The Vitamins
Classifying Vitamins
Fat Soluble Vitamins
A
D
E
K
Water Soluble Vitamins
Vitamin C
B Vitamins:
Thiamin -- Biotin
Riboflavin -- Pantothenic acid
Niacin
B6
Folate (folic acid)
B12
Water Soluble Vitamins
Digestion, Absorption, and Transport
No chemical digestion needed
Absorbed in the SI into the capillaries
• Vitamin B12 must bind with a protein called the
intrinsic factor (IF) in the stomach for absorption to
occur in the SI
No carriers required for transport in the blood
Water Soluble Vitamins
Storage and excretion
Travel freely in the blood
Cells take up water soluble vitamins as
needed
• Limited storage beyond tissue saturation
Excess excreted in the urine
Water Soluble Vitamins
Deficiency ismore common than toxicity
for the water soluble vitamins
Why??
Any toxicity is likely to be due to overuse of
vitamin supplements, not food intake
Water Soluble Vitamins
Other interesting information:
Many are destroyed by light, heat, or
exposure to oxygen
Best to cook whole in a minimum amount of
water
• Why??
Frozen vegetables are often higher in vitamin
content than grocery store “fresh” veggies
• Why??
Fat Soluble Vitamins
Digestion, Absorption, and Transport
Bile needed to emulsify fat soluble vitamins
Form chylomicrons (along with long chain
fatty acids and monoglycerides)
Chylomicrons are absorbed into the lacteals
Travel through lymph system blood liver
Many require protein carriers to be
transported in the blood
Fat Soluble Vitamins
Storage
Stored in liver and fatty tissue
Unlimited stores possible
Greater risk of toxicity than deficiency for
fat soluble vitamins
Why??
Fat Soluble Vitamins
Other interesting facts:
Found in the fatty parts of food
Removed with the fat when low-fat products
are made
• Many low-fat foods are supplemented with these
vitamins to make up for this
E.g. milk is vitamin A and D enriched
The Vitamins
For each vitamin we will consider:
Functions
Dietary needs and food sources
Deficiency
Toxicity
Thiamin
History
Functions:
1. Needed for energy metabolism
• E.g. -- required for conversion of pyruvate to
acetyl CoA
2. Needed for nerve and muscle function
Thiamin
Recommended Intake
1.1-1.2 mg/day
Food Sources
Found in small amounts in many foods
Easily destroyed by heat (cooking)
Lost in cooking water
Good sources include
• Pork products, soy, legumes, vegetables, whole
grains, watermelon….(pg 327)
Thiamin Deficiency
Prolonged deficiency leads to beriberi
Results in damage to nervous system and
muscles (to include the heart)
Thiamin Deficiency
Symptoms Beriberi:
1. Dry form- muscle wasting, poor coordination
Muscle weakness
2. Legs heavy, hard to walk, calf pain
3. Apathy, confusion, memory loss
4. Anorexia and weight loss
5. Wet form has additional symptoms of:
– edema, irregular heart beat, enlarged heart
In alcoholics thiamin deficiency results in
Wernicke-Korsakoff syndrome.
Symtpoms
• Mental confusion
• Staggering
• Rapid eye movements or paralysis of the eye
muscles
Thiamin Deficiency
Populations at risk:
Alcoholics
• See in alcoholics who obtain the majority of their
calories from alcohol
• Alcohol inhibits thiamin absorption and hastens its
excretion
Cultures that eat primarily refined grains (and
little else)
Thiamin deficient moms infant deaths
The City of New York
DEPARTMENT OF HEALTH AND MENTAL HYGIENE
Michael R. Bloomberg Thomas R. Frieden, m.d., m.p.h.
Mayor Commissioner
_______________________________________________________________
nyc.gov/health
2003 Health Alert # 39:
A cluster of infantile thiamine (vitamin B1) deficiency (beri-beri) has
been reported in Israel among infants fed a vitamin B1-deficient
kosher soy-based formula distributed by Remedia. It is possible
that this product may be imported into New York City and there
may be children in the Orthodox Jewish community who have
consumed it.
