All Nutrition Articles Testable Points Flashcards
In a study evaluating plasama vitamin D metabolites and CRP in Stage-Stop racing endurance sled dogs JVIM 2015
Dogs used as a model for examining effects of exercise on vitamin D status because of their lack of vitamin D synthesis by UV exposure. Inflammatory response of exercise may be associated with hypovitaminosis D
Racing dogs compared to controls
Racing dogs showed significant increase in calcidiol (25 (OH) D3) on day 2 and day 8 of race, while no increases were seen in controls.
Plasma concentrations of 24,25 (OH)D3 (dihydroxycholecalciferol) significantly increased by day 8
No significant changes in calcitriol concnetrations across all time points and groups
Racing dogs ahad signifcantly increased CRP concentrations by day 2 but not day 8
Overall - increases in vitamin D metabolites as well as increases in CRP observed in racing sled dogs - increases in dihydroxycholecalciferol may suggest metabolic variations in dogs that lead to enhanced disposal of vitamin D
What are tight regulators of the active form of vitamin D (calcitriol - or 1,25 (OH)D3?
Parathyroid hormone activation of renal 1 alpha hydroxylase
Which diseases have demonstrated low vitamin D concentrations?
PLE, renal disease, neoplasia, cardiovascular disease
In a Cohort Study evaluating the success of controlled weight loss programs for obese dogs (JVIM 2015)…
Successful weight loss was positively assocaited with a faster rate of weight loss, a longer duration, and feeding a dried weight management diet, but negatively associated with starting body fat and use of dirlotapide (gut selective microsomal triglyceride transfer protein inhibitor)
> 50% of obese dogs on a controlled weight loss program reach their target weight
61% completed program, 31% stopped prematurely, 8% euthanized
In a Study evaluating the association of obesity with serum leptin, adiponectin, and serotonin and gut microflora in beagle dogs (JVIM 2015)…
Peripheral leptin, adiponectin, serotonin and CSF serotonin levels measured in beagle dogs free fed vs good restricted
Fecal samples obtained in both groups for 16S rRNA sequencing
Leptin concentrations higher in obese group compared to lean group
Adiponectin and serotonin or CSF (5HT-CSF) concentrations, and TT4 were higher in lean group than in obese group
Leptin, cholesterol, and cortisol levels higher in obese group
Microbiome analysis revealed diversity of microbial community was lower in obese group
phylum firmicutes (85%) were predominant in group in lean dogs
Phylum proteobacteria (76%) were prdominant group in obese dogs
Decreased 5HT levels may increase risk of obesity b.c of increased appetite.
Name three bioactive peptides/ adipokines secreted from adipose tissue
Leptin, adiponectin, pro-inflammatory cytokines
Describe the actions of serotonin (5HT) in the body. What is Serotonin’s full chemical name?
5 hydroxytriptamine
Biochemical marker of mood and is association with several behavioral and psychological factors
Involved in hypothalamic regulation of energy consumption and serotoin levels in the CNS and is influenced by energy conditions
What is the theory behind the gut brain axis?
Gut microbiota can regulate gut/ brain axis. Hypothalamus and brain stem are central sites of appetite regulation, and gut microbiome can stimulate vagal sensory neurons, which is a major neural pathway that conveys information from gastrointestinal luminal contents to the brain and modulates GI motility and feeding behavior.
Gut microbiome can influence neuronal signaling to the brain through vagal afferent neurons
An enrichment of gram negative bacteria predominating in the gut can do what?
Influence the level of intestinal LPS (essential cell wall compartoment of gram negative bacteria that triggers systemic inflammation) - and this may be associated with chronic inflammation in obese subjects
In a study evaluating the effect of feeding a weight loss food beyond caloric restrition priord on body composition and resistance to weight gain in dogs. (JAVMA 2015)
Attempted determine if feeding a food with coconut oil and supplemental L-carnitine, lipoic acid, lysine, leucine, and fiber on weight loss and maintenance - prospective clinical study
Trial 1 - 30 dogs allocated to three groups to be fed dry maintenance dog food to maintain boy weight, or dry test food at same amount on mass or energy basis
Trial 2 - each of 20 dogs was fed test food and clorici ntake was adjusted to maintain weight loss rate of 1-2%/week
Trial 3- weight maintenance phase
Trial 1 - dogs in groups 2 and 3 lost significantly more weight than those in group 1
Trial 2 - dogs lost a significant amount of body weight and fat mass but retained lean body mass during weight loss phase
Trial 3- continued to lose body fat but gain lean body mass during weight maintenance phase
Metabolomic data evaluation suggested that fat metabolism and lean body mass retention were improved from baseline for dogs fed test food
What are metabolic consequences of obesity?
Insulin resistance, hyperlipidemia, low grade inflammation
Heart disease, etc
What body fat percentage is considered ideal in dogs?
15-25%
Waht is the primary means for reducing excessive bodyweight in overweight dogs?
Calorie restriction
Which dietary fats can increase energy expenditure at the expense of fat deposition
Medium chain fatty acids - more readily abosrbed and rapidly oxidized than are long chain fatty acids
Which micronutrients may increase conversion of dietary fat to energy?
