70 terms

Ch. 8 Water soluble vitamins

water soluble vitamins: general
1. Vitamin C and the B vitamins
2. Cooking and washing cut foods with water can these vitamins out of the food.
2. Absorbed easily and easily excreted in urine.
• "The most expensive urine in town"
3. Foods NEVER deliver a toxic dose of them
• but large doses concentrated in some vitamin supplements can reach toxic levels.
Vitamin C: functions (5)
**1. Assists enzymes involved in the formation and maintenance of collagen. Collagen synthesis=protein that gives strength to connective tissues
• Chief protein of most connective tissues
**2. Acts as an antioxidant
• especially protecting the immune system cells from free radicals generated during their assault on invaders
• Protects iron from oxidation, promoting its absorption
• Protects & recycles Vitamin E
3. Immune system functioning
4. Synthesis of bile, and certain neurotransmitters
and hormones
5. not part of a coenzyme
Vitamin C: sources
peppers, citrus fruits, papayas, broccoli, cabbage, berries
Vitamin C: name
ascorbic acid
Vitamin C: deficiency symptoms
1. most scurvy symptoms due to collagen breakdown
Loss of appetite
- Growth cessation
- Tenderness to touch
- Bleeding gums
- Swollen ankles and wrists
- Anemia
- Red spots on skin - Weakness
- Loose teeth
vitamin C: common cold (5)
1. More than 30 years ago, Linus Pauling, a Nobel Prize Winner, become a vocal supporter of vitamin C supplements.
2. The scientific community all but discounts his claims because research fails to support Pauling's theories.
3. One review of the literature did reveal a modest benefit - a difference in duration of less than one day per cold in favor of those taking a daily dose of at least 1 gram of vitamin C.
4. The effect may be greater in children than in adults (adults may need doses near the UL of 2 grams a day).
5. In drug-like doses, Vitamin C may act as a week antihistamine
Vitamin C: hazardous to health? (5)
1.Possible adverse effects of taking 2 grams a day:
- Alteration of the insulin response to carbohydrate
- Interference with blood clotting medications
- Kidney stones (calcium oxalate)
- Gout
- Digestive upsets
vitamin C: the need for (2)
1. There is a slight increased need for Vitamin C from a variety of Chemical and Physical stressors
- Tobacco Use
- Demanding physical activity
- Extremely cold environmental conditions
2. At high levels, Vitamin C may act as a pro oxidant (causing more damage) by altering the chemistry of metals like copper and iron, which can cause oxidative damage
vitamin c: intake
RDA = 75 to 90 mg/day (smokers have higher RDAs)
vitamin C: UL & toxicity
• UL is 2000 mg/day
• Kidneys excrete excess amounts of the vitamin &
oxalate, a byproduct of vitamin C metabolism.
- Increases risk of oxalate kidney stones, particularly in susceptible persons
Thiamin: Number
Riboflavin: number
Niacin: number & other names
B3, niacinamide
Pantothenic number
Biotin number
Folate number & other names
B9, folic acid, folacin
cobalamin number & other names
B12, commonly cyanocobalamin in vitamin supplements
pyridoxine number & other names
B6, pyridoxal, or pyridoxamine, or pyridoxine hydrochloride
B vitamins in unison (3)
1. B vitamins function as part of coenzymes
- help enzymes do their jobs
• Combines with enzyme to activate it as part of the enzyme's active site
2. Help the body use the energy-yielding nutrients for energy
3. Role in Cell multiplication
- formation and replication of DNA and protein
water soluble vitamins: general function
1. Most function as components of specific coenzyme
coenzyme: definition & characteristic
1. Coenzymes: small molecules that regulate chemical reactions by interacting with enzymes
2. coenzymes are composed of B vitamins & a nitrogen-containing substance
coenzyme action
Many enzymes require coenzymes to function.
Once activated, the enzyme-coenzyme complex
enables the reaction to occur.
