Nutritional Sciences: Alcohol, Water-Soluble Vitamins, Metabolism, and Fat-Soluble Vitamins

Comprehensive vocabulary flashcards covering alcohol metabolism, water-soluble vitamins, macronutrient metabolism, and fat-soluble vitamins.

Ethanol

The chemical name for the alcohol found in beverages; a central nervous system depressant and narcotic that provides $7\,\text{kcal/g}$ but is not an essential nutrient.

Standard Drink

A beverage portion providing approximately $14\,\text{g}$ of pure alcohol, defined as $12\,\text{fl oz}$ of regular beer ($\approx 5\%$ alcohol), $8\text{--}9\,\text{fl oz}$ of malt liquor ($\approx 7\%$ alcohol), $5\,\text{fl oz}$ of table wine ($\approx 12\%$ alcohol), or $1.5\,\text{fl oz}$ of 80-proof distilled spirits ($\approx 40\%$ alcohol).

Moderate Drinking

Alcohol consumption defined as up to $1$ standard drink per day for women and up to $2$ standard drinks per day for men.

Binge Drinking

The rapid consumption of alcohol defined as $4$ or more drinks for women or $5$ or more drinks for men within a $1\text{ to }2\text{-hour}$ period.

Alcohol Dehydrogenase (ADH) Pathway

The principal enzymatic pathway in the stomach and liver that metabolizes about $90\%$ of consumed alcohol during low to moderate intakes, converting ethanol to acetaldehyde and then acetate.

Microsomal Ethanol Oxidizing System (MEOS)

An energy-requiring enzyme pathway in the liver that assists in metabolizing alcohol during moderate to excessive intake, increasing in activity as intake rises.

Cirrhosis

The irreversible end stage of liver damage wherein normal hepatic tissue is replaced by fibrous scar tissue, destroying liver cells and severely impairing metabolic function.

Wernicke-Korsakoff Syndrome

A severe neurological complication of thiamin deficiency frequently observed in alcohol use disorder, characterized by eye muscle paralysis, staggering gait (ataxia), distorted thought processes, and memory impairment.

Coenzyme

An organic small molecule or ion (frequently derived from B-vitamins) that binds to an inactive enzyme to activate it and facilitate biochemical reactions.

Enrichment

The statutory restoration process of re-adding specific micronutrients—thiamin, riboflavin, niacin, folic acid, and iron—that are lost during the milling and refining of whole grains.

Thiamin Pyrophosphate (TPP)

The active coenzyme form of thiamin (vitamin B-1) responsible for decarboxylation reactions, such as converting pyruvate to acetyl-CoA and alpha-ketoglutarate to succinyl-CoA in carbohydrate and energy metabolism.

Beriberi

The deficiency disease of thiamin (vitamin B-1), occurring as dry beriberi (affecting the peripheral nervous and muscular systems) or wet beriberi (causing congestive heart failure and pitting edema).

Ariboflavinosis

The deficiency disease associated with riboflavin (vitamin B-2) deficiency, characterized by inflammation of the throat, mouth, and tongue (glossitis), and cracked tissue at the corners of the mouth (angular cheilitis).

Pellagra

The deficiency disease caused by severe niacin (vitamin B-3) deficiency, historically prevalent in populations with untreated corn-based diets, characterized by the 4 D's: diarrhea, dermatitis, dementia, and death.

Niacin Equivalents (NE)

The dietary unit of measurement that accounts for preformed niacin in foods as well as niacin synthesized endogenously from tryptophan, where $60\,\text{mg}$ of dietary tryptophan yields $1\,\text{mg}$ of niacin.

Coenzyme A (CoA)

The active coenzyme containing pantothenic acid (vitamin B-5) that shuttles 2-carbon acyl fragments from the breakdown of carbohydrates, fatty acids, amino acids, and alcohol into the citric acid cycle.

Avidin

A protein present in raw egg whites that binds tightly to biotin (vitamin B-7) and inhibits its intestinal absorption.

Pyridoxal Phosphate (PLP)

The primary active coenzyme form of vitamin B-6 that mediates transamination reactions in nonessential amino acid synthesis, glycogen breakdown, and heme and neurotransmitter production.

