Bone Health: Nutrition and Vit D

Question 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?

Answer 1

Peak bone mass is 35years old

and for women after menopause bone mass rapidly declines

Question 2

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

Answer 2

Calcium and vit D

Question 3

Bone health varies markedly between countries independently of what?

Answer 3

Calcium Intake

Question 4

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

Answer 4

Hip Fractures

Question 5

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

Answer 5

Dietary factors
Less diary
More fish and more veggies

Question 6

Dietary calcium intakes appear unrelated to bone health why?

Answer 6

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.

Question 7

Plasma Ca2+ concentration is highly regulated by what?

Answer 7

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

Question 8

What are the adaptive responses to low calcium intakes?

Answer 8

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

Question 9

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

Answer 9

Rickets (African) (w/o Vit D deficiency)

• -increased amounts of unmineralized bone
• -fibroblast growth factors

Question 10

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

Answer 10

Impair peak bone mass development

–pubertal girls only partially adapt to very low dietary Ca2+ intakes

Question 11

Extra calcium reduces what?

Answer 11

Bone Mass Loss

Question 12

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

Answer 12

Post menopausal women to a greater extent than Ca2+ alone

Question 13

Fruits and veggies are important for bone health. Why?

Answer 13

Provide alkali to neutralize dietary acid

Question 14

Cereals and high protein foods produce what?

Answer 14

Acid

–bone mineral balance is therefore sensitive to this

Question 15

Bone mineral balance is extremely sensitive to what?

Answer 15

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

Question 16

Dietary acid can be buffered by what foods?

Answer 16

Fruits and veggies

Question 17

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

Answer 17

K and HCO3

Na and Cl

Question 18

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

Answer 18

Acidic

Question 19

What supplementation improves Ca2+ and PO4 balance

Answer 19

KHCO3

–as does carbonated mineral water

Question 20

Fruit and vegetable intakes are associated with better what?

Answer 20

Bone Health

Question 21

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

Answer 21

Improved calcium balance

Question 22

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

Answer 22

Ca Citrate/malate

Question 23

Vitamin D regulated what?

Answer 23

Ca2+ and PO4 homeostasis

Question 24

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

Answer 24

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

Question 25

What is a measure of vitamin D status?

Answer 25

25-OH vitamin D

Question 26

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

Answer 26

1,25(OH)2D3

Question 27

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

Answer 27

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

Question 28

Where do we get vit D from?

Answer 28

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

Question 29

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

Answer 29

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

Question 30

What populations are at risk for vit D deficiency?

Answer 30

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

Question 31

What is the cut-off point for rickets?

Answer 31

less than 25.0nmol/l

Question 32

What is the cut off point for deficiency in most labs?

Answer 32

less than 40nmol/l

Question 33

What are the causes for vitamin D?

Answer 33

1. Reduced skin synthesis
2. Decreased bioavailability
3. Increased catabolism
4. Decreased synthesis of 25-hydroxyvitamin D
5. Increased urinary loss of 25-hydroxyvitamin D

Question 34

What is the main cause for the recurrence of Rickets in the past 14 years?

Answer 34

Sunlight avoidance

Question 35

What are the consequences of vit D deficiency?

Answer 35

1. Classical Vit D deficiency disease
2. Children: rickets and osteomalcia
3. Adults: osteomalacia
   - -occurring in the US and UK

Question 36

Rickets is a particular problem amongst what population?

Answer 36

Asian Community in the northern hemisphere

–due to decreased sun exposure, diet and inadequate calcium requirements

Question 37

Vit D is a multifactoral chronic disease, that can cause what?

Answer 37

• –Falls/neuromuscular function
• –type I diabetes
• –CVD
• –Cancer
• –HTN

Question 38

Vit D deficiency is believed to be a major _____ _____ problems which requires action

Answer 38

Public health