B vitamin deficiencies (3)
1. In a B vitamin deficiency every cell is affected.
2. symptoms:• Abnormal heart action • Skin problems
• Swollen red tongue• Teary, red eyes• Pain in muscles
3. difficult to pin down individual deficiencies. rarely are isolated deficiencies
B vitamins: roles in metabolism (3)
1. Thiamin, riboflavin, niacin, pantothenic acid, and biotin - participate in the release of energy from the energy nutrients
2. Folate and vitamin B12 help cells multiply
3. Vitamin B6 helps the body use AA to synthesize proteins
Thiamin: functions (5)
- Plays a critical role in the energy metabolism of all cells. Part of coenzyme involved in release of energy from carbohydrates
- Metabolism of certain amino acids
- Synthesis of neurotransmitters
- Occupies a site on nerve cell membranes.
- Nerve processes and their responding muscles depend heavily on thiamin.
thiamin deficiencies (3)
1. Beriberi:
2. Wernicke-Korsakoff syndrome
3. very little stored so deficiency onset rapid
thiamin deficiencies: beriberi
1. People are weak, have poor muscular coordination, and may develop cardiovascular problems and edema. Note severe pitting edema in woman's left leg.
- First observed in East Asia, where rice provided 80 to 90 percent of the total calories most people consumed.
• Polished rice became widespread, and beriberi became epidemic (takes out vitamins)
• Thiamin was in the bran (brown rice), discarded when making white rice
- Wet Beriberi - with edema - Dry Beriberi - no edema
Effects=Loss of sensation in hands and feet, Muscular weakness, Advancing paralysis, Abnormal heart
thiamin deficiencies: Wernicke-korsakoff
In developed countries today, alcohol abuse often leads to a severe form of thiamin deficiency, Wernicke-Korsakoff syndrome.
- Alcohol impairs thiamin absorption & increases excretion
Symptoms =
• Apathy, irritability, mental confusion, memory loss, jerky movement, staggering gait
thiamin: sources
pork, wheat germ, enriched breads & cereals, brewer's yeast
thiamin: intakes
RDA = 1.2 mg/day (men) 1.1 mg/day (women)
Riboflavin: functions
1. coenzyme for metabolism of carbs, lipids & AA
riboflavin: general characteristics (2)
1. UV light & irradiation destroys riboflavin
- Keep milk in opaque containers
2. Stable to heat
riboflavin: intakes
- RDA = 1.3 mg/day (males) 1.1 mg/day
riboflavin: sources
milk, yogurt & other milk products, enriched breads & cereals, liver
riboflavin: deficiencies
1. May occur in people who do not drink milk or eat enriched grains
2. When thiamin is deficient, riboflavin usually is also
- Children whose diets lack milk, meat
- Some elderly
niacin: function
1. Part of two coenzymes that participate
in at least 200 reactions
-Participates in energy metabolism of every cell.
niacin: deficiency
1. pellagra
- which appeared in Europe in the 1700s when
corn from the New World became a staple food.
- Corn is low in a.a. tryptophan • Body can make niacin from tryptophan
- In the early 1900s in the U.S., pellagra was affecting hundreds of thousands in the South and Midwest.
niacin: pellagra (5)
1. Pellagra symptoms: 4 "D's"
- Diarrhea- Dermatitis - Dementia - Death
2. which appeared in Europe in the 1700s when
corn from the New World became a staple food.
- Corn is low in a.a. tryptophan • Body can make niacin from tryptophan
3. In the early 1900s in the U.S., pellagra was affecting hundreds of thousands in the South and Midwest.
4. still common in parts of Africa and Asia.
Pellagra still occurs in the U.S. among people,
especially those with alcohol addiction.
