NUTR400 part4

• 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)

• 1. Ad libium
• 2. Meal feeding
• 3. Pair feeding
• 4. Dark and light cycle
• 5. Fasting a rodent

• 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

• 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

• - w/w or g/kg
• - Corn oil, deextrose, corn startch, glutamine, inulin, celluolose

• 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.

• Control over the composition of the diet
• Degree of compliance/adherence required

• Low-
• 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
• High-

Behavior modification: Counseling of subjects to adhere to a specific dietary modification

• Issues:
• –Designing the diet recommendations
• –Documenting the intervention (?standardized)
• –Training others to counsel subjects
• –?control treatment
• –Adherence; ensuring & assessing

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.

• 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?

• Expensive
• 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

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 )