NSC-150 Nutrition Exam Study Guide: Carbohydrates, Lipids, Proteins, Vitamins, and Minerals

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Carbohydrates

Functions and Types of Carbohydrates

Carbohydrates are the primary energy source for cells. They are absorbed as monosaccharides and converted to glucose in the liver for energy use.

Main Energy Source for Cells: Glucose is absorbed and used for cellular energy.
Glycemic Response: Refers to the change in blood sugar levels after consuming foods containing carbohydrates.
Monosaccharides: Glucose, fructose, and galactose.
Disaccharides: Sucrose (glucose + fructose), lactose (glucose + galactose), maltose (glucose + glucose).
Polysaccharides: Starch, glycogen, and fiber.

Digestion and Absorption

Carbohydrates are broken down into monosaccharides in the small intestine and absorbed into the bloodstream.

Enzymatic Breakdown: Enzymes such as amylase and lactase facilitate digestion.
Absorption: Monosaccharides are absorbed in the small intestine.

Fiber

Dietary fiber is classified as soluble or insoluble and plays a role in digestive health.

Soluble Fiber: Dissolves in water; found in oats, beans, and some fruits.
Insoluble Fiber: Does not dissolve in water; found in whole grains, vegetables.
Health Benefits: Promotes bowel health, reduces cholesterol, and regulates blood sugar.

Glycemic Index

The glycemic index ranks foods based on their effect on blood glucose levels.

High GI Foods: Cause rapid increases in blood sugar.
Low GI Foods: Cause gradual increases in blood sugar.

Recommended Intake

Fiber: 25-38 grams per day recommended for adults.
Added Sugars: Should be limited to reduce risk of chronic disease.

Lipids (Fats)

Types and Functions of Lipids

Lipids are a diverse group of compounds that include fatty acids, triglycerides, phospholipids, and sterols. They provide energy, support cell structure, and aid in nutrient absorption.

Fatty Acids: Classified by chain length (short, medium, long) and degree of saturation (saturated, monounsaturated, polyunsaturated).
Triglycerides: Main form of fat in the diet and body.
Phospholipids: Essential for cell membrane structure.
Sterols: Cholesterol is the most well-known sterol.

Types of Fatty Acids

Saturated Fat: No double bonds; found in animal products and some plant oils.
Monounsaturated Fat (MUFA): One double bond; found in olive oil, avocados.
Polyunsaturated Fat (PUFA): Multiple double bonds; includes omega-3 and omega-6 fatty acids.

Essential Fatty Acids

Omega-3 (alpha-linolenic acid): Found in fatty fish, flaxseed, walnuts; supports heart and brain health.
Omega-6 (linoleic acid): Found in vegetable oils, nuts, seeds.

Lipoproteins

HDL (High-Density Lipoprotein): "Good" cholesterol; removes cholesterol from the blood.
LDL (Low-Density Lipoprotein): "Bad" cholesterol; deposits cholesterol in arteries.

Dietary Guidelines

Fat should make up 20-35% of total calories.
Saturated fat should be less than 10% of calories; trans fats should be avoided.

Proteins

Structure and Function

Proteins are made of amino acids and are essential for growth, repair, and maintenance of body tissues.

Amino Acids: Building blocks of proteins; 20 total, 9 are essential (must be obtained from diet).
Enzymes: Proteins that speed up chemical reactions.
Complete Proteins: Contain all essential amino acids; found in animal products and soy.
Incomplete Proteins: Lack one or more essential amino acids; found in most plant foods.

Protein Digestion and Absorption

Proteins are broken down into amino acids in the stomach and small intestine.
Amino acids are absorbed in the small intestine and transported to the liver.

Recommended Intake

General population: 0.8 g protein/kg body weight per day.
Athletes: 1.2-2.0 g protein/kg body weight per day.

Nitrogen Balance

Positive Nitrogen Balance: Intake exceeds loss; occurs during growth, pregnancy.
Negative Nitrogen Balance: Loss exceeds intake; occurs during illness, malnutrition.
Equation:

Vitamins and Minerals

Vitamins

Vitamins are organic compounds required in small amounts for various metabolic processes.

Fat-Soluble Vitamins: A, D, E, K; stored in body fat, risk of toxicity if consumed in excess.
Water-Soluble Vitamins: B-complex, C; not stored, excess excreted in urine.

Minerals

Minerals are inorganic nutrients divided into macro-minerals and trace minerals.

Macro-minerals: Needed in larger amounts; include calcium, magnesium, sodium, potassium, chloride, phosphorus.
Trace Minerals: Needed in smaller amounts; include iron, zinc, copper, selenium, iodine.

Calcium

Function: Bone health, muscle contraction, nerve transmission.
Recommended Intake: Adults need 1000-1200 mg/day.
Absorption: Enhanced by vitamin D, reduced by phytates, oxalates, and polyphenols.

Iron

Function: Oxygen transport in hemoglobin, energy metabolism.
Deficiency: Leads to anemia; symptoms include fatigue, pale skin, weakness.
Sources: Red meat, beans, fortified cereals, spinach.

Vitamin Deficiencies

Vitamin D: Deficiency causes rickets in children, osteomalacia in adults.
Vitamin C: Deficiency causes scurvy.
Folate: Deficiency causes neural tube defects in pregnancy.

Micronutrient Deficiency Anemia

Iron Deficiency Anemia: Most common; symptoms include fatigue, weakness, pale skin.
Groups at Risk: Women of childbearing age, infants, children, vegetarians.

Epigenetics and Nutrition

Epigenetics

Epigenetics refers to how environmental factors, including nutrition, influence gene expression without changing DNA itself.

Example: Nutrient intake can affect methylation patterns and gene activity.

HTML Table: Types of Fatty Acids

Type	Structure	Sources	Health Impact
Saturated	No double bonds	Animal fats, coconut oil, palm oil	Raises LDL cholesterol
Monounsaturated (MUFA)	One double bond	Olive oil, avocados, nuts	Lowers LDL cholesterol
Polyunsaturated (PUFA)	Multiple double bonds	Fish, flaxseed, walnuts	Supports heart health
Trans Fat	Hydrogenated, trans configuration	Processed foods	Raises LDL, lowers HDL

HTML Table: Water-Soluble vs. Fat-Soluble Vitamins

Type	Examples	Storage	Risk of Toxicity
Water-Soluble	B-complex, C	Not stored	Low
Fat-Soluble	A, D, E, K	Stored in body fat	Higher