Lecture 22- Human nutrition Flashcards
What are functional foods?
- “Foods that provide benefits beyond basic nutrition”
- Food innovation
- Connecting food with population health messages
- “healthy foods”
- Estimated worth of US $30-50 billion
- AUS $1 billion in 2003, growing 8-14% per annum
- Opportunity to grow the market in Australia
- Export opportunities
- National Centre for excellence in Functional Foods
What are the opportunities for functional foods in terms of business?
- Opportunities for:
- Primary industry
- manufacturing/processing
- Retailing
- Minimally transformed foods
- Contain known bioactives (fruits & veg)
- Substantially & elaborately transformed
- Food & beverage ingredients
- Added bioactives
- Success depends on consumer responsiveness • Time poor consumers • Need for convenience • People are more interested / aware of what is in their food (publicity)
What are some of the functional foods?
- omega 3
- probiotics
- high fibre
- energy drinks
- fortified alcohol
What is the case with omega 3?
- Added Omega-3 DHA
- E.g. Dairy farmers kids milk has 75% RDI of Omega-3 in 250mL
- Omega-3 enriched eggs • Fed flaxseeds
What about heart health functional foods?
• Contains plant sterols that lower LDl cholesterol, margerine and milk
- recent evidence suggests that similar effects can be gained from consuming lower doses of these sterols
- consumption of plant foods
What about probiotics?
- advertised as the magic bullet
- contains microorganisms (bacteria etc.), GI tract targeted
- there are benefits when taking biotic
- reduce the severity of the diarrhea
- prevent the onset of diarrhea
- IBS= mixed evidence
- we discussed the microbiome, are they not all different?
- a better treatment, faecal transplant =cured 94% of infections, diarrhea,(antibiotics cure 27%)
What about high fibre?
- important for GI tract
- can reduce incidence of some cancers and heart disease
- too much fibre?
- more than 50-60g per day can reduce mineral and vitamin absorption and causes GI discomfort
What about energy drinks?
- Consumption is increasing
- Particularly in adolescents
- Higher in males
- Caffeine does improve attention
- Temporary
- Reduces memory
- Energy drinks:
- Decrease reaction time
- Increase alertness
- Improve memory & concentration
- Increase exercise endurance
-limited evidence that they improve energy, some ingredients have not been established as safe
What is the case with fortified alcohol?
- Added alcohol in wine
- Alcohol + energy drinks
Have many functional foods exaggerated the health claims?
- In Sept 2009 Dannon settled a case for US $35 million
- Exaggerated health benefits in yoghurt products (Activa)
- They had to change the labelling
- “clinically proven” etc.
When does food preference in humans develop?
- Develop in utero?
- What is consumed in pregnancy may shape food preferences for baby
- Sensory stimuli can be perceived during the latter stages in utero
- Foods can ‘flavour’ the amniotic fluid & milk
- E.g. vanilla, carrot, garlic, mint, anise etc.
- Food experienced in utero are accepted better once born
- Nature Vs nurture
- Siblings raised the same way can have varied preferences
- Genetic influences on taste? (BUT not specific to foods)
- Role for both preference and aversion
- Religion, demographics, race, age, socioeconomics etc.
- Cannot discount the role of social activities and influences
- Classical conditioning
- Pavlov’s dogs
- Bad flavours or ill feelings lead to food aversions
- Reflex responses to tastes are present in the neonate
- Prefer sweet
- Reject sour and bitter foods
- Preference for salt develops at about 4 months old
What do twin studies tell us about food preference?
- Studies of twins show:
- A substantial genetic effect on protein tastes (umami)
- Moderate genetic effect on veggies and fruits
- Small genetic effect on sweet tastes
- Preferences for dairy and starch are highly environment driven
What is the problem of obesity like?
- Food selection has a strong adaptive value
- So does the storage of energy
- Advantage when resources are scarce
- In 2005, WHO reported that >400 million adults are obese
- Complex interactions between genetic, nutritional, metabolic, hormonal, medical, behavioural and environmental factors
- Role of food preferences?
- Particularly in children
What are homeostatic signals?
- maintenance of physiological equlibrium
- Insulin
- Glucagon
- Catecholamines (eg. Epinephrine)
-going on all the time, maintain steady glucose level in the body
What is homeorhesis?
