Nutrition Macronutrients: Carbohydrates, Lipids, Proteins & Metabolism

What is photosynthesis?

Plants use sunlight, carbon dioxide, and water to produce glucose and oxygen.

How many kcal per gram of carbohydrate?

4 kcal/g.

What are the three monosaccharides?

Glucose, fructose, and galactose.

What is a monosaccharide?

A carbohydrate containing one sugar unit.

What is a disaccharide?

Two monosaccharides bonded together.

What makes up sucrose?

Glucose + fructose.

What makes up lactose?

Glucose + galactose.

What makes up maltose?

Glucose + glucose.

Where is sucrose found?

Table sugar, sugarcane, sugar beets, honey, and maple syrup.

Where is lactose found?

Milk and dairy products.

What is fermentation?

Conversion of carbohydrates into alcohols, acids, and carbon dioxide.

What is an oligosaccharide?

A carbohydrate containing 3-10 sugar units.

What are raffinose and stachyose?

Indigestible oligosaccharides.

What is a polysaccharide?

A complex carbohydrate made of many sugar units.

What is starch?

The storage form of carbohydrate in plants.

What is glycogen?

The storage form of carbohydrate in animals and humans.

Where is glycogen stored?

Liver and skeletal muscle.

What is the role of liver glycogen?

Helps maintain blood glucose between meals.

What is the role of muscle glycogen?

Supplies energy for the muscle itself.

About how much energy is stored in glycogen?

About 1,800 kcal total: 400 in liver and 1,400 in muscles.

What is amylose?

The mostly straight-chain form of starch; about 20% of food starch.

What is amylopectin?

The highly branched form of starch; about 80% of food starch.

What is fiber?

Plant carbohydrate that human digestive enzymes cannot digest.

What is soluble fiber?

Fiber that dissolves or absorbs water, often forming a gel.

What is insoluble fiber?

Fiber that does not dissolve in water and adds stool bulk.

What may soluble fiber help lower?

Blood LDL cholesterol and the rise in blood glucose after a meal.

What may insoluble fiber help prevent?

Constipation by increasing stool bulk and promoting bowel movements.

What is a prebiotic?

A fermentable fiber that supports beneficial gut bacteria.

What are the three parts of a whole grain?

Bran, germ, and endosperm.

What part usually remains in refined grain?

Mainly the endosperm.

Whole grain vs refined grain: which has more fiber?

Whole grain.

What are added sugars?

Sugars added during processing or preparation, not naturally present in the food.

What are nutritive sweeteners?

Sweeteners that provide calories, such as sugar, honey, and syrup.

Examples of nonnutritive sweeteners?

Sucralose, aspartame, saccharin, stevia, and acesulfame-K.

What does ADI mean for sweeteners?

Acceptable Daily Intake: estimated amount safe to consume daily over a lifetime.

Name two sugar alcohols.

Sorbitol and xylitol.

How much energy do sugar alcohols provide?

About 2.6 kcal per gram.

What can excess sugar alcohol consumption cause?

A laxative effect, gas, or diarrhea.

Where does carbohydrate digestion begin?

The mouth, with salivary amylase.

Where does most carbohydrate digestion occur?

The small intestine.

What does pancreatic amylase digest?

Starch into smaller carbohydrate units.

What do intestinal disaccharidases do?

Break disaccharides into monosaccharides for absorption.

What carbohydrate forms can be absorbed?

Monosaccharides: glucose, fructose, and galactose.

What organ receives absorbed monosaccharides first?

The liver through the portal blood.

How does the liver use excess glucose?

Stores it as glycogen or converts surplus energy to fat.

Why is glucose important?

It provides energy; certain tissues depend heavily on glucose.

What happens if carbohydrate intake is very low?

The body relies more on fat and may produce ketones.

What is ketosis?

A metabolic state with increased production of ketone bodies from fat.

What is insulin?

A pancreatic hormone that lowers blood glucose by promoting glucose uptake and storage.

What is glucagon?

A pancreatic hormone that raises blood glucose, especially through liver glycogen breakdown.

