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Chapter 7 – The Vitamins
Definitions and Classifications of Vitamins
●Vitamins
-Organic Compounds
-Vital to life
-Indispensable to body functions
-Needed in minute amounts
-Noncaloric essential nutrients
●Fat-Soluble Vitamins
-In general, absorbed into the lymph
-Travel in blood in association with protein carriers
-Stored in the liver or with other lipids in fatty tissues; some can build up to toxic concentratrions
-Vitamin A
-Vitamin D
-Vitamin E
-Vitamin K
●Water-Soluble Vitamins
-Absorbed directly into the blood stream
-Travel freely in blood stream
-Most are not stored to any great extent
-Excess excreted in urine
-Lower risk of toxicity than fat-soluble vitamins
-B vitamins
Thiamin (B1)
Riboflavin (B2)
Niacin (B3)
Folate
Vitamin B12
Vitamin B6
Biotin
Pantothenic acid
-Vitamin C
●Precursors = provitamins
-Transform to one or more active vitamin forms
The Fat-Soluble Vitamins
●ADEK
-Found in fats and oils of foods
-Require bile for absorption
-Stored in liver and fatty tissues until the body needs them
●Body can survive weeks of consuming foods that lack these vitamins
-As long as a diet as a whole provides average amounts that approximate recommended
intakes
-Excess vitamins A and D from supplements can easily reach toxic levels
●Deficiency is likely when diet is consistently low in fat-soluble vitamins
●Fat malabsorption diseases can cause loss in dissolved undigested fat
-Likewise, mineral oil laxatives
●Extraordinarily-low-fat diets
-Such diets interfere with absorption of these vitamins
●Three forms active in the body
-Retinol
-Stored in the liver
-Converted to other forms as needed
-Retinal
-Retinoic acid
●Plant-derived precursor: beta-carotene
Vitamin A
●A Jack of All Trades
-Vision
-Maintenance of body linings and skin
-Immune Defense
-Growth of bones and the body
-Reproduction
-Normal cell development
●Control of Gene Expression
-Retinoic acid activates or deactivates certain genes
-Affecting protein production
●Eyesight
-Light passes through the cornea before striking the retina
-Keratin accumulation (keratinization) of the cornea can occur with vitamin A
deficiency
-Can lead to xerosis (drying) and to thickening and permanent blindness
(xerophthalmia)
-If discovered early, can be reversed with vitamin A supplementation
-Can be prevented if a child regularly consumes fruits and vegetables
-The retina contains light-sensitive nerve cells
-Light bleaches the vitamin A-containing pigment rhodopsin
-This breaks off the vitamin, initiating an impulse to the optic center in the brain
-The vitamin reunites with the pigment, and there is a little vitamin A destruction
-Vitamin A must regenerate the supply
-If vitamin A supply runs low, a lag occurs before the eye can see again after a flash of
bright light (night blindness)
-May indicate vitamin A deficiency
●Skin and Body Linings
-Vitamin A is needed by all epithelial tissues
-These tissues serve as protection from invasion by pathogens as well as to other
damage
-Vitamin A promotes cell differentiation
-When deficient, cell differentiation and maturation are implied
-Leading to, for example, a failure of mucus-producing cells to produce mucus
and a subsequent increase in keratin-producing cells
-Making tissue more vulnerable to infection
-Retinoic acid is being studied as a possible cancer treatment
●When deficient:
-Keratinization of the cornea leads to xeropthalmia
-In the lungs, displacement of mucus-producing cells increase the risk of repiratory
infection
-In the vagina, this process leads to vaginal infections
●Immunity
-Plays a role in the regulation of genes that produce immune system proteins
-Vitamin A deficient child, for example:
-Weak immune system  severe measles  vitamin A stores used by immune
system and disease infection causes vitamin A to be lost from body  less
vitamin A, the worse the disease  even if disease is survived, there is likely to
be corneal damage
●Vitamin A Deficiency around the World
-Worldwide about 3-10 million of children suffer from signs of severe Vitamin A
deficiency
-Xeropthalmia, blindness, diarrhea
-Reduced food intake worsens condition
-About 275 million more children suffer milder deficiency
-Impaired immune system and increased infection risk
●In some areas, Vitamin A and other deficiencies are the norm
●Supplemental vitamin A cuts childhood death rates by about 50%
-In U.S. vitamin A supplements are recommended for certain groups of infants and
children with measles
●Vitamin A supplementation is of benefit to those suffering complications from diseases
such as malaria, lung diseases, and HIV
●Vitamin A Toxicity
-From supplements or fortified foods
-Abdominal pain, hair loss, joint pain, stunted growth, bone and muscle soreness,
cessation of menstruation, nausea, diarrhea, rashes, liver damage, enlarged spleen, may
weaken the bones