Carnitine - essential cofactor in transfer of LCFA from cytosol into mitochondria of cells where they undergo beta oxidation - increasing L carnitine intake may increase oxidation of LCFAs
Lipoic acid - directly involved in energy metabolism and has antioxidant effects in reduced forms
Supplementation with which amino acids may reduce protein degradation and reduce loss of lean body mass during periods of restricted energy intake?
Lysine and leucine
How do weight loss diets compare to traditional weight loss diets?
Weight loss diets contain less energy and fat and ghigher concentrations of essential amino acids, vitamins, minerals, and fiber so that adeqaute nutrition is provided during periods of caloric restriction
Why are dogs and cats unique from humans/ other species in regards to vitamin D synthesis?
They lack ability to synthesize vitamin D3 in the skin, likely b/c of high acitvity of 7 dehydrocholesterol delta7 reductase
This means that dogs and cats require dietary supplementation with vitamin d to meet nutritional requirements
What are two dietary forms of vitamin D?
Cholecalciferol (vitamin D3) - typically comes from animal food sources
Ergocalciferol (vitamin D2) - plant sources
Cats don’t utilize plant source as easily, dogs can utlize both
What is the path that vitamin D takes once ingested?
Transported to liver via the portal system and intestinal lymphatics
Process requires digestive enzymes, chilomicrons, bile acids and VDBP or transcalciferon
After cholecalciferol is tranported to the liver, it is hydroxylated by 25 - hydroxylated by 25 hydroxylase to form 25 (OH)D aka calcidiol/ calcifediol
Calcidiol the binds to VDBP in circulation
Calcidiol - most reliable indicator of systemic vitamin D status in humans
How is vitamin D converted to its most active form (1,25 (OH)2D - Calcitriol)?
It is hydroxylated via 1 alpha hydroxylase in the kidney (predominantly) and other tissues that express the enzyme
How is the expression of 1 alpha hydroxylase regulated?
Serum concentrations of calcium, PTH, 1,25,OH2D (calcitriol), FGF23, and the klotho gene
How are calcidiol and calcitriol inactivated?
By 24 hydroxylase to form 24,25 (OH)2D and 1,24,25-trihydroxyvitamin D and other metabolites that are excreted in urine and bile
Name some roles of vitamin D
Influence on Ca-Phos homeostasis via the bone - parathyroid kidney axis, differentiation of immune cells, reductions in inflammation and proteinuria, increases in insulin secretion, improvement of hematopoiesis
Name the mechanisms by which vitamin D can be disrupted in patients with kidney disease.
Decreased dietary intake of vitamin D
Decreased enzymatic converstion from cholecalciferol to calcidiol in the liver
Decreased activation via 1 alpha hydroxylase from calcidiol to calcitriol
Increased inactivation of calcidiol and calcitriol
Urinary loss of vitamin D bound to vitamin d binding proteins
Decreased endocytosis of calcidiol into renal cells b/c of decreased megalin expression in proximal renal tubules
Vitamin D metabolites and more significantly decreased in which IRIS stage of CKD?
III
What occurs in a patient with CKD mineral bone disorder?
Plasma FGF23 concentrations are increased to promote phosphoruresis
Eventually PTH increases to compensate for hyperphosphatemia and secondary hyperparathyroidism occurs
Calcitriol supplementation has been shown to have antineoplastic properties agains which cancers?
Osteosarcoma SCC Prostatic carcinoma AGASACA Mammary gland cancer MCT
Which vitamin D metabolites have been noted to be decreased in patients with malabsorptive GI disease?
Calcidiol and calcitriol
Hypoalbuminemia may contribute to vitamin D loss d/t loss of vitamin D binding proteins
Hypovitaminosis d may also contribute to protein loss through vitamin d effect on immune response
How do calcidiol and calcitriol modulate inflammation?
Inhibit production of IL6 and TNFa
What are options for vitamin D supplementation?
Ergocalciferol (vit D2), vitamin D3 (cholecalciferol), calcidiol, calcitriol, or vitamin D receptor activators
Run through vitamin D metabolism
Cholecalciferol and ergocalciferol from diet —> goes through intestines and enters blood w/ vit D binding protein to be stored in fat cells OR to be activated to calcidiol in the liver by 25-hydroxylase —> calcidiol enters bloodstream again and goes to prox tubule via megalin mediated endoctytosis —> activated to calcitriol by 1 alpha hydoxylase —> calcitriol binds to vitamin D receptor to increase Ca and Phos absorption in gut and Ca resorption from bone
FGF23 and Klotho at kidney act to increase phos excretion and have neg feedback on 1 alpha hydroxylasis, as does increased Ca and Phos
In a study assessing the protein and amino acid concentrations and labeling adequacy of commercial vegetarian diets formulated for dogs and cats (JAVMA 2015)…
Cross sectional study evaluating 13 dry and 11 canned vegetarian diets for dogs and cats - crude protein and AA concentration was determined for each diet and compared with AFFCO dog and cat nutrient profiles
Minimum crude protein concentrations for specified species and life stages ere met by 23/24 diets, and remaining diet passed AAFCO feeding trials
6/24 diets did not meet all amino acid minimums, compared with the AAFCO nutrient profiles
1 was below AAFCO minimum requirements in 4AA (leucine, methionin, methionin-cystine, taurine)
2 were below in 3 AAs (methionine, methionine-cystine, and taurine)
2 were below in 2 AAs (lysine, tryptophan
1 was below in tryptophan
Only 3 and 8 diets (wtih and without statement of calorie content as a requirement) were compliant with all pet food label regulations established by AAFCO
**MOST diets assessed in study were not compliant with AAFCO labeling regulations, and concerns raised regarding adequacy of AA content
24% of OTC diets and 100% of veterinary therapeutic diets met all requirements for labeling and nutritional adequacy
96% met clains for minimum crude protein
75% met AAFCO amino acid minimum requirement
Why have vegetarian pet foods been linked to concerns related to nutritional adequacy?
