CAM101 Lecture Notes - Lecture 2: Lipid Peroxidation, Kidney Bean, Riboflavin
Learning Objectives
• Describe the role of micronutrients in human function and good health
• Describe why meeting the required intake of micronutrients each day is important in health
and disease
Vitamins
• Essential organic (carbon containing) substance needed for normal function, growth and
maintenance of the body
• Classified as a vitamin when:
• Ca’t e sythesised y the ody i suffiiet aouts (essential)
• Chronic deficiency is likely to cause physical symptoms
• Vitamins are classified as:
• Water-Soluble Vitamins
• B Group vitamins, Vitamin C
• Fat-Soluble Vitamins
• Vitamins A, D, E and K
Minerals
• Naturally occurring inorganic compounds
• All minerals are elements and remain intact during absorption (already in simplest form)
• Can't be synthesised in laboratory, by plants or animals
• Classified as:
• Major/Macro Minerals
• Consumed in amounts >1000mg/day, at least 5g of mineral in the body
• Ca, P, K, S, Na, Cl, Mg
• Trace Minerals
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• Less than 20mg/day, body contains less than 5g
• Zn, Fe, Cu, Se, Cr, I, F, Mn
Function
Regulate Cellular Metabolism
• As coenzymes/cofactors and with hormones
• Are involved in both catabolism (energy production) and synthesis of macromolecules
Provide Structure
• Bones
• Teeth
Maintain Normal
• Heart rhythm
• Muscle contractility
• Neural conductivity
• Acid-Base balance
• Fluid balance
Micronutrient Absorption
Absorbed in the small intestine and remain intact during digestion and absorption
Vitamins A, D, E and K
• Fat-soluble vitamins are packaged with fatty acids and bile in micelles
• Stored in liver and adipose tissue
B Group Vitamins, Vitamin C
• Water-soluble vitamins are absorbed with water directly into the blood stream
• Limited/No storage capacity (excreted in urine)
Minerals
• Protein carriers/transporters required
Deficiency/Toxicity
• 'Hypervitaminosis' or vitamin toxicity is rare, deficiency is more common
• Excess vitamins/minerals can damage cells and will only result from consuming megadose
levels of vitamin/mineral supplements
Bioavailability
Refers to the degree to which a nutrient is absorbed from food and used in body
• Only ~3-10% of micronutrients eaten are absorbed into blood stream
• Regular consumption is essential, as is meeting RDIs
• Micronutrient content of food and level of absorption may be affected by cooking methods,
storage of food and types of food eaten
• Particularly susceptible to
• Air
• UV light
• Temperature
• Boiling
• pH
• Fat-soluble vitamins tend to be more stable
• Minerals (exception of K) are very stable
• Micronutrients in plants are typically less bioavailable than animal foods
• Mineral absorption is affected by amount of mineral stored in the body (more stored, less
absorbed)
• Minerals often compete with each other for absorption in the GIT
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Summary Thus Far
It is important to meet (& not exceed) dietary recommendations on a daily basis as:
• Many micronutrients are not well absorbed
• Many nutrients (particularly water-soluble vitamins) may not be stored in the body
• They are essential for good health and disease prevention.
• Some nutrients are stored (particularly fat-soluble vitamins, minerals) and therefore may
reach toxic amounts if eaten in high quantities (usually only with supplementation)
Micronutrient Functions
Energy Production & Metabolism
B Group Vitamins, Fe, Cu, Zn
Antioxidant
Vitamins A, C, and E (ACE)
Micronutrients & Antioxidants
• Free radicals are atoms with unpaired electrons in their outermost shell causing them to be
highly reactive
• Antioxidants work by stabilising free radicals (donate an e- or H+) or by opposing oxidation
• Micronutrients which have an antioxidant function include:
• Vitamin A
• Beta-Carotene
• Vitamin C
• Intracellular
▪ DNA transcription
▪ DNA repair
▪ mRNA translation
▪ Protein stability
▪ Apoptosis
• Extracellular
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Document Summary
Learning objectives: describe the role of micronutrients in human function and good health, describe why meeting the required intake of micronutrients each day is important in health and disease. Fat-soluble vitamins: vitamins a, d, e and k. Less than 20mg/day, body contains less than 5g. Zn, fe, cu, se, cr, i, f, mn. Regulate cellular metabolism: as coenzymes/cofactors and with hormones, are involved in both catabolism (energy production) and synthesis of macromolecules. Maintain normal: heart rhythm, muscle contractility, neural conductivity, acid-base balance. Absorbed in the small intestine and remain intact during digestion and absorption. Fat-soluble vitamins are packaged with fatty acids and bile in micelles. B group vitamins, vitamin c: water-soluble vitamins are absorbed with water directly into the blood stream. "hypervitaminosis" or vitamin toxicity is rare, deficiency is more common: excess vitamins/minerals can damage cells and will only result from consuming megadose levels of vitamin/mineral supplements.
