vitamins
- Organic compounds that are essential in the diet in small amounts to promote and regulate body processes necessary for growth, reproduction, and the maintenance of Health
- named alphabetically in approximately the order they were identified
- some vita
vitamin groups
- assigned to two groups based on solubility in water or fat and this chemical characteristic allows generalizations to be made about how vitamins are absorbed, transported Comics created drama and stored in the body
Water soluble vitamins
- Vitamin B and vitamin C
- most are bound to blood proteins for transport
- not stored to any great extent so supplies of most are rapidly depleted so they must be consumed regularly
- it takes more than a few days to develop but deficiency even when one
Fat soluble vitamins
- Vitamin A vitamin D vitamin E and vitamin K
- incorporated into chylomicrons for transport from the small intestine and the bioavailability of a vitamin depends on the availability of these Transport Systems
- excess can be stored in the liver and fatty
B vitamins
- first thought to be a single chemical substance but were later found to be many different vitamins and for this reason were distinguished by numbers
- vitamins b6 and b12 are the only ones that are still referred to by their numbers
- act as coenzymes
Foods lacking certain vitamins
- grains, fruit, and vegetables lack vitamin B12
- grains, Derry, and protein are low in vitamin C
Fortification
- adds nutrients to food and some nutrients are added to foods to comply with government programs that mandate additions to prevent vitamin or mineral deficiency
- grains are enriched with B vitamins and iron
Pellagra
- in the early nineteen-hundreds this niacin deficiency caused more than 3,000 deaths annually in the Southern United States and then 1938 Bakers begin enriching flour with B vitamins voluntarily which led to a decline in mortality from this deficiency an
Government-supported fortification programs
- helped prevent deficiencies in vitamins A and D and niacin
- Toddlers and preschoolers showed that a significant percentage had in takes off vitamin A Kama folate, and think that exceeded the uls and much of the excess zinc is likely from fortified brea
Vitamins in food
- can be damaged by exposure to light or oxygen, washed away during preparation, or destroyed during cooking
Provitamin
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-A compound that can be converted into the active form of a vitamin in the body
Vitamin Precursor
-A compound that can be converted into the active form of a vitamin in the body.
Coenzymes
-An organic nonprotein substance that binds to an enzyme to promote its activity.
Antioxidants
- A substance that decreases the adverse effects of reactive molecules on normal physiological function.
Vitamin absorption continued
- once absorbed into the blood vitamins must be transported to the cells
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Oxidative Damage
- Damage caused by highly reactive oxygen molecules that steal electrons from other compounds, causing changes in structure and function.
Pro vitamins and vitamin precursors
- some vitamins are absorbed in an inactive form called a pro vitamin or a vitamin precursor
- to perform vitamin functions of vitamins must be converted into active vitamin forms once they are inside the body. How much of each pro-vitamin can be converte
Vitamin functions
- promote and regulate the body's activities
Vitamin A
- needed for vision as well as normal growth and development
Vitamin K
- needed for blood clotting and bone health
Antioxidant vitamins
- vitamin C, vitamin C, and pro-vitamin a
- protect us from oxidative damage
Vitamins needed to keep blood healthy
- folate vitamin B12 , vitamin B6 , and vitamin K
Vitamins needed for normal growth and development
- vitamin A and D
Vitamins needed to produce ATP from carbohydrates, fat, and protein
- the B vitamins thiamin, riboflavin ,niacin , biotin, pantothenic acid , vitamin B6
Vitamins important for protein and amino acid metabolism
- folate, vitamin B6, vitamin B12
Vitamins needed for healthy immune function
- vitamin E, B6, C , d
Vitamins needed for bone health
Vitamins D, A, K, C
Coenzymes
Needed for enzyme activity. They act as carriers of electrons, atoms, or chemical groups that participate in the reaction. All B vitamins are coenzymes but there are also coenzymes that are not dietary Essentials and therefore not vitamins
Coenzymes process diagram
1. The vitamin combined with a chemical group to form the functional coenzyme (active vitamin)
2. The functional coenzyme combines with the incomplete enzyme to form that active enzyme
3. The active enzyme binds to one or more molecules and accelerates th
Oxidative damage cause
- when reactive oxygen molecules steal electrons from other compounds causing changes in their structure and function.
