Nutrition and Metabolism Fundamentals

Diet

The total food a person regularly eats.

Nutrient

A food substance required for maintenance, growth, and survival.

Essential nutrient

A nutrient the body needs but cannot make enough of by itself, so it must come from food.

Six categories of nutrients

Water, carbohydrates, lipids, proteins, vitamins, and minerals.

Energy-yielding nutrients

Carbohydrates, lipids, and proteins.

Carbohydrates kcal per gram

4 kcal/g.

Protein kcal per gram

4 kcal/g.

Lipids kcal per gram

9 kcal/g.

Alcohol kcal per gram

7 kcal/g.

Macronutrients

Nutrients needed in larger amounts: water, carbohydrates, lipids, and proteins.

Micronutrients

Nutrients needed in smaller amounts: vitamins and minerals.

Organic nutrients

Carbon-containing nutrients such as carbohydrates, lipids, proteins, and vitamins.

Inorganic nutrients

Nutrients that do not contain carbon, such as minerals.

Phytochemicals

Plant chemicals that may have positive health effects.

Examples of phytochemicals

Flavonoids and carotenoids.

Flavonoids

Plant chemicals that give blue, red, or dark pigmentation and may have antioxidant, anti-inflammatory, and anti-tumour effects.

Carotenoids

Plant chemicals that give yellow, orange, or red pigmentation and may have antioxidant effects.

Toxins

Naturally occurring substances in plants or animals that can harm the body above a threshold intake.

Food fortification

Adding nutrients to foods during manufacturing.

Example of mandatory fortification

Iodine added to table salt.

Whole foods

Foods with the least amount of processing.

Ultra-processed foods

Foods that are highly processed and associated with higher risk of type 2 diabetes, CVD, and mortality.

Food additives

Substances added to foods to affect taste, appearance, safety, freshness, or other qualities.

Organic foods

Foods grown or raised with minimal synthetic/artificial inputs and methods that preserve biodiversity.

Genetically modified foods

Foods that have had alterations made to their DNA.

Do GM foods change human DNA?

No, genetically modified foods do not change human DNA.

Sustenance

The maintenance of the body and life.

Balance

Consuming nutrients and energy in proportions that promote health.

Variety

Consuming a diversity of foods to reduce risk of nutrient deficiency.

Moderation

Not consuming too much or too little.

Nutrient density

The amount of nutrients in a food compared to a reference amount, such as 100 kcal.

Epigenetics

Changes in gene expression without changing the DNA sequence.

Diet and DNA

Diet can influence gene expression but does not change DNA itself.

Agouti mouse example

Pregnant mice fed different diets had offspring with different gene expression and health outcomes.

Dutch Famine example

People exposed to famine before birth had higher later risk of diseases like depression, CVD, type 2 diabetes, and schizophrenia.

Scientific method

A process used to test questions through observation, hypothesis, testing, results, and conclusions.

Experimental study

A study where researchers manipulate a variable, often using control and experimental groups.

Randomized controlled trial

A strong study design where participants are randomly assigned to treatment or control groups.

Experimental group

The group that receives the treatment or intervention being tested.

Control group

The group that does not receive the treatment or receives a placebo.

Placebo

A fake treatment used for comparison, such as a sugar pill.

Why RCTs are strong

They help test cause-and-effect because one main factor is changed while other factors are controlled.

Epidemiological study

A population-based study that observes trends without manipulating variables.

Main limitation of epidemiology

Association does not equal causation.

Anecdotal evidence

Personal testimony based on experience; weak scientific evidence.

Credible nutrition sources

PubMed, Google Scholar, and library databases.

Two-Eyed Seeing

Using both Western science and Indigenous ways of knowing to understand food, health, and nature.

Western science lens on food

Often studies individual nutrients and sees food as a resource for human use.

Indigenous lens on food

Often sees food as whole, living, relational, and connected to land and community.

Nutritional status

The condition of the body with respect to nutrition.

Ways to assess nutritional status

Diet analysis, laboratory tests, and health/disease state.

Diet analysis

Recording everything eaten over a period and comparing intake to recommendations.

