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The Role of Food in Nutrition

by Eleanor Kurtus, PhD (revised 10 August 2015)

The nutrients in food fuel the entire chemical circuit that sustains our life—from the molecular to the organ system level. Chemical bonding at the atomic level enables the formation of complex molecules to allow cells to function.

Questions you may have include:

This lesson will answer those questions. Health Disclaimer


Food is nourishment for both the body and psyche. Food plays an integral role in many of our celebrations, social gatherings, rituals and family traditions. Even though the mental and emotional aspects of food are important, here we’ll concentrate on the physical reasons of why we need to plan and select the food we eat wisely.

Food provides the nutrients that are the building blocks of our physical body. Our physical structure, our energy level and our mental and physical health all depend on having adequate nutritional status.

Chemistry, nutrition and food

We can look at the human body as a system containing levels of structural organization.  The lowest level is the atomic level where atoms combine to form simple and complex molecules, such as water, sugar and protein. Chemical bonding allows the atoms to form into complex molecules such as lipids, proteins, and nucleic acids. These complex molecules are vital to cell functioning and are formed from the nutrients in foods that are eaten.

Molecules combine into cells and organelles, which are the smallest units of living things.  Cells form tissues; tissues form organs and organs are grouped into organ systems.

Important point: Chemistry and chemical reactions form the underpinning of why our body functions. The entire hierarchical flow is fueled by the chemicals, aka nutrients, consumed via our diet.

Atomic level

Atoms are the building blocks of matter e.g. oxygen and hydrogen

Molecular level

The chemical bonding of 2 or more atoms to form molecules
such as water, sugar, and proteins.

Cellular level

Structural and functional units of living organisms formed by molecules

Tissue level

Groups of similar cells that form together to provide a common function

Organ level

Organs, such as skin, heart, brain, lungs, glands, are formed by two or more types of tissue.
Organs perform specific functions and work interdependently
to perform physiological functions.

Organ systems

Organ systems work in constant communication to ensure
 that common functions are coordinated
and performed according to the needs of the body.

Organ Systems

There are 11 organ systems which are listed here with the major organs and structure that compose them.

Intergumentary Skin, hair, nails, sweat glands
Skeletal Cartilage, joints, bones
Muscular Smooth, cardiac, and skeletal muscles
Nervous Brain, sensory receptors, spinal cord, nerves
Endocrine Endocrine glands
Circulatory Blood vessels, lymph vessels, lymph nodes and organs, heart
Respiratory Lungs, nose, mouth, throat,  trachea
Digestive Mouth, esophagus, stomach, small intestine, large intestine, liver, gallbladder, salivary glands, pancreas
Urinary Kidneys, bladder, ureters
Reproductive Genitals, gonads
Immune White blood cells, lymph vessels, bone marrow, lymphatic tissue


The foods we eat are the raw materials of the human body.  Food starts a chemical reaction at the molecular level that works upward to engage cells, tissues, and organs.   In other word, our entire body is affected by the quality of food we consume.  You are a product of everything your mother ate and everything her mother ate.  Food influences physical and mental health.

“You are what you eat”

Resources and references

Author's Credentials


Dr. Joel Fuhrman - "How to live, for life" website

Nutrition Resources


(Notice: The School for Champions may earn commissions from book purchases)

Essentials of Human Anatomy and Physiology by E. N Marieb; Cummings (2009)

Nutritional Sciences: From Fundamentals to Food by Michelle McGuire and Kathy A. Beerman; Brooks Cole (2012)

Super Immunity by Dr. Joel Fuhrmann (2012)

Secrets of Healthy Cooking by Dr. Joel Fuhrmann (2007)

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