Micronutrients Flashcards
What are micronutrients?
They are essential compounds that are required in small amounts in the diet; they consist of organic vitamins and inorganic trace elements.
What’s the role of micronutrients generally?
Help to maintain general health as they may help in maintaining structure of the body, regulation in genetic control, act as antioxidants, coenzymes or cofactors to enable the body to perform its daily functions.
What are the two different types of vitamins?
Water-soluble and fat-soluble
What is the difference between fat-soluble and water-soluble vitamins?
Fat-soluble vitamins can be stored, but water-soluble vitamins usually act as coenzymes for reaction and cannot be stored, their excess is excreted in the urine
Name 4 fat-soluble vitamins
Vitamin A, D, E and K
Name 4 water-soluble vitamins
Vitamin B, C folate and biotin
Name 6 trace elements that are essential in the diet
Copper, zinc, selenium, iron, phosphate and calcium
What is a good dietary source of calcium?
Dairy products (milk and yoghurt etc.)
What is the consequence of calcium-deficiency?
Reduced bone mass and osteoporosis, paresthesia, muscle spasms, laryngeal spasm and convulsions, increased intracranial pressure, mental changes, Chvostek’s and Trousseau’s sign positives
What is the function of calcium in the body?
Mechanical stability of the skeleton, neuromuscular activity and signal transduction
What is a good dietary source of phosphate?
Seeds, nuts, lentils and soya
What is the function of phosphate in the body?
it is a component of structural proteins, enzymes, transcription factors, ATP and nucleic acids
What is the consequence of phosphate-deficiency?
Bone pain, pseudofractures, and proximal muscle weakness or, rickets and short stature in children neurological manifestations
What is a good dietary source of iron?
Red meat, dark vegetables and watermelon
What is the function of iron in the body?
Part of the haem protein and enzymes
What is the consequence of iron-deficiency?
Anaemia
What is a good dietary source of selenium?
Seafood, red meat and cereal
What is the function of selenium in the body?
Component of glutathione peroxidase and deiodinase enzymes
What is the consequence of selenium-deficiency?
Cardiomyopathy may occur
What is a good diary source of zinc?
Meat, shellfish, nuts and legumes
What is the function of zinc in the body?
Synthesis and stabilization of proteins, DNA, and RNA ; normal spermatogenesis, fetal growth, and embryonic development
What is the consequence of zinc-deficiency?
Growth retardation, alopecia, dermatitis, diarrhoea, immune dysfunction, gonadal atrophy, congenital malformations
What is a good dietary source of copper?
Shellfish, liver, legumes, bran and offal
What is the function of copper in the body?
Part of numerous enzymes for iron metabolism; melanin, elastin and collagen synthesis; and central nervous system function
What is the consequence of copper-deficiency in the body?
GROWTH RETARDATION, anemia, defective keratinization and pigmentation of hair, hypothermia, mental deterioration
What may be the consequence of vitamin-A deficiency?
Can lead to xerophthalmia - the abnormal dryness of the conjunctiva and the cornea of the eye
What may be the consequence of vitamin-D deficiency?
This can lead to rickets in children or osteomalacia in adults
What may be the consequence of vitamin-E deficiency?
This can lead to peripheral neuropathy
What may be the consequence of vitamin-K deficiency?
This can lead to coagulopathy (issues with clotting and the coagulation cascade)
What important molecule does vitamin B1 give rise to?
Thiamine a co-factor of the PDC complex
What may be the consequence of vitamin-B1 deficiency?
Thiamine deficiency leads to beri beri
What may be the consequence of vitamin-B2 deficiency?
Angular stomatitis
What may be the consequence of vitamin-B3 (niacin) deficiency?
Pellagra
What may be the consequence of vitamin-B6 deficiency?
Neuropathy
What may be the consequence of vitamin-B12 deficiency?
Macrocytic anaemia
What may be the consequence of vitamin-C deficiency?
Scurvy
What may be the consequence of folate deficiency?
Macrocytic anaemia
What is the difference between Ergocalciferol (D2) and Cholecalciferol (D3)?
Ergocalciferol is a type of vitamin D that is obtained from plant sources, whereas cholecalciferol is from animal sources (and is formed in the skin by the action of UVB on the digested vitamin d
What is the main circulating form of vitamin D?
