Chapter 7: Vitamins
Vitamins
Essential organic substances
Yield no energy, but facilitate energy-yielding chemical reactions
If absent from a diet, it will produce deficiency signs and symptoms
Fat-soluble vitamins
Water-soluble vitamins
Fat-soluble vitamins
Fat-soluble vitamins overview
Dissolve in organic solvents
Not readily excreted; can cause toxicity
Absorbed along with fat
Concern for people with fat malabsorption
Vitamin A
Preformed
Retinoids (retinal, retinol, retinoic acid)
Found in animal products
Proformed
Carotenoids
Must be converted to retinoid form
Found in plant products
Transport and storage of
vitamin A
Liver stores 90% of vitamin A in the body
Reserve is adequate for several months
Functions of vitamin A
Reproduction
Supports growth and cell maturation
Night and color vision
The anti-infection vitamin
Uncertain of the action of vitamin A and resistance to disease
Deficiency reduces activity of some immune-system cells
High-dose therapy of vitamin A increase immune response
Growth and development
Necessary for cellular differentiation
Important for embryo development
Synthesis of bone protein and enlargement of bone
Cancer and vitamin A
Role in cell development and immune-system
Role as an antioxidant
Lower risk of breast cancer with vitamin A supplements
Megadose is not advise
Vitamin A and Acne
Topical treatment and oral drug
Can induce toxicity symptoms
Must limit sun exposure
Not recommended for pregnant women
Sources of vitamin A
Preformed
Liver, fish oils, fortified milk, eggs
Contributes to half of all the vitamin A intake
Proformed
Dark leafy green , yellow-orange vegetables/fruits
Contributes to half of all the vitamin A intake
Who is at risk for deficiency
Breast fed infants
Preschooler with poor vegetable intake
Urban poor
Elderly
Alcoholics and people with liver disease
Individual with fat malabsorption
Toxicity of vitamin A
Acute
Ingestion of LARGE dose(s) of vitamin A (within a short period)
Result in intestinal upset, headache, blurred vision, muscular incoordination
Symptoms disappear when supplements are stopped
Toxicity of vitamin A
Chronic
Large intake of vitamin A over a long period
Bone/muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss, increased liver size, vomiting
Discontinue supplementation is recommended
Possible permanent damage
Toxicity of vitamin A
Teratogenic
Tends to produce physical defect on developing fetus as a result of excess vitamin A intake
Spontaneous abortion, birth defects
May occur with as little as 3 x RDA of preformed vitamin A
Fatal dose
12 g of vitamin A (12,000 x RDA) can be fatal
Vitamin D
Prohormone
Derived from cholesterol
Synthesis from sun exposure
Deficiency can cause diseases
Vitamin D influences
Food sources of vitamin D
Fatty fish (salmon, herring)
Fortified milk
Some fortified cereal
Who is at risk for deficiency?
Vitamin D as a medicine
Type II (age-related) osteoporosis
Loss of bone mass
Psoriasis
Skin disorder
Topical treatment is being investigated
Toxicity Warning
Vitamin D can be very toxic
Regular intake of 5-10 x the AI can be toxic
Result from excess supplementation (not from sun exposure or milk consumption)
Sign and symptoms: overabsorption of calcium (hypercalcemia), increase calcium excretion
Vitamin E
Amount absorbed is dependent on fat intake
Found concentrated in areas where fat is found
Anti-cancer properties
Anti-oxidant
Prevents the alteration of cell’s DNA and risk for cancer development
Could more vitamin E be better?
Vitamin E is only one of many antioxidant
It is likely that the combination of antioxidant is more effective
Diversify your antioxidant intake with a balanced and varied diet
Megadose of one antioxidant may interfere with the action of another
Other functions of vitamin E
Protects the double bonds in saturated fat
Role in iron metabolism
Maintenance of nervous tissue and immune function
Anti-aging vitamin?
Food sources of vitamin E
Plant oils
Wheat germ
Asparagus
Peanuts
Margarine
Nuts and seeds
Actual amount is dependent on harvesting, processing, storage and cooking
Who is at risk for deficiency?
Premature infants
People with fat malabsorption
Signs & symptoms: red blood cell fragility, neurological disorders affecting the spinal cord
Toxicity of vitamin E
Supplements up to 800 IU is probably harmless
Inhibit vitamin K metabolism and anticoagulants
Drugs and vitamin K
Food sources of vitamin K
Liver
Green leafy vegetables
Broccoli
Peas
Green beans
Resistant to cooking losses
Limited vitamin K stored in the body
Water-soluble vitamins
Overview of water-soluble vitamins
Dissolve in water
Generally readily excreted
Subject to cooking losses
Functions as a coenzyme
Participate in energy metabolism
50-90% of B vitamins are absorbed
Marginal deficiency more common
Enrichment Act of 1941 and 1998
Many nutrient lost through milling process of grains
Grain/cereal products are enriched
Thiamin, riboflavin, niacin, folate, iron
Whole grains contain original nutrients
B Vitamins
Thiamin Riboflavin
Niacin Pantothenic acid
Biotin Vitamin B-6
Folate Vitamin B-12
Thiamin
Contains sulfur and nitrogen group
Destroyed by alkaline and heat
Coenzyme: carbohydrate metabolism
Surplus is rapidly lost in urine; non toxic
Deficiency of thiamin
Occurs where polished rice is the only staple
Affects cardiovascular, muscular, nervous & GI systems
Dry beriberi
Weakness, nerve degeneration, irritability, poor arm/leg coordination, loss of nerve transmission. No edema.
