2 - Micronutrients2 Flashcards
Definition of micronutrients
Essential compounds required in small amounts in diet
vitamins + trace elements
Dietary sources of vitamins
- A,D,E,K,C,B1,B2,B3,B6,Biotin, B12, Folate
A - liver, fish D - oily fish, dairy E - oils, nuts, soybean K - dark green, prunes C - Fruits, green veg B1 - Yeast, whole grains B2 - Dairy products, bread and cereal B3 - Beans, milk B6 - Tuna, poultry Biotin - Liver, soy beans B12 - Meat and dairy Folate - Fruits and veg
Uses of micronutrients
Cofactor Coenzymes Genetic control Anti oxidant Structure
Functions of micronutrients
Maintains homeostasis
Energy supply, growth and development in children
How can preventing iron deficiency benefit children
Improves cognitive ability
Benefit of folic acid
Prevents spina bifida and macrocytic anaemia
What are the intake requirements for micronutrients
Intake to meet req for 98% of population
Fat soluble vitamins
ADEK
Features of fat soluble vitamins
Can be stored
Occasionally toxic
How are fat soluble vitamins transported
Converted into micelle
Becomes chylomicrons in the intestine
Goes into the lymph fluid
Water soluble vitamins
B, Biotin, Folic and C
Features of water soluble vitamins
Not stored
Excess excreted
Acts as co enzymes
Goes into the portal vein
What causes deficiency of fat soluble vitamins
Fat malabsorption
Alcoholism
Liver disease
Vitamin A deficiency
Xerophthalmia, night blindness, bitot spots, follicular hyperkeratosis, impaired embryonic development
Causes of vitamin A deficiency
Infection, measles, protein-energy malnutrition
Vitamin D deficiency
Rickets, osteomalacia
Causes of vitamin D deficiency
Ageing, lack of sunlight exposure
Vitamin E deficiency
Peripheral neuropathy, spinocerebellar ataxia, retinopathy, skeletal muscle atrophy
Cause of vitamin E + K def
Antibiotic use
Vitamin K deficiency
Coagulopathy
Causes of water soluble vitamin deficiency
Alcoholism, any maladaptive state, drugs
Vitamin C deficiency
Scurvy
Cause of vitamin C deficiency
Smoking
B1 deficiency
Beri Beri
B2 deficiency
Angular stomatitis
B3 deficiency
Pellagra
B6 deficiency
Neuropathy
Anaemia
Glossitis
caused by isoniazid use
B12 deficiency
Anaemia, neurological disorders
caused by gastric atrophy
Folate deficiency
Anaemia, atrophic glossitis, depression
Cause of vitamin deficiency in developed countries
Decreased intake Decreased absorption Renal disease long term enteral and parental feeding Drugs e.g methotrexate and folate
Alcoholism
B1 deficiency
Small bowel disease
Folate and B9 deficiency
Vegans
Vitamin D and B12 deficiency
Elderly with poor diet
Vitamin D and folate def
Anorexia
Folate def
Ileal disease + resection
Vitamin B12 def
Liver and biliary disease
Fat soluble vitamins
Intestinal bacterial overgrowth
Vitamin B12 def
Antibiotics
Vitamin K def
Renal disease
Vitamin D deficiency
What are trace elements
Dietary minerals required in minute quantities for the normal function
Examples of trace elements
Calcium Phosphorus Iron Selenium Zinc Copper
Calcium deficiency
Osteoporosis
Paresthesia
Muscle spasms
(from dairy)
Phosphorus deficiency
Bone pain, pseudofractures and proximal muscle weakness
or rickets and short stature in children
neurological manifestations
(seeds, nuts, lentils, soya)
Iron deficieny
Anaemia, impaired cog development
red meat, dark veg
Selenium deficiency
Cardiomyopathy
seafood, red meat, cereal
Zinc deficiency
Growth retardation, alopecia, dermatitis, diarrhoea, congenital malformations
(meat, shellfish, nuts, legumes)
Copper deficiency
Growth retardation, anaemia
shellfish, liver, nuts, legumes
Amount of deaths from malnutrition
1/3
What is kwashiorkor
Protein wasting disease
causes acites
micronutrient and antioxidant deficiency
usually in older children
What is marasmus
Severe malnutrition of all types of energy sources
Muscle wasting
usually in neonates
What is refeeding syndrome
Severe electrolyte disturbance (low serum levels of phosphate, magnesium and potassium and metabolic abnormalities in under-nourished patients undergoing refeeding)
What can refeeding cause
Respiratory failure (pulmonary oedema) Confusion Coma Cardiac failure Death
Pathophysiology of refeeding syndrome
o 1) Starts with chronic malnutrition and fasting
o 2) leads to reduced insulin, increased glucagon and increased cortisol
o 3) Increased glycogenolysis, gluconeogenesis and protein catabolism
o 4) Reduced electrolytes, proteins, fats, minerals and vitamins
o 5) When refeeding occurs, insulin secretion occurs
o 6) Intracellular synthesis of proteins and glycogen occurs
o 7) This requires increased uptake of thiamine, phosphorus, mangesisum and potassium
o 8) Leading to low levels in the serum and also sodium and water retention
o 9) Causes convulsion, wernicke’s encephalopathy, hypotension, arrhythmias, heart failures, renal failure.
