Micronutrients involved in Bones and Blood Flashcards
Why Are Bones Important?
- Support for the body
- Protects our organs (ribs, skull, vertebrae)
- Support for muscles- muscles attach to bones
- Storage reservoir for calcium, phosphorus and fluoride
- Blood cells are produced in the marrow of our bones
Nutrients involved in bone health: calcium, Vitamin D, Phosphorus, magnesium, fluoride, Vitamin K
Bone Composition
- Minerals calcium & phosphorus
- Comprises majority of bone- 65%
- Crystallize to hydroxyapatite crystals → hardness of bone
- Protein fibers made of collagen
- Comprises 35% of bone
- Strength & flexibility of bone
Bone Development
Remodeling: building & breaking down of bone
- Continuously occurring in adults
- Allows for release of Ca and P in the blood
- Allows for repair of damaged areas
Bone Growth
- Determines bone size
- Begins in the womb
- Continues until early adulthood
Bone Modeling
- Determines the bone shape
- Begins in the womb
- Continues until early adulthood
Bone Remodeling
- Maintains integrity of bone
- Replaces old bone with new bone to maintain mineral balance
- involves bone resorption and formation
- occurs predominately during adulthood
Cells Involved in Bone Remodeling
- Osteoclasts: dissolve bone, resorption, “crushing”
- Osteoblasts: bone “building” cells
- Osteocytes: fully matured osteoblasts, bone cells
Phases of Bone Development Throughout Life
-Teens: bone growth achieved ~14 yo for girls & ~17 yo for boys
-Early adulthood: add bone density but max. reached by 30
~ 90% of body density reached by the age 17 for women and 20 for men
-35 & older: bone density begins irreversible decline
Calcium
-Most abundant mineral in our body
Functions:
- provide structure to bones and teeth
- acid-base balance (Ca basic)
- transmission of nerve impulse
- muscle contraction
- regulation of hormones & enzymes
- blood clotting
Calcium Absorption
- Absorption via passive & active transport (Vitamin D)
- Acidic environment
- Older adults with atrophic gastritis (~10-30% in 50s, 40% 80s), reduced HCL, consume with a meal
- ↑ absorption in times of greater need
- Absorption ~30% for healthy adults, ~60% in pregnancy, infants, children, adolescents
- ↑ intake ↓ absorption (and the reverse)
- Maximum absorption ~ 500mg at a time
- Dietary binders but not enough to cause deficiency
- Phytates (legumes, rice, grains), oxalates (spinach, teas), minerals (iron)
Blood Levels of Calcium Are Tightly Regulated
Think for a minute, how might our bodies regulate calcium?
- Storage: bones
- Excretion: kidneys
- Absorption: GI
RDA & Food Sources for Calcium
- RDA established in 2010
- 9-18 yo = 1,300 mg/day
- 19-50 yo = 1,000 mg/day
- Older men & women: 1,200 mg/d for
- Many women & adolescents are below the RDA
- Nutrient of concern in the U.S.
Calcium Toxicity
-Supplemental form
*Increase the risk of calcification of soft tissues
~Meta-analysis of 12,000 people from 15 studies found supplemental calcium (without D) increased the risk of heart attack by 30%. (BMJ. 2010 Jul 29;341)
~WHI data reanalyzed and found same association (with or without D) (BMJ. 2011 Apr 19;342)
*Mineral imbalances: iron, zinc, magnesium
*Kidney stones: calcium deposits
Calcium Deficiency
- ↓ bone density(mineralization)
- Children: stunted growth
- Adults: osteoporosis
- Low bone mass, deterioration of bone tissue
- Porous brittle fragile bones- ↓ ability to put weight on the bone
- High risk of spine and pelvic fractures
- Loss of height
- -Loss of bone in spine= compression of the spine
- Kyphosis: hunching of the spine
Factors Affecting Risk of Osteoporosis
-Genetics: family history, race (Caucasian and Asian at higher risk)
-Female gender: lower bone density, menopause, live longer
-Aging: reduced estrogen and testosterone, ↓ stomach acidity, ↓ physical activity, ↓ vit D synthesis
-Amenorrhea
-Exercise
-Body size
-Smoking: direct toxic effect on the bone
-Low peak bone mass: “A pediatric disease with geriatric consequences”
-Calcium, vitamin D intake
Emerging data: high caffeine intake (>3c coffee/d) in elderly
Management & Prevention
No cure for osteoporosis but drugs can slow or reverse somebone loss
Prevention by maximizing peak bone mass before early adulthood
- Optimal calcium & vitamin D
- Active lifestyle: weight bearing exercise- strength training, running, stair climbing
Vitamin D
-Fat soluble vitamin
-Is it essential?
