Lipids, Proteins, Vitamins & Minerals: Essential Nutrients Overview

Roles of fats in the body

Provide energy (9 kcal/g), store energy for long-term use, insulate and protect organs, aid in absorption of fat-soluble vitamins (A, D, E, K), build cell membranes and hormones.

Three types of lipids

Triglycerides (main dietary fat), Phospholipids, Sterols (including cholesterol).

Saturated fats

No double bonds, solid at room temp, mostly animal fats, can raise LDL cholesterol → heart disease risk.

Monounsaturated fats

One double bond, liquid at room temp, olive oil, avocado, nuts, can improve cholesterol profile.

Polyunsaturated fats

Multiple double bonds, liquid at room temp, fish, walnuts, flax, includes omega-3 & omega-6, good for heart health.

Omega-3

Alpha-linolenic acid (ALA): anti-inflammatory, heart and brain health.

Omega-6

Linoleic acid (LA): supports growth, skin health, energy.

Sterols

Plant-based (e.g., phytosterols), help block cholesterol absorption.

Cholesterol

Animal-based, used to make steroid hormones, bile acids, vitamin D, cell membranes.

Phospholipids

Lipids with a phosphate group that form cell membranes and help transport fats in blood (e.g., lecithin in lipoproteins).

Hydrogenation

Adds hydrogen to unsaturated fats → creates trans fats → raises LDL, lowers HDL.

Interesterified fat

Fats chemically rearranged → can also negatively affect blood lipids.

AMDR for fat

20-35% of total calories; Saturated fats < 10% of total calories.

Long-chain triglycerides digestion

Require bile and pancreatic lipase, absorbed via lymph.

Short/medium-chain triglycerides digestion

Absorbed directly into blood, don't need bile.

Chylomicrons

Largest lipoproteins, carry dietary fat, least healthy if high.

VLDL

Carry triglycerides from liver.

LDL

Bad cholesterol, can deposit in arteries.

HDL

Good cholesterol, removes cholesterol from arteries, smaller and denser, protective.

Fat use in exercise

Fat fuels low to moderate intensity exercise. Aerobic training improves fat oxidation, conserves glycogen, and increases endurance.

Components of an amino acid (AA)

Amino group (NH₂), Carboxyl group (COOH), Side chain (R group), and Central carbon. The bond linking amino acids are peptide bonds.

Roles of AAs

Build proteins (muscle, enzymes, hormones), energy (if needed), make neurotransmitters, nitrogen transport.

Essential AAs

Must come from diet (9 total).

Non-essential AAs

Can be made by the body.

Deamination

Removal of nitrogen from amino acids.

Nitrogen balance

Positive: intake > excretion → growth, muscle building; Negative: intake < excretion → muscle breakdown; Equilibrium: maintenance.

RDA for protein

0.8 g/kg body weight; may be insufficient for athletes or highly active individuals.

Muscle repair and growth

One of the primary roles of dietary protein for athletes.

Recovery after exercise

A primary role of dietary protein for athletes.

Hormone and enzyme production

A primary role of dietary protein for athletes.

Energy source

A role of dietary protein for athletes when carbohydrates and fats are low.

Free radicals

Unpaired electrons formed during metabolism, exercise, pollution, toxins.

Antioxidants

Vitamins C, E, selenium that neutralize free radicals to prevent cell damage.

Fat-soluble vitamins

Vitamins A, D, E, K that are stored in the liver/fat and not needed daily.

Water-soluble vitamins

B vitamins and vitamin C that are excreted and needed regularly.

Vitamin A

Important for vision and growth; found in carrots; deficiency leads to night blindness.

Vitamin D

Essential for bone health; obtained from sunlight and fortified milk; deficiency leads to rickets and affects calcium/magnesium absorption.

Vitamin E

An antioxidant found in nuts/oils; deficiency can cause nerve damage.

Vitamin K

Essential for blood clotting; found in leafy greens; deficiency can lead to bleeding.

Vitamin C

An antioxidant important for collagen; found in citrus; deficiency leads to scurvy.

B vitamins

Involved in energy metabolism and red blood cell formation; found in whole grains and meat.

Vitamin D supplementation

Should be taken with fat to improve absorption.

Bertrand's rule

Both deficiency and excess of a micronutrient can be harmful; there's an optimal intake range.

Electrolytes

Sodium, potassium, chloride, magnesium important for fluid balance, nerve signaling, and muscle contraction.

Calcium

Essential for bone and teeth health; found in dairy; deficiency can lead to osteoporosis; toxicity can cause kidney stones.

Iron

Involved in oxygen transport; found in meat and beans; deficiency can lead to anemia.

Magnesium

Important for muscle and nerve function; found in nuts; deficiency can cause cramps.

Potassium

Essential for heart and muscle function; found in bananas; deficiency can lead to arrhythmias.

Sodium

Important for fluid balance; found in salt; excess can lead to high blood pressure.

Anemia

Characterized by low red blood cells/hemoglobin; affected by iron, vitamin B12, folate.

Long chain triglycerides

Need bile and pancreatic enzymes for digestion.

