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NUTR100 (67)

Feb 25 ch 9 bone health.doc

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Sabina Valentine

Feb 25 – Ch 9 Nutrient Involved in Bone Health 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 There 2 types of bone tissue: 1.) Cortical bone (compact bone): very dense tissue making up 80% of the skeleton (outer surface of all bone) 2.) Trabecular bone (spongy bone): “scaffolding” on the inside of bones; supports cortical bone and makes up 20% of the skeleton. (found on ends of long bones and vertebrae) Bones develop through 3 processes 1.) Bone growth – increase in bone size; completed by age 14 in girls and age 17 in boys 2.) Bone modelling – shaping of bone; completed by early adulthood 3.) Bone remodelling – reshaping of bone; occurs in adults to maintain bone; repair process 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 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 Dual Energy X-ray absorptiometry (DXA) • Measures bone density • Uses very low x-ray energy • Provides a full body scan • Is a non-invasive procedure • Recommended for postmenopausal women Quantitative Ultrasound • Measures bone density • Uses sound waves • Measures at heel, wrist or kneecap • Is a non-invasive, portable procedure • Recommended for screening Peripheral measurements • Peripheral DXA (pDXA) measures one site • Ex. Measure of bone on one finger • Is a non invasive portable procedure • Useful for screening Calcium Calcium is the most abundant major mineral in the body Functions of calcium • Form and maintain bones and teeth • Assists with acid-base balance • Transmission of nerve impulses • Assist in muscle contraction Recommended intake for calcium There are no RDA values for calcium AI values vary with age • 1000 mg per day (19-50 years) • 1300 mg per day (9-18 years) Calcium intake from CCHS 2.2 for adults over 19 years • Women: 793 mg per day • Men: 931 mg per day Best food sources of calcium • Skim milk, low-fat cheese, non-fat yogurt, green leafy veg
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