Calcium

Question 1

How is calcium most efficiently absorbed

Answer 1

Vitamin D/saturable (limited amount of Calbindin)

Question 2

How is calcium absorbed without VitD

Answer 2

paracellular diffusion/nonsaturable; ability increases as saturation of Calbindin occurs

Question 3

What nutrients Enhance Calcium absorption

Answer 3

VitD, sugar (lactose), Protein

Question 4

Under what conditions does protein enhance Calcium absoprtion

Answer 4

High protein, low Calcium intake; regulated more by Ca intake

Question 5

What nutrients Enhance urinary Excretion of Calcium

Answer 5

Sodium, Protein, Caffeine

Question 6

What nutrients Inhibit Calcium absorption; How?

Answer 6

Fiber, Phytate, Oxalate(leafy greens), Unabsorbed FA, Zinc, Mg; Binding in Lumen

Question 7

What nutrients does Calcium inhibit absorption of

Answer 7

Iron, Fatty Acids

Question 8

What are sources of Calcium

Answer 8

Dairy, Broccoli, Leafy greens, Almonds

Question 9

What is the RDA for Calcium 19-50years

Answer 9

1,000mg

Question 10

What is the RDA for Calcium 51-71years for Men

Answer 10

1,000mg

Question 11

What is the RDA for Calcium 51-71years for Women

Answer 11

1,200mg

Question 12

What is the RDA for Calcium 71+years

Answer 12

1,200mg

Question 13

What is the Natl Osteoporosis Found Calcium recommendation

Answer 13

Agree with RDA, >1200-155mg unlikely to benefit, may be harmful

Question 14

What is the UL for Calcium

Answer 14

2,500mg

Question 15

What can result from prolonged UL intake of Calcium

Answer 15

Calcium deposits in joints, kidneys

Question 16

What are the supplement forms of calcium

Answer 16

Calcium carbonate (27%) and Calcium citrate-malate (35%)

Question 17

What is the Calcium bioavailability of dairy products

Answer 17

29% (290mg/serv)

Question 18

What is the Calcium bioavailability of spinach

Answer 18

5% (122mg/serv)

Question 19

What is the Calcium bioavailability of bok choy

Answer 19

50% (79mg/serv)

Question 20

What is the Calcium bioavailability of broccoli

Answer 20

57% (31mg/serv)

Question 21

What is the Calcium bioavailability of almonds

Answer 21

20% (75mg/serv)

Question 22

How is Calcium status measured

Answer 22

Mainly based on intake; Bone densitometry DEXA

Question 23

Is serum Calcium a measurement of Calcium status

Answer 23

Not measured well in blood because highly regulated by hormones

Question 24

What senses a drop in blood Calcium

Answer 24

Parathyroid gland

Question 25

What is secreted when blood Calcium drops

Answer 25

Parathyroid Hormone (PTH)

Question 26

What are the functions of PTH in Calcium homeostasis

Answer 26

Stimulates activation of VitD in the kidney (resorption of Calcium); Draws Calcium out of bone for use in blood

Question 27

What senses an increase in blood Calcium

Answer 27

Thyroid gland

Question 28

What is secreted when blood Calcium rises

Answer 28

Calcitonin

Question 29

What hormone opposes PTH

Answer 29

Calcitonin

Question 30

What does Calcitriol (VitD) bind to when entering enterocyte for Calcium absorption (Step 1)

Answer 30

VitD Receptor (VDR)

Question 31

What is the next step for VitD after binding to VDR for Calcium absorption (Step 2)

Answer 31

VDR-Calcitriol complex binds to DNA in nucleus of the enterocyte

Question 32

What is the next step for VitD after binding to DNA for Calcium absorption (Step 3)

Answer 32

Transcription of VDR-Calcitriol to form Calbindin-mRNA

Question 33

What is the next step for VitD after transcription of Calbindin-mRNA in nucleus for Calcium absorption (Step 4)

Answer 33

Calbindin-mRNA Translation of Calbindin protein in cytosol

Question 34

What is the next step for VitD after translation of Calbindin protein for Calcium absorption(Step 5)

Answer 34

Calbindin protein acts as a carrier for Calcium at the brush border of the enterocyte

Question 35

How much Calcium can the lumen handle at a time

Answer 35

500mg

Question 36

Why do Multivitamins usually contain small amounts of Calcium

Answer 36

Competes with Iron, Zinc and Magnesium and will make pill too large

Question 37

How does Sodium effect Calcium absorption

Answer 37

Calcium is pulled along with Sodium during Sodium excretion

Question 38

How much Calcium is lost (in urine/feces/skin) each day

Answer 38

250-300mg

Question 39

How much Calcium needs to be replaced what is being lost (in urine/feces/skin)

Answer 39

250-300mg

Question 40

Why is the RDA for Calcium so much higher than the amount needed to replace what is lost each day

Answer 40

Because of the poor bioavailabilty of Calcium; Based on bioavailability of Dairy products (29%)