Management of refeeding syndrome
Electrolyte replacement Nutritional supplement (simple sip drinks, early ng feeding, parenteral vitamins) Treat underlying medical problems Early dietician review Cardiac monitoring
How many adults in the UK affected by malnutrition
> 2 million adults
2wice as common in old age and 3x in institutional care
Why is nutrition important
Wound healing, immune system, cardiac function, muscle strength, inactivity (DVT, pressure sores), depression
Normal uses of iron
O2 transport in haem
Myoglobin function in muscles
Where is iron absorbed
how is it transferred and stored
Absorbed in upper bowel
Transferrin-iron protein transport in serum
Iron stored in lever and bone marrow as ferritin
What do haem chelators do
Prevent iron overload/oxidative damage in patients
Iron deficiency
Microcytic anaemia
Lethargy and fatigue - adults
Cognitive impairment (children)
Exacerbation of inflammatory states
Iron excess
Haemochromatosis - Lethargy and fatigue, abdominal and joint pain, reduced libido, bronzing of skin, diabetes, cirrhosis, cardiomyopathy
Calciferol
Ergo-D2
Chole - D3
Calcidiol
25-hydroxyvitamin D
Calcitriol
1a 25-dihydroxyvitamin D
- short half life
- linked to PTH production
- not a good reflection of vitamin D status
How much sunlight do caucasians need
20-30 minutes of sunlight
2000iU vitamin D
2/3 exposures a week in summer
How much sunlight do non-caucasians need
Require 2-10 times than Caucasians
e.g cod liver oil, salmon, mackerel, milk
Which months does UK have insufficient UV
October - March
Contributing factors to vitamin d deficiency
Obesity
Smoking + betel nut (reduces calcitrol)
Alcohol
Exercise
What percent of UK have insufficient vitamin D
50%
in winter 16% have severe deficincy
What are rickets
In children prior to epiphyseal fusion
Growth retardation
Expansion of the growth plate
Osteomalacia
Reduced bone strength, increased bone fracture, bone pain, waddling gait
Vitamin D guidelines
<25nmol/l = deficient >75 nmol/l = adequate RDA guidelines - <1yrs- 400 IU - 1-70yrs - 600IU - >70yrs - 800IU
Where is thiamine/B1 absorbed
Jejunum
What is thiamine/vitamin b1 involved in
Glycolysis and Krebs cycle
Involved in BCAA metabolism
Involved in pentose phosphate metabolism
What is thiamine deficiency seen in
Alcoholism
Anorexia
Weight loss
= causes cognitive impairment and muscle weakness
Types of Beri beri (b1 def)
Dry
Shoshin
Wet
What is dry beri beri
Symmetric peripheral neuropathy
What is shoshin beri beri
Fulminant cardiac failure
Lactic acidosis
What is wet beri beri
- Cardiac (enlarged heart, tachycardia, high out put CCF, peripheral oedema)
- Neurological (peripheral neuritis)
Wernicke’s encephalopathy
Horizontal nystagmus
Ophalmoplegia
Cerebellar ataxia
Metal impairment
What does niacin/B3 deficiency cause
Pellagra
What are the symptoms of early pellagra
Loss of appetite Generalised weakness Irritability Abdominal pain Vomiting Bright red glossitis
Symptoms of late pellagra
Casal's necklace - skin rash of area exposed to sunlight Vaginitis Oesophagitis Diarrhoea Depression Seizures
4 Ds of pellagra
Dermatitis
Diarrhoea
Dementia
Death
What is hartnup’s disease
Congenital defect of kidney and intestinal absorption of tryptophan
What is carcinoid syndrome
Increased conversion of tryptophan to serotonin
Two forms of niacin
Nicotinic acid
nicotinamide
Form two pyridine nucleotides (NAD and NADP) which act as hydrogen acceptors in many oxidative reactions and their reduced forms (NADH and NADPH) act as hydrogen donors in reductive reactions.
Niacin toxicity
Flushing Glucose intolerance Macular oedema Macular cysts Fulminant hepatitis
Vitamin B12 deficiency - haematological issues
Megaloblastic anaemia
Neutropaenia and thrombocytopaenia
Vitamin B12 deficiency - Gastrointestinal issues
Beefy red glossitis
Malabsorption and diarrhoea
Anorexia
Vitamin B12 deficiency - Neurological problems
Sensory disturbance
Gait abnormalities
Memory loss and disorientation
Vitamin B12 absorption
Dissociated from proteins in stomach
Complexes with intrinsic factor in small intestine
Absorbed via specific receptors in the terminal ileum
40% absorbed - the rest
Which other forms is vitamin B12 available as
o Cyanocobalamin used therapeutically
o Cofactor for methionine synthase and methylmalonyl–coenzyme A (CoA) synthase
Causes of vitamin B12 deficiency
inadequate intake - vegans Disorders of terminal ileum o Defective release of cobalamin from food o Inadequate production of IF o Transcobalamin II deficiency (rare) o Congenital enzyme defects (rare)
