Chapter 15: Bone Health and Body Defense Systems

Nutrients involved in bone health

- minerals: calcium, phosphorus, magnesium, fluoride

- fat soluble vitamins: Vitamin D

Bone compostion

- Calcium and phosphorus form lattice-like crystal (hydroxyapatite)

- collagen fibers

Compact bone

- Outer, dense shell of bone

- ~75% of skeletal mass

Spongy bone

- Hard, spongy network

- Add strength without weight

- Minerals move into and out of the bone

Osteoblasts

Build bone, produce collagen, add minerals to form healthy bones

Osteocytes

Take up calcium from blood and release it back into the blood

Osteoclasts

Dissolve bone, stimulated by vitamin D activation, release calcium from bone into blood stream

Calcium

- Essential mineral

- Needed for bone and tooth development

- 99% found in bones & teeth

Calcium functions

- Primary: developing and maintaining bones

- Secondary: Blood clotting,

Transmission of nerve impulses, Muscle contraction, Cell metabolism

Calcium found in foods

- Dairy products

- Plant based foods

Calcium needs

RDA based on promoting bone growth and maintenance

Calcium supplements are used to...

prevent bone loss and fracture

Blood calcium concentration is regulated by what two hormones?

- Calcitonin

- Parathyroid hormone

Calcium deficiency

- At risk: Postmenopausal women, Lactose intolerance, Vegan diets

- Osteoporosis

Calcium toxicity

- Kidney stones

- Hypercalcemia

- Decreased absorption of other minerals

Osteoperosis

- Calcium deficiency over time

- Body withdraws calcium from bone --> Bone loss over time

- Problems: falls, broken bones, height loss

Osteoperosis risk factors

non-modifiable: Female sex, Small frame, Older age

modifiable: dietary pattern, physical lifestyle, alcohol consumption, smoking status

dietary osteoporosis prevention

calcium, magnesium, potassium, vitamin D, phosphorus, vitamin K

Vitamin D

- Fat soluble vitamin

- 'Conditionally essential'

- Synthesize vitamin D: Presence of sunlight

- Insufficient sunlight: Must come from dietary intake

Functions of Vitamin D

- Maintains blood calcium & phosphorus levels

- Immune function

- Secretion of hormones

- Gene regulation

Vitamin D Synthesis

Synthesized with exposure to sunlight

Vitamin D Deficiency

Rickets

Phosphorus

- essential mineral

- required by every cell in the body

Functions of phosphorus

- 80% in bones & teeth

- Fluid balance

- Energy production and storage

- Component of cell membranes

Sources of phosphorus in foods

- Animal & plant proteins

- Food additives

- Soda as phosphoric acid

Magnesium Functions

- Fluid balance

- Bone structure and mineralization

- Helps stabilize ATP

- Energy metabolism

- Nerve and muscle function

- Glucose and insulin metabolism

sources of magnesium

- Green leafy vegetables

- Animals

- Hard tap water

- Coffee and tea

Fluoride

nonessential trace mineral

Functions of fluoride

- Support calcium and phosphorus deposits in teeth and bones

- Protect against development of cavities

- Strengthens tooth enamel

Sources of fluoride

Fluoridated water, Tea, Seafood, Toothpaste, mouthwash

Antioxidant defenses

Help maintain integrity of cell membranes by stopping chain reactions caused by free radicals

free radical

very unstable compounds

Process of antioxidant defenses

1. Free radicals attack foreign pathogens

2. Antioxidants donate an electron to 'neutralize' free radical

function of antioxidant

- Protect the body

- Regulate free radical activity

- Avoid potentially damaging effects

How do antioxidants prevent free radical damage?

By donating electrons to free radical and destroying free radicals

Antioxidants come from which nutrients?

Vitamin E, Vitamin C, Selenium, beta-carotene, manganese, copper, zinc

Vitamin E

Essential fat-soluble vitamin

Functions of Vitamin E

- Antioxidant activity

- Protects cell membranes

Vitamin E in foods

- Plant oils

- Products made from plant oils

Vitamin E Deficiency

- Rare

- Can impair immune function

- Hemolytic anemia: Premature breakdown of red blood cells

Vitamin C

Essential water-soluble vitamin

Vitamin C Functions

- Antioxidant activity

- Cofactor in many reactions

- Immune function

- Collagen synthesis

- Iron absorption

Vitamin C is found in what foods?

fruits and vegetables

Vitamin deficiency

Scurvy: Fatigue, pinpoint hemorrhages, gums and joints bleed

Selenium

essential mineral

Functions of selenium

- Component of many enzymes and proteins

- Antioxidant activity

- Thyroid metabolism

- Immune function

Vitamin A

Essential fat-soluble vitamin

Retinoids

Biologically active forms of vitamin A

Carotenoids

Precursor to vitamin A

Vitamin A functions (retinoid)

- Immune function

- Growth and development

- Cell differentiation

- Roles in dermatology

What sense does vitamin A aid

Vision

Vitamin A function (carotenoids)

- Carotenoids are provitamins - once converted, have same functions as retinoid vitamin A

- Suggested to have other functions to lower disease risk

Examples of specific carotenoids are

Beta-carotene, Lutein and zeaxanthin, Lycopene

Vitamin A in foods

- Retinoids: Fish, fish oils, Dairy, Eggs

- Carotenoids: Dark green and yellow-orange vegetables

Cancer

Abnormal and uncontrolled division of altered cells

Non-modifiable factors that can cause cancer

Genetics & Environmental factors

Modifiable factors that can cause cancer

Smoking, Lack of physical activity, Obesity, Poor dietary pattern

Dietary factors that lead to risk of certain cancer development

- low consumption of fruits and veggies

- excess energy intake and obesity

- high intake of red meat

- fried foods

- alcohol

- refined grains