Nutrients Involved in Bone Health

1
Nutrients Involved in Bone Health

• Calcium, Phosphorous, Magnesium chapter 12
• Fluoride chapter 13
• Vitamin D, Vitamin K chapter 11
• Highlight 12- Osteoporosis

2
Bone Health

• Bone structure
• Provides strength to support the body
• Allows for flexibility
• Contains about 65 minerals providing the
  hardness of bone
• Contains 35 organic structures for strength,
  durability, flexibility
• Collagen fibrous protein in bone tissue

3
Bone Health
4
Bone Formation

• Hydroxyapatite
• Chief crystal of bone.
• Made of calcium phosphorus.
• Formed on a matrix of collagen.
• Gives strength rigidity to bones.

5
Tooth Formation

• Hydroxyapatite crystals
• form on a collagen matrix
• create dentin enamel (fluoride)
• Turnover is not as rapid as bone.

6
Bone Health

• Two types of bone tissue
• Cortical bone (compact bone) very dense tissue
  making up 80 of the skeleton.
• Outer surface of all bone
• Trabecular bone (spongy bone) scaffolding on
  the inside of bones supports cortical bone and
  makes up 20 of the skeleton.
• Provides Ca storage bank
• Ends of long bones, vertebrae

7
Bone Health

• Stages of bone development
• Bone growth increase in bone size completed by
  age 14 in girls and age 17 in boys
• Bone modelling shaping of bone completed by
  early adulthood
• Bone remodelling reshaping of bone occurs in
  adults to maintain bone repair process

8
Bone Health

• Bone remodelling involves
• Resorption surface of bones is broken down
• Osteoclasts cells that erode the surface of
  bones
• Formation of new bone in resorption pit
• Osteoblasts cells that produce the
  collagen-containing component of bone

9
Bone Health
10
Bone Health

• Bone density
• Peak bone density is reached before the age of 30
• Remodelling maintains bone density during early
  adulthood
• Density begins to decrease after age 40 because
  resorption exceeds new bone formation

11
Bone Health

• Dual energy X-ray absorptiometry (DXA)
• Measures bone density
• Uses very low level X-ray energy
• Provides a full body scan
• Is a non-invasive procedure
• Recommended for postmenopausal women

12
Calcium

• Calcium is the most abundant major mineral in the
  body.
• 99 found in bones as bone structure calcium
  storage
• Rest in body fluids
• Functions of calcium
• Form and maintain bones and teeth
• Assists with acid-base balance
• Transmission of nerve impulses
• Assist in muscle contraction blood clotting
• Involved in secretion of hormones activation of
  some enzyme reactions.

13
Calcium Balance

• Calcium homeostasis strictly maintained via
  hormones (calcitonin parathyroid hormone) and
  vitamin D
• Blood calcium above normal ? calcium rigor
  hardness or stiffness of muscles.
• Blood calcium below normal ? calcium tetany
  mild tingling of fingers, toes lips, acute
  severe muscular contractions, tremors and cramps.

14
Calcium Balance

• ? blood calcium
• Calcium deposited in bones
• Thyroid gland secretes calcitonin ? inhibits vit
  D activation ? prevents Ca reabsorption in
  kidneys ?limits Ca absorption in intestines
  ?inhibits osteoclasts from breaking down bone

15
Calcium Balance

• ? blood calcium
• Parathyroid gland secretes parathyroid hormone
  ? stimulates vit D activation
• Vit D enhances Ca absorption in intestines
• Vit D parathyroid hormone
• Stimulate osteoclasts to release Ca from bones
• Stimulate Ca reabsorption in kidneys

16
Calcium

• Recommended intake
• AI values vary with age
• 1000 mg per day (19 to 50 years)
• 1300 mg per day (9 to 18 years)
• Best food sources of calcium
• Skim milk, low-fat cheese, non-fat yogurt, green
  leafy vegetables
• Must consider bioavailability

17
Calcium

• What if you consume too much calcium?
• Over the UL (2.5 g), problems can occur
• Excess calcium, over time, can lead to mineral
  imbalances and kidney damage

18
Calcium

• What if you dont consume enough calcium?
• Blood calcium is maintained by increased bone
  resorption to meet calcium need
• Hypocalcemia (low blood calcium) can be caused by
  kidney disease or vitamin D deficiency, not
  calcium deficiency alone.

19
Vitamin D

• Vitamin D
• Fat-soluble vitamin
• Excess is stored in liver and fat tissue
• Can be synthesized by the body by exposure to UV
  light from the sun
• Is a hormone since it is synthesized in one
  location and acts in another location

20
Fig. 11-9, p. 377
21
Vitamin D

• Functions of vitamin D
• Regulates blood calcium and phosphorus levels
• Regulates absorption in GI tract reabsorption by
  kidneys mobilization from bones to blood
• Stimulates osteoclasts
• Necessary for bone calcification
• New functions immunity cell differentiation
• Protect against TB, gum inflammation, MS, and
  some cancers

22
Vitamin D

• Recommended intake
• AI values range from 5 to 15mg/day (200-600 IU)
  depending on age.
• AI values assume that a persons sun exposure is
  inadequate.
• Extreme latitudes (gt 40 N or gt 40 S) receive
  inadequate sun in the winter to make vitamin D.

