Nutrition Basics Notes
Definitions and Core Concepts
Nutrition: the science of the nutrients in foods and of their actions within the body; a broader definition includes the study of human behaviors related to food and eating.
Diet: the combination of foods and beverages a person eats or drinks.
Nutrients: chemical substances obtained from food and used in the body to provide energy, structural material, and regulating agents that support growth, maintenance, and repair of the body’s tissue.
Essential nutrients: nutrients that cannot be made by the body and therefore must be obtained from food.
Energy density: energy-dense foods and beverages provide a significant amount of calories (or energy) to the body.
Nutrient density: nutrient-dense foods and beverages provide vitamins, minerals, and other health-promoting components and have little added sugars, saturated fat, and sodium.
Energy from Food and Calorimetry
Food energy is released from the digestion of carbohydrate, fat, and protein.
This energy is measured in kilocalorie (kcal).
1 kcal is the amount of energy needed to raise the temperature of 1 kg of water by 1 degree Celsius.
For simplicity and consistency in this course, the term "calories" is used when referring to kcal.
Calories are measured by a calorimeter; the device used to measure energy content in foods is the calorimeter.
The Calorimeter
Macros, Micros, and Nutrient Composition of the Body
Classes of nutrients listed: Carbohydrates, Lipids, Proteins, Vitamins, Minerals, Water.
Macronutrients: nutrients our body needs in relatively large amounts (grams) to support normal function and health; provide energy; energy yield depends on carbohydrate, fat, and protein content; energy is stored in chemical bonds and released when bonds are broken.
Macronutrients and glucose: Glucose serves as a key example of a carbohydrate’s role as the body’s preferred energy source.
Macronutrients: Glucose (Carbohydrates), Proteins, Lipids (Fats) are major macronutrients.
Carbohydrates:
Composition: C, H, O; chains of single or multiple sugar molecules
Food sources: bread, rice, oats, fruits, sweets
Main function: body’s preferred energy source (glucose)
Proteins:
Composition: C, H, O, N
Food sources: meat, dairy, eggs, tofu, tempeh
Main functions: form enzymes and hormones essential to normal body function
Lipids:
Composition: C, H, O; a family of organic compounds insoluble in water
Food sources: olive oil, butter, avocados, nuts, seeds
Main functions: cellular membranes, insulation, energy
Water and Body Composition
Water:
Made up of two elements: H and O
Makes up approximately ~60% of the body’s composition
Main functions: provides the environment for nearly all body activities; participates in many metabolic reactions; transports vital materials to cells and carries waste products away from them
Micronutrients
Micronutrients are needed in relatively small amounts to support and regulate normal health and body functions.
In contrast to macronutrients, micronutrients are not sources of energy (calories).
Vitamins (fat-soluble or water-soluble): organic (carbon-containing) compounds indispensable for body function; examples include Vitamin D, Folate, Niacin, Vitamin K; note: vitamins can store energy in carbon bonds, but the body does not use these bonds to release energy; breaking them down to use for energy would be wasteful and is unnecessary for their roles.
Minerals: naturally occurring chemical elements from the periodic table; examples include Iron, Potassium, Magnesium.
Check Your Understanding (Micronutrients)
Nutrient classification (Organic vs Inorganic; Energy-yielding vs Non-energy-yielding; Macro- vs Micro-nutrients) is summarized with categories: Carbs, Lipid, Protein, Vitamin, Mineral, Water.
Energy-Yielding Nutrients and Caloric Values
Energy-yielding nutrients and calories per gram:
Carbohydrate:
Fat:
Protein:
Fat:
\%P = \frac{60}{388} \approx 0.155 \appr
Dietary Reference Intakes (DRIs)
DRIs are a set of estimates of nutrient intakes to be used for planning and assessing diets for healthy people in the US and Canada.
Macronutrient DRIs include:
EER - Estimated Energy Requirement
AMDR - Acceptable Macronutrient Distribution Range
Micronutrient DRIs include:
RDA - Recommended Dietary Allowance
AI - Adequate Intake
EAR - Estimated Average Requirements
TUL - Tolerable Upper Intake Levels
DRIs (ENERGY & MACRONUTRIENTS)
EER (Estimated Energy Requirement): the average dietary energy intake that maintains energy balance and good health in a person of a given age, sex, weight, height, and level of physical activity.
AMDR (Acceptable Macronutrient Distribution Range): the ranges of intakes for the energy-providing nutrients that provide adequate energy and nutrients and reduce the risk of chronic diseases.
Macronutrient AMDR values:
\text{Carbohydrate: } 45\% - 65\%\text{Fat: } 20\% - 35\%\text{Protein: } 10\% - 35\%$$
AMDR Profiles and Micronutrient DRIs
EAR (Estimated Average Requirement): the daily nutrient intake estimate that meets the requirements of half the population; half the population will fall below EAR and half above it; the average amount sufficient for half the population; EARs must be established before RDAs can be set.
RDA (Recommended Dietary Allowance): set to meet the needs of the vast majority (97 to 98 percent); the average daily amount considered adequate to meet the known nutrient needs of practically all healthy people; a goal for dietary intake by individuals.
AI (Adequate Intake): the average daily amount that appears sufficient for most healthy people when there isn't enough data to set EAR and establish RDA; used instead of the RDA when EAR cannot be established.
TUL (Tolerable Upper Intake Levels): maximum daily amount of a nutrient that appears safe for most healthy people; beyond which there is an increased risk of adverse health effects; as intake increases beyond the TUL, toxicity risk rises.
DRIs cover both MICRONUTRIENTS and MACRONUTRIENTS with nutrient intake ranges.
DRI Overview and Practice
DRIs overview summary: AMDR, EER, EAR, RDA, AI, TUL; macronutrient DRIs vs micronutrient DRIs.
Check Your Understanding (DRI-focused questions):
The estimated average requirement (EAR) meets the needs of the population at about 50%.
The tolerable upper intake levels (TUL) protect against toxicity/adverse effects.
The RDA meets the needs of most healthy people in the population.
The Adequate Intake (AI) is used when there isn’t enough evidence to establish the EAR; it is used instead of the EAR and RDA.
The RDA will always be set above the EAR.
Nutrition Application: Assessment and Deficiency
Nutrition Assessment involves:
Diet history/recall
Anthropometric measures (height, weight, waist circumference, etc.)
Nutrition-focused physical exam (NFPE)
Laboratory testing (e.g., Iron, Vitamin D, Vitamin B12, etc.)
Nutrient deficiency concepts:
Primary deficiency: due to inadequate dietary intake of a nutrient.
Secondary deficiency: due to something other than inadequate intake (e.g., disease condition or drug interaction that reduces absorption).
Chronic Disease and Risk Factors
Chronic diseases: diseases characterized by slow progression and long duration.
Within genetics, an individual’s behaviors can influence health; diet and lifestyle can affect risk for many diseases.
Not all chronic diseases are driven by nutrient intake, but diet and lifestyle are closely linked to many. (Heart attack, cancer, stroke)
Risk factors in chronic disease:
A risk factor is a condition or behavior associated with an elevated frequency eat of a disease but not proven causal.
Leading modifiable risk factors include:
Cigarette smoking
Alcohol consumption
Physical inactivity
A diet high in added fats (saturated)
A diet low in vegetables, fruits, and whole grains
High blood pressure
High blood cholesterol
Abdominal body fat (visceral adiposity)