-the adaption to these process to particular stage in life
- Pregnancy
- Lactation
- Growth
- co-ordinated changes in metabolism of body tissues to support a physiological state
How is fat stored, how does this system work?
- if you consume dietary fat, made into glycerols, then nonesterified fatty acid and then into adipocyte for storage= same for glucose
- this process is positively influenced by insulin and negatively by epinephrin and glucagon (as you would need energy readily)
- the reverse can also happen when the stored fat is made into available
What is the effect of feeding on plasma insulin, glucagon and glucose?
-insulin and glucagon keep the glucose low after food intake
What happens in the cow after feeding with the insulin?
- really big difference when lactating or dry
- lactating has lower levels
- it differs across species
What is the hyperinulinemic/euglycemic clamp?
• Technique to study insulin metabolism without altering glucose and glucagon
-you give insulin and maintain glucose so can tell that the difference is then due to the efficiency of the animals to maintain homeostasis
- hyperinsulinemic = high insulin
- euglycemic = glucose maintenance
- clamp = keep insulin and glucose constant
- Infuse insulin to increase plasma insulin while infusing glucose to maintain plasma glucose (glucagon won’t change)
Why are these studies done?
- how well are things taken up into fat
- glucose uptake relative to the insulin
What happens when inject glucagon?
- glucagon injection at time zero, then increase in glucose and eventually go back to steady state
- increase in insulin as well
What also happens with glucagon injections?
-glucagon then increases the glucose but first have to break down the NEFA (non esterified fatty acids so it can be used by the body)
What happens to NEFA when inject epinephrine?
- injection of epinephrine get an increase in plasma NEFA
- also in glucose
What is the homeorhesis?
- Changing metabolism to support a physiological state
- Can be achieved through altering responses to homeostatic signals
- changing sensitivity (receptor related= to bind the hormone etc.)
- changing responsiveness (post-receptor related)
What happens in pregnancy and insulin?
- in non pregnant animal, the response rate is different
- the insulin is different
- at different stage of pregnancy this also differs
- how responsive the fat is to provide energy differs, less responsive in early pregnancy then later
What happens in pregnancy?
- Decreased sensitivity to insulin with respect to glucose utilisation (need more)
- Marginal changes in responsiveness to insulin of endogenous glucose production
- Decreased responsiveness to insulin with respect to NEFA metabolism
- Increased responsiveness to catecholamines
-more stress responsive when pregnant
What is the glucose uptake in pregnant and dry animals in their hind limbs?
- glucose uptake in the hindlimb
- in dry animal more readily uptaken
- when pregnant won’t take it up as quickly since want circling glucose for the fetus
How do animals respond to an epinephrine challenge?
- dry animal doesn’t really respond to the epinephrine
- the pregnant does
- lactating even more!
What about lactation in general?
- Decreased sensitivity and responsiveness to insulin with respect to glucose utilisation
- Decreased responsiveness to insulin of endogenous glucose production
- Decreased responsiveness to insulin with respect to NEFA metabolism?
- Increased responsiveness to catecholamines
What are the homeorhetic signals?
• Bauman and Currie (1980)
- somatotropin
- placental lactogen
- prolactin
• Bines and Hart (1982)
• somatotropin
What effect does somatotropin have?
- somatotropin (growth hormone)
- high yielding animal has more, and is more responsive
What about responsiveness to insulin?
-high yielding animal is also more responsive
What is true of milking cows?
- Negative energy balance is NOT more severe in TMR fed genetically superior cows (may not be the case for pasture cows)
- the cow produces more and doesn’t expend more energy
What happens if inject bST (bovine somatotropin)?
- increase in productive input
- bigger decrease in energy balance so will need more energy input to not waste
- see more NEFA in plasma as need more energy
- become more sensitive to epinephrine (so more responsive to stress)
- they don’t respond to insulin as much
What is the case with somatotropin?
- Increases responsiveness to catecholamines
- Reduces responsiveness with respect to glucose insulin stimulation of glucose utilisation by peripheral tissues
- Reduces effect of insulin in inhibiting hepatic glucose production
- Metabolic effects similar in lactating and growing animals