Vegetarian protein sources - poor sources for specific essential vitamins (Vit D, Vit A, niacin, cobalamin), fatty acids (arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid), and minerals (calcium, potassium)
Plants are highly variable in protein concentration and provide incomplete AA profiles for pets
Why is taurine an essential aa in cats and only considered conditionally essential in dogs?
Cats - Retinal function, cardiac function, reproduction, growth - cannot snythesize it
Dogs - have metabolic capacity to synthesize it when adequate concentrations of sulfer containing AA precursors (methionine, cysteine) are available
What are the 3 means of substantiating claims that pet foods are complete and balanced?
- To formulate a diet to meet AAFCO dog and cat food nutrient profiles
- Conduct a feeding trial by use of AAFCO recognized protocols for specified life stage - if successful, then food is exempt from needing to meet AAFCO nutrient profiles
- If in nutritionally similar product family to lead product that has completed AAFCO feeding trial, then lable may state that AAFCO feeding trials substantiate the claim of complete and balanced and nutritional adequacystatements are indistinguishable
If it does not meet these requirements, then must labels as “intended for intermittent or supplemental feeding only”
How do dogs and cats differ from other species in regards to bile acid conjugation?
Obligatory bile acid conjugation with taurine
Dogs can synthesize taurine from cysteine and methionine
In a study evaluating integration of a physical training program in a weight loss plan for overweight pet dogs… (JAVMA 2015-2016)
Prospective nonrandomized clinical study using 19 client owned overweight or obese ogs
All dogs fed the same calorie restricted diet to achieve weight loss weight of 1-2%/week for 12 weeks
Split into diet only and fitness groups
Fitness and diet group lost a mean of 13.9% body weight, and diet only group lost a mean of 12.9% body weight - not significantly different
Lean body mass was preserved in the fitness and diet group and lost in the diet only group during intervention
In a study evaluating marketing claims, ingredients, and nutrient profiles of OTC diets marketed for skin and coat health of dogs (JAVMA 2015)….
Looked at 24 OTC diets (dry and canned)
Most diets incorporated useless marketing terms: digestive health, sensitive or premium
Types and numbers of major ingredients differed
Total number of unique major ingredients in each diet ranged from 3-8
Total number of uniquire ingredients in each diet ranged from 28-68
Concentrations of nutrients assocaited with skin and coat health also differed
Large variation in OTC diet ingredients markened for skin and coat health
What are essential nutrients that can impact skin and coat condition in dogs?
Essential fatty acids (play a role in membrane fluidity, metabolic regulation, maintenance of transepidermal water barrier, and eicosanoid syntehsis)
Vitamin A
Minerals
What is the simplest form of carbohydrate?
Monosaccharides
What are complex carbohydrates?
Oligosaccharides, polysaccharides, starches, dietary fibers
Consist of 3-10 or >10 sugar units
How does carbohydrate digestion occur?
Mechanical breakdown of food in mouth (limited production of alpha amylase in mouth of dogs, enzymatic digestion does not start in mouth) —> alpha amylase released by pancreas in dogs allowing for digestion
Once starch is digested, glucose and galactose are actively transported across the mucosal brush border of the SI by sodium dependent glucose transporter 1 (SGLT1) - may be able to upregulate amount of transporter depending on amount of carbohydrates consumed
Once glucose is absorbed it can be used for ATP production by glycolysis, stored in the liver and skeletal muscle as glycogen, or converted to fat and stored as adipose tissue
Glucokinase or hexokinase (or both) are necessary for the first rate limiting step of glycolysis
Run through the steps of glycolysis
- Glucose phosphorylated to G6P (by hexo/glucokinase - negative feedback of G6P on hexokinase) - 1 ATP used (ATP —> ADP)
- G6P converted to fructose 6 phosphate by phosphohexose isomerase — 1 ATP used (ATP —> ADP)
- F6P converted to Fructose 1,6 diphosphate (ATP —> ADP)
- F1,6,P converteed to dihydroxyacetone phosphate —> converted into two Glyceraldehyde 3 phos (G3P)
- Each G3P converted to one pyruvate (total to 2) (2 ATP and 2 NADH GAINED from this)
- Pyruvate enters Krebs/ TCA cycle