-Early symptoms: loss of appetite, blurred vision, growth failure in children,
headache, skin itching, irritability
-Pregnant women
-Chronic use of supplements about 3x-4x amount recommended for pregnancy
may cause fetal malformation
-Single large dose (100x need) may cause fetal malformation
●Children who mistake chewable vitamin pills for candy are at risk
●Adolescents who take large doses thinking it will correct acne
-Accutane is derived from vitamin A
-Vitamin A itself has no effect on acne
●With the possible exception of liver, healthy people amounts of vitamin A-rich foods
without risking toxicity
●Vitamin A Recommendations
-Since the vitamin is stored, even though recommendations are given as a daily amount,
the vitamin need not be consumed every day
-DRI
Male: about 900 micrograms / day
Female: about 700 micrograms / day
-Higher when lactating
Children: less
●Diet that includes 5+ servings of vegetables and fruit per day is sufficient to meet needs
●Some food tables and supplements express vitamin A content in international units
(IU)
-1 IU = 0.3 micrograms retinol
●Avoid taking supplements that exceed the UL of 3,000 micrograms
●Sources of Vitamin A
-Vitamin A is found in foods of animal origin
-Richest sources are liver and oil
-Also milk, milk products, and fortified foods
-Plants contain beta-carotene, a vitamin A precursor
●Beta-Carotene
-Most abundant of the caratenoid precursors
-Vitamin A activity for vitamin A precursors is measured in retinol activity equivalents
(RAE)
-about 12 micrograms of beta-carotene = about 1 RAE
●Excessive beta-carotene will not cause vitamin A toxicity
-However, it can cause people to turn a bright yellow due to deposition in subcutaneous
fat
●Does Eating Carrots really promote good vision?
-Yes, as do all bright (deep) orange fruits and vegetables
-Along with dark green vegetables
●Carotenoids and Diseases
-Lack of dietary beta-carotene increases the increase of the most common form of
untreatable age-related blindness, macular degeneration
-Progressive loss of function of the part of the retina most crucial to vision
●Beta-carotene from foods and elevated beta-carotene in the blood are associated with
reduced cancer risk
-Beta-carotene supplements do not show the association
-Smokers who take beta-carotene supplements are at an increased risk of cancer
●Beta-carotene is one of the major dietary antioxidants
-Along with: vitamin E, vitamin C, selenium, and many other phytochemicals
-Dietary antioxidants are just one class of a large number of substances in whole foods
that seem to benefit health synergistically
Vitamin D
●Not essential in the sense that the body can make all it needs with the help of sunlight
-However, many people, especially African and Mexican Americans, may border on
vitamin D insufficiency
●Roles of vitamin D
-Regulation of blood calcium and phosphorus levels
-Often at a generous level
-When more calcium is needed vitamin D acts to raise blood calcium levels
-Draws calcium from bone
-Promotes calcium absorption
-Promotes calcium retention by the kidneys
●Functions as a hormone
●Plays a role in the brain, heart, stomach, pancreas, skin, reproductive organs, some
cancer cells, stimulates cell maturation (including immune system cells)
●Deficit promotes:
-high blood pressure, some cancers, type 1 diabetes, heart disease, rheumatoid arthritis,
multiple sclerosis
●Too Little Vitamin D – A Danger to Bones
-Rickets
-Vitamin D deficiency disease in children
-Characterized by abnormal bone growth
-Bowed, or knock-knees, outward-bowed chest, knobs on ribs
●Adolescents who consume soft drinks rather than fortified milk and who prefer indoor
to outdoor activities often lack the vitamin D that is needed to prevent bone loss later in
life
●Older individuals may have painful joints and muscles due to low vitamin D levels
●Osteomalacia, the adult form of rickets
-Characterized by an overabundance of unmineralized bone protein
-Most often occurs in women with low calcium intake and little exposure to the sun and
who go through repeated pregnancies and periods of lactation
●Too much Vitamin D – A Danger to Soft Tissue
-Most potentially toxic of all vitamins
-May be directly toxic to the bones, kidneys, brain, nerves, heart, arteries
-Toxicity symptoms include: appetite loss, nausea, vomiting, increased urination,
increased thirst, severe form of psychological depression due to effects on the central
nervous system
●If overdoses continue: dangerously high blood calcium levels arise, forcing calcium to
be deposited in soft tissues
-Such as the heart, blood vessels, lungs, kidneys, pulp cavity of teeth (while enamel thins)
●At risk:
-Infants whose parents think that if some is good more is better
-Older people who over-supplement
●Intakes of 5x recommendations have been associated with signs of vitamin D toxicity
●UL: 50 micrograms per day (2,000 IU on supplement labels)
●How Can People Make a Vitamin from Sunlight?
