Micronutrients Flashcards
Concerns about marginalised groups, minority groups are associated with…
- Poor dietary intake
- Excessive energy dense diets
- Nutrient light diets
- Extreme diets
Iron-deficiency anaemia
- Definition
- Prevalence
Low haemoglobin due to low iron.
Seen more in adult women and older girls.
Low vit.D
Prevalent in the UK- affects adults and older children
Increases risk of rickets and osteomalacia.
Micronutrient deficiencies in the UK
Iron- esp in women
Vit.D
B2
Micronutrient deficiencies associated with alcohol liver disease
B1
Vitamin D
Micronutrient deficiencies associated with IBD
Iron
B12
Vit D, K, B6, B1
Folic Acid
Selenium
Zinc
Micronutrient deficiencies associated with obesity
Vit D
Copper
Zinc
Vitamin C
- property
- Dietary source
Water soluble
Obtained from foods of plant origin
Site of absorption for Vit C
Buccal mucosa
Stomach
Small intestine
Vitamin C
- mechanism of absorption
Buccal- passive diffusion, through carrier mediated transport
Very rapid absorption when mucosal concentration is very low (<6mmol/L)
- >100mmol/L only 6% absorbed
Vitamin B1
- property
- Dietary source
- Site of absorption
Water soluble
Common in all foods
Absorbed at: Jejunum and Ileum
Mechanism of absorption for B1
When low in concentration:
- Co-transport with Na+
At high concentrations (>8mg)
- Passive diffusion
Wernicke Korsakoff syndrome
Thiamine deficiency (B1) - Found in chronic alcoholics.
B2
- Other name
- Dietary source
- Site of absorption
Riboflavin
In most foods- in coenzyme form
Small intestine
Mechanism of absorption for B2
- Released from proteins via proteolytic enzymes.
2. Hydrolysed by brush border enzymes.
B12
- Property
- Dietary source
- Site of absorption
Water soluble
Synthesised by micro-organisms in animals and concentrated in the food chain.
Absorbed in the distal ileum.
Calcium
- Property
- Site of absorption
- Dietary source
Inorganic element
Site of absorption:
- Mainly duodenum
- Jejunum
- Fermentation of plant products in colon.
Dietary source:
- Diary
- Plants
Iron
- Property
- Site of absorption
- Dietary source
Inorganic elements
Dietary source:
- Iron in animal food
- Iron in plant food
Site of absorption:
- Mainly proximal small intestine
Vitamin A [retinol]
- Property
- Site of absorption
- Dietary source
Fat soluble vitamin
Site of absorption:
- Small intestines
- Carotenes: jejunum and duodenum
Dietary source:
- Long chain fatty acids in animals
- Carotenoids in plants
Mechanism of absorption for Vitamin A
The protein:
- Hydrolysed by pepsin in the stomach.
- Hydrolysed by other proteolytic enzymes in the upper SI, then absorbed.
Carotenes:
- Made into micelles then absorbed.
- Converted to retinol
Vitamin D
- Property
- Site of absorption
- Dietary source
Fat soluble vitamin
Found in animal food
Also synthesised from skin from UV light
- Dietary = D2
- UV= D3
Absorption:
- Half of it absorbed in the SI
Mechanism of absorption for Vitamin D
At the intestinal mucosal cell- passive diffusion of micelle.
D2 and D3 converted to 25 hydroxy-vitamin D by the liver via 25-hydroxylase enzymes.
- This vitamin is then converted to the active 1,25-dihydroxyvitamin D
Mechanism of absorption for Vitamin B12
- In the stomach:
B12 binds with R factor in HCl. - B12-R Is degraded to release free B-12. B-12 combines with intrinsic factor.
- B12-IF binds to IF receptors. In the presence of Ca2+, B12 absorbed into plasma.
Risk factors for Vitamin D deficiency
Pigmented skin
Lack of sunlight exposure
Skin concealing garments
Multiple short interval pregnancies
Elderly/ Housebound people
Vegan/ Vegetarian diet
Malabsorption conditions
Anticonvulsant use
Mechanism of absorption for calcium
20-30% absorbed in acid medium
In duodenum- Vit.D dependant transport when intake is low and requirement is high.
When intake is high- passive diffusion in jejunum
Mechanism of absorption for iron
Haem iron- Absorbed as intake porphyrin complex
Non haem- ionised from ferric to ferrous
35% absorbed when iron supply is low
5% absorbed when iron is high.