Calcidiol (25-hydroxyvitamin D)
What happens to vitamin D2 and D3 (ergocalciferol and cholecalciferol) in the liver?
They are hydroxylated to form calcidiol (25-hydroxyvitamin D)
Outline the steps of vitamin D metabolism in the body
Ergocalciferol (D2) and cholecalciferol (D3) are transported to the liver where they are hydroxylated to form calcidiol (25-hydroxyvitamin D) and then this ravels to the kidneys where it is converted to calcitriol (1a-25-dihydroxyvitamin D)
What is the active metabolite of vitamin D?
Calcitriol (1a-25-dihydroxyvitamin D)
Outline the action of calcitriol (active form of vitamin D) on metabolism
Calcitriol can act on the small intestine to increase absorption of dietary calcium or act on the bone to cause the release of calcium and phosphorus
How is vitamin-D deficiency induced osteomalacia/rickets treated?
Through the administration of high-dose calciferol
What are common causes of vitamin B1 (thiamine) deficiency?
Alcoholism and malignancy
Outline the action of thiamine/vitamin B1 on metabolism
Vitamin B1 is absorbed in the jejunum and is involved in the metabolism of carbohydrates and branched-chain amino acids.
What is the difference between dry and wet beri beri disease?
Dry beri beri involves symmetrical peripheral neuropathy whereas wet beri beri involves cardiac concerns and peripheral oedema in addition to peripheral neuritis
What neurological conditions can vitamin B1 deficiency lead to?
Wet/dry beri beri, Wernicke’s encephalopathy and Wernicke-Korsakoff syndrome
What is Wernicke’s encephalopathy and what may it be caused by?
Where an individual has horizontal nystagmus, ophthalmoplegia (paralysis of eye muscles) and cerebellar ataxia and this can occur due to thiamine/vitamin B1 deficiency
What is Wernicke-Korsakoff syndrome and what may it be caused by?
This may be caused by thiamine/vitamin B1 deficiency and this condition involves the symptoms of Wernicke’s encephalopathy (ataxia, ophthalmoplegia and nystagmus) in addition to memory loss and confabulatory psychosis
What is the main function of vitamin B3 (niacine)?
Niacine is central to redox reactions and is the precursor of NAD and NADP
What may cause a vitamin B3/niacine deficiency?
Vegetarian diet, alcoholism, Hartnup’s disease (congenital defect of the intestinal and renal absorption of tryptophan), carcinoid syndrome (increased conversion of tryptophan to serotonin) and isoniazid use (as in the treatment of TB)
What is Hartnup’s syndrome and how may it cause vitamin B3/niacine deficiency?
This is a congenital defect of the intestinal and renal absorption of tryptophan, and without tryptophan niacine cannot be produced
What is carcinoid syndrome and how may it cause vitamin B3/niacine deficiency?
This is where there is an increased conversion of tryptophan into serotonin, and therefore there is insufficient tryptophan left to produce niacine
What are the symptoms of pellagra?
Loss of appetite, general weakness, irritability, abdominal pain, vomiting, bright red tongue, vaginitis, oesophagi’s, depression, diarrhoea and seizures
What is the cause of pellagra?
Vitamin B3/niacine deficiency
What are the 4 D’s of pellagra?
Dermatitis
Diarrhoea
Dementia
Death
What is another name for vitamin B12?
Cobalamin
Describe the absorption of vitamin B12 (cobalamin)
This vitamin is absorbed as it dissociates from protein in the stomach, where it then forms a complex with intrinsic factor (IF) in the small intestine and thereafter the complex of vitamin B12 and intrinsic factor is absorbed via specific receptors
What may lead to vitamin B12 deficiency?
Inadequate intake (vegan diet), terminal ileum disorders, inadequate IF production, defective release of cobalamin from proteins in food
What may the haematological effects of vitamin B12 deficiency be?
Neutropenia (loss of neutrophils), thrombocytopenia (loss of platelets) or megaloblastic anaemia
Where is iron absorbed in the body?
Upper small intestine, mainly the duodenum
What are the consequences of iron-excess?
Haemochromatosis which can cause lethargy, fatigue, abdominal/joint pain, reduced libido, skin bronzing, diabetes, cirrhosis and cardiomyopathy.