23
Vitamin D

• Sources of vitamin D
• Most foods contain very little vitamin D.
• Fatty fish (salmon, sardines) best sources
• Also found in egg yolks, liver, beef, veal
• Most vitamin D is obtained from fortified foods
  such as milk, butter, margarine, juices, cereal
  etc.
• Vegetarians not consuming dairy foods may receive
  vitamin D from the sun, fortified plant-based
  milks or supplements.

24
Vitamin D

• What if you consume too much vitamin D?
• Skin synthesis (sun exposure) cannot cause excess
  vitamin D formation
• Can occur from excess supplements or fish oils
• Results in hypercalcemia high blood calcium.
• Leads to disability and death due to
  calcification of soft tissues
• UL set at 50 µg or 2000 IU

25
Vitamin D

• What if you dont get enough vitamin D?
• Can also occur with diseases that reduce
  intestinal absorption of fat
• Rickets bending of soft bones in children
• Abnormal bone growth, bowed legs, bowed chets,
  beaded ribs
• Osteomalacia weak, painful bones in adults
• Lose minerals protein structure
• Soft, easy to break, can bow
• Canadians more at risk for vitamin D deficiency
  than previously thought

26
Rickets
27
How much sun exposure is needed ?

• Depends on darkness of skin degree of exposure
• exposure a few times/wk should be sufficient
  (hands, face arms)
• 10 - 15 minutes for fair skin
• up to 1.5 hours for dark skin

28
Factors affecting vit D synthesis from sunlight

• Heavy clouds, smoke or smog
• Blocks UV rays that promote vit D synthesis
• Window glass or screen heavy clothing
• Blocks UV rays
• Increase in skin melanin pigmentation or
  application of sunscreen
• Absorbs solar UV B photons - significantly reduce
  production of vit D in skin.
• Latitudes
• Regions above 40 N latitude below 40 S
  latitude, synthesis in skin is absent during most
  of winter months.

29
Fig. 11-11, p. 380
30
Who is at risk for deficiency?

• Infants exclusively breastfed
• Need to be provided with oral supplement
• Older adults
• Skin, liver kidneys lose capacity to make
  active Vit D
• Less sun exposure milk consumption
• Persons with limited sun exposure
• Persons with fat malabsorption

31
Vitamin K

• Vitamin K
• Fat-soluble vitamin stored in the liver
• Phylloquinone plant form of vitamin K
• Menaquinone form of vitamin K produced by
  bacteria in the large intestine (1/2 our needs)
• Functions of vitamin K
• Synthesis of proteins involved in
• Blood coagulation
• Bone metabolism

32
Vitamin K

• Recommended intake
• AI values are 120 µg/day for men and 90 µg/day
  for women.
• Sources of vitamin K
• Green leafy vegetables, cabbage-type vegetables,
  vegetable oils
• Bacterial synthesis in GI tract

33
Vitamin K

• Vitamin K Deficiency
• Hemorrhagic disease - reduced blood clotting,
  excessive bleeding
• Rare
• Long-term antibiotic use can kill vit K-producing
  bacteria in intestine
• Anticoagulant drugs interfere with vit K
  metabolism activity.
• Poor fat absorption
• Newborn infants who have no bacteria in
  intestinal tract yet.

34
Vitamin K

• Vitamin K Toxicity
• No known side effects from large quantities
• No upper limit set
• Can interfere with anticoagulant medications
• Important to consume moderate and consistent
  amounts

35
Phosphorus

• Phosphorus (as phosphate) is the primary
  intracellular negatively charged electrolyte.
• Functions of phosphorus
• Critical to mineral composition of bone
• Crystal component of hydroxyapatite
• Required for proper fluid balance
• Component of ATP, DNA, membranes

36
Phosphorus

• Recommended intake
• RDA for phosphorus is 700 mg/day.
• Sources of phosphorus
• High in protein-containing foods such as milk,
  meats, eggs
• In processed foods as a food additive
• In cola soft drinks as phosphoric acid

37
Phosphorus

• Phosphorous Toxicity
• High blood phosphorus can occur with kidney
  disease or over consuming phosphorus-containing
  antacids
• Causes muscle spasms, convulsions, calcification
  of non-skeletal tissue (esp. kidneys)
• High phosphorous intakes often correspond with
  low calcium intakes
• UL 4000 mg/day

38
Phosphorus

• Phosphorus Deficiency
• Deficiencies of phosphorus are rare
• Those at risk are premature infants, elderly
  people consuming poor diets, or people who abuse
  alcohol

