Lecture 17 Flashcards
What food are an iron source?
- Legumes/beans
- Shellfish
- Liver
- Fortified iron foods e.g. wheetbix, baby rice ceral
What is bio-availability of iron influenced by?
- Host related factors = characteristics to do with the person
- >low iron status -> body will increase uptake - Chemical form of the iron (heam vs non-heam)
- Enhancers and inhibitors in the meal
- >bind to iron in gut lumen, has to be consumed at the same time to give the effect
What % of heam iron is absorbed?
approx 25-30%
Where does heam iron come from?
Flesh food i.e meat, fish, poultry
What % of non-heam iron is absorbed?
approx 5-15%
Where does non-heam iron come from?
Bread, legumes, milk, eggs
What is non-heam absorption affected by?
Iron status and inhibitors/enhancer
What are enhancers of iron absorption?
- Vit C
- Fermented foods
- MFP Factor (meat, fish, poultry factor)
What type of iron does MFP increase absorption of?
Non-heme
What are inhibitors of iron absorption?
- Tannins - tea and coffee
- Phyates - a way that nuts and seeds store phosphates needed for germination. Found in wholegrain cereals, beans
What % of body iron does Haemoglobin account for?
Approx 67% (2/3)
What is the function of Haemoglobin?
Transports oxygen and carbon dioxide
What are the consequences of Iron Deficiency?
- Iron Deficiency Anemia
- Depletion of iron stores
What is Iron Deficiency Anemia caused by?
Reduction in haemoglobin concentration due to not enough iron
What are the symptoms of Anenima?
- Reduced growth in young people
- Behavioural disturbances
- Decreased cognitive function
- Fatigue
- Decreased work tolerance (get tired faster)
- SEVERE = spoon shaped nails
What are the symptoms of Depletion of iron stores?
The following are unsure (?)
- decreased cognitive function
- increased fatigue
- decreased mood
- decreased work performance
Increased risk of iron deficiency anemia (this is definite)
What groups are at risk for Iron deficiency?
- Premature infants
- Infants
- Toddlers
- Menstruating women
- Pregnant women
- Blood donors
- Times of rapid growth
What % of toddlers have suboptimal iron levels?
Approx 30%
What is acute iron toxicity caused by?
Unintentional overdose of supplements
->lethal dose = 200mg/kg
Describe Hereditary haemochromatosis?
- Issue with controlling iron absorption
- >no mechanism for how to excrete the iron therefore it becomes stored
What are the consequences of Hereditary haemochromatosis?
- Iron can inflame the joints
- Accumulation in the liver = jaundice
- Accumulation in pancreas = diabetes
- Accumulation in muscle tissue = cardio myopathy
What is the treatment for Hereditary haemochromatosis?
Secrete the blood
What foods are sources of Zinc?
- Meat
- Shellfish
- Legumes
- Oysters
- Dairy
(same as iron with the addition of dairy)
What is the bioavailability of Zinc influenced by?
- Host related factors
- Enhancers and inhibitors in meals
What are enhancers of Zinc?
Animal protein
- > not just the flesh food
- > includes eggs and dairy
What are the inhibitors of Zinc?
- Iron supplements when in high dose but only when taken BETWEEN MEALS
- Phyate inhibits absorption
- Calcium and phyate together
- > calcium by itself has no effect
What are the main functions of Zinc?
- 300+ enzymes need it for function/regulation
- Biosynthesis
Describe what was seen in the Middle East in the 1960’s
-Male adolescent dwarfs
- Clinical features were
- > stunting
- > little/no secondary sexual development
- Diet
- > unleaved bread (didn’t use yeast for fermentation causing inhibition of Zn absorption)
- > low intake of animal foods
- > geophagia = urge to eat earth/clay which binds to Zinc
What are the impacts on health a Zinc deficiency has?
- Impaired growth
- poor weight gain in infants
- poor linear growth in children - Impaired Immune Competence
- increased mobility, diarrhoea, pneumonia
- Increased mortality
What groups are at risk for Zinc Deficiency?
- Infants, toddlers, young children, adolescents
- Pregnant and lactating women
- Elderly -could be due to lower energy intake diet
- Vegetarians/vegans
- Low socioeconomic groups (cost of food)
- Individuals with prolonged diarrhoea
What is the toxic dose for Zinc?
> 1g zinc/day
What are the symptoms of zinc toxicity?
- Metallic taste in mouth
- Nausea
- Gastric distress
- Can be fatal
What intake of Zinc cause reduced copper status?
> 40mg/day