Wet beriberi
Edema, enlarge heart, heart failure
Wenicke-Koisakoff Syndrome
Mainly in alcoholics
Involuntary eye movement
Staggering, mental confusion, "drunken stupor"
Food sources of thiamin
Wide variety of food
White bread, pork, hot dogs, luncheon meat, cold cereal
Enriched grains/ whole grains
Thiaminase found in raw fish (destroys thiamine)
Who is at risk for deficiency?
Poor
Alcoholics
Elderly
Diet consisting of highly processed foods
Riboflavin
Coenzymes:
Carbohydrate and fat metabolism
Yellow color
Formerly called Viramin B-2
Athletes’ need may increase to 1.5x RDA
Toxicity not documented
Deficiency of riboflavin
Inflammation of the tongue
Dermatitis
Sensitivity to the sun
Who is at risk for deficiency?
Low milk/dairy intake
Alcoholics
Long term phenobarbital use
Food sources of riboflavin
Milk/products
Enriched grains
Liver
Oyster
Brewer’s yeast
Sensitive to uv radiation (sunlight)
Stored in paper, opaque plastic containers
Niacin
Coenzyme
Carbohydrate and Fat digestion
Metabolic reactions
Deficiency of niacin
Pellagra
Occurs in 50-60 days
Decrease appetite & weight
Prevented with an adequate protein diet
Enrichment Act of 1941
Who is at risk?
(Untreated) corn as main staple, poor diet, Hartnup disease, alcoholics
Food sources of niacin
Niacin as a medicine
75-150 x RDA can lower LDL and TG and increase HDL
Slow/ reverse progression of atheroscelerosis
Benefit for Type I diabetes?
Toxicity effects
Flushing of skin, itching, nausea, liver damage
Pantothenic Acid
Essential for metabolism of CHO, fat, protein
Deficiency rare
Burning foot syndrome, listlessness, fatigue, headache, sleep disturbance, nausea, abdominal distress
Alcoholics at risk
Usually in combination with other deficiencies
Food sources of pantothenic acid
"From every side"
Meat
Milk
Mushroom
Liver
Peanut
Biotin
Metabolism of CHO, fat, protein (C skeleton)
DNA synthesis
Sources of biotin
Cauliflower, yolk, liver, peanuts, cheese
Intestinal synthesis of biotin
Unsure as to bioavailablity of synthesized biotin
Appears non-toxic
Who is at risk for deficiency?
High intake of raw egg white diet
Alcoholics
Anticonvulsant drug use
Signs & symptoms: skin rash, hair loss, convulsion, neurological disorders, impaired growth in children
Vitamin B-6
Activate enzymes needed for metabolism of CHO, fat , protein
Synthesis of hemoglobin and oxygen binding and white blood cells
Synthesis of neurotransmitters
Athletes may need more
Food sources of vitamin B-6
Meat, fish, poultry Whole grains (not enriched back)
Banana Spinach
Avocado Potato
Heat and alkaline sensitive
Who is at risk for deficiency?
Elderly
Alcoholics
Alcohol decreases absorption
Destroy the coenzyme form
Reduce immune response and Peripheral nerve damage
B-6 as medicine?
PMS
B-6 to increase the level of serotonin
Improve depression
Not a reliable treatment
Carpal tunnel syndrome
Toxicity potential
Can lead to irreversible nerve damage with > 200 mg/day
Folate (folic acid)
Help to form DNA
Some stored in the body
Neurotransmitter formation
Who is at risk for folate deficiency?
Pregnant women (spina bifida)
Alcoholics
Toxicity of folate
Epilepsy
Skin, respiratory disorder
FDA limits supplements to 400 ug per tablet
Excess can mask vitamin B-12 deficiency
Vitamin B-12
Folate metabolism
Maintenance of nervous system
Food sources: Animal products, Organ meat, Seafood, Eggs, Hot dogs, Milk
B-12 stored in the liver
Non-toxic
Deficiency of vitamin B-12
Who is at risk for deficiency?
Vegans
Elderly
Failure to thrive infants
HIV infected individuals
Vitamin C
Ascorbic acid
Synthesized by most animals (not by human)
Decrease absorption with high intakes
Excess excreted
Functions of vitamin C
Antioxidant
Iron absorption
Synthesis of cell compounds
Immune functions
Collagen synthesis
Deficiency of vitamin C
Food sources of vitamin C
Citrus fruits
Potatoes
Green peppers
Cauliflower
Broccoli
Strawberries
Romaine lettuce
Spinach
Easily lost through cooking
Sensitive to heat
Sensitive to iron, copper, oxygen
