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Lecture

Week 10 - Blood Health.doc

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Department
Nutrition
Course
NUTR 1010
Professor
Andrea Buchholz
Semester
Winter

Description
Week 10: Blood Health What is blood? • Plasma (Fluid: water and electrolytes) makes 55% of blood volume • Red blood cells (45% of blood volume) • White blood cells (part of the immune system) and platelets (for blood clotting makes less than 1% of blood volume What does blood do? • Transports oxygen and nutrients • Removes waste products • Helps with the healing process (blood carries platelets for clotting) • Support the immune system (blood carries white blood cells) Red Blood Cells • Contain hemoglobin o Hemoglobin binds oxygen, delivers oxygen to cells • If there are too few red blood cells or if the red blood cells are damaged in some way, oxygen transport doesn’t happen • Too few blood cells = anemia • Note: there are several kinds of anemia o Macrocytic anemia B Vitamins • B1 (Thiamin) • B2 (Riboflavin) • B3 (Niacin) • B6 (Pyridoxine) • Folate (Folic Acid) • B12 (Cobalamin) • Biotin • Pantothenic Acid *Bolded terms help maintain blood health Folate (Latin for “foliage”) • Water-soluble B vitamin • RDA for men and women >19 y is 400 ug/d What happens if we consume too much folate? • No problems w/consuming too much from naturally-occurring food sources • Too much from fortified foods or supplements- that is, in folic acid form- can mask vitamin B12 deficiency (Upper level for folic acid= 1000ug/day) What happens if we consume too little folate? • Our body will not be able to produce folic acid • Consequences: o Increases homocysteine levels o Impaired DNA synthesis and cell division, leading to macrocytic anemia o Possible neural tube defects in babes Macrocytic Anemia • Signs and symptoms: o Tired, pale o Headache, irritable o Dizzy, weak o Loss of appetite > weight loss • Good news: Reversible with folic acid supplements Who’s at risk for macrocytic anemia? • Infants (lots born prematurely) • Those fed goat milk (low in folate) • Elderly • People who abuse alcohol • Cigarette smokers • People on certain anti-cancer drugs • Pregnant women Folate and pregnancy • Folate RDA is 600ug/day to support high rates of division for uterus, placenta, and fetus • Expansion of moms red blood cell mass • Deficiency of folate can lead to: o Macrocytic anemia (in mom) o Neural tube defects (in infants if genetically predisposed) Neural Tube Defects (NTD) • Improper closure of the neural tube can lead to NTD • If improper closure happens in the spinal cord: o Results in spina bifida (some forms are minor, can be surgically repaired; 80-90% of children survive to adulthood) • If improper closure happens in brain: o Result is anencephaly (partial absence of brain tissues; fatal) Since the introduction of folic acid fortification in 1998, incidence of NTD’s has decreased by 30% Vitamin B12 • Another water soluble B vitamin involved in energy metabolism • Other functions: o Activates folate o Like folate, helps prevent macrocytic anemia and control homocysteine levels • Helps make red blood cells • Maintains nerve fibers o Essential for healthy functioning of the nervous system (brain, spinal cord, nerves) B12 Sources and Requirements • B12 is bound to animal proteins, so it is found in animal foods only o Meat, fish, poultry, milk, and eggs o Long-term vegans must take supplements • RDA for man and women >19 years old is 2.4 ug/day o Typical western diet provides 3-30 ug/day B12 Absorption • B12 separated from animal protein in stomach due to action of gastric acid • “Free” B12 then binds to intrinsic factor o Intrinsic factor is a protein made in the stomach o Required for B12 absorption in small intestine • What is you don’t produce gastric acid or intrinsic factor? o You won’t absorb B12 What happens if we consume too much vitamin B12? • Not much – there are no known toxic effects • No upper level (UL) established What happens if we consume too little B12? • Macrocytic anemia o Deficiency of B12 means folate cannot be activated o Deficiency of other vitamin can lead to macrocytic anemia • Pernicious Anemia o Can be caused by years of too little intake of vitamin B12, but can also be caused by decreased production of gastric acid and/or intrinsic factor (B12 not absorbed) o Remember B12 helps maintain nerves, so deficiency affects the nervous system Pernicious Anemia • Early: o Mild impairment of intelligence, orientation and short term memory o Reversible • Advanced o Paralysis begins at extremities, works inward and up the spine o Not-so-good news: irreversible Who’s at risk of B12 Deficiency? • Vegans/fruitarians o Low intake (no animal products) o Decreased production of intrinsic factor • Infants weaned from breast milk to vegan diets o Low B12 stores coupled w/low intake • Elderly o Many have decreased gastric acid secretion AND decreased production of intrinsic factor Deficiency of folate and/or B12 causes macrocytic anemia • Folic acid can treat macrocytic anemia, regardless of whether anemia is caused by folate OR B12 deficiency Folic acid treats the macrocytic anemia of B12 Deficiency, but NOT the pernicious anemia of B12 (folic acid does not maintain nerve fibers) Iron • Trace mineral needed in very small amounts • Part of hemoglobin o Oxygen-carrying protein found in red blood cells o Transports oxygen around the body • Part of myoglobin o Like hemoglobin, but found in the muscle cells o Helps carry oxygen into muscle cells Iron is found in the heme group of hemoglobin (Think of the heme group as the nest and the iron as the egg) • Helps w/ energy production o Found in enzymes needed to metabolize energy from CHO, fat, and protein • Helps make: o Amino acids o Collagen o Hormones o Neurotransmitters • Plays a role in immunity How much iron do we need? • RDA for men is 8mg/day • RDA for premenopausal women is 18mg/day • RDA for women 51 and older is 8mg/day Types of iron influences absorption •
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