Vitamins

Definition and Classification
* Non-caloric organic nutrients
* Needed in very small amounts
* Facilitators – help body processes proceed; digestion, absorption, metabolism, growth etc.
* Some appear in food as precursors or provitamins

Definition and Classification
* 2 classes, Table 7.1
o Fat soluble:
o Water soluble:
* Fat soluble vitamins
o Found in the fats and oils of food.
o Absorbed into the lymph and carried in blood with protein transporters = chylomicrons.
o *Stored in liver and body fat and can become toxic if large amounts are consumed.
* Water soluble vitamins
o Found in vegetables, fruit and grains, meat.
o Absorbed directly into the blood stream
o Not stored in the body and toxicity is rare. Alcohol can increase elimination, smoking, etc. cause decreased absorption.

Fat Soluble Vitamins
* Vitamin A (precursor – beta carotene)
o 3 forms: retinol (stored in liver), retinal, retinoic acid
o Roles in body:
+ Regulation of gene expression
+ Part of the visual pigment rhodopsin, maintains clarity of cornea (yes eating carrots is good for your eyesight)
+ Required for cell growth and division - epithelial cells, bones and teeth
+ Promotes development of immune cells, especially “Natural Killer Cells”
+ Antioxidant
* Vitamin A
o Deficiencies cause:
+ Night blindness, xerophthalmia (keratin deposits in cornea), macular degeneration.
+ Skin and mucous membrane dryness and infection, keratin deposits.
+ Anemia
+ Developmental defects – bones, teeth, immune system, vision

o Toxicities (RetinA/Accutaine, single large doses of supplements, eating excessive amounts of liver) cause:
+ Fragile RBCs, hemorrhage
+ Bone pain, fractures
+ Abdominal pain and diarrhea
+ Blurred vision
+ Dry skin, hair loss
+ Liver enlargement
o DRI: 700(women)-900(men) micrograms/day, UL 3000 micrograms
o Sources, see snapshot 7.1

* Vitamin D – precursor is cholesterol, converted by UV from sunlight exposure, therefore is a “non-essential” vitamin.
o Roles:
+ Increases calcium absorption in bone, intestines, kidney. Promotes bone growth and maintenance.
+ Stimulates maturation of cells – heart, brain, immune system, etc.

o Deficiencies: rickets (children), osteomalacia (adults). What are some of the causes of deficiencies?
o Toxicities (5X DRI)
+ Loss of calcium from bone and deposition in soft tissues.
+ Loss of appetite, nausea and vomiting, psychological depression.

Bowed legs – Characteristic of rickets

Beaded ribs – Characteristic of rickets
* Vitamin D
o DRI – 5 micrograms/day for ages 19-50, 10 for ages 51-70, 15 for ages >70.
o Sources, see snapshot 7.2

Fat Soluble Vitamins
* Vitamin E – tocopherol, *alpha-, beta -, gamma-, and delta-
o Roles:
+ Antioxidant (protects polyunsaturated fats)
+ Prevention of damage to lungs, RBCs, WBCs (immunity), heart
+ Necessary for normal nerve development
* Vitamin E
o Deficiencies (decreased absorption of fats- liver disease, low fat diets)
+ Premature babies – fragile RBCs (hemolysis)
+ Loss of muscle coordination, vision, immune functions
o Toxicities (more than 1000 milligrams/day)
+ Increases the effects of anticoagulants (Coumadin, Warfarin)
o DRI 15 milligrams/day (alpha-tocopherol)
o Sources, see snapshot 7.3
* Vitamin K – produced by bacteria in large intestine
o Roles
+ Promotes synthesis of blood clotting proteins (**Interferes with Coumadin)
+ Bone formation
o Deficiencies are rare but seen in infants, after prolonged antibiotic therapy, and in patients with decreased bile production.
o Toxicities (>1000 mg/day): rupture of RBCs and jaundice

o DRI: 90(women) – 120(men) micrograms/day
o Sources, see snapshot 7.4

Water Soluble Vitamins
* 8 B vitamins – Tender Romance Never Fails with 6 to 12 Beautiful Pearls (Thiamin, Riboflavin, Niacin, Folate, B6, B12, Biotin, and Pantothenic acid)
o Aid in metabolism of and energy release from carbohydrates, lipids, amino acids.
o Mode of action – coenzymes or parts of coenzymes that are necessary for the proper activity of enzymes, Without the coenzyme, compounds A and B don’t respond to the enzyme.