5. Low-protein, corn-based diet
niacin: sources definition
1.The key nutrient that prevents pellagra is niacin
2. Or, consuming adequate tryptophan which can be converted to niacin in the body
3. The amount of niacin in a diet is stated in terms of niacin equivalents (NE), a measure that takes available tryptophan into account
niacin: sources
enriches bread & cereal, beef, liver, tuna, salmon, poultry, pork, mushrooms
niacin: as a drug (2)
1. Supplements may be taken as a treatment to lower blood lipids associated with cardiovascular disease.
- Take only under the supervision of a physician
2. Symptoms of toxicity
- Lower doses - Niacin flush
- Higher doses
• Life-threatening drop in blood pressure
• Liver injury
• Peptic ulcers
• Vision loss
niacin: intake
RDA = 14-16 mg/day
folate: general
1. Folate helps synthesize DNA
- and so is important for making new cells
2. Also involved in the normal metabolism of several amino acids
3. Easily destroyed by heat and oxidation
4. mostly not coenzyme
folate: deficiency (3)
1. Deficiency of folate causes anemia, diminished immunity, and abnormal digestive function.
- Any cells/tissues/organs that replace cells often (blood, skin, digestive tract)
2. Deficiencies are related to increased risk of cervical cancer (in women infected with HPV), breast cancer (in women who drink alcohol) and pancreatic cancer (in men who smoke).
3. Lack of folate affects cells, such as RBC, that rapidly divide.
• Mature RBCs do not have nuclei and live ~ 4 months.
- Without folate, RBC precursor cells enlarge, but cannot divide. (DNA is needed for division.)
• Bone marrow releases some large, immature, abnormal RBCs with nuclei (megaloblasts) into the blood stream.
folate: birth defects (4)
1. Adequate intakes of folate during pregnancy can reduce a woman's chances of having a child with a neural tube defect (NTD).
- NTD arise in the first days or weeks of pregnancy, long before most women suspect they are pregnant.
2. In the late 1990s the FDA ordered fortification of all enriched grain products with an absorbable synthetic form of folate, folic acid.
3. Since fortification began, the U.S. incidence of NTD dropped by 25 percent.
4. Women of child-bearing age are recommended to take in 400 micrograms per day of folic acid in addition to dietary food sources
- From supplements or enriched foods
folate: neural tube defects
• During the first few weeks after conception, the neural tube forms.
- Neural tube develops into the brain and spinal cord.
• Folate-deficient pregnant women are at risk of giving birth to infants with neural tube defects.
neural tube defects: types (2)
• Anencephaly
- Brain does not form
• Spina bifida
- Spine does not form properly before birth and fails to enclose the spinal cord.
folate: UL & toxicity
1. Tolerable Upper Intake Level for folate is 1,000 micrograms a day for adults
- Excess folate may suppress immune function
2. A concern about fortifying the nation's food supply with folic acid is folate's ability to mask deficiencies of vitamin B12
folate: functions
1. Part of coenzyme tetrahydrofolic acid (THFA)
• THFA involved in DNA and amino acid metabolism
• Conversion of homocysteine to methionine
folate: sources
- Fresh, leafy greens, and uncooked fruits and vegetables are good sources
folate: intake
RDA = 400 mcg DFE/day
vitamin B12: general (3)
aka cobalamin
1. Vitamin B12 and folate are closely related: each depends on the other for activation.
2. Main roles:
- Helps maintain sheaths around nerve fibers
- and is a part of coenzymes needed in new blood cell synthesis.
3. B12 is only present in foods of animal origin. no plant sources contain active B12
- Especially important for vegetarians
Vitamin B12: deficiency general (3)
1. Symptoms of deficiency of either folate or vitamin B12 include the presence of immature red blood cells.
2. Administering extra folate often clears up this blood condition but allows the B12 deficiency to continue.
- Vitamin B12's other functions then become compromised, and the results can be devastating: damaged nerves, creeping paralysis, and general muscle and nerve malfunctioning.
3. The body can store up to six years worth of B12
- Deficiency may not show up right away and the anemia be masked by adequate folate
vitamin B12: deficiency
1. Food-Cobalamin Malabsorption
• Declining gastric acid production (older adults) • Alcoholism • Gastric bypass surgeries • Certain medications
2. Pernicious Anemia
• Genetic defect reduces production of intrinsic factor,
resulting in poor B-12 absorption.
