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Bone Health (Major Minerals in Bone (Calcium (Intake (Food sources…

- - - - Average 25-30% absorption
        
        Absorption is enhanced by...
        
        Active vitamin D in interstitial cells
        
        Estrogen increases vitamin D
        
        Growth needs
        
        Children and young people have higher absorption than elderly
        
        Pregnant women have ~50% absorption
        
        Lactose
        
        Absorption is decreased by...
        
        Old age
        
        Menopause
        
        Supplement use (Mg, P, Zn)
        
        High fibre diet (50+ g/ day)
        
        Very high fat intake
        
        Polyphenols (tea, coffee)
        
        Vitamin D deficiency
        
        Phytic acid (legumes, whole grains)
        
        Oxalic acid (vegetables
        
        % absorbed is inversely related to amount of intake
        
        Mostly absorbed in acidic duodenum
    - - Bone roles
        
        Essential for bone formation and maintenance
      - Non-bone roles
        
        Blood clotting
        
        Formation of fibrin and clot
        
        Nerve transmission and muscle contraction
        
        During action potential
        
        Calcium flows into muscle cell to cause contraction
        
        Calcium flows out of muscle cell to cause relaxation
        
        Above-normal levels of calcium in muscle cells can cause
        
        Rigour (muscles can't relax after contracting)
        
        Below-normal levels of calcium in muscle cells can cause
        
        Tetany (Spasmodic relaxation)
        
        Inverse relationship with calcium and hypertension
        
        1000mg of Calcium/day for preventative effect against hypertension
    - - Toxicity
        
        Effects
        
        Hypercalcemia
        
        High blood and urinary calcium levels
        
        Calcium deposits in soft tissues (kidney, heart, arteries)
        
        Can cause permanent organ damage
        
        Causes
        
        Hyperparathyroidism
        
        Excessive production and secretion of parathyroid hormone
        
        Causes
        
        Kidneys to retain calcium in blood
        
        Bone release calcium into blood
        
        Most affected
        
        People with kidney disease
      - Supplements
        
        Decreases absorption of other minerals
        
        Common calcium supplements: carbonate, citrate, lactate, phosphate
      - Deficiency
        
        Osteoporosis
        
        Naturally occurring degenerative bone disease characterized by decreased bone density,
        increased bone fragility, and increased risk of fractures
        
        Multi-factorial disease
        
        Genetics
        
        Genes affect bone growth, peak bone mass, and rate of bone loss
        
        Race
        
        African American populations tend to have greater bone density than Caucasian populations
        
        Body weight
        
        Underweight or anorexic women are at higher risk
        
        Physical Activity
        
        Weight bearing exercises increase bone strength
        
        Smoking
        
        Smokers have lower body weights and may breakdown estrogen more rapidly
        
        Alcohol
        
        Toxic to bone--> slows bone formation
        
        Women
        
        At menopause, the rate of bone loss is accelerated for 5-10 years because of
        decreased estrogen levels
        
        Prevent by...
        
        Consuming adequate calcium intake during years of peak bone mass (teens and up to 25-30)
        
        Reducing rate of bone loss
        
        Biphosphonate therapy
        
        Estrogen therapy
        
        Vitamin D therapy
        
        Calcitonin therapy
      - Food sources
        
        Most mlk and milk products
        
        Including fortified milk alternatives
        
        Most nutrient-dense source of calcium is skim milk
        
        Some seafood
        
        Bones in canned fish
        
        Oysters
        
        Vegetables
        
        May contain oxalic acid which causes decreased bioavailablity
        
        Some vegetables may have low calcium but relatively high bioavailability
        
        e.g. cauliflower, watercress, bok choy
        
        e.g. kale, brussels sprouts, broccoli
        
        Hard water in Prairies
        
        Soup with bones
  - - - 60-90% is absorbed
      - Wide availability in the diet
        
        Less of a dietary concern than Calcium
      - Regulation of phosphorous blood levels
        
        Primarily regulated by kidneys
    - - Food sources
        
        Milk and milk products
        
        Animal foods
        
        Meat, fish, poultry
        
        Supplements
        
        Not needed since we eat plenty in diet
        
        Legumes, cereal, bran, nuts
      - Deficiency
        
        Unlikely
        
        May see neuromuscular, skeletal, hematological and renal malfunctioning
      - Toxicity
        