Free radicals
- reactive oxygen molecules such as free radicals can be generated by normal oxygen requiring reactions inside the body such as cellular respiration or can come from environmental sources such as air pollution or cigarette smoke
- cause damage by snatchin
Antioxidants
- act by reducing the formation of or destroying free radicals and other reactive oxygen molecules before they can do damage
- some antioxidants are produced in the body and others such as vitamin C, vitamin E, and mineral selenium are consumed in the die
How antioxidants work
- many antioxidants including vitamin C function by donating electrons to free radicals and a donated electron stabilizes a free radical so that it is no longer reactive and cannot steal electrons from important molecules in and around cells
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ULs
Because more is not always better when it comes to nutrient intake The DRIs have also established ULs as a guide to amounts that avoid the risk of toxicity
Food labels
- required to list the amounts of vitamin A and vitamin C in Foods as a percentage of daily values and the proposed changes to food labels will require that they list the amount of vitamin D (in micrograms and % daily value
- amount of vitamin A and vitam
Stores
- 75% of stores comply with voluntarily providing nutrition information for raw fruits vegetables and fish that are most frequently purchased
Vitamins on food labels
- if the percent daily value is 20% or more the food is an excellent source of the nutrient
- if it is 10 to 19% the food is a good source
- if it is less than 5% the food is a poor source
Free Radicals
- A type of highly reactive atom or molecule that causes oxidative damage.
Tips for preserving vitamins in food
1 store food away from heat and light
2 cut fruits and vegetables as close as possible to when they will be consumed
3 don't soak vegetables instead cook vegetables with as little water as possible
4 don't rinse rice
Vitamin bioavailability
- 40 - 90 percent of vitamins in small intestine percent of vitamins in food are absorbed primarily from the small intestine
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Vitamin absorption
1. In the mouth chewing breaks food down to help release vitamins
2. In the stomach digestion of food releases vitamins and some niacin is absorbed here
3. The gallbladder releases bile which emulsifies fat and helps absorb fat-soluble vitamins
4. The pan
Bioavailability
-The extent to which the body can absorb and use a nutrient.
- affected by composition of diet, and conditions in the digestive tract and body
- if diet is low in fat, absorption of fat soluble vitamins is impaired
B Vitamin function
Directly involved in transferring energy in carbohydrates, fat, and protein to ATP.
Vitamin C
Needed to synthesize connective tissues and to protect us from damage by oxidation
How thiamin functions
- the role of thiamine in producing ATP from glucose and synthesizing neurotransmitters has been linked to the neurological symptoms of the thiamine deficiency disease beriberi
- thiamine is needed to convert pyruvate into acetyl Co a period acetyl Co a c
Thiamin (B1)
- A B vitamin needed in energy metabolism.
- first B vitamin discovered in 1926
- polishing the bran layer off rice kernels to make white rice removes the thiamin rich portion of the grain
- a coenzyme needed for the breakdown of glucose to provide energy
Beriberi
- A thiamin deficiency disease that may manifest in one of two forms: dry beriberi, which causes weakness and nerve degeneration, or wet beriberi, which causes heart changes.
- flourished in east asian countries for 1000 years ago
- came to Western attent
thiamin deficiency
- wet and dry beriberi
- neurological symptoms such as impaired motor and sensory reflexes (dry beriberi)
- neurological symptoms of dry beriberi can be related to the functions of thiamin but it is not clear why thiamin deficiency causes the cardiovascular sym
- cardiovascular
Neurotransmitters
A chemical substance produced by a nerve cell that can stimulate or inhibit another cell.
Beriberi
- A thiamin deficiency disease that may manifest in one of two forms: dry beriberi, which causes weakness and nerve degeneration, or wet beriberi, which causes heart changes.
