Role of Diet Flashcards

1
Q

What amino acid do cats require in their diet?

A

Taurine

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2
Q

What neurobiological effect does eating have?

A

Positive dopamine

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3
Q

What factors influence taste preference?

A

Experiences and genetics

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4
Q

Give three “popular beliefs” about diet and behaviour in dogs

A

Hyperactive/aggresive dogs need a low protein diet to calm them
High carbohydrate diets calm anxious dogs
Artificial preservatives eg. ethoxyquin affect behaviour more than natural preservative eg. vit C

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5
Q

What amino acids is serotonin made up from?

A

Tryptophan and tyrosine

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6
Q

Which NT does tryptophan contribute to?

A

Serotonin (MOOD)

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7
Q

Which NT does tyrosine contribute to?

A

Catecholamines (STRESS)

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8
Q

Which NT does histidine contribute to?

A

Histamine (IMMUNE)

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9
Q

Which factors affect how much the NT levels are affected by food?

A

Timing of food, composition of diet, Digestability of diet

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10
Q

What have diets high in tryptophan shown?

A

Conflicting results - Decreased and increased aggression (rodents and primates)
Reduced self injurious behaviour in primates
Increased exploratory behaviour in foxes

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11
Q

What have diets low in tryptophan shown?

A

^Aggression, anger and frustration in humans
Increased turnover of tryptophan and serotonin in acute stress
Decreased turnover of tryptophan and serotonin in chronic stress/depression

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12
Q

Where does conversion of tryptophan to serotonin occur? How much trypotohan is converted? What is tae of conversion affected by?

A

1% in GIT
Conversion affected by - trypotphan, other LNAAs, fatty acids, carbohydrates (->insulin release -> aa uptake, often aa other than tryptophan are more favourable)

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13
Q

Why is getting int o the brain difficult?

A

Has to compete with other Large Neutral Amino Acids (LNAAs) to cross BBB

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14
Q

What happens to free tryptophan?

A

Binds to albumin in plasma and cants cross BBB

Fat levels important for albumin

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15
Q

How do carbohydrates affect tryptophan levels?

A

Stimulate relase of insulin -> aa uptake (other aa than tryptophan more favourable so decreased competition at the BBB)

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16
Q

Which enzyme is the rate limited step for trypotophan -> serotonin conversion?

A

Tyrptophan hydroxylase

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17
Q

What is the purpose of albumen in tryptophan transport?

A

Binding to tryptophan “keeping it safe” until reaching the BBB

18
Q

What NTs does tyrosine form?

A

Catecholamines - Dopamine, noradrenaline, adrenaline

19
Q

When does NA turnover increase?

A

During periods of high stress therefore high tyrosine diet protective of effects of acute stress (rodent studies)

20
Q

How does tyrosine impact other aa levels?

A

Competes with other AAs at BBB

Generally higher concentration in normal protein than tryptophan so high protein meal ^tyrosine, vtryptophan

21
Q

What did Dodman et al 1996 show?

A

No effect of dietary protein levels for dominance aggressive, hyperactive or control dogs
Significant effect of protein level of territorial aggression dogs due to fear (low protein -> v aggression)

22
Q

What did De Napoli et al 2000 show?

A

No change in behaviour within each group (dominance/territorial/hyper)
But combined, decrease in territorial aggression for dogs fed low protein + tryptophan supplement (i.e. ^trypotophan)
Increase in dominance aggression for dogs fed high protein no tryptophan supplementation (ie. vtryptophan)

23
Q

What did Bosch et al 2009 show?

A

No difference in response in mildly anxious dogs

24
Q

How may carbohydrates affect behaviour?

A

Digestible - Starch ->monosaccharides eg. glucose. Fluctuations in blood glucose -> hyperactivity etc. Also impacts aa uptake into muscles by ^insulin release from pancreas. Uptake of other aa leaves ^conc of tryptophan at BBB

Indigestible - Fibre-> fermented in colon to produce fatty acids, lactate and gases, affects feeling of satiety

25
Q

What form of tryptophan will not be affected by insulin release?

A

Albumin bound tryptophan

26
Q

What is the popular diet theory for dogs?

A

Feed wholemeal pasta 2x daily after protein meal

Supplement vit B6 (cofactor for enzymes breaking down protein, direct hormonal effect (?))

27
Q

Does the impact of carbohydrate intake actually have an impact of tryptophan levels?

A

Yes, but minute - an increase of 4% protein in the diet eliminates the effect totally
Change in protein level has a more significant effect

28
Q

What other factor also influences change in mood and tryptophan levels?

A

Genetics

29
Q

Does high or low viscosity food take longer to digest?

A

Low! eg. soup

30
Q

What effects does dietary fibre have on satiety?

A

^ satiety
^ viscosity in stomach
^ release of GLP to inhibit gastric emptying
^ intestinal transit time

31
Q

What did Bosch 2009a show?

A

Decreased food seeking behaviour and voluntary food consumption with high fibre diet

32
Q

What did Bosch 2009b show?

A

Decreased activity with high fermentable fibre diet

No change in response to stressors with high fermentable fibre diet

33
Q

What are lipids used for in the body?

A

cell membranes
steroid hormone precursor
energy source

34
Q

What are PUFAs? What are they used for in the body?

A

Poly unsaturated fatty acids - Brain tissue, eg. omega 6

35
Q

What effect of PUFA in the diet have been shown?

A

V learning ability in rodent when deficient in PUFAs and ^ when supplemented
PUFA deficient rats sometimes show ^behavioural stress response

36
Q

How has fat been shown to affect humans?

A

Increased reaction times (slower) with low fat diet

37
Q

What has been shown to reduce the rate of cognitive decline in lab dogs?

A

Anti-oxidant enrichment and mitochondrial cofactor enrichment

38
Q

What have lipids been shown to affect in dogs?

A

Retinal development in puppies
Cognitive decline
Difference in ratio of some fatty acids found in association with aggressive v non-aggressive dogs, but no causality proven.

39
Q

What is the overall conclusion regarding role of diet on behaviour?

A

Insufficient evidence to conclude effects
- small scale studies, results not in agreement
Tryptophan uptake important bu only small part of the picture

40
Q

What is a neutraceutical?

A

Food substance marketed as having a pharmaceutical effect
Non prescription
Often limited evidence
Marketed as natural and with decreased side effects

41
Q

Give an example of a neutracuetical

A

Zylkene - Alpha casein hydrosylate protein from milk
Thought to act at GABA a receptor (=benzodiazepene mechanism of action) calming
Some effect shown in rodent and human studies
Mixed results in dogs and cats (Beeta 2007, Palestrini 2010)