Calcium and Vitamin D Flashcards
1
Q
Bones function
A
Skeleton provides the support and move
2
Q
Bones composition
A
65% mineral crystals -strength and structural support
35% collagen- flexibility (to avoid cracking when jumping,etc.)
3
Q
What is the characteristic of bone strength?
A
Bone mineral density
4
Q
2 bone types
A
- Cortical
- Trabecular
5
Q
Proportion of cortical and trabecular bones
A
80 and 20%
6
Q
Two types of bones are nourished by___
A
Blood vessels
7
Q
Cortical bone :characteristic
A
Hard outer shell
Gives calcium to the blood when needed, not so goof as trabecualr
Slow and steady rate
8
Q
Trabecular bone :characteristic
A
- Lacy matrix
- Gives up calcium when diet runs short, readily releases minerals into the blood
- Impacted by day-to-day intake and need for calcium
9
Q
Three stages in bone turnover
A
- Bone growth
- Bone modeling
- Bone remodeling
10
Q
Describe each bone stage
A
- Bone growth- determines bone size, begins in the womb,continue until early adulthood(growth in length)
- Bone remodeling -determines bone shape, -begins in the womb,-continues until early adulthood(growth in diameter)
- Bone remodeling (in both types of bones) - Maintains integrity of bone with new bone to maintain mineral balance (continually 10 % of the bones are replaced),-Involves bone resorption and formation,-Occurs mainly during adulthood
11
Q
What percentage of bones are replaced in the first year?
A
100 %
12
Q
Bone modeling happens until
A
Girls 14( 2 years after the start of menstruation), men 17 years
13
Q
Two types of cells involved in bone remodelling
A
-Osteoclasts- cells that erode the surface of the bone, releases calcium
-Osteoblasts- cells that produce collagen-containing component of bone, does repairing
In both types of bones
14
Q
Why we are becoming smaller with the age? and how much we lose
A
Because the spine cord compresses
15 cm of height loss between 55 and 73 years old
15
Q
Osteoporosis is
A
A bone breakdown disease
16
Q
The prevalence of osteoporosis in Canada
A
1 in 3 women
1 in 5 men
17
Q
Consequences of osteoporosis
A
Compressed vertebrae-pain,mobility
Hip fracture -mortality, morbility
18
Q
What is the most common disease?
A
Osteoporosis
19
Q
Why women are more at risk with the hip fracture and osteoporosis in general than men?
A
After the menopause estrogen declines, which plays in important role in calcium absorption and number of osteoblasts
20
Q
What is the risk for the hip fracture in men and women
A
women -75 %
men -25%
21
Q
Hip fracture complications
A
- Death( because of surgery complications and malnutrition)
- Inability to walk
- Need to live in the nursing home
22
Q
Type 1 osteoporosis: its other name,age, type of bone loss,fracture sites,gender incidence ,primary cause
A
- Postmenopausal osteoporosis
- 50-70 years
- Trabecular bone
- Wrist and spine
- 6 women to 1 men
- Rapid loss of estrogen after menopause; loss of testosterone in men with advancing age
23
Q
Type 2 osteoporosis: its other name,age, type of bone loss,fracture sites,gender incidence ,primary cause
A
- Senile osteoporosis
- 70+
- Both trabecular and cortical bone
- Hip
- 2 women to 1 man
- Reduced calcium absorption,increased bone mineral loss,increased propensity to fall
24
Q
Does falling causes hip fracture?
A
No, hip fracture causes falling
25
Risk factors for osteoporosis( 11 points)
- Older age
- Low BMI
- Caucasian, Asian and Hispanic
- Cigarette smoking
- Alcohol consumption in excess
- Sedentary lifestyle
- Use of drugs that prevent calcium absorption
- Female gender
- Genetics
- Inadequate calcium and vitamin D
- Estrogen deficiency in women( not only with the menopause )
26
Advantages of men against osteoporosis
-Men have greater bone density and smaller losses in later life
27
How much bone is lost in women after menopause?
20% in 6-8 years after menopause
28
How to measure the bone density?
DXA
| Measures the proportion of absorption of X-rays of soft tissue and bones. It gives a proportion of 2 types of bones
29
Two diseases with bone mass loss and their criteria
Osteopenia -reduction of bone density
Bone mineral density 1-2.5 SD below the mean established for a young normal population (T score-1 to -2.5)
Osteoporosis-exhilarated loss ( t score >-2.5)
30
Bone growth team
"Players"
- protein- collagen( where the crystals bound)
- minerals- Ca,P,Mg,F
"Coaches"
- Vit D,parathyroid hormone
- calcitonin
"Assistants"
-Vit A,C,K
31
Calcium can be found in
Bones, teeth, blood
32
How much calcium is stored in our bones and teeth and in blood?
