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Flashcards in Lecture 2 Deck (39):
1

Bioavailability

Not all consumed is absorped

2

Absorption of Calcium

10-60% of intake

3

What effects uptake

Uptake control via PTH is dependant on demand for example pregnancy

Bioavailability differs between foods e.g. phytate, oxalate and dietary fibre decrease availability

4

Bioavailability of Ca from Milk

30-35%

5

Bioavailability of Ca from Spinach

5%

6

Reason for Vitamin C

Necessary for collagen synthesis

7

Electrolyte Balancing

We need a 1:1 balance between calcium and phosphorus

8

Result of consuming excess phosphorus

Causes leaching of Ca from bone mineral

9

Food examples of ratios

Milk: 1.25:1
Cola: 0.2:1

10

Nutrients required for the metabolic processes related to bone formation

Calcium, protein, magnesium, phosphate, Vitamin D, potassium, fluoride.

11

Nutrients required for the metabolic processes related to bone formation

Manganese, copper, boron, iron, zinc, Vitamins A, K, C and the B vitamins

12

Effect of caffeine on bone

Certain epidemiological studies have shown a correlation between consumption of high- caffeine beverages and low BMD, Too much caffeine is detrimental

13

How has caffeine shown to affect bone metabolism

Calciuresis, Altered Calcium Absorption, Altered Sex steroid Levels

14

The significance of calciuresis to calcium balance is questionable

Calciuretic effect of caffeine is biphasic

15

Other problems with caffeinated beverages

May contain other compounds that affect bone health, e.g. Phosphoric Acid.

16

Caffeine Conclusions

Any effect of caffeine upon BMD is likely to be mild for the majority of the population

Effect will be dependent on dose and factors related to :
Diet
Gender
Genetic Predispostion
Current physical states

17

What is Tea

Processed leaf of Camellia sinensis

Contributes up to 80% of the Uk dietary intake of Flavonols and Flavones.

18

Polyphenol

Flavonols and Flavones.

19

Black Tea

.
Bright orange colour, low astringency, sweet flavour

20

PPO

Polyphenol Oxidase

21

Oolong Tea

Fermentation stage half the time as for black tea,
Light, subtle flavour, bright yellow colour

22

Green Tea

No defined fermentation stage, PPO deactivated, very little oxidaisation of catechins, subtle, bitter flavour and pale in colour

23

Role of tea and bone health

Consumption of tea has been associated with high BMD/ low incidence of fracture in several populations e.g. MEDOS

Greater benefits for those with longer drinking habits Wu et al, 2002

24

Tea and Flavonoids

Increase numbers and activity of osteoblasts (Bone Making)
Decrease numbers and activity of osteoclasts (Bone reabsorbing)
Reduce damage to osteoblasts caused by oxidative stress.

25

Tea and Fluorine

Occurs as salts in vivo, Fluorine ion becomes incorporated into bone, increasing overall stability
This is fluorapatite

26

Fluorosis

Associated with doses of >8 mg/day

27

Problems with Brick Tea

Brick tea in small populations such as Tobet consume vast quantities of Brick Tea, Theses are made from much older leaves, which results in a greater storage of fluoride.

28

Protein and the acid base theory

Skeleton acts as a buffer, maintaining in vivo pH
Base- forming components neutralise acid- forming components thus limiting resorption of skeletal calcium

29

Effect of Onions

Rats fed diets rich in animal protein (casein) or vegetable protein, similar total protein, Ca and phosphate content
Casein diet gave lower urine pH
Addition of onion slightly raised urinary pH and decreased acid content and decreased bone resorption
Muhlbauer et al, 2002

30

Effects of flavonoid

Found in orange peels, has many benefits, including protecting the heart and brain, reducing diabetes symptoms and preventing cancer.

31

Chiba et al 2003

Previously shown hesperdin treatment has prevented bone loss in OVX mice (removed ovaries).
Reduced numbers of osteoclasts, increased Ca content of bones.

32

Effect of Soy

Isoflavones: May benefit post- menopausal women, in terms of general as well as bone- specific health.

33

Genetic Predisposition

Effects on peak bone mass as well as activity of osteoclast cells.

34

Race and Ethnicity

Osteoporosis risk is reported to be higher in white race compared to back race.
for example: African populations have higher bone mass compared to chinese populations

35

Body Weight

Low body weight increases risk of osteoporotic fractures

36

Physical Activity

Bones lose structural strength due to inactivity

37

Smoking

Decreased Ca absorption in gut

38

Alcohol

Influences on PTH, Vit D metabolism and osteoblast proliferation

39

HRT use in PM women

Benefits to BMD possible overshadowed by other effects