-Most people rely on exposure to sunlight to maintain adequate vitamin D nutrition
-UV exposure to a cholesterol compound in the skin transforms it into a vitamin D
precursor which is absorbed into the blood
-The liver and kidneys finish converting the precursor to the active form of
vitamin D
●Skin synthesis of vitamin D poses no risk of toxicity
-The sun itself begins breaking down excess vitamin D made in the skin
-Sunbathers are at risk of skin damage and skin cancer
-Sunscreens with SPFs of 8 or above can reduce these risks, but they also prevent
vitamin D synthesis
●In most places, during warmer months, just being outdoors when the sun is overhead,
even in lightweight clothing, promotes skin synthesis of vitamin D
●Factors affecting sun exposure and vitamin D synthesis
-Skin color, air pollution, city living, clothing, geography, indoor lifestyle, season,
sunscreen, time of day
●Recommendations for vitamin D intake increases with age
-19 to 50 years: 5 micrograms / day
-51 to 70 years: 10 micrograms / day
-70+ years: 15 micrograms / day
●Sources:
-Small amounts from butter, cream, fortified margarine
-Fortified milk, sunlight
-Only two fortified plant sources exist:
margarines and certain cereals
Vitamin E
●Consists of four tocopherol comounds
-Alpha, beta, gama, delta
-Alpha-tocopherol is the standard for vitamin E activity
●The Extraordinary Bodyguard
-Antioxidant defending the body against oxidative damage
-Damage that results when free radicals formed during normal metabolism disrupt the
structure of cellular lipids, DNA, proteins
●Free radical activity may lead to cancer, heart disease or other diseases
●Vitamin E is preferentially oxidized, thus protecting cells
●Vitamin E’s antioxidant effect is especially crucial in the lunds
-Where cells are exposed to high oxygen concentrations
●Also protects red blood cells, white blood cells, may play other roles in immunity, plays
a role in nerve development
●Supplements do not provide health benefits
-However, supplements may improve the immune response in healthy elderly
people
●Vitamin E Deficiency
-Wide variety of symptoms in laboratory animals, most symptoms not reproduced in
humans
-Vitamin E is widespread in food, making it difficult to create a vitamin E-deficient diet
-Body stores large amounts in fatty tissues
-Cells recycle vitamin E
●Infants born before the transfer of vitamin E from the mother to the infant
-Erythrocyte hemolysis, resulting in anemia
●Adults: loss of muscle coordination and reflexes with impaired movement, vision, and
speech
●Associated with fat malabsorption diseases
-disease or injury to the liver, gallbladder, pancreas
●Low intakes likely when extremely-low-fat diets are consumed for years
-People who rely solely on fat replacers to the exclusion of real fat
●Vitamin E is destroyed by food processing and heating
●Chronically low intake may play a role in other diseases
-Low body stores of vitamin E and selenium promote viral virulence
●Research has discredited claims that supplemental vitamin E:
-Improves athletic endurance and skill
-Enhances sexual performance
-Cures male sexual dysfunction
●Vitamin E Requirements, Toxicity, and Sources
-DRI: 15 milligrams / day
-Average U.S. intake falls below this
●Need increases with increased polyunsaturated fatty acid (PUFA) intake
●Destroyed by heat processing and oxidation
●No toxicity from food sources
●Ordinary supplemental doses over a period of months do not seem to induce toxicity
●In humans, occasional reports of breast soreness in women, fatigue, emotional distress,
and other vague complaints
●Large doses may increase the effects of anticoagulant medications
●Brain hemorrhages may occur in smokers taking 50 milligrams / day for over 6 years
●UL for alpha-tocopheral: 1,000 milligrams (450 IU)
●Widespread in foods
-Most raw oils
-20% of dietary vitamin E comes from vegetable oils
-20% from fruits and vegetables
-none of which qualify as a good source
-15% from fortified cereals and other grain products
●Smaller amounts from meat, poultry, fish, eggs, milk products, nuts, seeds
●Wheat germ is a good source
●Animal fats have almost no vitamin E
Vitamin K
●Functions:
-Synthesis of blood clotting proteins
-Does not improve clotting in those with diseases such as hemophilia
-Interferes with function of blood thinners
-Synthesis of normal form of bone proteins that bind minerals to bone
-Adequate intake may reduce risk of hip fracture
●Sources:
-Leafy green vegetables
-Cooked spinach and collard greens average 300 micrograms / 3 ounces
-Lettuce, broccoli, other members of the cabbage family average 100 micrograms