- "I cannot" refers to extreme weakness and depression that are the earliest sym
Wernicke-Korsakoff Syndrome
- A form of thiamin deficiency associated with alcohol abuse that is characterized by mental confusion, disorientation, loss of memory, and a staggering gait, hallucinations which can progress to coma and death
- occurs often in alcoholics b/c alcohol dec
thiamin abundancy
- abundant in pork, legumes, and seeds
- in enriched grains and the bran layer of brown rice and other whole grains
thiamin RDAs
- 1.2 mg/day for men
- 1.1 mg/day for women
Riboflavin
The B vitamin that provides a visible indicator of excessive consumption, the excess is excreted in the urine turning it a bright fluorescent yellow. , adverse effects of high doses of riboflavin have been reported. Forms 2 Co enzymes active coenzymes tha
Best sources of riboflavin
-Milk (exposure to light can cause an off flavor and losses in vitamin A and vitamin D and riboflavin is destroyed by light)
- dairy products red meat poultry fish whole grains enriched Breads and cereals. Vegetable sources include asparagus broccoli mush
Riboflavin deficiency
Injuries heal poorly because new cells cannot grow to replace the damaged ones. The tissues that grow most rapidly such as the skin and Linings of the eyes, mouth and Tom are the first to be affected. Deficiency causes symptoms such as cracking of the lip
Riboflavin RDAs
1.3 mg/day for men
1.1 mg/day for women
Pellagra
- A disease resulting from niacin deficiency, which causes dermatitis, diarrhea, dementia, and, if not treated, death.
- filled hospitals in SE united states in early 1900s
Niacin
-A B vitamin needed in energy metabolism.
- forms coenzymes essential for glucose metabolism and the synthesis of fatty acids and cholesterol
- need is so widespread in metabolism that a deficiency causes major changes throughout the body
Niacin toxicity
No evidence of adverse effects from consuming foods that naturally contain niacin but niacin supplements can be toxic. Excess niacin supplementation can cause flushing of the skin, a tingling sensation in the hands and feet, a red rash, nausea, vomiting,
Niacin UL
For adults it is 35 milligrams per day. Doses of 50 milligrams per day or greater of one form of niacin are used as drugs to treat elevated blood cholesterol
Biotin
A coenzyme that functions in energy metabolism and glucose synthesis. It is also important in the metabolism of fatty acids and amino acids
Biotin sources
Good sources in the diet include eggs, liver, yogurt, and nuts. Fruit and meat are poor sources. Bacteria in the gastrointestinal tract synthesize Biotin and some of this is absorbed into the body and helps to meet our needs.
AI of biotin
30 (10^-6)g/day has been established for adults
Biotin deficiency
Uncommon but it has been observed in people with malabsorption and those taking certain medications for long periods. Eating raw eggs can cause biotin deficiency. Biotin deficiency in humans causes nausea, thinning hair, lots of hair color, a red skin ras
Biotin toxicity
High doses have not resulted in toxic symptoms and there is no UL for biotin
Raw eggs and biotin bioavailability
Raw egg whites contain a protein called adivin that tightly binds biotin and prevents its absorption.
Pantothenic acid
Baby vitamin widely distributed in Foods. Particularly abundant in meat eggs whole grains and legumes and it is found in lesser amounts in the milk vegetables and fruits. Needed almost everywhere in the body, it is part of coenzyme a which is needed for b
Pantothenic acid UL
Is relatively non-toxic so there's not enough data to establish a UL
Vitamin B6
important for Amino acid and protein metabolism. It is needed to synthesize non-essential amino acids, neurotransmitters, synthesize hemoglobin, convert tryptophan into niacin, and break down glycogen to release glucose into the blood.