When is insulin released?

When blood glucose rises, such as after eating.

When is glucagon released?

When blood glucose falls, such as between meals.

What hormone can raise blood glucose during stress?

Epinephrine (adrenaline).

What is hyperglycemia?

Abnormally high blood glucose.

What is hypoglycemia?

Abnormally low blood glucose.

What is the adult carbohydrate RDA?

130 g/day.

What is the carbohydrate AMDR?

45-65% of total calories.

What is the fiber goal per 1,000 kcal?

14 g.

What is the fiber goal on a 2,000-kcal diet?

28 g/day.

What fiber intake figures are given for women and men?

25 g/day for women; 38 g/day for men.

What is type 1 diabetes?

Autoimmune destruction of insulin-producing pancreatic cells; little/no insulin production.

What is type 2 diabetes?

Insulin resistance with progressive difficulty controlling blood glucose.

Which diabetes type requires insulin therapy?

Type 1 diabetes.

What lifestyle habits help manage type 2 diabetes?

Physical activity, dietary changes, and weight management when appropriate.

What is prediabetes fasting glucose range?

100-125 mg/dL.

What is a common diabetes symptom?

Excess thirst, frequent urination, fatigue, or unexplained weight loss.

What are major long-term diabetes complications?

Heart, kidney, nerve, and eye disease.

What is HbA1c used for?

To assess average blood glucose over about 2-3 months.

What is a triglyceride made of?

Glycerol + three fatty acids.

How many kcal per gram of fat?

9 kcal/g.

What are the three main classes of lipids?

Triglycerides, phospholipids, and sterols.

What is a phospholipid?

A lipid containing fatty acids and a phosphate-containing head; important in membranes.

Why can phospholipids form membranes?

They have a water-loving head and water-repelling tails.

What is an emulsifier?

A substance that helps fat and water stay mixed.

What is lecithin?

A phospholipid that serves as an emulsifier.

What is a sterol?

A lipid with a multiple-ring structure, such as cholesterol.

Where is dietary cholesterol found?

Animal-derived foods, not plant foods.

What are phytosterols?

Sterols found in plants.

What are fatty acids made of?

A carbon chain with a methyl end and a carboxyl end.

What is saturated fat?

Fatty acids with no carbon-carbon double bonds.

What is monounsaturated fat?

Fatty acids with one carbon-carbon double bond.

What is polyunsaturated fat?

Fatty acids with two or more carbon-carbon double bonds.

What is a cis double bond?

Hydrogens are on the same side of the double bond.

What is a trans double bond?

Hydrogens are on opposite sides of the double bond.

What is hydrogenation?

A process that adds hydrogen to unsaturated oils; partial hydrogenation can create trans fats.

Name the two essential fatty acids.

Linoleic acid (omega-6) and alpha-linolenic acid (omega-3).

Why are fatty acids called essential?

The body cannot synthesize enough; they must come from food.

What does omega-3 mean?

The first double bond is at the third carbon from the omega end.

What does omega-6 mean?

The first double bond is at the sixth carbon from the omega end.

What are DHA and EPA?

Long-chain omega-3 fats associated with nervous-system and cardiovascular functions.

What is DHA especially important for?

Fetal nervous-system and retinal development.

Food sources of alpha-linolenic acid (ALA)?

Flaxseed, chia, walnuts, canola, and soybean oils.

What are food sources of linoleic acid?

Flaxseed, chia, walnuts, canola, safflower, sunflower, corn oils, nuts, and seeds.

Which foods supply EPA and DHA?

Fatty fish such as salmon, sardines, and herring.

What is the slide recommendation for fatty fish?

Two servings per week.

What are eicosanoids?

Hormone-like regulatory compounds made from fatty acids.

What functions do fats serve in the body?

Energy storage, insulation, cushioning, membranes, hormones, vitamin absorption, and satiety.

Which vitamins require dietary fat for absorption?

A, D, E, and K.

How does fat affect food?

Adds flavor, texture, moisture, and helps transfer heat.

What is fat rancidity?

Breakdown of fats producing off-flavors and odors.