Nutrition 251 Exam 3: Chapter 13 Water Soluable Vitamins
60 mg of tryptophan will produce ____ mg of niacin
1 mg
How many milligrams of tryptophan are required to yield 200 mg of niacin?
12,000
The RDA for vitamin C in smokers is _____ higher than those who do not smoke
35 mg/day
What are the best methods for retaining the water-soluble vitamins when preparing food?
Microwaving Stir frying
Why are corn-based diets associated with pellagra?
Niacin in corn is unavailable. Corn contains little tryptophan.
Which of the following is characteristic of many of the water-soluble vitamins?
Organic compounds Have important roles in energy metabolism Low toxicity risk
Why is there a loss of water-soluble vitamins when preparing foods?
The vitamins may leach into the cooking water.
Niacin serves as a ______ in energy metabolism.
coenzyme
Wernicke-Korsakoff syndrome is a thiamin deficiency mainly found in _____
alcoholics
The red blood cells of a folate-deficient person differ from a healthy person by _____
becoming very large and being unable to divide due to the lack of DNA
Which specific reactions involve THFA?
conversion of histidine to glutamic acid conversion of homocysteine to methionine conversion of glycine to serine
A person suffering from weakness, muscle wasting, enlargement of the heart, and edema caused by lack of thiamin is experiencing the deficiency disease known as _____
beriberi
Vitamin C is involved in the conversion of cholesterol to ______
bile acids
One of vitamin C's main functions in the body is to _____
donate electrons in oxidation-reduction reactions
Functions of riboflavin include ______
energy-yielding metabolism assisting antioxidant reactions
The coenzymes of which B-vitamin are needed for the synthesis and maintenance of new cells?
folate
The synthetic form(s) of the B vitamin folate is (are) called ______
folic acid
Water-soluble vitamins ______
help maintain body tissues are needed for the growth of body tissues are needed for the normal function of body tissues
Vitamin B-12 is required for an enzymatic reaction involved in _____ metabolism
homocysteine
When either folate or vitamin B-12 is lacking, the amount of homocysteine in the body ______
increases
White bread ______ a good source of vitamin B-6 because it is lost in the refining of grain and ______ added back during refinement.
is not, is not
identify the food sources of thiamin.
legumes sunflower seeds pork
What type of anemia occurs when large red blood cells are unable to divide due to a folate deficiency?
megalblastic
he generic name of the B-vitamin folate refers to the form of the vitamin found _____
naturally in foods
NAD+ and NADP+ are coenzyme forms of which B vitamin?
niacin
The function of PLP, the coenzyme form of vitamin B-6, pertains mainly to enzymatic reactions involving ______
nitrogen-containing compounds
Vitamin C enhances the absorption of ____ iron.
nonheme
Folate is involved in the formation of the neurotransmitters ________
norepinephrine dopamine serotonin
Vitamin B-6 participates in ______ metabolic reactions
numerous
Corn-based diets are associated with which condition?
pellagra
Other possible roles for folate in the body include _____
reducing the risk of stroke maintaining normal blood pressure
Decarboxylation is defined as the ______
removal of 1 molecule of carbon dioxide from a compound
The deficiency disease for vitamin C is called ______
scurvy
The signs of scurvy include ____
slowed wound healing bone pain bleeding gums
Water-soluble vitamins are essential organic substances needed in _____ amounts
small
Smokers need more vitamin C daily than nonsmokers because _____
smoking increases vitamin C turnover
The food sources of riboflavin include _____
spinach liver mushrooms
Which organ produces the intrinsic factor that enhances vitamin B-12 absorption?
stomach
THFA is especially involved in amino acid metabolism via _____
the interconversion of amino acids
The risk of water-soluble vitamin toxicity is low because ______
the kidneys filter out the excess daily
A riboflavin deficiency usually occurs with a deficiency of several other B-vitamins because ______
these nutrients often occur in the same foods
The B vitamin required as a coenzyme to metabolize carbohydrates and some amino acids is _____
thiamin
Thiamin is a key component required to metabolize the macronutrient ______
Carbohydrates
Vitamin C is necessary for the synthesis of which of the following compounds?
