Iron and Zinc Flashcards
Iron food sources
Fortified foods are also really important for souring iron from food
Naturally rich foods include meat, shellfish, poultry, legumes and fish
What is bioavailability?
Bioavailability is the proportion of intake of a nutrient that is absorbed and utilised
In terms of iron - iron absorption is a huge problem, utilised normally
What is bioavailability influenced by?
Host related factors - iron status, the lower your iron status the more iron you will absorb, the higher your iron status is the less you absorb, or if you’re pregnant - substantial increase in iron absorption
Haem iron vs. non-haem iron
Haem iron absorption is higher than non-haem iron, wider range for non-haem than haem ~25-30% compared to ~5-15%
Non haem much more affected by enhances and inhibitors
Haem and non haem iron can be absorbed from meat, non-haem can also be absorbed from non-meat foods e.g. bread
Main enhancers and inhibitors of iron absorption
Main enhancers: vitamin C/ascorbic acid, meat, fish and poultry
Main inhibitors: tannins in coffee/tea, phytate (germinating seeds that store phosphate groups) inhibits absorption of iron
If you consume your iron containing food and then have the inhibitors it should be fine and absorption of iron will still occur
All to do with ensuring the enhancers with the meal and inhibitors away from the meal
What is Iron deficiency anaemia?
Iron deficiency anaemia - levels of iron become so low that the body cannot make enough haemoglobin
Decreased growth, behavioural disturbances, decreased cognitive function, fatigue, decreased work tolerance, spoon-shaped nails
What is depletion of iron stores ?
Depletion of iron stores is where you have low haemoglobin but not anaemia, facing physiological problems, increases risk of iron deficiency anaemia
Associated with decreased cognitive function, increased fatigue, decreased mood and work performance
Physiological problems include difficulty getting pregnant
Groups at risk of developing iron deficiency
Pregnant women
Older people/elderly
Younger children (infants/toddlers)
People who are menstruating/premenopausal
Vegetarian and vegan diet (lower iron stores)
Premature infants
Blood donors
What is Iron overload?
Acute iron toxicity
Hereditary haemochromatosis
African iron overload
Other iron overload conditions
What is hereditary haemochromatosis?
Suggested a mutation in viking stock that had advantages in women who were carriers - fatal in later age
More prominent in northern European culture
Don’t have appropriate control of iron absorption, build up in joints, yellowly skin, cardio myopathy, diabetes
Treatment: given large volumes of blood and removing iron from stores so body can reach a normal level of iron status
What are zinc food sources?
Zinc food sources include meat, poultry, fish, shellfish, legumes and dairy
Enhancers and inhibitors of zinc
Enhancers include meat, dairy, poultry, fish
Inhibitors include: iron supplements, phytate (seeds, nuts, legumes, grains)
We can refine grains (white flour has less phytate than whole grain flour) to remove phytate, yeast fermentation (destroys some phytate during fermentation), soak food in water as phytate is water soluble, canned foods (beans) gets rid of the phytate
Main functions of zinc
Found in more than 200 enzymes for function or regulation
Biosynthesis of nucleic acids, amino acids, proteins, hormones
Important for growth, immunity, vitamin A metabolism, reproduction and appetite
First zinc deficiency reported in 1960s
Severe zinc deficiency - stunted growth, little or no secondary sexual development (facial hair, voice deepening, broadening shoulders). Diet was unleavened wheat bread (50-90% of food energy), low intake of animal foods and geophagia (consumption of earth)
Zinc Impacts on health
Impaired growth: infancy = poor weight gain, children = poor linear growth
Impaired immune competence seen in low income countries: increased morbidity (diarrhoea and pneumonia) and as a result increased mortality