*Depends where you live. If you live in a place with lots of sun, than no. But if you leave in a place that has no sun, than yes, the vitamin D is essential
-Functions
*Regulates blood calcium, what are the 3 ways it works with PTH to increase blood calcium?
~Enhance osteoclast activity (crush bones)
~Increase calcium absorption
~Increase blood calcium by signaling the kidneys to not secrete so much calcium and absorb it
*Maintain bone health
~↑ Ca absorption and
~Assists with crystallization of Ca & Phos into hydroxyapatite crystals
*Role in cancer and heart disease
RDA: Vitamin D
- 1-70 y.o.= 600 IU ->70 y.o.= 800 IU
- Many experts suggest 800-2,000 IU
- UL vitamin D is 4,000 IU
- Average intake
men: 200-288 IU Women:144-276
Vitamin D & Food
- Forms in food
- Ergocalciferol (D2) in plants (inactive form)
- Cholcalciferol (D3) in animal foods (active form)
- Fatty fish (salmon, mackerel, sardines), cod liver oil, milk, fortified dairy, fortified cereals
- 1 Tbs cod liver oil: 1,360 IU
- 3 oz sockeye salmon: 375 IU
- Tuna in oil (3 oz): 200 IU
- Total fortified cereal (3/4 c): 100 IU
- 1 c milk: 80 IU (all milk in US is fortified with vit D)
- 1c fortified yogurt: 80 IU
Sunlight & Vitamin D
Enhanced synthesis:
- June & July
- Sunny, no clouds or smog
- Latitude: closer to equator (changes at 40 deg N or S)
- 9-3 pm
- younger age
- SPF<8 (above 8 reduces synthesis)
- exposed skin (clothing blocks)
- lighter skin color
~3,000 IU from 5-10 min mid-day mid-year sun exposed on arms & legs, weight the pro against risk of skin cancer
Vitamin D: Toxicity
From supplementation not from sun (skin breaks down excess, limits production)
- ↑ blood calcium levels
- Calcium deposits in heart, liver, kidney
- Can be fatal
Vitamin D: Deficiency
- Rickets
- Children
- Inadequate mineralization, soft bones
- Bowed legs
- Osteomalacia
- Adults
- Osteoporosis
Risk of Vitamin D Deficiency
High risk people include:
- Breastfed infants
- Older adults: 4x ↓ ability to synthesize
- Darker pigmented adults: need more sun time
- Those with limited sun exposure
- Those with fat malabsorption
- Gastric bypass
- Obese (Vit D gets stored in the fat tissues and not in blood)
- Kidney and liver disease patients (two organs activate Vit D)
Phosphorus
Functions
-Calcium and Phosphorus crystallize to form hydroxyapatite crystals → hardness of bone
- Principle intracellular anion (electrolyte), aids in cellular fluid balance
- Part of ATP
- Activates & deactivates enzymes
- Part of DNA, RNA, cell membranes & lipoproteins as phospholipids
Phosphorus (food source)
- Milk
- Meat
- Beans
- Grains
Phosphorus: Toxicity and Deficiency
Toxicity:
-Concern if pre-existing kidney disease
Kidney excrete it
Deficiency:
-Rare- most people easily meet their needs
Soda Consumption Linked to Reduced Bone Mass
- Soda contains phosphoric acid
- Sharp tart flavor
- Slows growth of mold and bacteria
- Theories (why soda is detrimental to bone health)
- Acid leaches calcium from the bones
- Caffeine causes calcium depletion in urine- younger people compensate with increased absorption, elderly with high intake do not
- Probable Cause: Soda – Milk displacement effect
Fluoride
Functions:
- Enhances tooth mineralization
- Fluoride + calcium + phosphorus → fluorohydroxyapatite
- Inhibits acid producing bacteria
- Stimulates new bone growth- Tx for osteoporosis?
