Exam 3 Vitamins Flashcards
Describe characteristics that make vitamins and minerals unique classes of nutrients
They don’t have a kcal value
List characteristics common to all vitamins
essential, no kcal, organic, molecules can have provitamin and precursors, water and fat soluble, most high rate of absorption.
water soluble
dissolves in water, excreted in urine, minimal storage, deficiency develops quickly, needed daily, toxicity unlikely
Fat soluble
dissolves in fat, not directly excreted, excess stored, deficiency develops slowly, not needed daily, toxicity possible
Explain how coenzymes function in an enzyme system
A coenzyme is an organic nonprotein that binds to an enzyme to promote its activity
What are provitamins (or precursors)
A compound that can be converted into the active form of a vitamin in the body
Explain why B vitamin deficiencies often result in a lack of energy
These vitamins are directly involved in transferring the energy in carbohydrate, fat and protein ATP
Explain why folate is important during pregnancy
If a pregnant woman has a low folate level, there is increased risks of birth defects called neural tube defect
Describe the digestion and absorption of vitamin B12.
The vitamin is bound to protein in food, stomach acid and pepsin help release the vitamin from food proteins, cells in the stomach lining release IF, in upper region of SI, IF binds to the vitamin, in lower part of SI the compound binds to receptor cells that allow absorption
Describe risks associated with high doses of niacin, vitamin B6, folate, and vitamin C.
Niacin: nausea, rash and tingling extremities
Vitamin B6: numbness and nerve damage
Folate: Masks B12 deficiency
Vitamin C: GI distress and diarrhea
What is an antioxidant? List which vitamins are antioxidants
Antioxidant: a substance that decreases the adverse effects of reactive molecules on normal physiological function. Vitamins: C, A, and E
Identify which population group is most vulnerable to the risk of low vitamin K status in the U.S. and why
Newborns are most at risk because when they are born they don’t have any bacteria in their GI tract to synthesize vitamin K.
What is the bottom line on the effect of high doses of vitamin C on the common cold? What cautionary information would you give someone taking high amounts of vitamin C supplements daily
Vitamin C does not prevent the common cold but it can help reduce the duration of common cold symptoms. High amounts of vitamin C can cause an increased risk of kidney formation, gives you the opposite effect
Jason’s roommate takes the drug Retin A prescribed to him by his doctor for acne. Jason is thinking about skipping the doctor and just treating his acne by taking large doses of vitamin A. Will Jason’s strategy work? What might be other consequences?
He’s strategy wouldn’t work because vitamin A might not have enough retina as retin A. Could develop a toxicity to vitamin A
Why must we be concerned with vitamin A toxicity compared to high intake of water-soluble vitamins? What level of vitamin A intake is toxic? Compare this to the RDA. Is beta-carotene toxic? What happens if you eat lots of carrots (e.g. 1 lb/day) over many weeks
Vitamin A is found in so many foods. Level that is toxic: 3000mg. RDA’s men: 682 mg and women 606 mg. Beta-carotene isn’t toxic but can cause your skin to turn orange
