Nutrition science

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What are lipids soluble in?
Organic solvents (ethers, acetone, chloroform)
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What are the simple lipids?
fatty acids, triglycerides and waxes
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What are the compound lipids?
phospholipids, glycolipids and lipoproteins
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What are the simplest lipids?
fatty acids
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what structure do fatty acids have?
straight hydrocarbon chain
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what are the 2 ends of a fatty acid?
methyl end and carboxylic end (terminal end)
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Which end of a fatty acid is hydrophilic and which end is hydrophobic?
Methyl end is hydrophobic and carboxylic end is hydrophilic
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how many carbons are found in fatty acids in food and the human body?
4-24
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what is a trans fatty acid?
A molecule that has been extended into a linear shape (similar to saturated fatty acids)
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What is a cis fatty acid?
A molecule that kinks and bends back into a U shape
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What is partial hydrogenation?
Where a polyunsaturated fatty acid is made to be solid at room temp
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What are the risks of fatty acids?
CVD
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How does the delta system work?
Counts the double bond from the carboxylic end of the fatty acid
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how does the omega system work?
Counts the double bond from the methyl end of the fatty acid
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How many carbons separate 2 double bonds in a fatty acid?
3
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How many carbons in a short chain fatty acid?
less than 8
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How many carbons in a medium chain fatty acid?
8-12
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How many carbons in a long chain fatty acid?
14-18
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How many carbons in a very long chain fatty acid?
20,22
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What are the 2 essential fatty acids and why are they essential?
linoleic acid and alpha-linoleic acid. they are essential because they can not be synthesised in animal cells
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What oil is the best source for n-3 fatty acids?
flaxseed/linseed oil
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What form is most stored body fat in ?
Triglycerides
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What percentage of dietary fat do triglycerides take up?
95%
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are short chain triglycerides oils or fats?
oils
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How are fatty acids attached to glycerol?
ester bonds
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what are acylglycerides?
a glycerol with only one fatty acid
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What do phospholipids contain?
Phosphate and one or more fatty acid residue
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What is the mian structural functionof phospholipids?
Lipid bilayer of cell membranes and lipoproteins
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Define amphipathic
both polar and non polar groups
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What is the most common glycerophosphatide in the diet and where is it found?
Lecithin (egg yolks and soy)
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What is the backbone of sphingolipids?
sphingosine
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What is ceramide?
sphingosine + fatty acid
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what is sphingomeylin?
Ceramide + phosphocholine
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Where is sphingomyelin found and what is it important for?
Found in plasma membrane especially myelin sheath of nerve tissues, important for nervous system function
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What structure do sterols have?
4 ring core structure (steroid nucleus)
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What are sterols made up of?
1 hydroxyl group and a range of side chains
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What NRV is used for cholesterol?
AI
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Where is cholesterol commonly found?
Egg yolks, meat and dairy
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What is cholesterol a precursor for?
Sex hormones, vitamin d3 and bile acids
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Where are phytosterols found?
Plant cells
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Where is the highest concentration of phytosterols found?
plant oils, nuts, legumes & seeds
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For australians, what is the main source of phytosterols?
Grain products
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In australia, what percentage of energy comes from saturated and trans fats? Monounsaturated fats? polyunsaturated fats?
14%, 14% and 4.7%
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How are lipids emulsified in digestion?
mechanical shearing and bile salts
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What percentage of lipids are digested in the mouth and stomach and by what?
10-30%, by lipases
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Where does most lipid digestion occur?
small intestine
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How does orlistat work and what are the consequences of taking it?
Reduces lipid absorption, fat in faeces
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What percentage of TAGs and phospholipids are absorbed?
~95%
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What percentage of cholesterol is absorbed in the body?
~30%
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Are plant sterols well absorbed in the body?
no
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Are short chain or long chains absorbed better in the body?
Short chains
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What percentage of lipids in plasma are transported by albumin
2%
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How are the majority of plasma lipids transported?
Carried as lipoprotein complexes
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What are chylomicrons and what do they do?
Small globules of fat and protein, they transport lipoproteins in the intestine
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How are lipoproteins transported in the liver?
VLDL-C, LDL-C, HDL-C
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What does LDL increase the risk of?
Atherosclerosis
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What is atherosclerosis?
Hardening of arteries
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What does HDL do?
removes cholesterol from cells and returns it to the liver to be excreted in bile
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What are apolipoproteins?
the protein component of lipoproteins