Flouride (Source, Deficiency, Toxicity)
Sources:
- Fluoridated water
- Fluoride-containing toothpaste/mouthwash
Deficiency:
-Dental caries
Toxicity:
-Fluorosis: white to dark stains
Magnesium
- Major mineral
- Functions:
- Makes up bone structure & regulates formation of bone crystals
- Cofactor for >300 enzymes
- DNA and protein synthesis and repair
- Supports vitamin D metabolism, muscle contraction & blood clotting
Magnesium (food sources)
- Green leafy vegetables
- Whole grains
- Seeds, nuts
- Seafood
- Beans
- Some dairy
Magnesium (Deficiency&Toxicity)
Toxicity:
- No disease
- Symptoms are diarrhea, nausea, cramping
Deficiency:
- Cramps, spasms, seizures, nausea, weakness
- Associated w/ osteoporosis, heart disease, high blood pressure, type 2 diabetes
Vitamin K
Functions:
- Fat soluble vitamin responsible for the production of proteins for
- Blood clotting
- Bones- high K, low fractures
Vitamin K (sources)
- Found in green leafy vegetables: kale, spinach, collard greens, turnip grns
- Made in the gut
Vitamin K (deficiency&toxicity)
Deficiency:
-Rare, but fatal resulting in severe bleeding
Risk of Deficiency:
-Diseases with fat malabsorption (GI diseases)
Newborns: in US receive vitamin K (no stores, bacteria)
-Toxicity : none
Micronutrients Involved with Blood Health
-Blood transports to the cells
all the components necessary for life!
-Removes waste generated from metabolism.
Iron, Zinc, Copper, Vitamin K, Folate, Vitamin B12
Iron: Functions
Major functions:
- Oxygen transport, part of
- Hemoglobin: Transports oxygen to cells
- Myoglobin: Transports and stores oxygen with in muscles
- Plays several roles in energy metabolism (part of proteins in TCA & ETC)
Iron In The Body
-Iron homeostasis is important
*Insufficient = anemia
*Excess iron = oxidative and can damage tissues
-Iron homeostasis is maintained by means of regulating
*Absorption: absorb more in times of need
*Storage: stored in enterocyte and liver cells for future needs
*Excretion:
~largely recycled, recycling provides 20x more iron to the body than the diet
~lost via GI cell turn-over, blood loss
Iron Homeostasis: Absorption
- ↑ absorption in times of deficiency:normal 14% abs. ↑ to 40%
- ↓intake , ↑absorption
- Amount of stomach acid → ferrous Fe2+ (who is at risk?)
- Heme (Fe2+) vs non-heme sources
- Presence of dietary factors with non-heme
- Enhance: Vitamin C, meat protein factor (MPF)
- Inhibit: phytates, polyphenols (oregano, tea, coffee, red wine), vegetable proteins (soy), fiber and calcium
- RDA assumes 18% absorption, but vegetarian ~10% thus higher RDA
Iron In The Diet: RDA
RDA
- 8 mg/day for men 19- >70 (14 mg/day for vegetarians)
- 18 mg/day for women 19-50, (32 mg/day for vegetarians)
- 27 mg/day for pregnant women
- 9 mg/day for lactating
- Higher in 14-18 y.o. too
Why is the RDA so varied?