DRIs

Dietary Reference Intakes; reference values for nutrient needs and safe upper limits.

EAR

Estimated Average Requirement; intake that meets the needs of 50% of the population.

RDA

Recommended Dietary Allowance; intake that meets the needs of 97% of the population.

How RDA is set

RDA is set using the EAR, usually two standard deviations above it.

AI

Adequate Intake; used when evidence is insufficient to set an RDA.

UL or TUL

Tolerable Upper Limit; highest intake unlikely to cause toxicity in most healthy people.

EER

Estimated Energy Requirement; energy needed to maintain current body weight and fat mass.

EER depends on

Sex, age, weight, height, and physical activity level.

AMDR

Acceptable Macronutrient Distribution Range; recommended percentage of calories from carbs, lipids, and protein.

Canada Food Guide year

Newest version was released in 2019.

Canada Food Guide plate

Half vegetables and fruits, one-quarter whole grains, one-quarter protein foods, with water as drink of choice.

Canada Food Guide vegetable/fruit recommendation

Have plenty of vegetables and fruits.

Canada Food Guide grain recommendation

Choose whole grain foods.

Canada Food Guide protein recommendation

Eat protein-rich foods.

Canada Food Guide drink recommendation

Make water your drink of choice.

Canada Food Guide eating habits

Be mindful, cook more often, enjoy food, eat with others, use labels, limit sodium/sugar/fat, and be aware of food marketing.

Canada Food Guide themes

Variety, accessibility, cultural relevance, and availability.

First Nations Healthy Food Guidelines

Focus on community health, traditional foods, less sugary drinks, more vegetables/fruits, reasonable portions, and community gardens.

Dietary Guidelines for Americans

Follow healthy eating across lifespan, focus on variety/nutrient density/amount, limit added sugars/saturated fats/sodium, shift to healthier choices, and support healthy patterns.

Canada's Healthy Eating Strategy

A Canadian food policy overhaul including the 2019 Food Guide, sodium reduction, vitamin D fortification expansion, trans fat elimination, and labelling changes.

Mandatory food label features

Nutrition Facts table, ingredients list, allergen information, and required label details.

Ingredients list order

Ingredients are listed by weight from greatest to least.

Nutrient content claim

A claim like "low fat" or "high fibre" that must meet legal standards.

High fibre claim

A product must have 4 or more grams of fibre per serving.

Very high fibre claim

A product must have 6 or more grams of fibre per serving.

Health claim

A claim linking food, a nutrient, or diet factor to health.

Disease-reduction claim

A claim linking food or nutrients to reduced risk of a disease.

Function claim

A claim linking a nutrient or diet factor to normal body function.

Front-of-package label

A label that highlights nutrients of concern such as sodium, sugars, or saturated fat.

Natural health product

A product like vitamins, minerals, probiotics, amino acids, essential fatty acids, homeopathic or traditional medicines.

Natural health product regulation

Regulated separately from foods and drugs by the Natural and Nonprescription Health Products Directorate.

Food safety basics

Clean surfaces, separate raw animal products, keep hot food hot, keep cold food cold, and refrigerate properly.

Digestion

Breaking food into smaller molecules so nutrients can be absorbed.

Absorption

Movement of nutrient subunits into blood or lymph.

Metabolism

The sum of chemical reactions in the body.

Mechanical digestion

Physical breakdown of food, such as chewing and stomach churning.

Chemical digestion

Enzymatic breakdown of large molecules into smaller molecules.

Polysaccharides digest into

Sugars or monosaccharides.

Triglycerides digest into

Fatty acids and glycerol/monoglycerides.

Proteins digest into

Amino acids.

Enzymes

Proteins that speed up chemical reactions.

Hydrolysis

Breaking molecules apart using water.

Condensation reaction

Joining molecules together while removing water.

Hormones

Chemical messengers released from one area and transported through blood.

Digestive tract order

Mouth, pharynx, esophagus, stomach, small intestine, large intestine.

Sphincters

Muscular valves that separate parts of the digestive tract.

Peristalsis

Wave-like muscle contractions that move food through the digestive tract.

Bolus

Chewed food mixed with saliva.