Lecture 16 Flashcards
What is the RDI for Calcium?
1000mg per day
Do New Zealanders reach the RDI for Calcium?
Men are close, but women tend to consume less than required
What are the main sources of calcium in NZ?
- Milk
- Bread
- Cheese
What percentage of Calcium is absorbed from the diet?
Approx 25-30%
What can influence Calcium absorption?
Psychological and dietary factors
What is bioavailability?
The proportion of a nutrient that is absorbed, utilised and thus available to the body
Is the content of Calcium entirely bioavailbable?
No
What are promotors of Calcium uptake?
- Protein and amino acids
- Lactose
- Acidic gut
What are inhibitors of Calcium uptake?
- Oxalate
- Phosphorus
- Phyate
Can calcium be stored?
No, the bones act as a reservoir
What nutrient can calcium be considered as?
A threshold nutrient, you can’t grow more than your genes permit
What is the main excretion route for Calcium?
Via ruine
What factors can increase Ca excretion?
An increase in:
- Protein
- Sodium
- Caffine
What factors can decrease Ca excretion?
- Bicarbonate
- Phosphorus
- Citrate
What is the percentage break down of Calcium binding
47% bound to proteins
47% are free or ionised
6% are bound to anions
What are the functions of Calcium?
- Intracellular messenger = <1% of body Ca
- Bone = 99% of Ca
- > structural role = skeleton
- > physiological role = reservoir of essential minerals
What are the two types of bone?
- Cortical
2. Trabecular
Describe Cortical bone
- Compact/dense
- Slow turn over
- 80% of bone mass
Describe Trabecular bone
- Spongy
- Is what will be broken down when body needs it
- 20% of bone mass
What does bone remodelling allow?
- Maintains bone integrity
- Reshapes bone to accomodate changing mechanical loads
What are the three bone cells?
- Osteoblasts = build bone
- Osteoclasts = break down bone
- Osteocytes = ‘sensors’
What is resorption?
Removal of old bone
What is formation?
Replacement with new bone
What is peak bone mass defined as?
The maximum bone mass
What are the determinants of peak bone mass?
- Genetics
- Environment (modifiable)
- > exercise, smoking, medication, nutrition
What happens to children and adults with Calcium deficiency?
- Children = have decreased growth and decreased bone mass
- Adults = have decreased bone mass
What is a bone healthy diet?
-Dairy (or a fortified alternative)
-Moderate protein
-Low sodium
(similar to DASH diet)