• Signs and symptoms:
- megaloblastic anemia, nerve damage, weakness,
sore tongue, memory loss, confusion, difficulty walking and maintaining balance, and eventual death
vitamin B12: functions (2)
Part of coenzymes needed for:
• Folate metabolism • Maintenance of myelin sheaths
vitamin B12: absorption
1. B-12 in food is bound to proteins sheaths
• HCL and pepsin required to release B-12 from proteins
2. B-12 must bind to intrinsic factor for absorption.
vitamin B12: intrinsic factor
1. Intrinsic factor is a compound made by the stomach needed for the absorption of B12.
- Stomach acid releases it from bound proteins, it binds to intrinsic factor, and is only then absorbed into the blood
- A few people have an inherited defect in the gene for intrinsic factor, which makes B12 absorption poor.
• Vitamin B12 must be injected to bypass the defective absorptive system.
2. This anemia of the vitamin B12 deficiency caused by a lack of intrinsic factor is known as pernicious anemia.
vitamin B12: sources
animal foods, fortified cereals & soy milk
vitamin B12: intakes
RDA = 2.4 mcg/day
vitamin B6: functions (7)
aka pyridoxine
1. Vitamin B6 participates in more than 100 reactions in body tissues.
2. ** Important in amino acid synthesis and breakdown
• Can convert one amino acid to another amino acid that is lacking
3. Aids in conversion of tryptophan to niacin
4. Plays important roles in the synthesis of
hemoglobin and neurotransmitters
5. Assists in releasing glucose from glycogen
6. Has roles in immune function and steroid hormone activity
7. Critical to fetal nervous system development
vitamin B6: AA metabolism
As a coenzyme, B-6 involved in amino acid conversion of homocysteine to cysteine
vitamin B6: deficiency
rarely occurs
1. Flaky, greasy, dermatitis
2. Many general symptoms = •Weakness, depression,
confusion, irritability, insomnia
3. Advanced deficiency leads to convulsions
4. Possible role in heart disease
5. Body's requirement is roughly proportional to protein intake
6. Plays large role in protein metabolism
7. DRI should cover most peoples needs
vitamin B6: general, excess (2)
1. Vitamin B6 excess
- Generally takes a long time for damage to manifest
- Numbness in feet and hands
- Later, inability to walk or work
- Other nerve, brain damage
2. Does not help carpal tunnel syndrome or premenstrual syndrome
vitamin B6: sources
meat, fish, poultry, potatoes, bananas, spinach, sweet red peppers, broccoli
vitamin B6: intakes
RDA = 1.3 to 1.7 mg/day
B vitamins: related to heart disease?
1. People with an inherited rare disorder that raises the blood level of the amino acid homocysteine almost invariably suffer from a severe form of cardiovascular disease.
2. CVD sufferers without the inherited disorder also sometimes accumulate homocysteine in the blood.
3. When healthy men with elevated homocysteine are given supplements of folate, vitamin B6, and vitamin B12, their homocysteine values drop significantly.
4. However, a drop in CVD has not emerged so far from controlled studies.
biotin: general (5)
1. important for energy metabolism
2. cofactor for enzymes
3. gene expression
4. no UL
5. readily available from food
biotin: deficiency (2)
1. Some diseases may cause deficiencies
2. Raw eggs have a protein that binds biotin and makes it unavailable
• Would need more than 2 dozen eggs per day to cause deficiency
• Cooking destroys the binding protein
pantothenic acid: general (4)
1. Key coenzyme in release of energy from energy nutrients
2. Participates in over 100 steps in synthesis of lipids, neurotransmitter, steroid hormones, and hemoglobin
3. readily available from food
4. deficiencies are rare
Non-B vitamins
1. Many substances that people claim are B vitamins are not.
- Choline - important in fetal development
• common in foods & we make plenty of it
- Carnitine, inositol, and lipoic acid - nonvitamins because they are nonessential
• Common in foods & we make plenty of it