The New York City Department of Health and Mental Hygiene
(NYCDOHMH) asks that providers report immediately any suspect
case of thiamine deficiency among infants who have been fed this
product to:
The New York City Poison Control Center at:
1-212-764-7667 (212-POISONS) or 1-800-222-1222.
Please distribute to Pediatric staff in the Departments of
Cardiology, Critical Care, Emergency Medicine, Family Medicine,
General Pediatrics, Outpatient Pediatrics, Neonatology, Neurology,
and Infectious Disease
Thiamin
Toxicity
None known
Excess thiamin is excreted and not stored
Riboflavin
Functions:
1. Needed for the metabolism of
carbohydrates, fats, and proteins
• Places a role in Kreb’s cycle
• Part of FAD
Riboflavin
Recommended Intake:
1.1 – 1.3 mg/day
Food Sources:
Destroyed by ultraviolet light (sun light)
Good sources include:
• Milk and milk products
• Liver
• Whole grain breads and cereals, oatmeal
• Clams and squid!
• Mushrooms (page 329)
Riboflavin
Deficiency Symptoms
1. Eyes are inflamed and sensitive to light
2. Cheliosis (cracks at the corners of the mouth)
3. Sore throat
4. Inflammation of the tongue and mouth –
painful
5. Inflamed skin, with lesions covered with
greasy scales
6. Anemia
Riboflavin
Populations at Risk for Deficiency
alcoholics
any one with a marginal diet
• Poor, elderly, eating disorders, drug addicts…
Toxicity
None reported
Excess excreted
Niacin
Functions
1. Plays an essential role in energy metabolism
• Part of NAD
• Needed by every cell of the body
Niacin
Recommended Intake:
14 – 16 mg/day of niacin or of NE
NE = Niacin Equivalents
• Niacin can be made from the essential amino acid
tryptophan
• It takes 60 mg of tryptophan to make 1 mg of
niacin
• Therefore, 1 NE is 60 mg of tryptophan
Niacin
Food Sources:
Sources of complete protein
• Dairy, meats, poultry, fish,…
Peanut butter
Tomato paste
Mushrooms
(page 332)
Niacin Deficiency
Niacin deficiency disease is called pellagra
Symptoms, 4 D’s:
1. Dermatitis with sun exposure (pg 330)
2. Diarrhea, vomiting
3. Dementia
4. Death
Other symptoms:
1. Inflamed, swollen, red, smooth tongue
2. Loss of appetite
Niacin
Pellegra - Other interesting information
Originally believed to be caused by infection
Common up to early 1900’s in US and Europe
• Many in mental hospitals in south had niacin
deficiency, not mental illness
Incidence declined in US after WW II when mandatory
enrichment of grains began
Still common in Africa and Asia
• Poor bioavailability form corn unless it’s soaked in
lime juice
Niacin
Toxicity
Tolerable Upper Intake Level (UL) = 35
mg/day
High doses of niacin are commonly used to
treat high cholesterol
• 1500 -3000 mg/day recommended for treating high
cholesterol
Niacin
Toxicity Symptoms
1. Niacin flush
2. Excessive sweating
3. Tingling
4. GI distress
5. Frequent need to urinate
• May mask prostrate cancer symptoms in men
6. Blurred vision, headaches
7. Liver damage
Folic Acid = Folate
Functions:
1. Needed for DNA synthesis
• Need to make all new cells
• E.g. Need to make new RBC
2. Reduces incidence of neural tube defects
• Defects occur in first weeks of pregnancy
Folate
3. Plays a role in protein synthesis
4. Breaks down the amino acid homocysteine
– High levels of homocysteine increases risk of
blood clot formation
5. May reduce risk some cancers
– Pancreatic cancer in men who smoke
– Breast cancer in women who drink
Folate
Absorption and Activation
Folate in foods must be acted upon by an
intestinal enzyme for it to be absorbed and
transported to cells
Folate in cells needs to be activated by
vitamin B12
• Process also activates the B12