/ 3 ounces
-Intestinal bacteria, canola and soybean oils, fortified cereals
-1 egg and 1 cup of milk: 25 micrograms each
●At birth newborns are given a dose of vitamin K to hold them until vitamin Kproducing bacteria establish themselves in their intestinal tract
●Deficiency
-Unlikely in adults
-Even if the seldom eat vitamin K-rich foods
-At risk:
-Newborns
-Those who have taken antibiotics that kill the beneficial, along with the harmful,
bacteria in their intestinal tract
-Low bile production
●Toxicity
-Rare among healthy adults
-No UL
-Infants and pregnant women:
-Toxicity can result from oversupplementation with synthetic vitamin K
●Symptoms of Toxicity
-Red blood cell breakage
-Colors skin yellow
-Liver release of bilirubin into blood
-leads to jaundice
-Bilirubin in the brain of an infant can cause brain damage or death
The Water-Soluble Vitamins
●Viamin C and the B Vitamins
-Cooking and washing with water leaches them out of food
-Easily absorbed
-Excess easily excreted in urine
-Some can remain in lean tissues for 1+ months
●Advice for meeting needs
-Choose foods that are rich in water-soluble vitamins to achieve the recommended
intakes over 3 days’ time
●Toxicity
-Never from food
-Can occur from the large doses concentrated in some vitamin supplements
-Those the usual result will be to have expensive urine
●Vitamins for Athletes
-Competitive athletes with an appropriate diet almost never need supplements
-The increased energy needed to fuel exercise requires increased energy
consumption
-With an appropriate diet, the needed vitamins automatically follow
Vitamin C
●Scurvy
-Vitamin C (ascorbic acid) deficiency
-Hazard of long distance seagoing journeys of 200+ years ago
-To avoid scurvy, British sailors were given lime juice
●The Work of Vitamin C
-Mainenance of connective tissues
-Formation and maintenance of collagen
-Component of bones, teeth, skin, tendons, scar tissue, capillaries
-Cofactor in the production of carnitine
-Plays a role in transporting fatty acids within cells
●Antioxidant
-Protects substances found in foods and the body by being oxidized itself
-Some oxidized vitamin C is lost and must be replaced by the diet
-Much is not lost and is recycled back to the active form
-In the intestines, protects iron from oxidation
-Thus promoting its absorption
●In the blood
-Protects blood constituents from oxidation
-Protects and recycles Vitamin E
●Supplements seem useless against heart disease, cancer, other diseases
-Unless they are prescribed to treat a deficiency
●In test tubes, high concentrations of vitamin C act as a prooxidant
-Activating oxidizing elements, such as iron and copper
-One study of men given 500 milligrams / day showed an increase in markers of
oxidation
●Deficiency Symptoms
-Most scurvy symptoms are due to the breakdown of collagen
-Loss of appetite, growth cessation, loose teeth, swollen ankles and wrists tiny red
spots in the skin where blood has leaked out of capillaries, anemia
●Risk of scurvy in the U.S. is low, with the exception of
-Some elderly people
-Low intakes of fruits and vegetables combined with a poor appetite lead to low
vitamin C intakes
-People addicted to alcohol or other drugs
-Infants fed cow’s milk who do not receive vitamin C in formula, fruit juice, or other
sources
-Breast milk and infant formula supply enough vitamin C
●Vitamin C supports immune system function and so protects against infection
Vitamin C and the Common Cold
●Studies are yet to conclusively show that vitamin C can prevent or reduce the severity
of colds
●One group of researchers have found the following
-Daily dosages of vitamin C, taken regularly, do not prevent colds
●The same group of researchers have also found
-Some small benefit from vitamin C in high doses (1 gram) taken at the onset of a cold
-This may shorten the duration of colds by about 1.5 days and reduce the severity of
symptoms by about 40%
-The effect may be greater in children then adults
-In adults, doses near the UL (2 grams/day) may be required to produce any effect
●Two grams per day for 2 weeks seems to reduce blood histamine
-The substance responsible for sneezing, runny or stuffy nose, swollen sinuses
-At these doses, Vitamin C may work like a weak antihistamine
-Or its antioxidant or other activities may improve the body’s immunity
●The placebo effect
-In one study, half the experimental subjects received a placebo but thought they were
receiving vitamin C
-This group reported having fewer colds than the group that had received vitamin C but
thought they were receiving the placebo
●Is too much Vitamin C Hazardous to Health?