39
Magnesium

• 50 60 of the bodys magnesium is found in the
  bones.
• Functions of magnesium
• A mineral found in bone structure
• Cofactor for over 300 enzyme systems
• Required for the production of ATP, DNA, and
  proteins
• Muscle contraction blood clotting
• Regulation of blood pressure
• Normal functioning of immune system

40
Magnesium

• Recommended intake
• RDA varies based on age and gender.
• 310 mg/day for women age 19 30 y.
• 400 mg/day for men age 19 30 y.
• Sources of magnesium
• nuts, legumes, whole grains, dark green
  vegetables, seafood, chocolate, cocoa

41
Magnesium

• Magnesium Toxicity
• No toxicity from magnesium in food
• Magnesium supplements can cause diarrhea, nausea,
  cramps, dehydration
• UL of 350 mg nonfood magnesium/day
• Can be fatal
• Magnesium Deficiency
• Hypomagnesemia can result in low blood calcium,
  osteoporosis, hypertension
• See with alcohol abuse, protein malnutrition ,
  kidney disease prolonged vomiting and/or
  diarrhea

42
Fluoride

• Fluoride is a trace mineral.
• 99 of the bodys fluoride is stored in teeth and
  bones.
• Functions of fluoride
• Development and maintenance of teeth and bones
• Combines with calcium and phosphorus to protect
  teeth from bacteria
• Replaces OH portion of hydroxyapatite to create
  fluorapatite
• makes bones stronger teeth more resistant to
  decay

43
Fluoride

• Recommended intake
• RDA varies by gender and increases with age,
  ranging from 1-4 mg/day.
• Sources of fluoride
• Fluoridated dental products
• Fluoridated water
• Naturally occurring in tea seafood

44
Fluoride

• Fluoride Toxicity
• Fluorosis (excess fluoride) creates porous tooth
  enamel teeth become stained and pitted.
• Occurs only during tooth development but
  irreversible
• Fluoride Deficiency
• Dental caries (cavities)

45
Osteoporosis

• Osteoporosis is a disease characterized by
• Low bone mass
• Deterioration of bone tissue
• Fragile bones leading to bone fractures
• Compaction of bone decreased height
• Shortening and hunching of the spine

46
Osteoporosis
47
Osteoporosis

• Factors influencing the risk of osteoporosis
  include
• Age
• Gender
• Genetics
• Physical activity
• Nutrition
• Lifestyle

48
Osteoporosis
49
Osteoporosis

• Age is a factor for osteoporosis because
• Bone mass decreases with age
• Age-related hormonal changes influence bone
  density
• Older adults are less able to absorb vitamin D
• Older adults are less able to make vitamin D in
  skin with same amount of sun exposure as younger
  adults

50
Osteoporosis

• Gender is a risk factor for osteoporosis.
• In Canada, more than twice as many women (16)
  as men (7) over 50 years have osteoporosis.
• Women have lower bone density than men.
• Estrogen loss in post-menopausal women causes
  increased bone loss.

51
Osteoporosis

• Genetics affect risk for osteoporosis.
• A family history increases risk
• Certain ethnic groups are more predisposed to
  osteoporosis than others
• Caucasian and Asian women have highest risk

52
Osteoporosis

• Physical activity influences the risk for
  osteoporosis.
• Regular exercise causes stress to bones, leading
  to increased bone mass.
• Weight-bearing activities (walking, jogging) are
  especially helpful in increasing bone mass.
• However, there is a female athlete triad of
  eating disorder, amenorrhea, and osteoporosis.

53
Osteoporosis

• Nutrition can help prevent osteoporosis
• Adequate bone-protective nutrients.
• Calcium, phosphorus, magnesium, vitamins D K.
• Adequate but not excess protein.
• Sufficient fruit and vegetable intake.

54
Nutrition

• Calcium Absorption
• Adults absorb 25 Ca ingested.
• Stomach acidity keeps Ca soluble.
• Absorption best when consumed with a meal.
• Vit D helps make calcium-binding protein.

55
Nutrition

• Factors that inhibit calcium absorption
• Vit D deficiency
• High fibre diet
• Phytates
• Oxalates
• Low stomach acid
• Polyphenols (tannins) in tea

56
Osteoporosis

• Lifestyle factors affect osteoporosis
• Cigarette smoking increases risk.
• Excess caffeine (gt 3 cups coffee) associated with
  bone loss.
• Soft drink use by children and adolescents is
  associated with less bone growth.

57
Osteoporosis

• The treatment for osteoporosis is to slow the
  progression of osteoporosis by
• Adequate calcium and vitamin D intake
• Regular exercise
• Lifestyle factors e.g., smoking
• Anti-resorptive medications

58
Osteoporosis

• Anti-resorptive medications slow bone resorption
• Bisphosphonates most common
• Effective with few side effects
• Estrogen replacement therapy effective
• Risk of breast cancer and heart disease
• Selective estrogen-receptor modulators
• mimics estrogen without cancer risk
• Calcitonin
• Hormone that slows bone loss but must be injected