The Water-Soluble Vitamins: B Vitamins and Vitamin C

Practice flashcards covering the characteristics, functions, and deficiencies of water-soluble vitamins and dietary supplement considerations based on the 17th Edition of Understanding Nutrition.

Vitamins

Individual units that regulate most body processes involved in supporting growth and maintaining life, required in small amounts such as $mg$ or $mcg$.

Structure of Vitamins

Individual units; they are not linked together like other nutrients.

Function of Vitamins

Assist enzymes that participate in the release of energy from carbohydrate, fat, and protein.

Water-soluble vitamins

Includes B-complex vitamins and vitamin C, which are absorbed directly into the blood and excreted by the kidneys.

Fat-soluble vitamins

Includes Vitamins A, D, E, and K, which are absorbed via the lymph, stored in liver and fat tissues, and can accumulate to cause toxicity.

Bioavailability

The amount of a nutrient absorbed and used by the body, affected by GI transit time, nutrition status, and food preparation methods.

Precursors

Vitamins available from foods in an inactive form that must be converted for use by the body.

Beta-carotene

A red-orange pigment found in fruits and vegetables that serves as a precursor to vitamin A.

Organic Nature of Vitamins

Vitamins found in fresh foods that can be readily destroyed during processing by heat, light, or oxygen.

UL (Tolerable Upper Intake Level)

The highest amount of a nutrient likely not to harm most healthy people when consumed daily; niacin, vitamin B6, folate, choline, and vitamin C have one.

Coenzymes

Small organic molecules, often containing a B vitamin, that bind to enzymes to allow chemical reactions to occur.

Thiamin

A B vitamin that is part of the coenzyme TPP ($ext{thiamin pyrophosphate}$).

TPP

The coenzyme form of thiamin, known as thiamin pyrophosphate.

Beriberi

The thiamin-deficiency disease, which can manifest as either dry or wet.

Dry beriberi

A form of thiamin deficiency characterized by damage to the nervous system and muscle weakness in the arms and legs.

Wet beriberi

A form of thiamin deficiency characterized by damage to the cardiovascular system, dilated blood vessels, and edema.

Riboflavin

A B vitamin that serves as a coenzyme in the forms of FAD and FMN.

FAD and FMN

Coenzyme forms of riboflavin that can accept and سپس donate two hydrogens during the TCA cycle and electron transport chain.

Niacin

A B vitamin that exists in two forms, nicotinic acid and nicotinamide (niacinamide).

Tryptophan conversion to niacin

The body can synthesize $1,mg$ of niacin from every $60,mg$ of the amino acid tryptophan.

Niacin Equivalents (NE)

The units used to express total niacin intake, accounting for both preformed niacin and that synthesized from tryptophan.

Pellagra

The niacin-deficiency disease characterized by diarrhea, dermatitis, dementia, and death (the "four Ds").

Niacin flush

A pharmacological effect resulting from large doses of nicotinic acid that causes dilated capillaries and a painful tingling sensation.

Biotin

A B vitamin that plays a critical role in the TCA cycle, gluconeogenesis, and fatty acid synthesis; can also be synthesized by GI-tract bacteria.

Pantothenic acid

A B vitamin that forms part of the chemical structure of coenzyme A, involved in lipid and neurotransmitter synthesis.

"Burning feet" syndrome

A specific neurological symptom associated with pantothenic acid deficiency.

Vitamin B6 forms

Three chemical forms: pyridoxal, pyridoxine, and pyridoxamine.

Vitamin B6 toxicity

Neurological damage caused by consuming $2,grams$ of vitamin B6 daily for 2 months or more.

Folate

Also known as folacin or folic acid, it is a B vitamin crucial for DNA synthesis and the regeneration of methionine from homocysteine.

THF

Tetrahydrofolate, the primary coenzyme form of folate that transfers 1-carbon units in metabolism.

Dietary Folate Equivalents (DFE)

A measurement that accounts for the fact that synthetic folate is $1.7$-fold more available to the body than food folate.

Neural tube defects

Birth defects of the brain and spinal cord, such as spina bifida, which folate supplements taken before and during early pregnancy can help prevent.

Macrocytic or megaloblastic anemia

A folate-deficiency condition characterized by large, immature red blood cells and GI-tract deterioration.

Vitamin B12 (Cobalamin)

A B vitamin that activates folate, maintains nerve fiber sheaths, and supports bone cell activity.

Intrinsic factor

A substance secreted by the stomach cells that binds with vitamin B12 to facilitate its absorption in the small intestine.

Atrophic gastritis

A condition that damages stomach cells, potentially caused by iron deficiency or H. pylori, leading to impaired vitamin B12 absorption.

Pernicious anemia

A blood disorder characterized by vitamin B12 deficiency caused by atrophic gastritis and a lack of intrinsic factor.

Choline

An essential nutrient used to make the neurotransmitter acetylcholine and the phospholipid lecithin.

Inositol

A nonvitamin found in cell membranes that can be synthesized by the body.

Carnitine

A nonvitamin made by the body that is responsible for transporting fatty acids into the mitochondria.

Vitamin B17

A misleading name for Laetrile, a substance dangerous and falsely marketed as a cancer cure.

Interaction between Riboflavin and B6

The riboflavin coenzyme FMN assists the enzyme that converts vitamin B6 to its coenzyme form, PLP.

Vitamin C (Ascorbic acid)

A water-soluble vitamin that acts as an antioxidant and a cofactor for collagen formation.

Free radical

An unstable and highly reactive molecule with one or more unpaired electrons.

Oxidative stress

Damage inflicted by free radicals that antioxidants like vitamin C help defend against.

Collagen

A fibrous structural protein of connective tissue that serves as the matrix for bones and teeth and forms scars in wound healing.

Hydroxylation

The chemical process of forming collagen using vitamin C and iron as cofactors.

Vitamin C and Histamine

Vitamin C can deactivate histamine, which helps reduce the nasal congestion associated with the common cold.

Scurvy

The vitamin C deficiency disease; symptoms are prevented by a daily intake of at least $10,mg$.

Pro-oxidant

A substance that promotes oxidation; vitamin C can act in this capacity if taken in quantities exceeding the body's needs.

Smoker requirement for Vitamin C

Cigarette smokers require an additional $35,mg$ of vitamin C daily to combat oxidants in smoke.

USP (US Pharmacopeia)

A seal that ensures a supplement contains the declared ingredients and will dissolve and release them into the body.

Nanoceuticals

Supplements produced via nanotechnology that claim better absorption but were introduced before established FDA guidelines.

FDA Supplement Regulation

Supplements are regulated as foods, not drugs, and do not require testing for safety or effectiveness before marketing.

FDA Disclaimer

A required label statement noting the product has not been evaluated by the FDA and is not intended to diagnose, treat, cure, or prevent disease.

Supplement energy intake threshold

Individuals whose energy intake is fewer than $1,600,kcalories$ per day may need multivitamin-mineral supplements.

Iron and Zinc interaction

An example of antagonistic action where iron supplements can hinder the absorption of zinc.

Calcium and Iron interaction

An antagonistic interaction where calcium supplements can hinder the absorption of iron and magnesium.

Vitamin E and K interaction

An antagonistic metabolic interaction where vitamin E supplements can antagonize the activity of vitamin K.

"High potency" claims

A common marketing gimmick on supplement labels that consumers are advised to avoid.