99% bones/teeth
| 1% blood
33
What is the name for the calcium form in our bones?
Hydroxyapatite
34
Calcium roles
- Helps maintain normal blood pressure
- Extracellular calcium( blood clotting, fibrinogen=calcium+vitaminK)
- Intracellular calcium: Regulation of muscle contraction( calcium contracts , Mg relaxes), transmission of nerve impulses,Secretion of hormones, activation of some enzyme reaction
35
Does a glass of milk will increase the concentration of calcium in our blood?
No, blood calcium is not a problem of a diet, low calcium in blood-> problem in metabolic regulation
36
What is the consequence of acute calcium deficiency and chronic in blood
Acute- tetany/rigor
| Chronic- robs the bones reservoirs->stunting in children, osteoporosis
37
Calcium absorption differences
Differ with age and life cycle
38
How much calcium is absorbed in adulthood and during pregnancy,growth, lactation
Adulthood-30 % of dietary calcium. Adjusts as dietary calcium decreases
Growth, pregnancy, lactation - 50-60% of dietary calcium
39
Calcium absorption can be increased by( 5 points)
- Anabolic hormones( helps the calcium be more available)
- Gastric acid(meal)
- Vitamin D( that is why the milk is fortified)
- low phosphate intake
- lactose ( in infants only)
40
Calcium absorption can decreased by( 7 points)
- Ageing ( decrease in estrogen and testosterone)
- Lack of stomach acid
- Vitamin D deficiency
- High phosphate intake ( in processed food like coca cola)
- High insoluble fiber
- Phytates( whole grains, nuts,seeds and legumes), oxalates( tea,cocoa,berries,celery,dark leafy vegetable)
- High protein intake
41
RDA for calcium
```
Adults 19-50 years 1000 mg/d
Men 51-70-1000
Women 51-70 1200
Adults 70+- 1200
Pregnancy and lactation 14-18- 1300
19-50- 1000
```
42
UL for calcium
Adults 19-50 2500
| Adults 50+-2000
43
When is UL exceeded?
Usually with supplements
44
When osteoporosis begin to develop
between 9-18 years
45
Do people consume enough calcium in Canada
No
46
The best sources of calcium
```
Milk and milk products
Tofu( fortified)
Sardines
Chinese cabbage
Broccoli
```
47
Why spinach is not the best source of calcium
It has a lot of calcium, but it is also high in oxalates( only 5 % of calcium bioavailable)
48
How the intake of foods with different bioavailability influence each other?
If you take milk with wheat bran( phytates), calcium from milk from 38% to 26%
49
Urinary calcium excretion influenced by
- Calcium intake
- Age
- Caffeine
- High sodium duets
- Dietary protein
50
Should we replace calcium from the duet with the supplements?
No, diet first
51
For whom calcium supplements can be important?
- Milk allergy
- Lactose intolerance ?
- Vegan
52
Calcium supplements and medications for better calcium absorption ,interactions
- Antacids ( neutralize acid in the stomach->less absorption)
- Calcium citrate,gluconate,malate,carbonate,etc.( alreasdy active, any time of the day)
- Bone meal, oysters,dolomite( contominants, not so well absorbed)
- Ca chews
- Multivitamins ( mineral interaction decrease absorption)
53
What can happen if the UL for calcium is exceeded?
- Risk of calcification of blood vessels
- Compromised iron status. Ca inhibits absorption
- Kidney stones
- Vitamin D toxicity and increased serum CA if supplements contain vit D
- Exposure to contaminants
54
How can we get vitamin D?
From food and from our skin
55
the pathway of vitamin D
Skin->Previtamin D->Vitamin D3 inactive form
Food( D3 animal sources(cholecalciferol, D2 plant sources(ergocalciferol)->Vitamin D 3( inactive form)
Inactive form D3-> in the liver hydroxylation with the help of calcidiol->25 hydroxy vitamin D3->in the kidneys hydroxylation with the help of calcitriol-> active 1,25-dihidroxyvitamin D3
56
Functions of Vitamin D( 5 points)
- Required for calcium absorption( calbindin)
- Regulates blood calcium levels
- Stimulates osteoclasts
- Necessary for bone calcification
- Immunity and cell differentiation
57
Vitamin D actions in the body
- Intestine( increase Ca absorption from the diet)
- Kidney( decrease Ca excretion in the urine )
- Bone ( increase release from the bone?)