-One effect observed with a 2-gram dose is alteration of insulin response to carbohydrate
in people with otherwise normal glucose tolerances
-Other adverse effects include digestive upsets, such as nauseas, abdominal cramps,
excessive gas, diarrhea
●Massive doses may interfere with medications to prevent blood clotting
●And may be dangerous for people with an overload of iron in the body
-Vitamin C increases iron absorption and releases iron from storage
●Rarely is consuming more than 100-300 milligrams / day beneficial
-Absolute minimum is 10 milligrams / day
-UL: 2 grams
●Those with kidney disorder and those with too much iron in their blood may be more
susceptible to adverse effects
-Should avoid taking vitamin C supplements
●Vitamin C from food is always safe
●The Need for Vitamin C:
-Adult DRI
-Males: 9 milligrams
-Females: 75 milligrams
-These amounts are close to the point at which the body’s pool of vitamin C is
full: about 100 milligrams / day
●Food Sources of Vitamin C
-300 milligrams : 1 cup orange juice for breakfast, salad for lunch, stalk of broccoli, a
potato for dinner
-Vitamin C in fruits and vegetables are prone to destruction by heat and oxygen
-Fresh, raw, and quickly cooked are best
-Store properly and consume promptly
The B Vitamins in Unison
●B vitamins act as part of coenzymes
-A small molecule that combines with, and activates, an enzyme
●B vitamins’ Role in Metabolism
-Metabolism of carbohydrates, lipids, and amino acids
-Thiamin, riboflavin, niacin, panthothenic acid, and biotin all help release the energy
stored in the energy-yielding nutrients
●Vitmain B6 helps the body make protein
●Folate and vitamin B12 help cells to multiply
●B Vitamin Deficiencies
-Every cell is affected
-Symptoms include: nausea, severe exhaustion, irritability, depression, forgetfulness, loss
of appetite and weight, muscle pain, impaired immune response, loss of control of the
limps, abnormal heart action, severe skin problems, swollen red tongue, teary or blood s
hot eyes
●Cell renewal depends on energy and protein which depend on the B vitamins
-Digestive tract and blood are damaged
-In children, full recovery may be impossible
-A thiamin deficiency during growth can cause permanent brain damage
●Deficiency of any one B vitamin rarely shows up alone
Thiamin (B1)
●Role
-Energy metabolism
-Nerve processes and tissue reponse
●Deficiency: beriberi
-Loss of sensation in the hands and feet, muscular weakness, advancing paralysis,
abnormal heart action
-Wet beriberi
-Characterized by edema
-Dry Beriberi
-No edema
●Deficiency: Wernicke-Korsakoff Syndrome
-Alcohol abuse with severe thiamin deficiency
-Alcohol displaces food in the diet, impairs thiamin absorption, promotes thiamin
excretion in the urine
-Symptoms: Apathy, irritability, mental confusion, disorientation, loss of memory, jerky
eye movements, staggering gait
-almost indistinguishable from alcohol abuse itself
-Treatment: thiamin injection
●Sources
-Small amounts in many foods
-Pork products, leafy green vegetables, whole grain cereals, legumes
-DRI:
-Men: 1.2 mg/day
-Women: 1.1 mg/day
-higher if pregnant or lactating
Riboflavin
●Role
-Energy metabolism of all cells
●Deficiency
-Likely when thiamin is deficient
-May go undetected because thiamin deficiency symptoms are more severe
-At risk:
-Children who lack milk products and meat
-Perhaps some U.S. elderly
-Symptoms: cracks at the corner of the mouth (cheilosis), Hypersensitivity to light,
reddening of the cornea, skin rash
-Treatment: A diet that remedies riboflavin deficiencies also remedies a thiamin
deficiency
●Sources
-Milk and milk products
-Leafy green vegetables
-Whole-grain breads
-Fortified cereals
-Some meats
Niacin
●Role
-Energy metabolism
●Deficiency
-Pellagra
-Diarrhea
-Dermatitis
-Dementia
-Death
●At risk for pellagra:
-Poorly nourished people living in urban slums
-Particularly those with alcohol addiction
-Still common in parts of Africa and Asia
●Sources
-Tryptophan, which is abundant in almost all proteins, can be converted to niacin
-Thus a person eating adequate protein will not be deficient in niacin
-Niacin in the diet is stated in terms of niacin equivalents (NE)
●Toxicity
-Large doses of a form of niacin may be a part of a treatment to lower blood lipids
associated with cardiovascular disease
-Do not try this at home
-Large doses of niacin can injure the liver, cause peptic ulcers, cause vision loss
●Certain forms of niacin supplements in amounts 2x-3x the DRI can cause niacin flush:
-Dilation of the capillaries of the skin with perceptible tingling that, if intense, can be
painful
Folate
●Role
-DNA synthesis
-Metabolism of several amino acids
●Deficiency
-Because immature red and white blood cells and cells of the GI tract divide rapidly, they
are most vulnerable to a deficiency
-Anemia
-Related to anemia of vitamin B12 malabsorption
-Diminished immunity
-Abnormal digestive function
●With deficiency, some evidence for increased
-Cardiovascular risk
-Colon cancer risk
-Cervical cancer risk
●Deficiency may result from
-Inadequate intake
-Illnesses that impair folate absorption
-Increased excretion
-Medications that interact with folate, or otherwise increase the body’s need
●Neural tube birth defects
-Range form slight problems in the spinal cord to mental retardation
-Severely diminished brain size
-Death shortly after birth
