Bone Health: Nutrition and Vit D Flashcards Preview

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Flashcards in Bone Health: Nutrition and Vit D Deck (38)
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1

Increase in bone mass happens with age and is rapid in puberty and continues in adult life. At what point does bone mass lower?

Peak bone mass is 35years old
and for women after menopause bone mass rapidly declines

2

Increased intake of what during rapid bone growth increases peak bone mass?

Calcium and vit D

3

Bone health varies markedly between countries independently of what?

Calcium Intake

4

Calcium intakes are actually higher in certain countries but still have an increased incidence of what?

Hip Fractures

5

In Gambian and China there is less cases of osteoporosis and few fractures, why???

Dietary factors
Less diary
More fish and more veggies

6

Dietary calcium intakes appear unrelated to bone health why?

The adaptation hypothesis
--dietary calcium intake above a min low level is unimportant as a regulator of bone health
--since plasma free calcium is regulated so finely, adaptive mechanisms exist to maintain calcium bones over a wide range of intakes.

7

Plasma Ca2+ concentration is highly regulated by what?

Vit D
PTH
--maintain plasma Ca2+ at a supersaturating level with respect to bone mineral and to prevent hypocalcemic neuromuscular tetany

8

What are the adaptive responses to low calcium intakes?

Low Dietary Ca ---- reduction in plasma Ca --- Increased PTH secretion
Increased Active Vit D --- increased intestinal Ca absorption
Decreased urinary Ca ---increased conservation of dietary Ca

9

The body, however, can not adapt to very low intakes of dietary calcium. This can cause what?

Rickets (African) (w/o Vit D deficiency)
--increased amounts of unmineralized bone
--fibroblast growth factors

10

Adequate calcium is needed for peak bone mass (PBM) development. Long-term low Ca2+ intakes results in what?

Impair peak bone mass development
--pubertal girls only partially adapt to very low dietary Ca2+ intakes

11

Extra calcium reduces what?

Bone Mass Loss

12

Supplementation with milk improves the nutritional quality of the diet of what kind of individuals?

Post menopausal women to a greater extent than Ca2+ alone

13

Fruits and veggies are important for bone health. Why?

Provide alkali to neutralize dietary acid

14

Cereals and high protein foods produce what?

Acid
--bone mineral balance is therefore sensitive to this

15

Bone mineral balance is extremely sensitive to what?

Acid base balance with demineralization occurring as pH drops below a critical point

16

Dietary acid can be buffered by what foods?

Fruits and veggies

17

We have markedly reduced dietary ____ and ____ and increased dietary ____ and _____ since preagricultural times

K and HCO3
Na and Cl

18

As people age the ability to excrete acid declines and they become slightly more _____?

Acidic

19

What supplementation improves Ca2+ and PO4 balance

KHCO3
--as does carbonated mineral water

20

Fruit and vegetable intakes are associated with better what?

Bone Health

21

DASH (dietary approaches to stop hypertension), high in fruits and vegetables and low-fat diary products, report what?

Improved calcium balance

22

What supplements supplies alkali and this may be part of their effectiveness for bone health?

Ca Citrate/malate

23

Vitamin D regulated what?

Ca2+ and PO4 homeostasis

24

Keeping Ca-P homeostasis in the body involves, what from the intestine, bone and kidney?

Intestine: Ca absorption
Bone: Ca release
Kidney: Ca retention

25

What is a measure of vitamin D status?

25-OH vitamin D

26

What is the active hormone in the body in the vitamin D pathway?

1,25(OH)2D3

27

Vit D has a wide range of tissue functions, what is the pathway?

1 alpha hydroxylase ---- 1.25(OH)2D3 --- various functions

28

Where do we get vit D from?

Sunlight is the major source
--few foods (oily fish, cod and liver oils, butter/cream/cheese, and fortified breakfast cereals)
--small quantities in fortified foods
--larger quantities in fish

29

The global burden of vitamin D deficiency disease is high. Deficiency disease is defined as what?

v-low 25OHD: less than 25nmol/l

30

What populations are at risk for vit D deficiency?

Infants, prego women and elderly
Ethnic minorities in temperature countries
Limited sun exposure