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Blood Health (Iron (Absorption (Increased Absorption
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Blood Health
Iron
Introduction
- 3-4 g in body
- 80% found in hemoglobin (RBC) and myoglobin (muscle)
- 5-25% absorbed from diet
- two oxidation states:
- 2+ (ferrous), 3+ (ferric)
- mostly associated with proteins in foods
- fibre and binders such as phytic acid and oxalic acid inhibit absorption
- competition for absorption with each other and other divalent minerals (ex: calcium and copper), especially at supplemental intake levels
- only DRI greater for women than men
- RDA: 18mg/day vs 8 mg/day
Absorption
- Increased Absorption
- high demand by body (ex: growth), low body stores
- heme type
- stomach acid
- vitamin C (primarily non-heme iron in plant foods)
- meat protein factor (MPF)
- Decreased absorption
- full body stores
- binders: phytic acid and oxalic acid found in plant foods
- decreased stomach acid
- polyphenols (ex: tannins in tea, caffeine in coffee)
- high dietary fibre (~50+ g/day)
- supplemental intakes of other minerals (ex: calcium and phosphorus) at low iron or zinc intakes
- non heme iron: ~5-15% absorbed, up to 10-fold increase
- heme iron: ~25-35% absorbed, up to 2-fold increase
Absorption, Transportation, storage, and recycling
- Iron in foods is consumed
- Intestinal cells (aka mucosal cells in SI) 2-3 day lifespan
- If the body does not need iron...
- Store excess in mucosal ferritin (a storage protein)
- iron excreted in shed intestinal cells
- If the body needs iron...
- iron packaged in mucosal transferrin (a transport protein)
- blood transferrin carries iron in blood
- some iron delivered to myoglobin of muscle cells
- bone marrow incorporates iron into hemoglobin of red blood cells and stores excess iron in ferritin (and hemosiderin)
- iron containing hemoglobin in red blood cells carries oxygen
- some losses is bleeding occurs (ex: menses)
- liver and spleen dismantles red blood cells, packages iron into transferrin for transport, and stores excess iron in ferritin (and hemosiderin)
- some losses via sweat, skin and urine
Roles
- support energy release from macronutrients
- cofactor for many enzymes
- synthesis reactions
- mostly associated with protein function
- Synthesis of...
- hemoglobin and myoglobin
- Cytochromes (ETC)
- Catalase (antioxidant enzyme)
Deficiency
- Iron Depletion (Stage 1)
- depleted stores of Iron, Ferritin
- Hb can still be in normal range, but at low end
- no physical symptoms
- Iron Deficiency (Stage 2)
- depleted Iron transport, transferrin
- reduced work capacity
- Iron Deficiency Anemia (stage 3)
- severe depletion of Iron stores and low Hb impacts oxygen-carrying capacity of the blood, results in reduced energy production
- low hematocrit value - % of whole blood volume that is RBC
- fatigue, pale skin, impaired immune function
- Normal Hb levels
- women: 12-16 g/dL
- men: 14-18 g/dL
- Normal Hct levels
Deficiency Diseases
- Characteristics
- microcytic, hypochromic RBC
- Populations at Risk
- everyone except healthy adult males
- newborns: born with ~ 6 month store
- infants/children: high demand, rapid growth
- adolescents:
- males: rapid growth
- females: onset of menses
- women of child bearing years: menses
- pregnant women: increased blood volume, muscle mass, growth needs of fetus
- athletes: increases iron loss, reduced intake (??)
- blood donors: ~2-5 mg/unit
- elderly: lower intake, poorer absorption
- Prevalence
- ~15% of North American women have ID
- ~8% of North American women have IDA
- Causes
- poor dietary intake (ex: vegans)
- heavy menstrual losses
- ulcers, infection, cancer
- pica
- Treatment
- usually ferrous sulphate supplement
Toxicity
- Hemochromatosis
- impaired mucosal block
- causes: genetic, lifestyle
- organs "rust"
- increased potential pro-oxidant (free radical) action
- increases risk of infection
- joint pain, fatigue
Foods and Food Preparation
- high bioavailability
- moderate bioavailability
- low bioavailability
- Iron poor foods
- milk and milk products
- breastmilk- low amounts but high bioavailability
- Iron cooking pots (cast iron)
- contribute to Iron intake especially when cooking acidic foods (ex: tomato sauce)
- reduced percentage of IDA (32% to 5.3%, 12 weeks) in young brazillian vegetarians
Food Sources
- High Bioavailability
- Animal Foods
- Liver, steak (heme)
- fish, shellfish
- Moderate or Low Bioavailability
- Plant Foods
- enriched grains and products
- tofu, legumes
Supplements
- Iron usually ferrous (Fe 2+) form
- Often less well absorbed than iron in food due to many factors in food that enhance iron absorption
- If tolerated take between meals
-when not consuming milk, tea, coffee, high fibre foods
- take with plenty of fluids
- can be constipating and cause cramping
- treatment of ID/IDA
- prescription level ferrous supplement
- ~200-300 mg/day for a monitored period of time
- supplements most common cause of young childrens accidental poisoning deathS in USA (no Canadian Data); keep out of reach of children