-Arise in the first few days or weeks of pregnancy
-Most women eat too few fruits and vegetables to supply even 50% of the folate
needed to prevent such birth defects
●All enriched grain products are fortified with folic acid
-An especially absorbable synthetic form of folate
-Since fortification began, folate intakes have increased and there has been an almost
25% drop in the national incidence of neural tube defects
-It is expected that there will also be declines in some other birth defects and
miscarriages
●Toxicity
-UL for synthetic folate from supplements and enriched foods is 1,000 micrograms/day
-Folate can mask vitamin B12 deficiency
-Excess folate may be antagonistic to the actions of some anticancer drugs
●Unit of measure
-Synthetic folate that enriches foods and is in supplements is absorbed more readily than
naturally occurring food folate
-Dietary Folate Equivalent (DFE) converts all forms of folate into units that are
equivalent to the folate in food
●Sources
-Leafy green vegetables
-Fresh, uncooked vegetables and fruits
-The heat of cooking and oxidation that occurs during storage destroy much of the
folate in foods
-Eggs contain folate
-Orange juice and legumes contain folate
-Contain factors that may interfere with folate absorption
-Milk may enhance folate absorption
●DRI
-Heathy adults: 400 micrograms / day
-Women of childbearing age: 400 micrograms / day of folic acids from supplements or
enriched foods in addition to the folate that naturally occurs in their foods
●Medications
-Of all the vitamins, folate is most likely to interact with medications
-Ten major groups of drugs, including antacids and aspirin and its relatives, oral
contracetptives, anticonvulsants, smoke interfere with the body’s use of folate
-Occasional use of these drugs is ok
-Frequent users need to pay attention to their folate intake
Vitamin B12
●Role
-Vitamin B12 is activated by folate
-Folate is activated by vitamin B12
-Maintenance of the sheaths that surround and protect nerve fibers
●Deficiency
-Damaged nerve sheaths
-Creeping paralysis
-General malfunctioning of nerves and muscles
●Deficiency results in failure of folate to make red blood cells
-Therefore, a vitamin B12 deficiency causes an anemia (pernicious anemia) identical to
that of folate
-Large, immature red blood cells
-Treatment: administration of folate
-However, this allows the deficiency of B12 to continue undetected
●At risk
-The possibility that folic acid enrichment of grains is masking B12 deficiencies
-Especially amoung vegetarians and the elderly
-Individuals who generally depend heavily on grains and consume little or no
meat or other animal products
-Malabsorption problems
●The uniformed, strict vegetarian is especially at risk
-May not show signs of deficiency right away because the body stores up to six years’
worth of the vitamin
●Pregnant or lactating vegetarian women may put their infant at risk of a vitamin B12
deficiency
-Resulting in irreversible nerve system damage
-Recognized when the infant displays nerve and cognitive problems that can last
into childhood
●All strict vegetarians must be sure to use vitamin B12 –fortified products
-Vitamin B12-fortified soy drink, supplements
●Diagnosis of deficiency is difficult
●Often the damage will proceed unchecked
●Absorption
-Requires intrinsic factor
-A compound made by the stomach
-The stomach’s acid liberates vitamin B12 from food; intrinsic factor then binds
to the vitamin
-The complex is then absorbed from the small intestine into the blood
-In a few people an inherited defect in the gene for intrinsic factor makes vitamin B12
absorption abnormal, beginning in mid-adulthood
●In later years, many people lose the ability to produce sufficient stomach acidity and
intrinsic facto
-Leaving them vulnerable to chronic stomach infections and reduced ability to absorb
vitamin B12
●Treatment for defective absorption is B12 injections
●Sources
-Foods of animal origin
-Not in foods from plants
Vitamin B6
●Role
-100+ reactions in the tissues
-Needed to convert one kind of amino acid into other nonessential amino acids
-Aids in the conversion of tryptophan to niacin
-Hemoglobin synthesis
-Neurotransmitter synthesis
-For example, assists in the conversion of tryptophan to serotonin
-Assists in release of stored glucose from glycogen
-Contributing to the regulation of blood glucose
-Immune function
-Steroid hormonal activity
-Fetal brain and nervous system development
-Deficiency during this stage causes behavioral problems later
●Deficiency
-Weakness
-Psychological depression
-Confusion
-Irritability
-Insomnia
-Greasy dermatitis
-Advanced cases of deficiency: convulsions
-May weaken the immune system
-Evidence that low intakes may be related to increased risk of heart disease
●Toxicity
-UL: 0.1 gram
-Women who took 2+ grams /day in a mistaken attempt to cure PMS symptoms
-Numb feet
-Lost sensation in their hands
-eventually became unable to walk or work
-Recovered after they stopped taking the supplements
●A single B6 supplement can deliver 2 grams of the vitamin, the equivalent of 3,000
bananas or 1,600+ servings of liver, or 3,800+ chicken breasts
●Need
-Due to its roles in protein metabolism need is proportional to protein intake
●Sources
-Protein-rich foods
-Meats, fish, poutry
-Potatoes, leafy green vegetables, some fruits
-Legumes and peanut butter
How Are B Vitamins Related to Heart Disease?
