FOOD20003 Lecture Notes - Lecture 21: Menopause, Osteoporosis, Tetany
28 Jun 2018
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9. Discuss the term bioavailability with reference to known nutrient binders.
• Bioavailability = extent to which a nutrient is absorbed & used
• Bioavailability of minerals varies à some foods contain binders that prevent minerals from being
absorbed
o Phytates & oxalates
10. Outline the major role of sodium, its deficiency and toxicity symptoms and food sources.
• Role: extracellular cation
o Has a favourable taste perception
o Essential for nerve impulse transmission & muscle contraction
o Highly soluble, readily absorbed by intestines à travels freely in blood
• Removed by glomerular filtration in kidneys & correct amount is added back into blood via kidney
tubule reabsorption
• More sodium ingested à induce thirst à drinks water à allows for water secretion which in turn
removes Na
• Excess: hypertension
• Food sources:
o low in fresh fruit & veggies & meat (high K+)
o high in processed food (but low in K+)
• Toxicity: results in oedema (swelling of blood tissues) & raised blood pressure (hypertension)
11. Outline the major role of potassium, its deficiency and toxicity symptoms and food sources.
• Predominates inside cell
• Essential for fluid/electrolyte balance & maintaining cell integrity
• Involved in nerve impulse, muscle contraction & heart beat regulation
• Food sources:
o All intact animal & plant cells
o Fruit/veggies = High K+, processed foods à leads to cell breakdown & loss of K+
• No upper limit found yet but most people fail to meet RDI for K+
• Deficiency:
o Muscular weakness, paralysis, increased blood pressure, salt sensitivity, kidney stones, bone
turnover
o Later signs: irregular heartbeats, glucose intolerance
• Toxicity:
o Results from supplements/overconsumption/medical conditions
o Results in muscular weakness & vomiting
o If given in a vein, K+ can cause heart to stop (murder)