Three forms of vitamin B6
Pyridoxal, pyridoxine, and pyridoxamine
- the three forms can be converted into active enzyme pyridoxal phosphate which is needed for the activity of more than 100 enzymes involved in the metabolism of protein from a carbohydrate and fat
Folate deficiency and macrocytic anemia
Folate is needed for DNA replication. Without fully developing red blood cells cannot divide. Instead they just grow bigger. The abnormally large immature red blood cells called megaloblast then mature into abnormally large red blood cells called macrocyt
Low folate
May increase the risk of developing heart disease. folates connection has to do with the metabolism of homocysteine
Elevated levels of homocysteine
Associated with increased risk of heart disease. Folate vitamin B12 and B6 are needed to prevent homocysteine levels from rising but despite this supplementation with these vitamins has failed to exert significant effects on cardiovascular risk
B vitamins and homocysteine metabolism
Folate and vitamin B12 are needed to convert homocysteine into methionine. When either folate, vitamin B12 or vitamin B6 are deficient homocysteine levels rise which increases the risk of developing cardiovascular disease
Population groups most at risk of folate deficiency
Pregnant women and premature infants because of their rapid rates of cell division and growth. The elderly because of their limited intake of foods high in folate and alcoholics because alcohol inhibits the absorption of folate and tobacco smokers because
Sources of folate
Leafy greens such as spinach, legumes, enriched grains, orange juice. Whole grains and many vegetables are there sources and only small amounts are found in Meats, cheese, milk, and most fruits
Folate RDA
400 micrograms per day
Supplementing folic acid
Women capable of becoming pregnant should consume 400 micrograms of synthetic folic acid (4-6 servings of fortified grain products) in addition to food consumed in the diet
High intake of folate
No known folate toxicity. High intake could potentially mask early symptoms of vitamin B12 deficiency which has led to a you are being set for adults at 1000 micrograms of folic acid per day
B12 absorption process
1. Vitamin B12 in food is bound to protein
2. In the stomach acid and pepsin help release vitamin B12 from food proteins
3. Cells in the stomach lining release intrinsic factor
4. In the upper portion of the small intestine duodenum intrinsic factor binds
Vitamin B12 or cobalamin functions
Necessary for the production of ATP from certain fatty acids to maintain the myelin coating on nerves and for a reaction that converts homocysteine to methionine and converts fully to the form that is active for DNA synthesis.
B12 deficiency
Homocysteine levels rise and folate is trapped in an inactive form. Without adequate active folate DNA synthesis Lowe's, red blood cells do not divide normally, and macrocytic anemia and develops. Lack of B12 also leads to degeneration of the myelin that
The relationship between folate and vitamin B12
When B12 is deficient it causes a secondary folate deficiency. So late is available but B12 deficiency prevents it from being activated. The folic acid provided by supplements and fortified foods does not need to be activated. This has raised concerns tha
Sources of B12
Naturally found only in animal products. Animal foods provide B12 but plant foods do not unless they have been fortified with it or contaminated by bacteria, soil, insects or other sources of B12.
B12 RDA
2.4 micrograms per day
B12 toxicity
No toxic effects have been reported 4 in takes up to 100 micrograms per day and insufficient data is available to establish and UL for vitamin B12
Vitamin C
Best known for her role in synthesis and maintenance of collagen which is the most abundant protein in the body which forms the basis of all connective tissue is the framework for bones and teeth and the main component of ligaments, tendons, and scars tha
Collagen
forms the basis of all connective tissue is the framework for bones and teeth and the main component of ligaments, tendons, and scars that bind wounds together. Give structure to the walls of blood vessels
Vitamin C deficiency
Collagen cannot be formed and maintained and the symptoms of scurvy appear
Vitamin C function and deficiency
A reaction requiring vitamin C is essential for the formation of bonds that hold adjacent collagen strands together and give the protein strength. Collagen is continuously being broken down and reformed so without vitamin C the bonds cross-linking adjacen
Scurvy
Occurs when vitamin C intake is below 10 milligrams per day. The gums become inflamed swell and bleed. The teeth loosen and eventually fall out. The capillary walls weaken and rupture causing bleeding under skin and into the joints. This causes raised red
More vitamin C functions
Functions in reaction that synthesize neurotransmitters, hormones, bile acids, and carnitine which is needed for the breakdown of fatty acids. It is an antioxidant that acts in the blood and other body fluids. It's antioxidant properties help maintain the
Vitamin C RDA
90 milligrams per day for men and 75 milligrams per day for women
Sources of vitamin
Citrus fruits and cantaloupe. Vegetables in the Cabbage family such as broccoli cauliflower bok choy and brussel sprouts, dark green vegetables, green and red peppers, okra, Tomatoes, potatoes. Meat fish poultry eggs dairy products and grains are poor sou
Vitamin C maintenance
Destroyed by oxygen, white, and heat so it is readily lost in cooking. This loss is accelerated and low-acid foods and by the use of copper or iron cooking utensils.