Short and medium chain triglycerides

Are absorbed more easily and go directly to the liver for energy.

Fat fuel in exercise

Fat fuels low to moderate intensity exercise.

Aerobic training

Improves fat oxidation, conserves glycogen, and increases endurance.

Amino acids (AAs)

Components that build proteins, transport nutrients, and make energy and neurotransmitters.

Peptide Bonds

Bonds linking amino acids together.

Essential amino acids

Necessary for survival and need to be consumed.

Nonessential amino acids

Produced in the body and don't need to be consumed as much.

Signs of Amino Acid breakdown

High levels of urea in the urine and muscle loss.

Primary protein structure

AA's forming one or more polypeptide chains.

Secondary protein structure

Coiling or folding of polypeptide chains due to hydrogen bonding.

Tertiary protein structure

3-D shape caused by weak interactions among the R-groups and interactions in the fluid environment.

Quaternary protein structure

Tertiary structures interacting.

Protein digestion steps

Mechanical digestion in mouth, digestion in stomach (HCL unfolds polypeptides), digestion in small intestine (Duodenum releases secretin and cholecystokinin, signaling pancreas to release enzymes), absorption into bloodstream.

Pepsin enzyme

Breaks up the polypeptide chains into shorter chains in the stomach (15% free).

Small intestine protein digestion

Enterokinase activates protein digesting enzymes. Trypsin activates chymotrypsin, carboxypeptidase A and B, and elastase (90% free).

AAs absorption location

Amino acids are absorbed in the small intestine (duodenum, jejunum).

ATP

Adenosine triphosphate, required for the transport of amino acids to the liver and their release into the systematic blood circulation.

Amino Acid Saturation

The condition where transporters for amino acids become saturated, leading to difficulty in absorbing excess amino acids consumed in one sitting.

Essential Amino Acid Deficiency

When an essential amino acid is missing during protein assembly, the body may break down some of its own protein.

Protein Needs for Athletes

Athletes may require 1.2-2.0 g/kg of protein per day.

Roles of Dietary Protein

The four primary roles of dietary protein in an athlete's diet are maximizing gains in muscle mass and strength, promoting adaptations in metabolic function, preserving lean mass during rapid weight loss, and providing structural benefits to bone and tendons.

Fat Soluble Vitamins

Vitamins that dissolve in fat, are absorbed with dietary fats in the small intestine, stored in the liver, can accumulate, and are involved in maintaining bone health and cell growth.

Water Soluble Vitamins

Vitamins that dissolve in water, are absorbed directly into the bloodstream, not stored in large amounts, and excess is excreted via urine, mainly acting in metabolism and energy production.

Examples of Fat Soluble Vitamins

Vitamins A, D, E, and K.

Examples of Water Soluble Vitamins

Vitamin C and all B vitamins.

Sources of Vitamin A

Liver, whole milk, fruits, and vegetables.

Xerophthalmia

Impaired night vision; rare in the US but common in developing countries.

Vitamin A Upper Limit

3000 mcg.

Vitamin A Deficiency Symptoms

Dry skin, cheilosis, gingivitis, muscle and joint pain.

Vitamin D Functions

Promoting calcium absorption, maintaining calcium and phosphorus levels, physiological effects on cell growth, muscle, and immune system functioning.

Sources of Vitamin D

Primarily dairy products, dietary supplements, and UV rays from the sun.

Vitamin D Absorption Issues

Decrease in calcium and phosphorus absorption.

Vitamin D Upper Limit

4000 IU; can become toxic from food, not sunlight.

Vitamin D Influence

Influences muscle function by regulating calcium transport and the uptake of inorganic phosphate; can improve strength, power, and aerobic capacity.

Vitamin E Functions

Antioxidant, immune function, cell signaling.

Sources of Vitamin E

Sunflower seeds and nuts.

Vitamin E Upper Limit

1000 mg; can inhibit anticoagulant medications.

Vitamin K Functions

Necessary for blood clotting, helps body make proteins for blood, bone, and kidneys.

Vitamin K1

Made in plants; high concentrations in green leafy vegetables.

Vitamin K2

Found in animal livers and some fermented foods.

Vitamin K Deficiency

Found in infants and those with malabsorption disorders; can cause bleeding and hemorrhage and greater risk for decreased bone mineralization.

Vitamin C Functions

An antioxidant that protects cells from free-radical damage, helps regenerate other antioxidants, and boosts immune system functioning.

Sources of Vitamin C

Found in fruits.

Vitamin C Deficiency

Can cause scurvy; rare.

Vitamin B1

Thiamin; involved in energy metabolism (CHO); found in whole grains and pork.

Vitamin B2

Riboflavin; involved in energy production (FAD); found in dairy and eggs.

Vitamin B3

Niacin; involved in energy metabolism and as a vasodilator; found in meat and peanuts.

Vitamin B5

Pantothenic acid; involved in metabolism of fats & carbs; widespread in food.

Vitamin B6

Pyridoxine; involved in metabolism of amino acids and lipids, and synthesis of hemoglobin; found in meat and whole grains.