●Homocysteine
-Inherited high levels correlate with a severe early form of cardiovascular disease (CVD)
-Some CVD sufferers without the inhereited disorder also accumulate homocysteine in
the blood
-Elevated homocystein may be an indicator of CVD risk
●A lack of some B vitamins in the diet contributes to elevated homocysteine levels
●Deficiencies of folate or vitamin B12 or B6 causes excess homocysteine to build up in
the blood
-Supplements of these vitamins lead to a significant drop in homocysteine level
-It is unknown how this affects a person’s CVD risk
●High dietary intakes of folate and vitamin B6 correlate with lower blood values of other
substances associated with CVD
-So far all evidence is circumstancial
Biotin
●Role
-Energy metabolism
-Cofactor for several enzymes in the metabolism of carbohydrate, fat, protein
●Deficiency
-Rare diseases
-Consumption of 24+ raw egg whites per day, which contain a protein that binds biotin,
will result in a deficiency
-Cooking eggs denatures this protein
-Symptoms: abnormal heart action, loss of appetite, nausea, depression, muscle pain,
weakness, fatigue, numbness of extremeties, dry around eyes, nose and mouth
●Sources
-Wide spread in foods
Pantothenic Acid
●Role
-Energy metabolism
-Coenzyme that plays a role in the release of energy from the energy nutrients
-Plays a role in 100+ steps concerned with the synthesis of lipids, neurotransmitters, and
hemoglobin
●Deficiency
-Rare diseases
-Symptoms: Vomiting, intestinal distress, insomnia, fatigue, hypoglycemia, increased
sensitivity to insulin
●Sources
-Widespread in foods
Non-B Vitamins
●Choline
-When there is none in the diet, the body cannot make enough to meet its needs
-Common in foods
-Deficiencies are practically unknown outside the laboratory
●Carnitine = vitamin BT
-Non-vitamin: not an essential nutrient from humans
-An important component of cells
-Deficiencies can be experimentally induced
-Abundant in ordinary foods
-Supplements unnecessary for healthy people eating a balanced diet
●Inositol
-Non-vitamin: not an essential nutrient for humans
●Lipoic acid
-Non-vitamin: not an essential nutrient for humans
Controversy: Vitamin Supplements: Who Benefits?
●Nearly 40% of the U.S. population take a vitamin supplement
●What the Experts are saying
-Some conclude that healthy people might benefit from a multiple vitamin supplement
taken every day or two
-Others conclude that the potential risks of supplementation outweigh the unproven
benefits
-Supplements should only be taken when there is a risk of deficiency
-People who omit any major food group probably need certain supplements
-Beta-carotene supplements are probably hazardous
-Especially to those who smoke and consume alcoholic beverages
-Limit intake of preformed vitamin A
-Elevated vitamin A in the blood is a marker for increased risk of hip fractures
●Some Valid Reasons for Taking supplements
-People with nutrient deficiencies
-Women in their childbearing years (supplemental or enrichment sources of folic acid are
recommended to reduce risk of neural tube defects in infants)
-Pregnant or lactating women (they made need iron and folate)
-Newborns (they are routinely given a vitamin K dose)
-Infants (they made need various supplements)
-Those who are lactose intolerant (they need calcium to forestall osteoporosis
-Habitual dieters (they may eat insufficient food)
-Elderly people often benefit from some of the vitamins and minerals in a balanced diet
-Victims of AIDS or other wasting illnesses (they lose nutrients faster than foods can
supply them)
-Those addicted to drugs or alcohol
-Those recovering from surgery, burns, injury, or illness (they need extra nutrients to help
regenerate tissues)
-Strict vegetarians (they may need vitamin B12, vitamin D, iron, and zinc)
-People taking medications that interfere with the body’s use of nutrients
●Supplements Must Be Safe, or the Government Would Not Allow Their Sales, Right?