Tetrahydrofolic Acid (THFA)

The active coenzyme form of folate (vitamin B-9) that functions in 1-carbon unit transfer reactions critical for DNA synthesis, amino acid metabolism, and red blood cell formation.

Dietary Folate Equivalents (DFE)

A metric reflecting the higher bioavailability of synthetic folic acid compared to naturally occurring food folate, calculated as: $\text{DFE} = \mu\text{g food folate} + (\mu\text{g synthetic folic acid} \times 1.7)$.

Neural Tube Defects

Congenital developmental abnormalities of the central nervous system, including spina bifida and anencephaly, linked directly to maternal folate deficiency during early pregnancy.

Intrinsic Factor (IF)

A glycoprotein produced by the parietal cells of the stomach that binds to vitamin B-12 in the small intestine, facilitating its absorption across the ileal mucosal cells.

Pernicious Anemia

A condition resulting from autoimmune destruction of gastric parietal cells (atrophic gastritis) and lack of intrinsic factor, leading to vitamin B-12 malabsorption and neurological deterioration.

Megaloblastic Anemia

A form of anemia characterized by the bone marrow release of large, abnormal, nucleated, immature red blood cells, caused by defective DNA synthesis secondary to folate or vitamin B-12 deficiency.

Scurvy

The clinical deficiency disease of vitamin C resulting from disrupted collagen synthesis, characterized by pinpoint hemorrhages, bleeding gums, impaired wound healing, and joint pain.

Metabolism

The sum total of all physical and chemical processes in the body by which cells break down nutrients to liberate energy and synthesize new compounds.

Anabolic Pathways

Endergonic metabolic pathways that use energy ($\text{ATP}$) to construct large, complex molecules (such as proteins, glycogen, and triglycerides) from smaller building blocks.

Catabolic Pathways

Exergonic metabolic sequences that degrade complex dietary molecules into simpler units, releasing carbon dioxide, water, and usable energy captured as $\text{ATP}$.

Cellular Respiration

The physiological process by which food molecules are oxidized to harvest energy and synthesize ATP, utilizing oxygen as the final electron acceptor in aerobic conditions.

Glycolysis

An anaerobic pathway occurring in the cytosol that converts $1$ molecule of 6-carbon glucose into $2$ molecules of 3-carbon pyruvate, yielding a net of $2\,\text{ATP}$ and $2\,\text{NADH} + 2\,\text{H}^+$.

Transition Reaction

An irreversible aerobic process taking place as pyruvate moves from the cytosol into the mitochondrial matrix, converting $2$ molecules of pyruvate into $2$ molecules of acetyl-CoA, $2\,\text{CO}_2$, and $2\,\text{NADH} + 2\,\text{H}^+$.

Citric Acid Cycle (TCA Cycle)

A cyclic series of mitochondrial reactions wherein acetyl-CoA combines with oxaloacetate to form citrate, generating $\text{NADH} + \text{H}^+$, $\text{FADH}_2$, $\text{GTP}$ (converted to $\text{ATP}$), and releasing $\text{CO}_2$.

Electron Transport Chain (ETC)

The primary pathway for aerobic ATP production located on the inner mitochondrial membrane, generating $28\,\text{ATP}$ per glucose molecule by transferring electrons from $\text{NADH}$ and $\text{FADH}_2$ to molecular oxygen.

Cori Cycle

The circular metabolic inter-organ pathway wherein lactate generated by anaerobic glycolysis in muscles travels via blood to the liver, where it is resynthesized into glucose using ATP and returned to muscles.

Lipolysis

The enzymatic breakdown of stored triglycerides into free fatty acids and glycerol by hormone-sensitive lipase, stimulated by glucagon and epinephrine and suppressed by insulin.

Beta-Oxidation

The mitochondrial pathway that breaks down fatty acids by cleaving 2-carbon fragments sequentially to produce acetyl-CoA, $\text{NADH} + \text{H}^+$, and $\text{FADH}_2$.

