9b. Minerals - Micro Flashcards
Which metalloenzyme functions is Zn a cofactor in?
Superoxide dismutase (SOD) - AO Alcohol dehydrogenase - breakdown of alcohol Carboxypeptidase - digestion of proteins Haem synthesis Folate absorption DNA/RNA synthesis
Food sources of Zn
Oysters Adzuki beans Rye flour Sesame seeds Calf's liver
What are the functions of Zn?
Reproduction Endocrine Digestion Immunity Sensory Cell proliferation
What are the functions of Zn in reproduction?
Production of sex hormones
Spermatogenesis
Inhibits 5a-reductase
(e.g. inhibits conversion of testosterone to more potent androgen DHT)
What are the functions of Zn in endocrine?
T4 to T3 conversion
What are the functions of Zn in digestion?
Production of HCl
Creation of pancreatic enzymes
What are the functions of Zn in immunity?
AO
Increases T and B cell activity
Anti-inflammatory
Anti-viral
What are the functions of Zn in sensory?
Taste and smell
Supports vision and hearing
What are the functions of Zn in cell proliferation?
Cell proliferation/differentiation e.g. skin
Gene expression
Aids tight junctions
What are the therapeutic uses of Zn in reproduction?
Low testosterone
Infertility
Erectile dysfunction
What are the therapeutic uses of Zn in endocrine?
Thyroid health
What are the therapeutic uses of Zn in digestion?
Weak digestion
Hypochlorhydria
What are the therapeutic uses of Zn in immunity?
Frequent infections
Inflammation
CV disease
What are the functions of Zn in sensory?
Poor taste/smell/vision
Tinnitus
What are the functions of Zn in cell proliferation?
Acne
Wound healing
Burns
Cancer
What percentage of Zn is absorbed by the body?
20-40%
What can enhance the absorption of Zn?
Protein
What can inhibit the absorption of Zn?
Phytates
Excess Ca, Cu, Fe
Food sources highest in phytates
Wholegrains
Legumes
Nuts
Seeds
How can phytate levels be reduced?
Soaking
Sprouting
Fermenting
What can Zn supplementation inhibit?
Cu absorption
What can cause Zn deficiency?
Malabsorption
Diet high in phytates
Diet low in Zn rich foods
Which groups are at risk of Zn deficiency?
Older adults
Alcoholics
Pregnant women
Athletes
Signs/symptoms of Zn deficiency
Poor sense of taste/smell Recurrent infections Delayed wound healing Skin disorders e.g. acne Infertility Weak digestion
Which forms of Zn supplements are best absorbed?
Citrate
Acetate
Glycinate
What can long-term Zn supplementation lead to?
Cu deficiency
What are the two forms of Fe present in the body?
Ferrous - Fe2+
Ferric - Fe3+
Which form of Fe is needed for absorption?
Ferrous
Where can we mostly find Fe?
Blood
Bone marrow
Muscles
Enzymes
From what food sources can we find non-haem iron?
Plants
Animals
Which form of Fe is non-haem iron?
Ferritic
From what food sources can haem iron be found?
Animals
Fish
Which form of Fe is haem iron?
Ferrous
Examples of Fe food sources
Meat Fish Pumpkin seeds Sesame seeds Quinoa Soy beans Spinach Dried apricots
What are the functions of Fe?
Oxygen transport and storage Energy Endocrine Immune Neurotransmitter synthesis
What are the functions of Fe in oxygen transport and storage?
A component of haemoglobin (O2 stores in blood)
A component of myoglobin (O2 stores in muscles)
What are the functions of Fe in energy production?
Enzyme cofactor in electron transport chain
What are the functions of Fe in endocrine?
Cofactor for the enzyme thyroid peroxidase (needed to synthesis thyroid hormones)
What are the functions of Fe in immunity?
Lymphocyte proliferation and maturation
What is the function of Fe in neurotransmitter synthesis?
Cofactor for tyrosine hydroxylase
converts tyrosine to dopamine
What are the therapeutic uses of Fe in oxygen storage and transport?
Anaemia
Fatigue
Muscle weakness
Exercise - endurance
What are the therapeutic uses of Fe in energy production?
Fatigue
Mitochondrial support
What are the therapeutic uses of Fe in endocrine?
Hypothyroidism
What are the therapeutic uses of Fe in immunity?
Immune support
What are the therapeutic uses of Fe in neurotransmitter synthesis?
Cognition/learning
Parkinson’s
Where is Fe not used for haemoglobin production stored?
In the protein ferritin
What happens to Fe when Fe stores are high?
Liver converts ferritin to hemosiderin which releases Fe more slowly
Once a RBC has come to the end of its lifespan what happens?
Spleen and liver dismantle it, salvage the Fe and recycle it to make more erythrocytes
Where does the body lose some Fe on a daily basis?
Via GI tract
When bleeding occurs
Is Fe excreted from the body?
No
How are Fe levels regulated?
By the amount absorbed in the intestine
higher levels in tissues = down regulation of gut absorption
What helps the body absorb Fe from food?
Proteins
What does mucosal ferritin do?
Receives Fe from food and stores it in the SI mucosal cells
What does mucosal transferrin do?
Transfers the Fe from SI mucosal cells to blood transferrin which transports the iron to the rest of the body
What happens if the body doesn’t need Fe?
It’s carried out when the intestinal cells are shed and excreted via faeces
(every 3 days)
What does Fe absorption depend on?
GI tract health
Presence of supporting/inhibiting nutrients e.g. vit C/phytates
Food source (haem vs non-haem)
What is the absorption rate of haem iron?
15-35%
What is the absorption rate of non-haem iron?
2-20%
Is haem or non-haem iron absorption more sensitive to body iron stores?
Non-haem
Why are supplement doses of Fe typically high?
Fe from supplements is less well absorbed than from food
How can non-haem Fe absorption be enhanced?
Vit C with every meal
Build meals around Fe-rich foods
Avoid drinking caffeine and dairy at meal times
Eat foods that contain yeast
Eat sprouted/fermented foods to reduce inhibitors like phytates
Eliminate junk food
How does vit C enhance non-haem Fe absorption?
A vit C dependent enzyme called vit C ferrireductase is embedded in the cell membranes of duodenal enterocytes that converts Fe from the Fe+3 to Fe+2 state
What can inhibit the absorption of non-haem iron?
Phytates Oxalates Polyphenols Calcium Tannins
Which life stages are vulnerable to iron deficiency?
Women of reproductive age
Pregnancy (increased blood volume)
Times of rapid growth (teenagers, young kids)
What are the symptoms of Fe deficieny anaemia?
Fatigue on exertion Weakness Headaches Apathy Breathlessness Poor resistance to cold temperatures
What are the signs of Fe deficiency anaemia?
Pallor
Nail spooning
Hair loss
Tachycardia
Why is Fe toxicity a risk?
Because there’s no physiological mechanism for excretion
Haem Fe is more efficiently absorbed and the body has less control over how much it absorbs
(unlike non-haem iron)
Why can Fe overload be harmful?
Free Fe is a pro-oxidant and can cause oxidative damage
(associated with atherosclerosis, cancer, AZD)
Fe is a bacterial growth factor and can cause increased infection rates
Excess Fe can accumulate in organs e.g. brain, liver
What can contribute to Fe overload?
Haemochromatosis (genetic disorder that enhances Fe absorption)
Indiscriminate use of Fe supplements
High dose vit C supplementation
Excessive red meat consumption
Which nutrients can enhance the absorption of Fe?
Vit C
Which nutrients inhibit the absorption of Fe?
Zn
Cu
Ca
Which amino acids can selenium be found bound to?
Cysteine
Methionine