-The FDA does not test supplements to ensure their safety and effectiveness
●The FDA is to ensure that supplements do not pose a “significant or unreasonable risk”
or illness or injury to consumers
-Requires safety documentation and reports of adverse effects from manufacturers
-Who are not required to supply such information
-Consumers may report adverse effects directly to the FDA
●Dietary Supplement Health and Education Act (DSHEA)
-Supplements
-Must provide a Supplement Facts panel of nutrient information
-Must not be adulterated
-Must not make label claims for the diagnosis, prevention, treatment, or cure of
illness
-May bear “structure/function” claims
●Result has been the deregulation of the supplement industry
●The FDA has identified hazardous supplements only after there has been actual harm to
consumers
●Problems Impending the FDA’s Oversight of Supplements: The FDA currently faces
four major problems with regard to supplemental oversight strategies:
1) The volume of supplement sales and use is too high to ensure adequate post-marketing
safety within the current legal structure
2) The FDA’s funding and staff are insufficient to allow identification of supplement
hazards and implementation of appropriate actions against them
3) The broad array of ingredients in the products sold impedes identification of hazards
4) Failure to require manufacturers to report serious adverse effects associated with
supplemental use undermines FDA efforts to ensure supplement safety
●Structure/Function Claims
-Less regulated than health claims
-Must include a disclaimer absolving the FDA from responsibility
●Marginal Deficiencies and Oxidative Stress
-For example, a diet lacking in vitamin C will have a subclinical increase in oxidative
stress before symptoms of scury appear
-Oxidative stress is damage inflicted on living systems by free radicals
●Suboptimal intakes of antioxidant nutrients may be linked to chronic disease
-As body cells use oxygen, they produce free radicals
-Radiation, pollution, tobacco smoke, etc. can also cause free-radical formation
-When free-radical activity in the body exceeds antioxidant defenses, a chain of oxidation
increases oxidative stress, triggering the onset of diseases
●The evidence linking antioxidant nutrients, oxidative stress, and chronic diseases is
inconclusive
●Diets rich in foods with abundant antioxidants correlate with low disease rates
●People whose blood is below normal for antioxidant nutrients have elevated rates of
chronic diseases
-Restoring these nutrients leads to a drop in chronic disease incidence
●Marginal Deficiencies, Cancer, and Other Diseases
-DNA damage from marginal deficiencies may mimic the cancer-causing damage from
radiation
-DNA is both damaged more readily when nutrients are lacking and more slowly repaired
-Resulting in a build up of damage that can cause disease
●Many forms of cancer occur among poorly nourished, low-income populations
-Reversing subclinical deficiencies may reduce the incidence of cancer and other diseases
among such people
●Menstruating women, young children and the elderly may suffer from the effects of
vitamin and mineral deficity
-Resolving these deficits may help reducte the incidence of a variety of illnesses
●Arguments Against Supplements For Chronic Disease Prevention
-The general results of research have shown the otherwise well-nourished people benefit
little, if at all, from taking supplements
-The healthy elderly may be an exception; they may benefit from taking supplements
●Should we Take Supplements to Ensure Adequate Nutrients?
-Food, not supplements, is the best source of nutrients
●Risks of supplementation
-High doses of vitamin A may delay blood clotting and may increase the risk of brain
hemorrhage
-For some people, vitamin C supplements may increase the risk of iron overload
-In high doses, vitamin C supplements increase markers of oxidation
-Daily supplements of beta-carotene may increase the risk of lung cancer in smokers
-Supplements of vitamins A and D and many minerals can be toxic in large doses
-High doses of vitamin E interfere with the blood clotting abilities of vitamin K
●Selection of a Multinutrient Supplement
-If you cannot meet your nutrient needs from food, a supplement containing nutrients
only can be of benefit
-When taking a supplement look for a USP on the label
-This means that the product contains the ingredients listed and that it will
dissolve or disintegrate in the digestive tract
-It does not mean that this supplement has been tested for safety or effectiveness
-Consider these questions
-What form do you want – chewable, liquid, pills?
-What vitamins and minerals do you need?
-Avoid supplements that provide a daily dose exceeding the DRI or the
UL for any nutrient
-Avoid
-“organic” or “natural” preparations with added substances are no better than
standard types, but cost much more
-“high potency” or “therapeutic dose”: more is NOT better
-items not needed in human nutrition
-“time release”: nutrients are incorporated into tissues where they are needed
whenever they arrive
-“stress formulas”: the DRI provides sufficient nutrients to meet your needs under
stress
-pills containing extracts of parsley, alfalfa, and other vegetable components
-Geriatric “tonics”: usually low in vitamins and minerals and high enough in
alcohol to inebriate
-any supplement sold with claims that today’s foods lack the nutrients they once
contained
-Local or store brands may be both cheaper and as good or better than nationally
advertised brands
-Take supplements with food