor that?
Controlled feeding trial (features): 12
- Precision of the diet: mathematically calculated then validated with chemical analysis
- Individually calculated based on study purpose & to ensure nutrient needs are met.
- Allowable variation in average daily nutrient content is very small
- Precisely prepared in a research kitchen: weighed
- If possible blinded to subjects
- Adherence is essential; unconsumed food carefully recorded
- Subject‟s routines are changed: restriction on consumption of other foods & beverages, travel, ?exercise, timing meals are consumed
- Usually used in randomized controlled (blinded) clinical trials
- Usually of shorter duration
- Controlled diet, strict/measured dietary adherence
- Diet is prepared & provided to the research volunteers
What factors influence compicance and adherence of the study (2)? How would you control these?
Recruitment & selection of subjects: (Screen your subjects carefully, Monitor compliance, Monitor subject moral- social support, Removal of subject who don‟t comply?)
Design of the study (study length, Menu cycle, Diet composition, Rigidity….Allowing self-selection? –?Alcohol –?Some free days –?Eating all food provided )
How might you measure compliance?
In a controlled feeding study?
In a behavioral modification study?
What factors influence adherence?
–In a behaviour modification study? ( think of 10 factors)
–In a controlled feeding study? (think of 10 factors)
How do to measure it?