        No true toxic effect of high phosphorus intake
        
        Adverse effects more to do with low calcium intake in
        combination with high phosphorus intakes
    - - Bone formation and maintenance
        
        Calcium and Phosphate salts form hydroxyapatite crystals
        
        Deposit onto the PRO collagen matrix of bone
        
        Provides strength and rigidity to bones
  - - - Calcium and phosphorus are essential for bone formation and maintenance
        
        Calcium and phosphorous salts combine to form
        
        Hydroxyapatite (a bone crystal)
        
        Deposited into
        
        Osteoid (bone's protein collagen matrix)
        
        Provides strength and rigidity to bones
    - - Bone and teeth
        
        Indirect effect on calcium balance because Mg is needed for the action of the calcium-regulating hormones, vitamin D and PTH
        
        Mg needed for the mineral crystal structure in bone; can replace calcium in hydroxyapatite
        
        Bone acts as a reservoir of Mg in body.
        
        Mg helps prevent dental caries by holding Calcium in the enamel
      - In blood and tissue
        
        Stabilizes high energy phosphate bonds (ATP)
        
        300 enzymes systems require Mg as a cofactor (ex, PRO, FAT and nucleic acid synthesis; generating E from CHO, PRO, FAT)
        
        Nerve Transmission and Muscle Contraction Activity
        
        Mg needed for neurotransmitter activity and inhibits muscle contraction
        
        Blood clotting
        
        Mg inhibits blood clotting
      - Hypertension
        
        Mg protects against hypertension and heart disease -acts as vasodilator
        
        Lower rates of heart disease are observed where people live in areas with hard water
    - - Deficiency
        
        Deficiency develops slowly due to storage of Mg in bones
        
        Rarely see deficiency symptoms
        
        Symptoms
        
        Irregular heart beat, loss of appetite, weakness, disorientation, hypertension
        
        Tetany at extremely low levels of Mg in the body
      - Toxicity
        
        Pharmacologic doses may result in diarrhea and abdominal cramps, and other symptoms similar to Mg deficiency
        
        No known adverse effects of supplemental magnesium intakes
      - Food sources
        
        Plant foods
        
        Spinach, beet greens, avocado, leafy green vegetables
        
        Whole grains, nuts, seeds, tofu, legumes, peanuts
        
        Milk and milk products
        
        Hard water contains Magnesium and Calcium
- - - - Primary Role
        
        Regulates blood calcium and bone metabolism
        
        Via calcitriol, parathyroid hormone, and calcitonin
        
        Calcitriol is the active form of vitamin D
        
        Low blood calcium levels
        
        Parathyroid gland secretes parathyroid hormone
        
        Stimulates activation of calcitriol (active vitamin D) in kidneys
        
        Acts on osteoclast cells in bone to raise blood calcium
        
        Vitamin D acts at 3 sites
        
        Intestine
        
        Increases absorption of calcium
        
        Kidneys
        
        Conserves calcium
        
        Bone
        
        Osteoclast cells cause bone to release calcium into blood
        
        Can lead to calcium tetany in muscles
        
        High blood calcium levels
        
        Thyroid gland secretes calcitonin
        
        Causing decreased action of osteoclasts
        
        Reduces amount of calcium leaving bone and entering the blood
        
        Can lead to calcium rigor in muscles
        
        Parathyroid hormone levels fall
        
        Increase in urinary calcium
        
        Calcitriol levels fall
        
        Decreases absorption of calcium
      - Other Roles
        
        Immune function
        
        Associated with maturation of immune cells
        
        Required to absorb phosphorous
    - - Only bone health nutrient that has two types of sources
        
        Endogenous source
        
        Acts as a hormone when exposed to the sun
        
        Activated into calcitriol via the liver and kidneys
        
        Can only rely on solar synthesis for 6 months of year in Vancouver
        
        Factors affecting synthesis of vitamin D
        
        Skin colour
        
        Age
        
        Distance from the equator
        
        Pollution
        
        Sunscreen use
        
        Time of day of exposure
        
        Exogenous source
        
        Consumed in the diet in an inactive (pro-vitamin) form
        
        Activated in the liver and kidneys to form calcitriol
    - - Deficiency
        
        Consequences for...
        
        Children
        
        Rickets disease
        
        Poor mineralization and shaping of bones
        
        Bowed legs
        
        Malformed ribs (rachitic rosary)
        
        Could be due to...
        