58
What happens when calcium blood level is low?
Signals to the parathyroid gland to secrete parathyroid hormone (PTH)------>PTH stimulates the activation of vitamin D---------->Vitamin D and PTH stimulate calcium reabsorption in the kidneys--------->Vit D enhances calcium absorption in the intestines ------------->Vit D and PTH stimulate osteoclasts to break down the bone
59
What happens when thyroid gland secretes calcitonin as a respond to the rising calcium in blood?
Calcitonin inhibits the activation of vitamin D------------>Calcitonin prevents calcium reabsorption in the kidneys-------->Calcitonin limits calcium absorption in the intestine ------------>Calcitonin inhibits osteoclasts
60
Calcitonin is released when the blood calcium is ____
PTH _____ Vit D activation.This enhances calcium_____ in the intestines. Osteoclast cells release _____ into the blood.PTH ____ blood calcium levels
```
High
Stimulates
Absorption
Calcium
Increases
```
61
Is Vit D a hormone or a vitamin
Both
62
Vitamin D as a hormone ( 4 points)
- Travels in the blood
- Activated in the liver and kidneys
- Acts on intestine,kidney,bones
- Increase Ca availability for bone mineralization and remodelling
63
Vitamin D as vitamin( 3 points)
- Essential in the diet( performs a specific function, deficiency lead to diseases)
- We cannot synthesize it in the amounts needed
- Vitamin is activated to a hormone
64
RDA for vitamin D
Children and adults 9-70- 600 IU
| Adults 70+- 800 IU
65
Why adults 70+ have a higher RDA
Because they stay more inside, their skin cannot synthesize vit D as good as before
66
UL for vitamin D
4000 IU
67
Signs of vitamin D deficiency
- abnormal bone growth
- Malformed teeth
- Muscle spasms
68
Signs of vitamin D toxicity
- Elevated blood calcium
- Calcification of soft tissues
- Excessive thirst
- Headache
- Nausea
- Weakness
69
Signs of calcium deficiency
- Stunted growth and weak bones in children
| - Bone loss- osteoposis in adults
70
Signs of calcium toxicity
- Constipation
- Interference with absorption of other minerals
- Increased risk for kidney stones
71
Sources of Vitamin D
Fortified foods(milk , margarine)
A little in fatty fish, egg yolk, liver and cheese
Supplements
72
Do we get enough vitamin D in canada?
No, especially from November to march
73
Can vitamin D toxicity happen from the sun?
No
74
Two diseases connected with Vitamin D deficiency
- Osteomalacia
| - Rickets
75
Describe osteomalacia
- In adults if the intake is less than 2.5 micrograms/day
- Decreased Calcium absorption
- Bone matrix is lost ->defective mineralization ( decreased bone remodelling,softening bone )
- Bone pain
- Hip fracture risk
76
Describe Rickets
Bones do not mineralize properly in children
- Stunting
- Bowed legs
- Teeth problem
- Breast milk children do not get vitamin D
77
Phosphorus and bones
- With Ca forms hydroxyapatite mineral of bone
- High intake decreases Ca absorption
- Typical intake is higher than RDA
78
Magnesium and bones
- Cofactor
- Bone structure and regulation of mineralization , vut D metabolism
- ATP synthesis
- Blood clotting, muscle contraction( Ca promotes, Mg inhibits), blood pressure regualtion
79
Vitamin K and bone
Co-enzyme synthesize bone protein
| Deficiency cannot bind minerals
80
Vitamin A and bone
Bone remodeling , osteoclast activity
| -but if exceeds UL, reduced bone density
81
Vitamin C and bone
-Cofactor for collagen synthesize ( organic matrix)
82
How to prevent osteoporosis?
Insure that maximal skeletal density has been achieved will prolong the time it takes for bone density to fall below the fracture threshold in response to age-related bone losses
83
When we start to loose bone mass
Mid thirties
84
Can be osteoporosis be improved in 70 old?
Yes, never to late
85
The correlation between exercise and bone density
Weight training improves bone density
86
Smoking and bone density
- Associated with leanness
- Earlier menopause
- Lower postmenopausal estrogen level
- Decreased blood flow to bone
87
Alcohol and bone density
Can increase urinary calcium excretion
- Associated with lower dairy food intakes
- May be toxic to osteoblasts