With the coenzyme in place, compounds A and B are attracted to the active site on the enzyme, and they react.
The reaction is completed with the formation of a new product. In this case, the product is AB.
Muscles and other tissues metabolize protein.
Brain and other tissues metabolize carbohydrates.
Bone tissues make new blood cells.
Liver and other tissues metabolize fat.
Digestive tract lining replaces its cells.

* Thiamin and Riboflavin
o Roles – energy metabolism in cells, part of nerve cell membranes.
o Deficiencies
+ Beri beri, edema &/or muscle weakness
+ Alcohol abuse – Wernicke-Korsakoff syndrome
o DRI thiamin:1.1(women) – 1.2(men) mg/day; riboflavin 1.1(women) – 1.3(men) mg/day
o Sources: All food groups except fats and oils
* Niacin – can be produced from the amino acid tryptophan.
o Roles: energy metabolism
o Deficiencies: Pellagra – dermatitis, diarrhea, dementia, death
o Toxicities (2 - 3X DRI): *prevents blood clotting, causes liver damage, enhances action of Coumadin
* Niacin
o DRI 14(women) -16(men) mg/day
o Sources, snapshot 7.8
+ Meats
+ Some vegetables and grains
* Folate
o Role: required for synthesis of DNA - ***pregnancy
o Deficiencies (drug interactions, smoking)
+ Anemia
+ Decreased immunity
+ Decreased digestive and cardiovascular function
+ Colon and cervical cancers
+ *Neural tube defects, ?other birth defects
o Toxicities (>1000 mg/day): rare, interferes with anticancer drugs.
o DRI 400 milligrams/day
o Sources, snapshot 7.8

* Vitamin B12 (requires intrinsic factor for absorption)
o Roles: works with folate, part of insulating sheath around nerves.
o Deficiencies:
+ Pernicious anemia
+ Paralysis
+ Nerve damage in fetus
o DRI 2.3 micrograms/day
o Sources, see snapshot 7.9
+ Meat and dairy
+ Implications for vegans??
* Vitamin B6
o Roles:
+ Conversion of amino acids to other amino acids
# Ex.: Tryptophan to niacin
+ Synthesis of hemoglobin and neurotransmitters
+ Release of glucose from glycogen
+ Immune function
+ Promotes steroid hormone activity
+ Development of nervous system
o Deficiencies
+ Anemia
+ Dermatitis
+ Muscle weakness
+ Behavioral problems
+ ?Heart disease
o Toxicities (>100 mg/day) – muscle weakness, nerve damage
o DRI 1.3 milligrams/day
o Sources, see snapshot 7.10
+ Meat and dairy
+ Vegetables and fruits
* Biotin and Pantothenic acid
o Roles:
+ Metabolism of carbohydrates, fats and proteins
+ Synthesis of lipids, neurotransmitters, steroid hormones, hemoglobin.
* “Non-B vitamins”: choline, carnitine, inositol, lipoic acid, etc. No beneficial effects proven!!

* Vitamin C, ascorbic acid – history of controversy
o Roles:
+ Connective tissue development, collagen
+ Antioxidant
+ Promotes iron absorption, immunity?
+ Protects vitamin E

o Deficiency – Scurvy (skin and mucous membrane damage), anemia.
o Toxicity (> 2grams/day) – pro-oxidant, activates oxidizing agents.
o DRI – 75(w) – (90(m) milligrams/day. Increased for smokers.
o Sources, see snapshot 7.11
o Notes: can interfere with diagnostic tests for diabetes, and blood clotting
o ??Prevents colds

Vitamin/Mineral Supplements

* Who needs them?
* Who does not need them?
* Oyo read - Controversy

Vitamins.ppt