        Breastmilk low in vitamin D
        
        Little exposure to sun
        
        Adults
        
        Osteomalacia disease
        
        "Soft bones" disease
        
        Osteoid (protein matrix) not mineralizing properly
        
        Osteoid accumulates and hydroxyapatite not deposited
        
        1 more item...
        
        Progressive weakness and increasing pain in lower back and legs
        
        Causes
        
        Kidney, liver, intestinal diseases
        
        2 more items...
        
        Low intake of vitamin D and little exposure to sun
        
        Closely spaced, repeated pregnancies
        
        Treatment
        
        Increase dietary intake of vitamin D
        
        Increase synthesis through careful exposure of skin to the sun
      - Toxicity
        
        Perhaps the most toxic of all vitamins when consumed in least amounts above DRI
        
        Narrower safety range than other fat-soluble vitamins
        
        Supplement use
        
        Most likely reason for toxicity
        
        Over 10,000 IU/day is toxic
        
        Solar exposure
        
        Non-toxic since body down-regulates production of vitamin D when circulating levels are adequate
        
        Food intake
        
        Safe, non-toxic at normal intake levels
        
        Effects
        
        Hypercalcemia (high blood calcium levels)
        
        Calcium deposits into soft tissue (e.g. kidneys, heart, arteries)
        
        Can cause irreversible damage to organs
        
        Children are most affected
        
        Parents unnecessarily supplement their infants causing vitamin D poisoning
      - Food Sources
        
        Egg yolks, liver, fish and fish oils
      - Supplements
        
        Caution against taking higher doses
        
        Could calcify and damage soft tissue
        
        Absorption for vitamin D is 50-80%
        
        Comparable to food intake
        
        Fish oil supplements are high in vitamin A and D
        
        Use with caution, adhere to dosages on labels
        
        Limited number of natural food sources with vitamin D
        
        Supplements could be useful for people not consuming milk or milk products
  - - - Calcium Mineralization in Bone Matrix
        
        Vitamin K needed by osteoblasts to synthesize osteocalcin
      - Blood Clotting
        
        Vitamin K necessary for proteins in the production of fibrin, a blood clotting protein
        
        Infants receive a dose of vitamin K at birth to prevent hemorrhaging
    - - Deficiency
        
        Infants
        
        Low levels at birth and in breast milk
        
        Low levels of gut bacteria to synthesize vitamin K
        
        Adults
        
        Rare, usually due to antibiotic use
        
        Individuals with fat malabsorption disorders, especially if taking antibiotics
        
        Excessive vitamin D intake can impair the role of vitamin K in blood clotting
      - Toxicity
        
        Food sources considered non-toxic
        
        Excessive vitamin K can hinder effect of anti-coagulant drugs(e.g., Warfarin)
        
        Symptoms: RBC hemolysis, jaundice, brain damage
      - Food sources
        
        Green leafy vegetables, peas, broccoli, green beans
        
        Liver, eggs, milk
        
        Bacterial synthesis in large intestine
        
        Non-food source
        
        Resistant to losses in cooking
- - - - Bone and teeth Mineralization
        
        F- replaces hydroxyl group in hydroxyapatite crystals found in bone and teeth to create fluorapatite (a stronger crystal in bones and teeth)
        
        Fluorapatite more resistant to decay from acid erosion
        
        Most effective before teeth erupt through the gums
        
        Topical treatment as adults helps protect against dental caries
        
        Fluoride is antimicrobial and helps fill in surface micro-lesions
    - - Deficiency
        
        Low fluoride in water supply can lead to an increased risk of dental caries
        
        Dental problems can contribute to a person's inability to chew properly and consume a wide variety of foods
      - Toxicity
        
        High F- intake during tooth development can lead to fluorosis
        
        Fluorosis: white specks, mottling, or brown streaks on teeth
        
        In skeleton: causes abnormal hardening of the skeleton making bones more brittle
        
        Stiffness and pain in joints
        
        May lead to osteoporosis
        
        Children consuming large amounts of toothpaste or given excessive fluoride drops are at greatest risk
      - Food sources
        
        Brewed tea, water (not usually bottled water), seafood, seaweed, shellfish, fish
        
        Non-food items: chewing gum, mouth wash, toothpaste