Ketogenesis

The pathway whereby excessive acetyl-CoA molecules from accelerated beta-oxidation unite in pairs in the liver to create ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone) when oxaloacetate is depleted.

Deamination

The initial chemical step in amino acid catabolism involving the enzymatic removal of the nitrogen-containing amino group ($-\text{NH}_2$), yielding ammonia and an amphoteric carbon skeleton.

Glucogenic Amino Acids

Amino acids whose carbon skeletons can be transformed into pyruvate or citric acid cycle intermediates to synthesize glucose via gluconeogenesis.

Ketogenic Amino Acids

Amino acids whose carbon skeletons are converted directly into acetyl-CoA, rendering them incapable of being converted to glucose.

Urea Cycle

The metabolic pathway in the liver that combines toxic ammonia ($\text{NH}_3$) from amino acid deamination with carbon dioxide to synthesize urea, which is transported to the kidneys for urinary excretion.

Retinoids

The collective name for preformed biologically active vitamin A compounds found in animal foods: retinol, retinal, and retinoic acid.

Carotenoids

Plant pigments such as beta-carotene that can serve as provitamin A precursors and function as lipid-soluble antioxidants.

Retinol Activity Equivalent (RAE)

The standard unit reflecting vitamin A activity based on biological conversion: $1\,\text{RAE} = 1\,\mu\text{g retinol} = 12\,\mu\text{g beta-carotene} = 24\,\mu\text{g alpha-carotene or beta-cryptoxanthin}$.

Rhodopsin

A light-sensitive protein complex composed of opsin and retinal located in the retinal rod cells, essential for visual dark adaptation and black-and-white vision.

Bitot's Spots

Hardened, foamy-appearing plaques of keratinized epithelial cells that develop on the conjunctiva of the eye, indicating severe vitamin A deficiency.

Xerophthalmia

Advanced ocular condition caused by severe, chronic vitamin A deficiency characterized by pathological dryness, conjunctival keratinization, and corneal clouding that progresses to irreversible blindness.

Hyperkeratosis

A condition in which vitamin A-deficient epithelial cells overproduce keratin, creating rough, hardened bumps around hair follicles in the skin.

Calcitriol ($1,25(\text{OH})_2\text{ D}_3$)

The active hormonal form of vitamin D, synthesized in the kidneys through hydroxylation regulated by parathyroid hormone (PTH), which promotes intestinal calcium and phosphorus absorption.

Cholecalciferol (Vitamin D-3)

The form of vitamin D synthesized endogenously in the epidermis from 7-dehydrocholesterol following ultraviolet (UV) solar radiation exposure.

Rickets

A pediatric bone-mineralization disease caused by insufficient vitamin D and calcium, characterized by malformed skeletal development, bowed legs, and enlarged head and joints.

Osteomalacia

The adult form of vitamin D deficiency characterized by poor bone mineralization, softening of bones, and high susceptibility to fractures.

Alpha-Tocopherol

The most biologically active isomer of vitamin E, functioning primarily as a chain-breaking antioxidant that inhibits lipid peroxidation of polyunsaturated fatty acids in cell membranes.

Free Radical

An unstable, highly reactive molecule or atom containing one or more unpaired electrons in its outer orbital, causing oxidative damage to cellular membranes, proteins, and DNA.

Phylloquinone (Vitamin K-1)

The dietary plant-derived form of vitamin K found abundantly in dark leafy green vegetables and vegetable oils.

Menaquinone (Vitamin K-2)

The form of vitamin K synthesized by commensal bacteria inhabiting the human large intestine and found in meats and fish oils.

Prothrombin

A circulating blood-clotting factor synthesized by the liver requiring vitamin K for carboxylase activation, which is subsequently converted to thrombin to form a fibrin clot.

Dietary Supplement Health and Education Act of 1994 (DSHEA)

The federal legislation establishing definitions for dietary supplements, classifying them distinctly from conventional foods and pharmaceuticals, and exempting them from stringent pre-market FDA approval.

USP Verified Mark

A voluntary third-party quality seal certifying that a dietary supplement contains the declared ingredients at stated potency, dissolves within a specified time, and is free of harmful contaminants.