NTR 108 1st EditionExam # 2 Study GuideModule IX: Nutrients and Bone Metabolism A. Bone and Skeleton - Bones are just part of the skeleton. Bone is a living tissue made up of cells in a mineral protein (primarily collagen) matrix. It is undergoing constant growth degradation. Skeleton is the part of the body left over after removal of the soft tissues. Skeleton is made up of bone, cartilage and ligaments.-Functions of bones/skeletono Storage of calcium and phosphateo Supporto Protection (rib cage, skull)o Movement (attachment of place muscle)o Formation of blood cells (bone marrow) -Bone Consumptiono 99% of all the calcium in the body is in the boneo Basic structure is calcium phosphate/calcium carbonate with protein-Bone Turnovero Childhood- formation is greater than breakdown o Adults 35 to 45 years Formation equals breakdown Humans have the most bone by the late 20s Maximum is mainly genetically controlled Can be much less if not enough calcium or vitamin D is present o Adults over 45- breakdown is greater than formationo After menopause Breakdown is much greater than formation Can be helped by hormone replacement therapy B. Calcium, phosphorus, fluoride, vitamin A and vitamin D - Calcium:o A major mineral nutriento Functions: Bone structure, Nerve transmission, Muscle contraction Blood clotting, Vascular control (blood pressure) o Deficiency signs/symptoms: Tetany (cramping), osteoporosis (calcium deficiency), hypertensiono Groups at risk Poor, children, pregnant women, elderly People with low calcium intake Post menopausal women o Dietary Sources: Dairy, beans, broccoli, dried fruits Tofu, molasses Fortified foods (juice) o Special Notes: Increased needs: growth, lactation, high phosphate diet - Kidney/liver failure (lack vit. D), age (elderly- decreased absorption)-Phosphoruso Found as phosphate- a negatively charged oxygen containing molecule o Part of DNA and RNA structure, phospholipids (makes that part water soluble) and ATP (contains high energy bonds) o Component of bone o Deficiency signs/symptoms: Weakness, loss of appetite, muscle pain o Groups at risk:  Rare, preterm infants, elderly, excess alcohol intake, postmenopausal women o Dietary Sources: meat, milk, eggs, nuts, fish, baked goods, soda pop o Special Notes Excess can upset calcium status Excess can decrease iron absorption -Fluorideo Very water soluble o Part of teeth (as a contaminant)o Makes teeth resistant to dental carieso Bone growth o Deficiency signs/symptomsDental caries with poor mouth hygiene o Groups at Risk:People who drink unfluoridates water People who use unfluoridated toothpaste o Dietary Sources: most public drinking water, toothpaste, tea, seafoodo Special Notes: toxicity- only seen as discoloration of teeth-Vitamin Do Fat soluble vitamin and Acts as a hormoneo Bone metabolismo Calcium absorption by intestineo Calcium reabsorption by kidneyo Deficiency sign/symptoms:Rickets- occurs in childrenOsteomalacia- mineral loss only, not protein matrix)o Groups at risk:People with fat malabsorptionPeople with kidney or liver failurePeople not getting enough sunlightPeople with low milk consumptionDiet Sources: fortified milk, egg yolk, fish oil -Sunlight o Special NotesMetabolism-Vitamin D can be formed in the skin-Turned into an active hormone by kidney and liver-Happens when blood levels of calcium are lowToxicity is likely since toxic level is only 10x RNAC. Relationship Between the Major Nutrients -Vitamin C is needed to make collagen- one of the main proteins-Vitamin A is needed to maintain the cells that remodel the bone- breakdown and formation-Low blood calciumo Can come from: high dietary phosphate, low dietary calciumo Results in: Bone breakdown: calcium released into blood, bone proteins degradedActivation of vitamin D Increased intestinal absorption of calcium- helped by active DDecreased urinary loss of calcium- helped by active D D. Osteoporosis -Loss of bone mineral and protein-Bones strength lessened-Incidence:o 50% of women over 45 years oldo 90% of women over 75 years oldo Over 1 million fractures a year in USo Fractures are the problem, but falling is the cause -Risk factors:o Age- after 45 or so bone mass decreases and risk increasesMost rapid bone mass loss after menopause- without hormone replacement therapy o Gender and HormonesFemales are more likelyMenopause is the lack of estrogen, in terms of bone loss o RaceCaucasians: high risk, low bone density Asians: Intermediate risk, lowest bone densityAfrican Americans: lowest risk, high bone density o Smoking: increases risk, causes earlier menopause o Alcohol: Increases risk (loss of calcium) and increases risk (falling) o Physical activityWeight bearing exercise decrease risk- can increase bone massDecreases change of fallingIncreases food intake which may decrease risk o Recommendations: Higher calcium intake when young (max bone density can be reached)Avoid high intake of phosphorus (soda)Calcium supplements-One of the few times that a supplement is recommended-1g/d at most-Avoid over 3g/d- cause iron deficiency, and kidney stones -Could have heavy metal contamination-Avoid amino acid supplements and caffeineExercise (especially weight bearing)E. Calcium Supplements -General Informationo All are absorbed about the same (30-35%)o Cost does not make a big differenceo Look at amount of calcium, not the total weight- some have a lot of chelatoro Chelators are what makes calcium more water soluble -Synthetico Calcium carbonate (good in tums and other supplements)o Calcium chloride (not good)o Calcium gluconate (good, but low percent of calcium) o Calcium citrate, malate and lactate (good, citracal and fortified OJ) -Natural (could be high in heavy toxic metals)o Oyster shellso Dolomite (type of rock)o Bone