Smoke and vitamin C
Cigarette smoking increases the requirement for vitamin C because the vitamin is used to break down compounds in cigarette smoke. It is recommended that smokers consume an extra 35 milligrams of vitamin C daily which can easily be supplied by a half cup o
Vitamin C supplements
Help reduce duration of cold symptoms and has been suggested to reduce the risk of cardiovascular disease and cancer but it is not supported by sufficient evidence
High doses of supplemental vitamin C
Can cause diarrhea, nausea, and abdominal cramps. In susceptible individuals high-dose supplements may increase the risk of kidney stone formation because vitamin C can be metabolized to a compound found in some kidney stones. In individual's who are unab
UL for vitamin C
2000 milligrams per day from food and supplements
Substances that form vitamin life functions but are not classified as Vitamins because adequate amounts can be synthesized in the body
Carnitine which is needed to transport fatty acids into the mitochondria where they are broken down to produce ATP, lipoic acid which functions as a coenzyme and inositol which is important for membrane function
Choline
A water soluble substance that may be included in vitamin B complex supplements period needed for the synthesis of the neurotransmitter acetylcholine, the structure and function of cell membranes, lipid transport, and homocysteine metabolism. It can be sy
Choline deficiency
During pregnancy it can interfere with brain development in the fetus and deficiency in adults causes fatty liver and muscle damage
DRI AI choline
550 milligrams per day for men and 425 milligrams per day for women
Sources of choline
Large amounts in egg yolks, liver, me and fish, wheat germ, and nuts. Deficiency is this unlikely in the US because intake is usually exceeded
riboflavin deficiency
- usually occurs in conjunction with other deficiencies b/c the same foods are sources of those vitamins and b/c riboflavin is needed to convert other vitamins into their active forms
Pellagra niacin deficiency
- A disease resulting from niacin deficiency, which causes dermatitis, diarrhea, dementia, and, if not treated, death.
- now rare in the US b/c of the enrichment of grains
- common in parts of Africa with corn based diet
- not common in central america b/
niacin deficiency
- early symptoms of pellagra include fatigue, decreased appetite, and indigestion and these symptoms are followed by symptoms (3 Ds)
- 3 Ds: dermatitis, diarrhea, dementia and if untreated, death
- cracked inflamed skin is characteristic and the rash most
good sources of niacin
- meat and grains
- fish, peanuts, whole and enriched grains
- can be synthesized in the body from the essential amino acid tryptophan
tryptophan
- essential amino acid used to make niacin
- used to make niacin only if enough is available to meet the needs of protein synthesis
- found in dietary protein
- 60mg of tryptophan can be used to make 1mg of niacin
niacin equivalents
- made because the need for niacin can be met through the synthesis of niacin from tryptophan
- one NE is equal to 1 mg of niacin or 60mg of tryptophan is needed to make 1 mg of niacin
niacin RDAs
- 16 mg NE/day for men
- 14 mg NE/day for women
Biotin
- One of the B vitamins, needed in energy production.
Pantothenic Acid
- One of the B vitamins, needed in energy metabolism.
AI for pantothenic acid
- 5 mg/day for adults
Vitamin B6 and functions
- One of the B vitamins, needed in protein metabolism.
