Energy and Nutrient Requirements Pt. 2

Question 1

How is vitamin D involved in normal bone formation?

Answer 1

. Vitamin D regulates intestinal and renal absorption of calcium (via calbindin) and phosphate
. Renal absorption of these = normal bone formation

Question 2

How is vitamin D involved in preventing neuromuscular, immune, apoptosis, and inflammation problems?

Answer 2

Vitamin D Receptors (VDRs) form dimers to regulate gene expression

Question 3

What conditions does a deficiency in Vitamin D result in?

Answer 3

Softening of bones= Rickets (children), Osteomalacia (adults)

Question 4

What are phytates and why can they be problematic?

Answer 4

. Phosphate polymers/ antioxidants found in whole grains, legumes, nuts, and seeds
. Can bind to certain dietary minerals (e.g. iron, zinc, manganese, calcium) and slow/inhibit their absorption

Question 5

Why is it not great to eat muesli/wheetabix with milk?

Answer 5

Phytates in the wholegrain cereal/seeds/grain will inhibit the uptake of calcium from the milk, so you’re not getting the full nutritional benefit of the milk

Question 6

What is the body’s response to low levels of calcium in the blood?

Answer 6

. PTH (parathyroid hormone) and Vit D synthesised

. Vit D increases intestinal absorption of calcium and decreases renal excretion of calcium (in urine)

. PTH increases calcium release from bone, increases intestinal absorption of calcium, decreases renal excretion of calcium (in urine)

Question 7

What is PTH?

Answer 7

Parathyroid hormone (involved in bone remodelling e.g. when low calcium, increases calcium release from bone)

Question 8

What happens when there’s high levels of calcium in the blood?

Answer 8

Thyroid gland secretes calcitonin, which increases calcium excretion in kidneys and prevents bone releasing calcium

Question 9

Which pathways are activated when there’s low calcium? How about when there’s high calcium?

Answer 9

. Low calcium: vitamin D and PTH synthesised (increased intestinal absorption of calcium, increased bone release of calcium, decreased renal excretion of calcium)
. High calcium: thyroid gland secretes calcitonin (increased calcium excretion in urine, prevent bones releasing calcium)

Question 10

At what age do you have peak bone mass?

Answer 10

30

Question 11

What is iron used for in the body?

Answer 11

Haemoglobin (RBCs), electron transport, cytochrome P450

Question 12

In which organs is iron stored in the body?

Answer 12

Liver, spleen, bone marrow

Question 13

What is ferritin? Why is it useful to look a plasma levels of ferritin?

Answer 13

Ferritin is a protein storage molecule for iron. Its levels in circulation (very small traces) reflect the total amount of iron stores in the body.

Question 14

How can you obtain iron through your diet?

Answer 14

Meat and vegetables

Question 15

How can you enhance iron absorption through diet?

Answer 15

Vitamin C, fructose, alcohol, and meat all increase iron absorption

Question 16

Name three conditions/states that increase iron absorption

Answer 16

Iron deficiency/anaemia, pregnancy, fasting

Question 17

Name three conditions/states that decrease iron absorption

Answer 17

Achlorhydria (absence of HCl in gastric secretions), Cu deficiency, decreased iron absorption