Folate
Recommended intake:
400 micrograms/day
Folate
Factors impacting needs
Pregnancy -600 mcg/day
Aspirin, antacids, smoking, oral
contraceptives reduce absorption
Some cancer drugs reduce absorption
GI tract damage reduces absorption
• Occurs with alcoholism, anorexia
• Poor absorption, leads to even more damage to GI
tract
Folate
Food Sources
Cooking destroys up to 50% of folate
Oxygen destroys folate
Good sources include:
• Green leafy vegetables
• Legumes
• Fortified cereals and Seeds
• Liver
• Orange juice (ok, but not great source) pg 341
Folate
Folate Deficiency
Impairs cell division and protein
synthesis
Symptoms:
1. Megaloblastic anemia
Fewer red blood cells (RBC) made
RBC larger than normal
RBC do not carry oxygen as well
Folate Deficiency
2. Confusion, irritability, weakness, fatigue
• Related to the anemia
3. GI tract deterioration
4. Elevated homocysteine levels
5. Smooth red tongue
6. Increased risk neural tube defects
Folate
Toxicity
No known symptoms
May mask a vitamin B12 deficiency
• B12 deficiency is VERY serious
Vitamin B12
Dorothy Crowfoot Hodgkin
Awarded the Nobel prize in chemistry for
deducing the structure of vitamin B12
• Took her eight years
Headline in the London paper announcing this
read
“Nobel Prize for British Wife”
Vitamin B12
Functions:
Needed to activate folate
• Therefore, needed for DNA and new cell (RBC)
synthesis
Helps maintain myelin sheath around nerve
cells
Vitamin B12
Recommended intake:
2.4 microgams per day
Food Sources*:
ONLY found naturally in animal products
• Meat, poultry, fish, eggs, dairy, liver….
Fortified grains
*Easily destroyed by microwave cooking
Vitamin B12
Deficiency:
Pernicious anemia (VERY SERIOUS)
• Megaloblastic anemia
• Nerve damage creeping paralysis
• Smooth sore tongue
• Fatigue
Vitamin B12
Pernicious anemia frequently goes
undiagnosed
Pernicious anemia can be masked by high
intakes of folate
Vitamin B12
Gastric by-pass patients and vegans are
at elevated risk
Takes several years to develop
Toxicity:
None reported
B6
Functions:
Need for protein and fatty acid metabolism
Need for amino acid metabolism
• E.g. For converting tryptophan to other niacin
• need to make serotonin form tryptophan
Helps make RBC
Other functions under study
B6
Recommended Intake:
1.3 mg/day
UL: 100 mg/day
Food sources: destroyed by heat
Meat, fish, poultry
Legumes
Seeds and nuts
Liver
Non-citrus fruits
B6
Deficiency: (rare)
Anemia Weakness and fatigue
Depression, confusion
Abnormal brain waves, convulsions
Greasy dermatitis
B6
Increased risk of deficiency:
Alcoholics
• Alcohol contributes to increased B6 breakdown
and excretion
Oral contraceptives may increase risk of B6
deficiency
Drug INH inactivates B6
INH used to treat tuberculosis
B6
Toxicity: Serious
Stored in muscle cells, toxicity seen with
supplements
Symptoms:
• Irreversible nerve damage numbness in hands
and feet Difficult to walk
• Convulsions
• Insomnia, restlessness
B6
B6 does not help with:
Carpal tunnel syndrome
PMS
Supplementation above the UL is NOT
recommended
Biotin
Functions:
Need for energy metabolism
Need to make glycogen
Plays a role in fatty acid and amino acid
synthesis
Biotin
Recommended Intake:
30 micrograms/day (AI)
Food Sources*:
Widespread in foods: liver, egg yolk,
legumes, fish, mushrooms, whole grains…
Some produced by GI tract bacteria
*easily destroyed by processing
Biotin
Deficiency:
RARE
• Skin rash
• Hair loss
• Depression
• Hallucinations
• Numbness in legs/arms
Biotin
be induced by eating
Deficiency can
LARGE quantities of raw egg whites
2 dozen daily for ~2 months!