- Vegetarians: poor absorption
- Women: menstruation
- Pregnancy: increased BV, fetal needs
- Lactating: lack of menstruation
Iron In The Diet: Sources
Iron is found in animal & plant sources
- Heme
- Found in animal protein as part of hemoglobin & myoglobin
- more absorbable form
- Non-heme
- Found in plants & animals: legumes, whole grains, some vegetables
- Iron skillets: tomato sauce glass pan 0.6 vs iron pan 5.7 mg
- acid enhances absorption
Iron Toxicity
-Accidental overdose (acute)
*Most common cause of poisoning deaths in children
*Damage intestinal lining, changes in pH, liver failure
-Iron overload (chronic)
*Over consumption of supplements/food
~Prooxidative: damage LDL, insulin resistance & cancer
~UL 45 mg/day from all sources
Iron Deficiency
- # 1 micronutrient deficiency worldwide: ~80% of the World’s population have low stores, 30% anemic
- Considered 1 of the top 10 greatest health risks worldwide
- Anemia: ↓ oxygen-carrying capacity of the blood
- reduced ability to produce energy
- body can’t make RBC
- tired, poor performance –> income, communities, nations
- impaired immune function–> increased healthcare $
- Children: premature birth, LBW, infections, premature death, impaired mental and physical development, behavioral problems
Iron Deficiency (causes)
- Causes: poor intake, poor absorption, increased needs, increased blood loss
- At risk groups
- Low income, vegetarians, toddlers, women, pregnant women, adolescents (boys & girls), elderly, athletes
- 25% of adolescent girls & women consume RDA
- Interventions
- Animal flesh at each meal, cast-iron pans, vitamin C w/meals
- Avoid iron-rich foods with milk, zinc or calcium supplements
- Anemia= supplemental doses to reverse
Folate: B-Vitamin
Highlight functions:
- Red blood cell synthesis
- Cell division & neural tube formation
Deficiency:
- Anemia
- Neural tube defects(spine bifia): increased RDA for pregnancy
- Grain supply is fortified to prevent
Sources:
- Folate food sources: fortified grains, green leafy vegetables (foliage)
- Folic acid: supplements & fortification, more bioavailable
Folate: Toxicity
Toxicity from supplements:
-Two studies have found folate supplements (with other b-vitamins) in people that have had a heart attack, can increase the risk of death
Vitamin B12
Highlight function: RBC synthesis, neurological function
Sources: animal foods, meat more than milk, fortified foods
Storage: humans have ~3-6 yr storage if completely removed from the diet, longer if some consumed
Absorption: HCL & intrinsic factor are needed
Deficiency: Macrocytic anemia, reduced cognition/dementia
At risk groups: vegans & lacto-ovo veg, elderly w/ atrophic gastritis & ↓ IF production ; 1.5-15% general pop deficient, higher in at risk groups
Management: >50 y.o. obtain mostly from fortified foods or supplements; injections
Zinc
-Trace mineral found in muscles & bone
-No storage sites in the body
-Functions
*Maintains protein structure with zinc fingers
~Allows for protein receptor binding & gene expression
*100+ enzymes need zinc to function
~Superoxide dismutase: antioxidant enzyme
~Enzymes for DNA synthesis
*Regulates cell signaling & hormone activity
*Needed for normal growth & sexual maturation
Does Zinc Cure the Common Cold?
- Zinc administered within 24 hours of onset of symptoms reduces the duration of common cold symptoms in healthy people.
- As the zinc lozenges formulation has been widely studied and there is a significant reduction in the duration of cold at a dose of ≥ 75 mg/day, for those considering using zinc it would be best to use it at this dose throughout the cold.
- When using zinc lozenges (not as syrup or tablets) the likely benefit has to be balanced against side effects, notably a bad taste and nausea
Zinc (RDA&Food Sources)
RDA:
- 11 mg for men
- 8 mg for women
Food Sources:
- Oysters (6 oysters >RDA)
- Fortified cereals
- Beef, crab
- Lentils
Zinc (Toxicity&Deficieny)
Toxicity:
- Not from food
- ↑↑ supplemental use can: ↓ iron absorption
Deficiency:
- Rare in US
- Growth retardation, delayed sexual maturity, infections