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What are the functions of apolipoproteins?
Grant specificity to lipoproetin complex to be recognised by specific receptors and stimulate certain enzymatic reactions
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How are apolipoproteins named?
With a letter from A to E followed by number
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What are the health implications of saturated and trans fatty acids?
Increased LDL-C
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Why are essential fatty acids required by the body?
To synthesise polyunsaturated fatty acids
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Why are polyunsaturated fatty acids needed by the body?
For membrane fluidity
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What are the symptoms of polyunsaturated fatty acid deficiency?
Dry, scaly skin, excessive thirst and growth retardation
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How long does it take to show symptoms of polyunsaturated fatty acid deficiency?
~100 days
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what are eicosanoids?
Molecules made by oxidation of polyunsaturated fatty acids (hormone like substances)
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What are eicosanoids involved in?
contraction/relaxation of smooth muscle, inhibition/stimulation of platelet aggregation, constriction/dilation of blood vessels and act on cells in the immune system
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Where is are excess lipids stored?
Adipose tissue (adipocytes)
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what are the functions of adipose tissue?
Insulation, maintain body temp, protect organs, back up energy source
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Why is easier to put weight back on?
Adipocytes can shrink but can never be destroyed once formed
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What are ways to assess lipid intake?
BMI, waist circumference, TAGs in blood, dietary inatke (estimate)
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What are the NRVs for lipids?
AI, UL, SDT, AMDR
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How is Australian doing with the intake of lipids?
Too high in saturated/trans fatty acids, too low in polyunsaturated fatty acids
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Where are chylomicrons synthesised?
enterocytes
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What are carbohydrates made up of?
Carbon, Hydrogen and oxygen
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What is the general formula for carbohydrates?
(CH20)n
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What is the function of carbohydrates dependant on?
Polymer size, linkages between monomers and monomers present
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How do plants synthesise CHOs?
By photosynthesis from water and CO2
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What are the classifications of CHOs?
Simple(monosachharides, disaccharides and polyols), oligosachharides and polysachharides (starch and non-starch)
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What are the 4 monosaccharides?
Galactose, fructose, glucose and pyranose
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How are disaccharides linked?
By glycosidic bonds
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What is maltose made up of?
glucose +glucose
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what is sucrose made up of?
glucose and fructose
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What is lactose made up of?
glucose and galactose
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where is glycogen mainly found?
In liver and skeletal muscle
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Which monosaccharide is absorbed the slowest?
Fructose
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What is glucose stored as?
Glucagon
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How is GI determined?
rate of digestion/absorption of food
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When does blood glucose peak and when does it return to normal?
Peaks around 15-45 mins after meal, returns to normal after 2-3 hours
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How do you calculate glycaemic load?
GI x amount of CHO
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What is GI affected by?
Cooking, size and shape of starch, type of sugar, type of fibre, presence of fat & (mainly) amount of CHOs in diet
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what percentage of food involves the TCA cycle?
90%
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When does glycogenolysis occur?
In fasting state
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What is the NRVv for CHOs?
AMDR (45-65%)
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where are fructose and galactose metabolised?
In the liver
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What happens to excess fructose?
Stored as fat
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What sources have the highest amount of CHOs?
Soft drinks, bread, sugar
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What are the 3 categories of fibre?
Soluble (pectin, gums and hemicellulose), insoluble (celluslose, hemicellulose and lignan) and other (sugar alcohols, oligosaccharides and lignin)
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What do prebiotics do?
Promote colonic growth
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What are the benefits of fibres?
Alleviate constipation, assist with weight control, alleviate/prevent chronic disease and reduce risk of colon cancer
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What are the effects of excess fibre?
Sigmoid volvulus, oesophogeal obstructions, mineral deficiency, flatulence and bloating
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What are the NRVs for fibre?
AI and SDT
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What food has the highest source of fibre?
unprocessed bran
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How is the amount of fibre assessed?
Clinical (Gastrointestinal symptoms), dietary intake
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What are the benefits of flavonoids?
Vasodilatory effects, anti-oxidant, anti-inflammatory
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How many amino acids in each protein?
50-1000
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How can proteins be charcterised?
Essential (indispensible), conditionally essential (indispensible) and non-essential (dispensible)
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Where does digestion of proteins occur?
stomach and small intestine
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Where does absorption of proteins occur?
Duodenum and jejunum
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Are essential or non-essential amino acids absorbed faster?
Essential
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How much and what what percentage of protein is in the body?
10-11kg (16%)
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What are the functions of proteins in the body?
Structural (skin, nails, myosin and actin for muscle), buffering (acid/bas balance, maintain pH), fluid balance (keeps water in particular location), catalysts (enzymes), messengers (hormones), immunoprotection, transport (cell membrane, blood)