Prevents biotin absorption
Toxicity: none reported
Pantothenic Acid
Functions:
Need for energy metabolism
• Part of acetyl CoA
Plays a role in the synthesis of many
substances:
• Lipids
• Hormones
• Neurotransmitters
• Hemoglobin
Pantothenic Acid
Recommended intake:
5 mg/day (AI)
Food Sources:
Widespread in foods
Pantothenic Acid
Deficiency: Rare
Fatigue
GI distress
Insomnia, depression
Apathy, irritable
Increased sensitivity to insulin
Pantothenic Acid
Toxicity: none known
Vitamin C
Functions:
Collagen synthesis
• Part of scar tissue
• Strengthens blood vessels
• Provides matrix for bone growth
Antioxidant
Need for healthy immune system
Need for thyroxine production
Vitamin C
Functions:
Need for thyroxine production
• Regulates body temperature and metabolic rate
Enhances iron absorption
Need to make hemoglobin
Vitamin C
Recommended intake:
Men: 90 mg/day
Women: 75 mg/day
Smokers: an extra 35 mg/day
• More free radicals that need to be “neutralized”
UL: 2000 mg/day
Vitamin C
Food sources*:
Citrus fruits
Strawberries, melon
Vegetables
• Tomatoes, dark green leafy vegetables, potatoes,
broccoli…
*Heat and oxygen sensitive
Vitamin C
Deficiency: Scurvy
Poor wound healing - Increased infection
Weakness
Bleeding gums
Loose teeth
Broken blood vessels
Loss of appetite
Joint pain and fragile bones
Anemia
Vitamin C
Populations at increased risk:
Alcoholics
Elderly
Babies and toddlers fed only milk/cereals
Smokers
After illness or stress
• Fever and stress deplete vitamin C stores
Vitamin C
Toxicity Symptoms:
Diarrhea
Cramps, nausea
Headaches, insomnia
May interfere with lab tests and meds
Increased risk kidney stones
Over-absorption of iron
Fat Soluble Vitamins
A
D
E
K
Vitamin A
Chemical nature:
Active forms of vitamin A
• Retinol
• Retinoic acid
• Retinal
Precursor form
• Beta-carotene
• Converted to active vitamin A as needed
Vitamin A
Functions:
Need for night vision
• See handout
Need for protein synthesis
Plays a role in cell differentiation
• Need to build healthy epithelial and mucous tissue
• Need to maintain healthy cornea
Vitamin A
Functions:
Plays a role in reproductive health
• Sperm production
• Fetal development
• Sexual maturation
Need for bone growth
Beta-Carotene
Functions beta-carotene;
Can be converted to active vitamin A as
needed
Antioxidant
Vitamin A
Recommended intake:
700-900 RAE micrograms/day
RAE = retinol activity equivalents
• Older unit is IU = International Units
• See page 360 for conversions between these units
UL 3000 RAE
• UL refers to active vitamin A only, not beta-
carotene
Vitamin A
Food Sources Vitamin A:
All animal sources
• In fatty portion of the food
• Dairy products
• Eggs
• Meat, liver
• Fortified skim milk and margarine
Beta-Carotene
Food Sources:
All plant sources
Yellow/orange/red fruits and vegetables
• Carrots, apricots, cantaloupe, mangos, pumpkin,
sweet potato, winter squash, peppers……
Dark green leafy vegetables
• Spinach, kale, broccoli, beet greens (but not the
beet!)
Vitamin A
Deficiency:
Night blindness
Blindness
• Leading cause of blindness worldwide
• ~ ½ million children go blind each year due to a
vitamin A deficiency
Vitamin A
Deficiency:
Keratinization dry, cracked skin
Reduced secretions
• GI tract
• Bladder
• Lungs
Above symptoms increase risk of infection
Vitamin A
Deficiency:
Anemia
Slow bone growth
Painful joints
Cracked, cracked teeth
Delayed sexual maturity
For others see pages 374
Vitamin A
Toxicity:
Teratogenic
• “monster producing”
GI distress, weight loss
Bone issues
• Joint pain
• Stunted bone growth and more
Vitamin A
Toxicity:
Headaches, pressure inside skull
Blurred vision
Fatigue, muscle weakness
Skin rashes
Dry, cracked, bleeding lips
Dry, brittle hair
Vitamin A
Vitamin A toxicity can be fatal
Polar bear liver story
Symptoms go away quickly if diet changes
Toxicity is never from beta-carotene
sources
Beta-carotene toxicity…..