- functions include amino acid metabolism, myelin formation, and red and white blood cell synthesis explain what occurs when B6 is deficient
good sources of B6
- meat and fish (chicken, organ meat, pork)
- whole grains and legumes, soybeans, sunflower seeds, brown rice
- bananas, broccoli, spinach
- refined grains (white rice and white bread) are not good sources of B6
- destroyed by heat and light
vitamin B6 deficiency
- leads to poor growth, skin lesions, decreased immune function, anemia, and neurological symptoms
- b/c it is needed for amino acid metabolism the onset of deficiency can be hastened by a diet low in vitamin B6 but high in protein
- many symptoms can be
coenzyme of vitamin B6 pyridoxal phosphate function
- needed for reactions that are essential to amino acid synthesis, the breakdown of amino acids for energy, and the use of amino acids for the synthesis of glucose and neurotransmitters
vitamin B6 and myelin
- needed for he synthesis of lipids that are part of the myelin coating on nerves
- myelin is essential for nerve transmission
- this role of vitamin B6 explains the neurological symptoms that occur with deficiency (numbness in tingling of hands and feet,
vitamin B6 and hemoglobin
- needed to synthesize hemoglobin, the oxygen carrying protein in red blood cells
- when deficient in B6 hemoglobin cannot be made so a type of anemia characterized by small pale red blood cells develops
- B6 is needed to form white blood cells which are
homocysteine
- if B6 is low homocysteine which forms from the amino acid methionine cannot be converted into the amino acid cysteine, so levels rise.
- a mild elevation in homocysteine levels increases the risk of cardiovascular disease
RDA B6
- for adults 19 to 50
- 1.3 mg/day
high intake of B6
- no adverse effects have been associated with high intake but large doses in food supplements can cause severe nerve impairment
B6 UL
- 100 mg/day
B6 Supplements
- reduce symptoms of premenstrual syndrome (PMS), carpal tunnel syndrome, and strengthen immune functions (old people)
Folate
- A general term that refers to the many forms of this B vitamin, which is needed for the synthesis of DNA and the metabolism of some amino acids.
- important during pregnancy for development of embryo
folate deficiency
- increases risk of birth defects called neural tube defects
- the formation of the tube which later develops into the brain and spinal chord occurs early so folate intake is important during early days of pregnancy
- cells cannot divide normally which le
Neural Tube Defects
- An abnormality in the brain or spinal cord that results from errors that occur during prenatal development.
Folic Acid
- An easily absorbed form of the vitamin folate that is used in dietary supplements and fortified foods.
- to ensure adequate folate intake in women of childbearing age in 1998 the FDA mandated that folic acid be added to all enriched grains and cereal pr
neural tube defects
- abnormalities in formation of neural tube result in defects such as spina bifida
- during the embryonic development a groove forms in the plate of neural tissue and then the edges fold ip to form the neural tube which will become the brain and spinal ch
spina bifida
- happens when the lower portion of the neural tube does not close normally
- spinal chord forms abnormally
- many have learning disabilities and nerve damage that causes varying degrees of paralysis of the lower limbs
anencephaly
- occurs when the head end of the neural tube does not close properly
- the brain does not form completely which results in partial or total absence of the brain
- babies are usually blind, deaf, and unconscious and die soon after birth
folate and folacin
- general terms for compounds whose chemical structures and nutritional properties are similar to those of folic acid
folic acid
- added to enriched grains and fortified products used in dietary supplements
- more easily absorbed so its bioavailability is twice of folate found naturally in foods
RDA for folate (DFEs)
- expressed in dietary folate equivalents (DFEs)
- correct for differences in the bioavailability for different forms of folate
- one DFE is equal to 1 microgram of food folate, .6 micrograms of synthetic folic acid from fortified food or supplements cons
folate coenzymes
- needed for synthesis of DNA and the metabolism of some amino acids
- cell must synthesize DNA to replicate so folate is important in tissues in which cells are dividing rapidly (intestines, skin, embryonic and fetal tissues, bone marrow- where red blood
Pernicious Anemia
- A macrocytic anemia resulting from vitamin B12 deficiency that occurs when dietary vitamin B12 cannot be absorbed due to a lack of intrinsic factor.
- death sentence in early 1900s (cured with 4 to 8 ounces of liver every meal- effective)
- lack a prote
Vitamin B12
- One of the B vitamins, only found in animal foods.