Recommendations
- Adults
- RDA
- males, all: 8 mg/day
- males, vegetarian: 14 mg/day
- UL
- RDA
- females, 19-50: 18mg/day
- females, vegetarian: 32 mg/day
- females, 51+: 8 mg/day
- UL
Zinc
Introduction
- 2-3 g in body
- high concentrations in eyes, prostate glands, bone, and muscle
- 10-35% absorbed from diet
- one primary oxidation state:
- mostly associated with proteins in foods
- fibre and binders such as phytic acid and oxalic acid inhibit absorption
- competition for absorption with each other and other divalent minerals (ex: calcium and copper), especially at supplemental intake levels
- DRI-RDA:
- males 11mg/day
- females: 8mg/day
Absorption
- Increased Absorption
- high demand by body (ex: growth), low body stores
- animal sources
- stomach acid
- vitamin C (primarily non-heme iron in plant foods)
- meat protein factor (MPF)
- Decreased absorption
- full body stores
- binders: phytic acid and oxalic acid found in plant foods
- decreased stomach acid
- polyphenols (ex: tannins in tea, caffeine in coffee)
- high dietary fibre (~50+ g/day)
- supplemental intakes of other minerals (ex: calcium and phosphorus) at low iron or zinc intakes
Absorption, Transportation, Storage and Recycling
- 2 sources of zinc can enter the intestine:
- Diet
- Pancreatic Secretions
- Zinc in food enters body
- mucosal cells in the intestine store excess zinc in metallothionein
- If the body does not need Zinc
- zinc is excreted in shed intestinal cells in the feces (Mucosal Block Regulation)
- If the body needs Zinc: ENTEROPANCREATIC CIRCULATION OF ZN
- Methallothionein releases zinc to albumin and transferrin for transport to the rest of the body
- blood carries zinc in albumin and transferrin
- liver stores excess as metallothionein
- blood carries zinc in albumin to other tissues
- some losses in urine, semen, skin and blood
- the pancreas uses zinc to make digestive enzymes and secretes them into the intestine
Roles
- support energy release from macronutrients
- cofactor for many enzymes
- synthesis reactions
- mostly associated with protein function
- Synthesis of...
- hemoglobin
- superoxide dismutase cytoplasm
- gene regulation
- sexual development
- wound healing
- thyroid function
Deficiency
- Recognized in early 1960's in Egypt and Iran
- diet low in animal protein, high in unleavened bread (ex: pita), legumes, whole grains, beans
- Pica practiced
- Symptoms
- poor sexual development in teen males
- dwarfism
- impaired digestive processes
- metallic taste
- slow wound healing
- diarrhea
Toxicity
- Zinc supplement use only
- can impair Iron and Copper absorption
- Zn intake 3-5x RDA can reduce HDL-c levels by ~15% and increase risk of heart disease
- excess Zn excreted through enteropancreatic circulation: protective effect
Foods and Food Preparation
- high bioavailability
- moderate bioavailability
- low bioavailability
Food Sources
- High bioavailability
- Animal Foods
- oysters, clams
- liver, steak
- milk, yogurt
- fish shellfish
Supplements
- Common form
- Zinc-gluconate
- claimed to reduce symptoms and duration of the common cold, especially when taken at first sign of a cold coming
- Zn-gluconate often taken with echinacea (herb)
- no reliable conclusive evidence to support claims
-
Copper
Introduction
- ~100 mg copper in body
- ~1/3 each in liver and brain; muscle; other tissue
Absorption
- ~25-40% absorbed; inverse proportionality
- copper in intestinal cells induce synthesis of Metallothionein, a storage protein for Copper and Zinc
- supplemental inatkes of Zn, Iron and high intakes of phytates or fibre reduce absorption of copper
Roles
- Iron Transport
- liver produces a Cu- containing protein, Ceruloplasmin
- ceruloplasmin assists in converting the Fe2+ found in portal blood entering the liver to Fe3+ for transport from liver to other tissues via transferrin (ex: to bone marrow)
- low ceruloplasmin levels cause Fe overload in liver, eventually damage ("rust") the liver
- Connective Tissue
- cofactor for collagen synthesis
- Antioxidant Role
- superoxide dimutase antioxidant enzyme (in cytoplasm, with Zinc)
Deficiency
- Rare
- may be seen in children with protein deficiency and IDA
- symptoms
- increased blood cholesterol and damage to arteries, increasing risk of heart disease
- anemia, low WBC count, poor growth, bone loss
Toxicity
- rare, only with copper supplements
Food Sources
- Animal Foods
- protein rich foods
- liver, organ meats, seafood, shellfish
- Plant Foods
- whole grains
- nuts, seeds
- legumes, peanut butter
- chocolate, cocoa
- dried fruits
Blood
What is it?
- only fluid tissue in body
- transports nutrients to cells
- removes waste products from cells
- quantity and quality are both important
- micronutrients are important to blood health
Basic Components
- Plasma (~55% of volume)
- contributes to blood volume
- red blood cells (RBC) (~45% of volume)
- white blood cells (WBC) (<1% of volume)
- contribute to immune function
- platelets (<1% of volume)
- contribute to blood clotting