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Nutrition 207 > Calcium and Vitamin D > Flashcards

Calcium and Vitamin D Flashcards

1
Q

Bones function

A

Skeleton provides the support and move

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2
Q

Bones composition

A

65% mineral crystals -strength and structural support

35% collagen- flexibility (to avoid cracking when jumping,etc.)

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3
Q

What is the characteristic of bone strength?

A

Bone mineral density

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4
Q

2 bone types

A
  • Cortical

- Trabecular

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5
Q

Proportion of cortical and trabecular bones

A

80 and 20%

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6
Q

Two types of bones are nourished by___

A

Blood vessels

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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

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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
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9
Q

Three stages in bone turnover

A
  • Bone growth
  • Bone modeling
  • Bone remodeling
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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
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11
Q

What percentage of bones are replaced in the first year?

A

100 %

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12
Q

Bone modeling happens until

A

Girls 14( 2 years after the start of menstruation), men 17 years

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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

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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

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15
Q

Osteoporosis is

A

A bone breakdown disease

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16
Q

The prevalence of osteoporosis in Canada

A

1 in 3 women

1 in 5 men

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17
Q

Consequences of osteoporosis

A

Compressed vertebrae-pain,mobility

Hip fracture -mortality, morbility

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18
Q

What is the most common disease?

A

Osteoporosis

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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

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20
Q

What is the risk for the hip fracture in men and women

A

women -75 %

men -25%

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21
Q

Hip fracture complications

A
  • Death( because of surgery complications and malnutrition)
  • Inability to walk
  • Need to live in the nursing home
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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
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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
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24
Q

Does falling causes hip fracture?

A

No, hip fracture causes falling

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25
Q

Risk factors for osteoporosis( 11 points)

A
  • 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 )
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26
Q

Advantages of men against osteoporosis

A

-Men have greater bone density and smaller losses in later life

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27
Q

How much bone is lost in women after menopause?

A

20% in 6-8 years after menopause

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28
Q

How to measure the bone density?

A

DXA

Measures the proportion of absorption of X-rays of soft tissue and bones. It gives a proportion of 2 types of bones

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29
Q

Two diseases with bone mass loss and their criteria

A

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)

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30
Q

Bone growth team

A

“Players”

  • protein- collagen( where the crystals bound)
  • minerals- Ca,P,Mg,F

“Coaches”

  • Vit D,parathyroid hormone
  • calcitonin

“Assistants”
-Vit A,C,K

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31
Q

Calcium can be found in

A

Bones, teeth, blood

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32
Q

How much calcium is stored in our bones and teeth and in blood?

A

99% bones/teeth

1% blood

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33
Q

What is the name for the calcium form in our bones?

A

Hydroxyapatite

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34
Q

Calcium roles

A
  • 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
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35
Q

Does a glass of milk will increase the concentration of calcium in our blood?

A

No, blood calcium is not a problem of a diet, low calcium in blood-> problem in metabolic regulation

36
Q

What is the consequence of acute calcium deficiency and chronic in blood

A

Acute- tetany/rigor

Chronic- robs the bones reservoirs->stunting in children, osteoporosis

37
Q

Calcium absorption differences

A

Differ with age and life cycle

38
Q

How much calcium is absorbed in adulthood and during pregnancy,growth, lactation

A

Adulthood-30 % of dietary calcium. Adjusts as dietary calcium decreases
Growth, pregnancy, lactation - 50-60% of dietary calcium

39
Q

Calcium absorption can be increased by( 5 points)

A
  • 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
Q

Calcium absorption can decreased by( 7 points)

A
  • 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
Q

RDA for calcium

A 
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
Q

UL for calcium

A

Adults 19-50 2500

Adults 50+-2000

43
Q

When is UL exceeded?

A

Usually with supplements

44
Q

When osteoporosis begin to develop

A

between 9-18 years

45
Q

Do people consume enough calcium in Canada

A

No

46
Q

The best sources of calcium

A 
Milk and milk products
Tofu( fortified)
Sardines
Chinese cabbage 
Broccoli
47
Q

Why spinach is not the best source of calcium

A

It has a lot of calcium, but it is also high in oxalates( only 5 % of calcium bioavailable)

48
Q

How the intake of foods with different bioavailability influence each other?

A

If you take milk with wheat bran( phytates), calcium from milk from 38% to 26%

49
Q

Urinary calcium excretion influenced by

A
  • Calcium intake
  • Age
  • Caffeine
  • High sodium duets
  • Dietary protein
50
Q

Should we replace calcium from the duet with the supplements?

