Nutrition Flashcards
What is a conditionally essential nutrient?
Not ordinarily required but have to be given to certain populations that don’t make enough e.g. premature babies
What is a non-essential diet component?
Not required for full growth or development but present in diet at levels causing physiological effect
Which are the water soluble vitamins?
C and several Bs (B1, B2, niacin, B12, B6, pantothenic acid, biotin, folic acid)
Which are the lipid soluble vitamins?
ADEK
What can iron bind to?
Oxygen, nitrogen and sulphur
What is ferrous and what is ferric?
Ferrous is 2+, Ferric is 3+
What keeps the free iron concentration low?
Transferrin and lactoferrin
Where are some places iron can be stored?
Haemoglobin, myoglobin, enzymes, cytochromes, liver, macrophages, bone marrow
How can iron be lost?
Desquamation of epithelial cells of skin, GI tract, bile duct, urinary tract
What is the sole means by which iron homeostasis is regulated?
Digestive tract
What does ferritin bind iron as?
Fe3+
How does increased iron increase infection rates?
Makes pathogens grow faster and decreases T cell responses
How can iron enhance tumour growth?
Stimulation of cell growth rate, exacerbation of gut inflammation, increased ROS formation, increased N-nitroso compound formation
What is the most common oral iron supplement?
Ferrous (FeII) sulphate
What gut bacteria has high iron requirement?
Bacteroides, sulphur-reducing bacteria
What do retinoic acids do to gene transcription?
Act like steroid hormones, bind to receptors RAR and RXR which act like transcription factors
What kinds of cancers can retinoic acids be used to treat/prevent?
Promyelocytic leukaemia and head and neck cancers
What is the main factor responsible for iron deficiency?
Low dietary intake
When is iodine deficiency the most damaging?
Developing brain during perinatal period during foetal and early postnatal development
Why are young children and pregnant women most vulnerable to iodine deficiency?
Thyroid production rate increased
Why is vitamin D really a hormone?
Can be synthesized in the skin from UV conversion of 7-dehydrocholesterol
What hormone produces 1,25-DHCC?
1-alpha hydroxylase
Which B vitamins can act as coenzymes?
Biotin, niacin, thiamin, riboflavin, pantothenic acid
What is pyridoxine a coenzyme for?
Transamination reactions necessary for amino acid synthesis, cofactor for decarboxylases, synthesis of neurotransmitters with vitamin C and haem and niacin synthesis from tryptophan
What type of reaction is B1 for?
Aldehyde transfer - e.g. carb metabolsim, carboxylation, coenzyme in acetyl CoA function, nerve function
What type of reaction is B2 for?
Oxidation reduction - Part of coenzyme FAD, TCA, lipid and sugar metabolism, ETC
What type of reaction is Niacin for?
Oxidation-reduction - coenzymes NAD and NADP, glycolysis, ETC, fat metabolism
What type of reaction is B6 for?
Amino group transfer - Cofactor in AA metabolism, glycogen phosphorylase reaction, neurotransmitter synthesis, haem synthesis, niacin synthesis from tryptophan
What kind of reaction is folate for?
One carbon transfer - single carbon transfer reactions, coenzyme in DNA synthesis and AA synthesis and erythropoiesis
What type of reaction is B12 for?
Alkylation - coenzyme in folate metabolism and methionine synthesis
Why can’t some animals make vit C from glucose?
Lack L-gulonolactone oxidase
What can destroy vitamin C?
O2, metal ions, increase pH, heat and light
How can you get oxalate kidney stones?
Vit C can be metabolised to oxalate and this can form kidney stones
What does vitamin C do to cofactors?
Keeps them in lower valence state
What are some enzymatic functions of vitamin C?
Collagen synthesis, bile acid formation, bone mineral metabolism, NA synthesis, steroidogenesis, immune function,
What are some non-enzymatic functions of vitamin C?
Antioxidant, free radical scavenger, chain breaking properties mainly in aqueous phase, promotes iron absorption and may prevent formation of N-nitroso compounds
How does ascorbate act as a free radical scavenger?
Accepts single electron from free radical to detox it
What happens to the ascorbyl free radical?
FOrms one molecule of ascorbate and one of dehydroascorbate
How many naturally occuring forms of vitamin C are there?
8
How many tocopherols and tocotrienols are there?
4 of each
What is the most active tocopherol?
Alpha
What are the most common tocopherols?
Alpha and gamma
What are the main functions of vitamin E?
Chain-breaking antioxidant preventing free radical damage in lipid rich membranes preventing polyunsaturated fatty acids from peroxidation, maintains cell membrane integrity, involved in sperm production and egg implantation
Other than K and Mg, what is the most common intracellular metal ion?
Zn
What are enzymatic functions of zinc?
Carb and energy metabolism, protein synthesis and degradation, nucleic acid synthesis, bone formation, antioxidant, pancreatic function, intercellular transport, spermatogenesis (testosterone metabolism)
What are non-enzymatic functions of zinc?
Immune function, regulation of IGF-1 growth factor function, gene transcription
How is Zn transported to liver?
Bound to albumin
How is Zn stored?
Bound to metallothionein in the liver, kidney or intestine
What inhibits Zn absorption?
Phytate-rich foods
Where are lutein and zeaxanthin found?
Green veg and eggs - macula of eye where they absorb blue light and prevent against light-induced oxidative damage
Where is lycopene found?
Tomatoes
What is the biggest subclass of polyphenolics?
Flavonoids
What are the most common flavonoids?
Luteolin (flavone), quercetin (flavonol), genistein, daidzein (isoflavones), catechins (flavanol)
What is bioavailability of polyphenolics like?
Low
What are some effect of polyphenolics?
Antioxidants, inhibit proinflammatory gene expression
What is the French Paradox?
Lower incidence of CVD in countries that drink lots of red wine because of antioxidant resveratrol (stilbene) in grape skin
When can major increases in ROS be detected?
Early apoptosis caused by p53 activation, ceramide release, staurosporine, TNF
