Intro to Human Nutrition

Nutrition

The science that studies how food, beverages, and their components affect the body through digestion, absorption, metabolism, and health

Nutrient

a substance that performs a necessary function in the body

Micronutrients

types of nutrients needed in smaller amounts for the body, like vitamins and minerals.

Macronutrients

various types of nutrients needed in larger amounts for the body, like carbohydrates, proteins, lipids and water.

carbohydrate (hydrated carbon, or carbon with water)

a macronutrient that provides energy, primarily in the form of sugars and starches. They are digested to be broken down into glucose, the primary energy source. Some carbs, like fiber, are not fully digested.

Simple carbs

Monosaccharides provide a simple unit of sugar, like Glucose, Fructose, Galactose, Dextrose

Double carbs

Disaccharides provide 2 units of sugar, like Lactose, Sucrose, Maltose

Complex carbs

Oligosaccharides (3-10 units) and Polysaccharides are long chains of sugar molecules, like Cellulose, Starch, Glycogen

Proteins (Macro)

Large, complex molecules made up of smaller units called amino acids (chain of 20). They build and repair muscles, skin, and organs, make enzymes and hormones, support the immune system (like antibodies), transport molecules (like hemoglobin carries oxygen). They’re made up of carbon, hydrogen, and oxygen, and nitrogen.

Lipids (Macro)

types of biological molecule that is not soluble in water but soluble in non-polar solvents (like alcohol or chloroform). Lipids are essential to life and play several important roles in the body.

Non-polar solvents

liquids that do not have positive and negative charges separated (no poles) — meaning their molecules share electrons more evenly. This makes them hydrophobic, or “water-hating,” just like lipids.

Common Types of Lipids

*Fats and oils (triglycerides) – used for long-term energy storage.

*Phospholipids – major components of cell membranes. Protects a cell from outside intrusion.

*Steroids – like cholesterol (found only in animal fats), cortisol and hormones (e.g., estrogen, progesterone, testosterone). They do not contain fatty acids.

*Waxes – found in plants and animals for protection and waterproofing.

Common Non-polar Solvents

Hexane — Used in oil extraction from seeds

Chloroform — Used in labs (not common for home use)

Benzene — Used in industrial chemistry (toxic)

Ether — Used in labs and some medical settings

Toluene — Found in paint thinners

Oil — Natural example — cooking oils are non-polar

Triglycerides

comprises a glycerol (a type of alcohol) and three fatty acids. It include monounsaturated and polyunsaturated fats (vegetable oils, fish oils and nuts), known as the healthier fats.

Fatty acid

an organic compound linking a fatty chain of carbon and hydrogen atoms on one end to an acid group at the other. They can be saturated, unsaturated, trans fats, or omega fatty acids (fish oils, some nuts oils). They (linoleic and linolenic) assist in absorbing and transporting fat-soluble vitamins A, D, E, and K. 

Purposes of triglycerides

supplying energy, protecting against temperature extremes and shock, and helping the body use carbohydrates and protein efficiently

Difference between carbs and lipids

Carbs are water soluble and are great for short-term energy storage. Lipids are water insoluble and are great for long-term energy storage.

Fats and oils (triglycerides)

Fats provide more than twice the energy of carbohydrates and proteins. Most unhealthy fats are solid at room temp and used by animals for insulation, protection and long-term energy storage. Fats also give the body its shape and insulate it, assisting in maintaining body temperature. Oils are unsaturated fats and liquid at room temp and used by plants for long-term energy storage.

Healthy fats

They tend to be liquid at room temperature, so most oils are part of the unsaturated fats group. Monounsaturated fat and polyunsaturated fat are known to have the benefit of lowering blood cholesterol levels and combating other associated adverse outcomes of bad fats. Omega-3 fatty acids have been shown to reduce inflammation, which helps decrease cholesterol build-up in artery walls and pain from arthritis.

Phospholipids

Essential molecules that act as the building blocks of cell membranes, allowing cells to function and interact with their environment. They have a unique structure that makes them ideal for forming membranes: Head (made of a phosphate group, which is polar and hydrophilic) and Tails (made of two fatty acid chains, are non-polar and hydrophobic)

Steroids

lipids that share a common 4-ring carbon structure rather than chain-like. They are vital for: hormonal regulation, membrane structure, metabolism, reproduction

Types of Steroids

Cholesterol, Steroid Hormones, Vitamin D, Anabolic Steroids

Cholesterol

Most basic and essential steroid. It helps maintain cell membrane fluidity and stability and serves as a precursor for other steroids.

Steroid Hormones

Made from cholesterol and function as chemical messengers in the body. They are sex hormones (estrogen, progesterone, testosterone) and corticosteroids (cortisol - regulates stress and metabolism, aldosterone - controls salt and water balance)

Vitamin D

A steroid derivative involved in calcium absorption and bone health.

Anabolic Steroids

Synthetic variants of testosterone, and used to build muscle mass but can have serious side effects when abused

Waxes

a type of lipid made up of long-chain fatty acids combined with long-chain alcohols or other hydrocarbons. They are hydrophobic, solid at room temperature, and protective and moisture-resistant. They are found in nature (plants, animals) and many human-made products

Functions of waxes

They are found on leaves, stems, and fruits as a cuticle (waxy coating) and they help prevent water loss and protects from insects or pathogens. Bees produce beeswax to build honeycombs. Earwax (cerumen) in humans protects the ear canal. Some birds and mammals secrete waxes to waterproof fur or feathers. They are also found in candles, polishes, cosmetics, food coatings

Linoleic acid

Omega-6 fatty acid and is important for cell membranes, helps with skin health and healing, can convert to arachidonic acid (found in animal products and vegetable oils), which can produce inflammatory compounds. They are found in vegetable oils (sunflower, corn, soybean, safflower), nuts, seeds.

Linolenic acid

Omega-3 fatty acid and is anti-inflammatory, can convert to EPA and DHA (beneficial omega-3s found in fish), supports heart, brain, and immune function. They are found in flaxseeds, chia seeds, walnuts, hemp seeds, leafy greens.

EPA (Eicosapentaenoic Acid)

key types of long-chain omega-3 fatty acids and it anti-inflammatory, supports heart health, reduces blood clotting, improves mood. It helps lower triglycerides, supports mental health (can reduce symptoms of depression), regulates the body’s inflammatory response. It is found in fatty fish (like salmon, sardines, mackerel), algae oil.

DHA (Docosahexaenoic Acid)

key types of long-chain omega-3 fatty acids and is good for Brain development, eye health, memory, and nervous system function. It is crucial for babies' brain and eye development, makes up a large part of the brain and retina, supports brain function and reduces age-related cognitive decline. It is found in fatty fish (like salmon, sardines, mackerel), algae oil.