Comprehensive Nutrition and Food Science Flashcards

Flashcards testing core nutrition and food science vocabulary, including energy systems, methods of calorimetry, protein structures, quality evaluation metrics, and digestive physiology.

Alimento (Food)

A complex matrix containing nutrients that can be ingested to provide nutritional value, originating from plants or animals in processed or unprocessed forms.

Nutrient

A substance contained in food that cannot be produced by the body in sufficient amounts and serves to supply energy, structural material, or metabolic regulators.

Nutrition

The science that studies food, nutrients, and their relationship to human health by analyzing biological, metabolic, and social processes.

Homeostasis

The tendency of the human organism to maintain a constant internal physiological equilibrium.

Alimentation (Feeding)

The initial stage of nutrition involving the selection and choice of items to consume, influenced by biological, social, and cultural factors.

Digestion

The mechanical and enzymatic process within the digestive tract that breaks down the food matrix into absorbable units prior to crossing the intestinal epithelium.

Metabolism

The set of biochemical processes that occur within cells and tissues using components that have already been absorbed across the intestinal barrier.

Macronutrients

Nutrients required daily in large quantities (measured in grams), comprising carbohydrates, proteins, and lipids, which supply energy ($4\,kcal/g$ or $9\,kcal/g$) or structural components.

Micronutrients

Essential non-caloric nutrients required in small amounts (milligrams or micrograms), comprising vitamins and minerals that act as metabolic regulators or cofactors.

Enrichment

The mandatory addition of specific nutrients to a food product dictated by legal or regulatory standards to address widespread population deficiency.

Fortification

The voluntary addition of nutrients by a manufacturer to enhance or differentiate a food product.

Nutrient Requirement

The specific quantity of a nutrient needed by an individual, determined by age, body size, sex, activity, physiological status, and health condition.

Nutrient Recommendation

A population-wide intake reference value designed to exceed average individual requirements and cover nearly all healthy individuals in a group.

EAR (Estimated Average Requirement)

The daily intake value estimated to meet the nutrient requirement of $50\%$ of healthy individuals in a specific life stage and gender group.

RDA (Recommended Dietary Allowance)

The average daily intake level sufficient to meet the nutrient requirements of nearly all ($97\text{--}98\%$) healthy individuals in a group.

AI (Adequate Intake)

An intake reference value established when scientific evidence is insufficient to set an EAR or RDA, based on observed or experimentally determined approximations.

UL (Tolerable Upper Intake Level)

The maximum daily intake level of a nutrient that is unlikely to pose a risk of adverse health effects to almost all individuals in the general population.

Energy Density

The amount of energy provided by a food relative to its mass, expressed as $\text{kcal}/g$.

Gross Energy (GE)

The total potential chemical energy contained in a food sample, measured by complete combustion in a bomb calorimeter.

Digestible Energy (DE)

Gross energy minus the energy lost in fecal matter ($DE = GE - \text{fecal losses}$).

Metabolizable Energy (ME)

Digestible energy minus energy losses in urine and gases ($ME = DE - \text{urinary and gas losses}$); the standard energy value listed on food tables.

Net Energy (NE)

Metabolizable energy minus the energy expended during digestion, absorption, and nutrient processing (thermic effect of food).

Atwater Factors

Conversion factors used to estimate metabolizable energy in human nutrition: $4\,kcal/g$ for carbohydrates, $4\,kcal/g$ for proteins, $9\,kcal/g$ for lipids, and $7\,kcal/g$ for alcohol.

Bomb Calorimeter

An enclosed laboratory device that measures gross energy of a food sample via direct combustion and heat transfer to surrounding water.

Direct Calorimetry

A clinical method that quantifies an individual's energy expenditure by measuring total body heat production inside an isolated calorimetric chamber.

Indirect Calorimetry

A method estimating metabolic energy expenditure by measuring oxygen consumption ($VO_2$) and carbon dioxide production ($VCO_2$).

Doubly Labeled Water Method

A gold-standard research technique using stable isotopes ($^2H$ and $^{18}O$) to measure total daily energy expenditure in free-living conditions over multiple days.

Total Energy Expenditure (TEE / GET)

The total daily energy consumed by the body, comprising Basal Metabolic Rate ($60\text{--}75\%$), Physical Activity ($15\text{--}30\%$), and the Thermic Effect of Food ($\approx 10\%$).

Basal Metabolic Rate (BMR / GEB)

The absolute minimum energy expenditure necessary to sustain vital cellular and organ functions, measured under strict conditions of fasting, complete rest, and thermoneutrality.

Nitrogen Conversion Factor

The standard numerical multiplier ($6.25$) used to convert total measured nitrogen content into estimated crude protein content ($\text{Protein (g)} = \text{Nitrogen (g)} \times 6.25$).

Zwitterion

A dipolar form of an amino acid containing equal numbers of positively ($-NH_3^+$) and negatively ($-COO^-$) charged groups, resulting in a net electric charge of zero.

Isoelectric Point (pI)

The specific pH level at which a particular amino acid or protein possesses a net electrical charge of zero, often resulting in minimum solubility.

Peptide Bond

A covalent amide linkage formed by a condensation reaction between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of $H_2O$.

Primary Protein Structure

The linear sequence of amino acids linked together by covalent peptide bonds.

Secondary Protein Structure

Local, repetitive spatial arrangements of the polypeptide backbone, such as $\alpha$-helices and $\beta$-sheets, stabilized primarily by hydrogen bonds.

Tertiary Protein Structure

The full three-dimensional, folded spatial conformation of a single polypeptide chain, stabilized by hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.

Quaternary Protein Structure

The spatial arrangement and non-covalent or covalent association of multiple polypeptide subunits in a multi-chain protein complex.

Protein Denaturation

The disruption and loss of native secondary, tertiary, and quaternary protein structures without breaking primary covalent peptide bonds.

Biological Value (BV)

A measure of protein quality reflecting the proportion of absorbed nitrogen that is retained by the body for protein synthesis ($BV = \frac{\text{N retained}}{\text{N absorbed}} \times 100$).

Net Protein Utilization (NPU)

The proportion of ingested nitrogen that is retained in the body, combining both protein digestibility and biological value ($NPU = \frac{\text{N retained}}{\text{N ingested}} \times 100$).

PDCAAS

Protein Digestibility-Corrected Amino Acid Score; a protein evaluation method determined by multiplying the limiting amino acid score by total protein fecal digestibility.

DIAAS

Digestible Indispensable Amino Acid Score; the FAO-recommended protein quality metric based on the individual true ileal digestibility of each indispensable amino acid.

Limiting Amino Acid

The indispensable amino acid present in the lowest concentration relative to the reference requirement pattern, which limits total protein synthesis.

Protein Complementation

The strategy of combining two or more incomplete protein sources with different limiting amino acids (e.g., grains and legumes) to create a meal with a complete amino acid profile.

Endopeptidase

A proteolytic enzyme (e.g., pepsin, trypsin, chymotrypsin, elastasa) that hydrolyzes internal peptide bonds within a polypeptide chain.

Exopeptidase

A proteolytic enzyme (e.g., carboxypeptidases, aminopeptidases) that cleaves amino acids sequentially from the terminal ends of a peptide chain.

Pepsin

An acidic gastric endopeptidase secreted as inactive pepsinogen and activated by $HCl$, which initiates internal protein cleavage.

Enteropeptidase

A brush-border enzyme in the duodenal mucosa that initiates pancreatic zymogen activation by converting trypsinogen into active trypsin.

PepT1

A high-capacity apical membrane transporter in enterocytes that mediates $H^+$-coupled cotransport of dipeptides and tripeptides into the cell.