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What is nitrogen balance affected by?
Pregnancy, growth, physical activity (positive), injury, burns, bleeding (negative)
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What are the NRVs for protein?
EAR, AMDR, RDI
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What are the effects of excess protein intake?
Rabbit starvation, increased urea, increased Ca excretion
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What are the different types of proetin deficiencies?
Marasmus (frail, weka, impaired growth), Kwashiorkor (odema, death), Protein-energy malnutriton (PEM)
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What is the leading cause for protein deficiency in Australia?
Disease
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What foods are the best sources of protein?
Gelatin, meat, cheese, nuts and soybean
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What is hyponatremia?
Not enough Na in body fluids outside the cells
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What are the symptoms of hyponatremia?
dry mouth, sunken eyes, weak pulse, vomiting
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What are the causes of hyponatremia?
Vomiting, heavy sweating, diuretics
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What are the NRVs for sodium?
UL, SDT and AI
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How can you assess sodium levels in body?
Biochemical (serum, urine) or dietary intake (difficult)
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What percentage of potassium is absorbed?
>85%
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Which hormone manages potassium absorption?
Insulin
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do fresh or process food have more processed food and why?
Fresh (cells are still intact)
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What are the different types of potassium deficiencies?
Hypokalemia (high GIT loss), potassium depletion (inadequate intake and magnesium deficiency) and refeeding syndrome (when malnourished people are provided with treatment that lacks potassium)
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What is the effect of excess potassium?
Hyperkalemia
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What are the NRVs for potassium?
AI
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What are the ways to assess potassium in the body?
Plasma, urine and symptoms
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How much iodine does the body contain and where is most of it stored?
15-20mg and thyroid (75%)
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What is the function of iodine?
Synthesis of thyroid hormones which regulate body temp, reproduction and metabolic rate
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what percentage of iodine is absorbed?
>90%
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What are the effects of not enough iodine?
Goitre, neonatal hypothyroidism and cretinism/ congenital hypothyroidism
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What are the 3 main micro-nutrient deficiencies worldwide?
iodine, vitamin A and iron
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What are the best sources of iodine?
Iodised salt, marine foods and dairy
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What are the NRVs for iodide?
UL, EAR, RDI
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How can you asses iodine levels in the body?
Excretion, daily intake and assessment of goitre
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What percentage of selenium is absorbed?
~80%
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Wheer is selenium absorbed?
Small intestine
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What is the name od the disease to do with selenium deficiency?
Keshan disease
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What are the benefits of selnium?
Anti-inflammatory, anti-oxidant possible prevention of cancer
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What are the NRVs for selenium?
EAR, RDI and UL
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What foods are the best sources of selenium?
Fish, organs and brazil nuts
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How can you asses selenium levels in the body?
plasma, excretion and toe nail/hair analysis
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What is the benefit of fluroide?
Improves dental health
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What are the sources of fluoride?
fluoridated water, sardines with bones, tea and toothpaste
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What are the NRVs for flouride?
UL
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What are the 4 stages of iron absorption?
Luminal, mucosal uptake, intracellular and release
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Where is iron mainly stored?
liver, spleen and bone marrow
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What is the most common deficiency in developed countries?
iron
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What are the symptoms of iron toxicity?
gastric bleeding and vomiting
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Which groups are at risk of iron deficiency?
Menstruating women, elderly, athletes and vegetarians/vegans
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What are the effects of chronic iron overload?
Haemochromotosis and thalassemia
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What are the NRVs for Iron?
UL and RDI
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Where does digestion of zinc occur?
Duodenum and jejunum
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What factors enhance zinc absorption?
Organic acids and low pH
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What factors inhibit zinc absorption?
polyphenols, oxalate and divalent cations
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where is zinc stored?
plasma and rbc
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What are the functions of zinc?
taste, component of insulin, cell and tissue growth and maintenance, co-enzyme, gene expression, CHO metabolism and immunity
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What are the NRVs for zinc?
RDI and UL
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What are the causes of zinc deficiency?
pregnancy, growth, diarrhoea, vomiting and eating disorders
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Why are stores of zinc used up so quickly?
Stored in very low amounts
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What are the best sources of zinc?
Meat, nuts, seafood and grains
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How can you asses zinc levels in the body?
Plasma, serum and urine
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What are the simple lipids?

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Card 3

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What are the compound lipids?

Back

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Card 4

Front

What are the simplest lipids?

Back

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Card 5

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what structure do fatty acids have?

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