- liver is a concentrated source
vitamin B12 absorption
- body stores and reuses B12 more efficiently than lost other water soluble vitamins so deficiency usually is caused by poor absorption
- absorption depends on presence of stomach acid, protein digesting enzymes, and intrinsic factor
Intrinsic Factor
A protein produced in the stomach that aids in the absorption of vitamin B12.
Cobalamin
The chemical term for vitamin B12.
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Atrophic Gastritis
- An inflammation of the stomach lining that results in reduced secretion of stomach acid, microbial overgrowth, and, in severe cases, a reduction in the production of intrinsic factor.
- results from B12 deficiency
- reduces the secretion of stomach acid
Vitamin C (ascorbic acid)
- A water-soluble vitamin needed for the maintenance of collagen.
Scurvy
A vitamin C deficiency disease characterized by bleeding gums, tooth loss, joint pain, bleeding into the skin and mucous membranes, and fatigue.
Choline
A compound needed for the synthesis of the phospholipid phosphatidylcholine and the neurotransmitter acetylcholine. It is important for a number of biochemical reactions, and there is evidence that it is essential in the diet during certain stages of life
Retinoids
Chemical forms of preformed vitamin a. includes retinol, retinal, and retinoic acid.
retinal and retinoic acid
formed in the body from retinol consumed in the diet
Carotenoids
Yellow, orange, and red pigments synthesized by plants and many microorganisms. Some can be converted to vitamin A
- once inside the body can be converted into retinoids
retinol activity equivalents
- used to express the amount of usable vitamin A in foods; 1 RAE is the amount of retinol, Beta carotene, alpha carotene, or beta cryptoxamthin that provides vitamin A activity equal to 1 microgram of retinol
carotenoids and retinol
- bound to proteins in foods so to be absorbed they must be released from protein by pepsin and other protein digesting enzymes. In the small intestine they combine with bile acids and other dietary fats to be absorbed. Low fat intake (less than 10g/day)
proteins and zinc and vitamin A
- vitamin A must be bound to retinol-binding protein to move from the liver stores to other body tissues
- zinc deficiency can cause a vitamin A deficiency b/c zinc is needed to make proteins involved in vitamin A transport and metabolism
Retinol-Binding Protein
A protein that is necessary to transport vitamin A from the liver to tissues in need.
Rhodopsin
- vitamin A
- retinal is part of this
- A light-sensitive compound found in the retina of the eye that is composed of the protein opsin loosely bound to retinal.
- when light hits it a series of events breaks apart rhodopsin and cause nerve signal to be s
Excess choline intake
Causes a fishy body odor, sweating, reduced growth rate, low blood pressure, and liver damage. The amount needed to cause the symptoms are much higher than can be obtained from foods
UL for choline
3.5 grams per day
Vitamin A
Needed for vision and healthy eyes
Beta carotene
A pro vitamin that can be converted into Vitamin A in the body. Most potent vitamin a precursor
Vitamin A in the diet
Is found preformed and then Pro vitamin formed in the diet.
Alpha carotene and beta crytoxanthin
Pro-vitamin a carotenoid that is not converted into retinoids as efficiently as beta keratin. Alpha keratin is found in dark green vegetables, carrots and squash. The other is found in papaya sweet red peppers and winter squash and are also provitamin A c
Carotenoids
When not converted into retinoids function as antioxidants and that may play a role in protecting against cancer and heart disease
Meeting vitamin A needs
Can be met by consuming plant sources of pro-vitamin a carotenoids as well as animal sources of the performed vitamin. Carrots and broccoli are plentiful and beta-carotene. Most orange and yellow vegetables and fruits are also good sources as our other da
Carrots Meeting vitamin A needs
Eating one half cup of cooked carrots can provide enough vitamin for the entire day
Vitamin A RDA
900 micrograms per day for men and 700 micrograms per day for women. No specific recommendations have been made for intakes of carotenoids in their intake is considered only with regard to the amount of retinol they provide
Vitamin A functions
needed for cell differentiation which is the process whereby immature cells change in structure and function to become specialized. Vitamin A helps us see light because the retinal is part of rhododendron