A

No, diet first

51
Q

For whom calcium supplements can be important?

A
  • Milk allergy
  • Lactose intolerance ?
  • Vegan
52
Q

Calcium supplements and medications for better calcium absorption ,interactions

A
  • 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
Q

What can happen if the UL for calcium is exceeded?

A
  • 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
Q

How can we get vitamin D?

A

From food and from our skin

55
Q

the pathway of vitamin D

A

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
Q

Functions of Vitamin D( 5 points)

A
  • Required for calcium absorption( calbindin)
  • Regulates blood calcium levels
  • Stimulates osteoclasts
  • Necessary for bone calcification
  • Immunity and cell differentiation
57
Q

Vitamin D actions in the body

A
  • Intestine( increase Ca absorption from the diet)
  • Kidney( decrease Ca excretion in the urine )
  • Bone ( increase release from the bone?)
58
Q

What happens when calcium blood level is low?

A

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
Q

What happens when thyroid gland secretes calcitonin as a respond to the rising calcium in blood?

A

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
Q

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

A 
High
Stimulates
Absorption
Calcium
Increases
61
Q

Is Vit D a hormone or a vitamin

A

Both

62
Q

Vitamin D as a hormone ( 4 points)

A
  • Travels in the blood
  • Activated in the liver and kidneys
  • Acts on intestine,kidney,bones
  • Increase Ca availability for bone mineralization and remodelling
63
Q

Vitamin D as vitamin( 3 points)

A
  • 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
Q

RDA for vitamin D

A

Children and adults 9-70- 600 IU

Adults 70+- 800 IU

65
Q

Why adults 70+ have a higher RDA

A

Because they stay more inside, their skin cannot synthesize vit D as good as before

66
Q

UL for vitamin D

A

4000 IU

67
Q

Signs of vitamin D deficiency

A
  • abnormal bone growth
  • Malformed teeth
  • Muscle spasms
68
Q

Signs of vitamin D toxicity

A
  • Elevated blood calcium
  • Calcification of soft tissues
  • Excessive thirst
  • Headache
  • Nausea
  • Weakness
69
Q

Signs of calcium deficiency

A
  • Stunted growth and weak bones in children

- Bone loss- osteoposis in adults

70
Q

Signs of calcium toxicity

A
  • Constipation
  • Interference with absorption of other minerals
  • Increased risk for kidney stones
71
Q

Sources of Vitamin D

A

Fortified foods(milk , margarine)
A little in fatty fish, egg yolk, liver and cheese
Supplements

72
Q

Do we get enough vitamin D in canada?

A

No, especially from November to march

73
Q

Can vitamin D toxicity happen from the sun?

A

No

74
Q

Two diseases connected with Vitamin D deficiency

A
  • Osteomalacia

- Rickets

75
Q

Describe osteomalacia

A
  • 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
Q

Describe Rickets

A

Bones do not mineralize properly in children

  • Stunting
  • Bowed legs
  • Teeth problem
  • Breast milk children do not get vitamin D
77
Q

Phosphorus and bones

A
  • With Ca forms hydroxyapatite mineral of bone
  • High intake decreases Ca absorption
  • Typical intake is higher than RDA
78
Q

Magnesium and bones

A
  • Cofactor
  • Bone structure and regulation of mineralization , vut D metabolism
  • ATP synthesis
  • Blood clotting, muscle contraction( Ca promotes, Mg inhibits), blood pressure regualtion
79
Q

Vitamin K and bone

A

Co-enzyme synthesize bone protein

Deficiency cannot bind minerals

80
Q

Vitamin A and bone

A

Bone remodeling , osteoclast activity

-but if exceeds UL, reduced bone density

81
Q

Vitamin C and bone

A

-Cofactor for collagen synthesize ( organic matrix)

82
Q

How to prevent osteoporosis?

A

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
Q

When we start to loose bone mass

A

Mid thirties

84
Q

Can be osteoporosis be improved in 70 old?

A

Yes, never to late

85
Q

The correlation between exercise and bone density

A

Weight training improves bone density

86
Q

Smoking and bone density

A
  • Associated with leanness
  • Earlier menopause
  • Lower postmenopausal estrogen level
  • Decreased blood flow to bone
87
Q

Alcohol and bone density

A

Can increase urinary calcium excretion

  • Associated with lower dairy food intakes
  • May be toxic to osteoblasts

Nutrition 207 (17 decks)

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