Introductory Human Nutrition: Digestion, Absorption, Microbiome, and Carbohydrates

Comprehensive vocabulary flashcards covering digestive structures, nutrient transport, probiotics, prebiotics, carbohydrate classifications, health risks of added sugars, functional and dietary fibers, and ultra-processed foods.

Small Intestine

The organ where $95\%$ of digestion occurs and where most nutrient absorption takes place.

Villi

Finger-like projections lining the small intestine that absorb nutrients and contribute to increasing its surface area to $600\text{ times}$ that of a simple tube.

Microvilli

Hair-like projections located on the small intestine lining that further increase surface area for nutrient absorption.

Probiotic Food Criteria

Scientific standards requiring a food to contain live microorganisms, provide a health benefit when consumed in adequate amounts, and contain specific, identified strains of bacteria.

Prebiotic

A type of fiber that beneficial gut bacteria use as food, helping them grow and thrive.

Resistant Starch

A form of starch found in foods such as cooked and cooled potatoes, cooked and cooled rice, green bananas, and beans that supports beneficial gut flora.

Lactobacillus rhamnosus GG (LGG)

A specific probiotic bacterium with weak evidence supporting its ability to help prevent diarrhea associated with antibiotic use.

Saccharomyces boulardii

A probiotic yeast that has weak evidence for helping prevent diarrhea associated with antibiotics.

Monosaccharides

Carbohydrates composed of a single sugar unit, including glucose and fructose.

Disaccharides

Carbohydrates composed of two joined sugar units, such as sucrose and lactose.

Oligosaccharides

Carbohydrates that consist of $3$ to $10$ sugar units.

Polysaccharides

Long chains of sugar units, which include starch, glycogen, and fiber.

Glucose

A monosaccharide found in fruits, vegetables, and honey that is used by cells throughout the body for energy and stored in the liver as glycogen.

Fructose

A simple sugar found in fruits, honey, and high-fructose corn syrup that is mostly processed by the liver, where excess amounts can be converted into fat.

Sucrose

Common table sugar that breaks down during digestion into $50\%$ glucose and $50\%$ fructose.

High-Fructose Corn Syrup (HFCS-55)

The leading source of fructose in the U.S. diet, commonly used in soft drinks and composed of approximately $55\%$ fructose and $45\%$ glucose.

Empty Calories

Calories derived from foods and beverages that provide little to no nutritional value, offering few vitamins, minerals, or other essential nutrients.

HDL Cholesterol

High-density lipoprotein, commonly called good cholesterol because it removes excess cholesterol from the bloodstream; its levels are lowered by high sugar-sweetened beverage intake.

American Heart Association Added Sugar Limits

Guidelines recommending that adult women consume no more than $25\text{ grams}$ of added sugar per day and adult men consume no more than $36\text{ grams}$ per day.

Fatty Liver Disease

A condition characterized by excess fat building up in the liver, potentially causing inflammation, scarring, cirrhosis, and liver damage.

Ectopic Fat

Fat that abnormally accumulates in tissues and organs where it is not normally stored, such as the liver, muscles, or pancreas.

Glycogen

The stored form of glucose in animals and humans, held primarily in the liver and muscles for future energy use.

Dietary Fiber

The non-digestible part of plant foods that occurs naturally in whole foods like fruits, vegetables, beans, and whole grains.

Functional Fiber

Fiber that has been isolated or extracted from natural sources or manufactured and added to foods or dietary supplements to provide specific health benefits.

Inulin (Chicory Root Extract)

A functional soluble fiber extracted from chicory roots that functions as a prebiotic to nourish beneficial gut bacteria.

Soluble Corn Fiber

A functional soluble fiber derived from corn starch that is added to commercial foods to improve texture, add bulk, and raise fiber content.

Adequate Intake (AI) Basis for Fiber

The physiological standard on which dietary fiber recommendations are based, specifically promoting normal laxation by preventing constipation and ensuring regularity.

Metabolic Syndrome

A clinical cluster diagnosed by having at least three of five conditions: large waist circumference, high blood pressure, high blood sugar, high triglycerides, and low HDL cholesterol.

Ultra-Processed Food

An industrially manufactured food formulation made primarily from refined substances and additives, often hyper-palatable and containing little to no whole food.

Soluble Fiber

Fiber that dissolves in water to slow digestion, help lower blood cholesterol, regulate blood sugar levels, and feed beneficial gut microbes.

Insoluble Fiber

Fiber that does not dissolve in water, functioning to add bulk to stool, promote regular bowel movements, and prevent constipation.

Minimum CFU Standard for Probiotics

The scientific benchmark requiring probiotic products to generally contain at least $1\text{ billion}$ colony-forming units (CFUs) per serving at the end of their shelf life.

Maltose

A disaccharide carbohydrate composed of two joined glucose units.

Sugar Weight to Teaspoon Conversion

The dietary metric where $4\text{ grams}$ of sugar equals $1\text{ teaspoon}$, which provides $16\text{ calories}$ of energy.

Major Beverage Sources of Added Sugar

Sugar-sweetened beverages ($38\%$) and sweetened coffee and tea ($10\%$), which together account for nearly half of all added sugars consumed by Americans.

Recommended Daily Dairy Intake

The guideline recommending $2\text{ to }3\text{ cup equivalents}$ of dairy foods per day, a target currently missed by approximately $90\%$ of the U.S. population.

Shortfall Nutrients in Milk

Three essential nutrients commonly underconsumed by Americans that are supplied by drinking milk: calcium, potassium, and vitamin D.

Human Gut Bacterial Population

A diverse community residing mainly in the large intestine consisting of approximately $38\text{ trillion}$ bacteria and $200\text{ to }1{,}100$ distinct species.

Hepatic Glucose vs. Fructose Metabolism

Glucose metabolism is regulated by an enzyme that directs surplus sugar into the blood, whereas fructose is absorbed entirely by the liver regardless of energy demand and converted into fat.

Health Risks of Ectopic Liver Fat

Metabolic disruptions caused by abnormal liver fat accumulation, primarily reduced insulin sensitivity and elevated non-fasting blood triglycerides.

Direct Mechanism of Sugar-Driven Tumor Growth

The process where excess unabsorbed glucose and fructose reach the colon, entering tumor cells directly to stimulate cancer growth independent of obesity.

Early-Onset Colorectal Cancer Sugar Risk

An observed epidemiological association where each additional sugar-sweetened beverage consumed daily during adolescence correlates with a $32\%$ higher risk of colorectal cancer before age $50$.

2025–2030 Dietary Guidelines Sugar Target per Meal

The proposed dietary limit recommending that individuals consume no more than $10\text{ grams}$ of added sugar per meal.

Sugar Content of a 20-Ounce Soft Drink

Approximately $16\text{ teaspoons}$ (or $64\text{ grams}$) of added sugar, which requires about $3\text{ miles}$ of walking to burn off.

Prebiotic Health Benefits

Physiological benefits including fueling beneficial gut bacteria, reducing systemic inflammation, enhancing mineral absorption, lowering cardiovascular risk, and normalizing bowel elimination.