Carnitine Thyroxine Epinephrine
Pantothenic acid
Coenzyme form is "CoA" and shuttles 2 carbon fragments from the metabolism of glucose, amino acids, fatty acids, and alcohol to the citric acid cycle during energy metabolism Pantothenic acid is widespread in foods and a deficiency is rare
Folate
Coenzyme form is tetrahydrofolic acid (THFA); accepts and donates 1-carbon groups Functions in DNA synthesis Works with Vit B12 to participate in homocysteine metabolism Good food sources are leafy green vegetables, oranges, legumes, fortified cereal grains Deficiency results in megaloblastic anemia and increases risk for neural tube defects (spina bifida)
Riboflavin
Coenzymes FAD and FMN participate in a wide variety of oxidation-reduction reactions, including energy-yielding pathways Deficiency is rare but if it occurs, it is ariboflavinosis Good food sources are dairy, enriched or whole grains, mushrooms
Niacin
Coenzymes NAD+ and NADP+ participate in a wide variety of oxidation-reduction reactions, including energy-yielding pathways Deficiency results in a disease called Pellagra, seen most often in corn-based diets Food sources include meats, whole or enriched grains, dried beans, dairy, mushrooms, seafood/fish The body can make niacin from the amino acid tryptophan; requires the coenzymes PLP and FAD Niacin taken in doses above the UL can lead to flushing; high doses are prescribed to improve blood cholesterol levels
Vitamin B6
Comes in 3 forms - attachment of phosphate activates it as a coenzyme PLP is the most common coenzyme form PLP participates in amino acid metabolism Synthesis of nonessential amino acids Breakdown of glycogen Form homocysteine Needed to make heme to form hemoglobin and to form neurotransmitters Good food sources are animal sources, whole grain cereals Toxicity results in nerve damage
Dietary folate equivalents (DFE) reflect the differences in the ______ of food folate and synthetic folic acid.
Absorption
Vit C functions as an electron donor acting to keep metal cofactors such as iron and zinc in their reduced forms.
Additional functions of Vit C include collagen synthesis, formation of neurotransmitters, and bile acid formation from cholesterol. Food sources include citrus fruits, red pepper, strawberries, and cruciferous vegetables (broccoli, cauliflower, brussels sprouts) The deficiency disease for Vit C is scurvy. The minimum amount the body needs is 10 mg/day so deficiency is rare with a healthy, balanced diet. Smokers have a higher requirement for Vit C.
Why are alcoholics more susceptible to Wernicke-Korsakoff syndrome?
Alcoholics consume a diet low in thiamin. Alcohol increases thiamin excretion in the urine. Alcohol decreases thiamin absorption.
How are folate requirements expressed?
Dietary folate equivalents (DFE)
Which of the following are common major functions across the water-soluble vitamins?
Energy metabolism Blood formation and clotting Protein and amino acid metabolism
Vitamin B12 (Cobalamin)
In coenzyme form (methylcobalamin) transfers 1-carbon groups Works with folate to participate in homocysteine metabolism Needed to make the myelin sheath that covers nerve cells Good food sources include animal proteins, fortified foods Digestion: R-protein it is bound to in food is removed in the stomach; in small intestine binds to intrinsic factor; Absorption: requires intrinsic factor for absorption that occurs in the small intestine Deficiency includes megaloblastic anemia, pernicious anemia, elevated homocysteine levels Atrophic gastritis, lack of intrinsic factor, and poorly planned vegan diet can cause B12 deficiency
What substance produced by the digestive system is necessary in order to absorb vitamin B-12?
Intrinsic factor
Which are functions of thiamin?
Involved in decarboxylation reactions Coenzyme required for the metabolism of carbohydrates and branched-chain amino acids
Biotin
Is a cofactor in enzymes that add carbon dioxide to a substance; these enzymes are required for the metabolism of energy-yielding nutrients Is widespread in foods and intestinal bacteria synthesize biotin; deficiency does not exist in healthy individuals
Which of the following are functions of vitamin B-6?
Major role in amino acid metabolism Converts homocysteine to the amino acid cysteine Required for the release of glucose from glycogen
Which of the following are good food sources of vitamin B-6?
Meat Poultry Fish
Ariboflavinosis, which causes inflammation of the throat, mouth, and tongue; cracking of the tissue around the mouth; and red, scaly skin is caused by a deficiency of ______
Riboflavin
Milk is an excellent source of ____
Riboflavin
Which B-vitamin is a component of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)?
Riboflavin
When vitamin B-12 is lacking, ______.
THFA levels decrease
Which vitamin is also known as cobalamin?
Vitamin B-12
______ enhances iron absorption
Vitamin C
Which vitamin has foods of animal origin as its only reliable food source and is the only vitamin that contains a mineral as part of its structure?
vitamin B-12
Which B-vitamin participates in transamination reactions that allow the synthesis of nonessential amino acids?
vitamin B-6
Which water-soluble vitamin acts as an electron donor and has a cofactor role for several metalloenzymes?
vitamin C
The category of vitamins that are stored only to a small degree in the body are the ______-soluble vitamins
water