Vitamin D
Chemical nature:
Vitamin D is a sterol
Body can make from cholesterol
• Requires sunlight exposure
Synthesis of vitamin D
• See page 376
Vitamin D
Functions:
Bone mineralization
• Works with other nutrients
Vitamins A, C. K
Several minerals
Vitamin D
Functions:
Regulates calcium and phosphorus levels
• Stimulates Ca and P absorption in SI
• Regulates movement of Ca and P in/out of bones
• Stimulates kidneys to retain Ca and P
• All of the above are related to bone mineralization
Vitamin D
Other Functions:
Acts as a hormone
• Not fully understood
• Many target organs:
Brain and CNS
Muscle
Reproductive cells…
Vitamin D
Recommended intake:
Depends upon sun exposure and skin color
5-10 micrograms/day (AI)
UL: 50 mcg/day
Vitamin D
Food sources*:
Fortified milk and margarine
Butter
Egg yolks
Liver
Fatty fish and fish oils
* animal sources
Vitamin D
Deficiency:
Bone abnormalities
• Kids rickets
• Adults osteomalcia
Vitamin D
Populations at risk for deficiency:
Inner-city kids
Dark skinned
Live in a northern climate
Limited sun exposure
Elderly
Kidney or liver disease
Vegans
Vitamin D
Toxicity:
Very toxic
• Can be lethal
• Milk story
Toxicity is never from sun exposure
Vitamin D Toxicity
Symptoms:
Calcium deposits in soft tissue
• Muscles, lungs, heart
Kidney stones
Calcium deposits on walls of arteries
Joint pain
Frequent urination
GI distress
Vitamin E
Chemical nature:
A type of tocopherol
4 forms
• Alpha, beta, gamma, delta
• Alpha-tocopherol is the most active form
• Other forms have very limited bioactivity
Vitamin E
Functions:
Antioxidant
• Component of animal cell membranes
• Protects unsaturated fatty acids in cell membranes
Other roles are not clearly defined, but likely
exist
Vitamin E
Recommended intake:
15 mg/day
Need more if eat more polyunsaturated fats
most students did not meet their vitamin E
requirement on the day analyzed
Vitamin E
Food sources*:
Vegetable oils
Nuts and seeds
Whole grains
Green leafy vegetables
Liver
Wheat germ
Egg yolks *easily destroyed by heat and oxygen
Vitamin E
Deficiency:
Rare as most vitamin E is recycled
See in premature babies
• Transferred from mom to baby in last weeks of
pregnancy
Cystic fibrosis patients
• Due to poor fat absorption
Vitamin E
Symptoms deficiency:
Hemolytic anemia
• RBC break open
Neurological problems with prolonged
deficiency
• Loss of coordination
• Vision and speech problems
• Does not prevent/cure MD
Vitamin E
Vitamin E may help with:
Leg cramps
• Intermittent claudication
Fibrocystic breasts disease
• “lumpy” breasts
Vitamin E
Toxicity: Rare
Supplements recommended by many, but not
above the UL = 1000 mg
• 200 mg supplement probably enough
May interfere with blood clotting
• Stop taking supplements prior to surgery
Other symptoms: nausea, fatigue, blurred
vision
VITAMIN K
Functions:
Need for synthesis of blood clotting proteins
Plays a role in regulation of calcium levels
Vitamin K
Recommended intake:
90-120 mcg/day
Sources:
Made by GI tract bacteria
Dark green leafy vegetables, cabbage family
Liver
Milk
Vitamin K
Deficiency: rare
Symptoms:
• Bleeding, hemorrhaging
• Bone weakness
Populations at risk
• Babies
• After long-term antibiotic treatment
• CF
Vitamin K
Toxicity: rare
Occurs with supplement overuse
• Take with caution, even if prescribed
Symptoms:
• RBC break open
• Jaundice
• Brain damage
• Interferes with anti-clotting meds