Lecture 2 Flashcards

1
Q

Bioavailability

A

Not all consumed is absorped

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2
Q

Absorption of Calcium

A

10-60% of intake

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3
Q

What effects uptake

A

Uptake control via PTH is dependant on demand for example pregnancy

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

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4
Q

Bioavailability of Ca from Milk

A

30-35%

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5
Q

Bioavailability of Ca from Spinach

A

5%

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6
Q

Reason for Vitamin C

A

Necessary for collagen synthesis

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7
Q

Electrolyte Balancing

A

We need a 1:1 balance between calcium and phosphorus

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8
Q

Result of consuming excess phosphorus

A

Causes leaching of Ca from bone mineral

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9
Q

Food examples of ratios

A

Milk: 1.25:1
Cola: 0.2:1

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10
Q

Nutrients required for the metabolic processes related to bone formation

A

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

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11
Q

Nutrients required for the metabolic processes related to bone formation

A

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

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12
Q

Effect of caffeine on bone

A

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

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13
Q

How has caffeine shown to affect bone metabolism

A

Calciuresis, Altered Calcium Absorption, Altered Sex steroid Levels

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14
Q

The significance of calciuresis to calcium balance is questionable

A

Calciuretic effect of caffeine is biphasic

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15
Q

Other problems with caffeinated beverages

A

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

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16
Q

Caffeine Conclusions

A

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
Q

What is Tea

A

Processed leaf of Camellia sinensis

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

18
Q

Polyphenol

A

Flavonols and Flavones.

19
Q

Black Tea

A

.

Bright orange colour, low astringency, sweet flavour

20
Q

PPO

A

Polyphenol Oxidase

21
Q

Oolong Tea

A

Fermentation stage half the time as for black tea,

Light, subtle flavour, bright yellow colour

22
Q

Green Tea

A

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

23
Q

Role of tea and bone health

A

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
Q

Tea and Flavonoids

A

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