Food serves a unique role in all societies of the world.  First and foremost, food provides energy in the form of calories.  Different foods deliver different amounts of energy relative to the amount and types of nutrients they contain.  The amount of energy a person needs depends on age, gender, size, metabolic rate, and activity level.  The health of a person depends, in a large part, on the variety, quality, and quantity of the foods that are consumed.  Food also serves lifestyle, religious, cultural, and psychological roles in people’s lives.  The foods that people consume are also strongly influenced by what is made available to them in the stores and markets where people live and travel.   In general, humans do not live in a hunter/gatherer society; our foods are provided to us by a vast network of growers, processors, manufacturers, distributors, and retailers who serve our neighborhoods.  As a result, there are many, many different diet regimens, voluntarily or involuntarily practiced, with new ones evolving every day.

Because humans depend on food for their health and the cost of disease is so high to society, the US government passed a Food and Agriculture Act of 1977 (Farm Bill) that established the Food and Nutrition Information and Education Resources Center (FNIC).  By 1994 the Center for Nutrition Policy and Promotion (CNPP) was created “to improve the health of Americans by developing and promoting dietary guidance that links scientific research to the nutrition needs of consumers.”  Together with the Food and Nutrition Service (FNS), another service of the USDA, the CNPP publishes and promotes Dietary Guidelines for Americans which are the cornerstone of federal nutrition policy and nutrition education programs.  The current guidelines were published in 2010 and are promoted through the MyPlate program launched in 2011.  Overall good health calls for low fat (not no fat), low sugar, portion moderation, and higher percentages of foods from the plant kingdom than the animal kingdoms. 

Why this matters:

Traditionally, people in the United States have shopped in natural food or health food stores because they offer an array of foods and nutritional supplements that are not found in the mass market supermarkets or pharmacies, including foods that are needed for their chosen diet regimen.   Customers who are investigating or exploring alternate diet philosophies typically ask health food store staff a wide variety of questions and expect the staff to be more knowledgeable about the products than the staff in their regular supermarket.

Basic Nutritional Components of Food


There are two types of carbohydrates – available and unavailable.  Sugars and starch are categorized as available carbohydrates.  Sugars are present naturally in fruit, vegetables, and milk and are also added to many processed foods.  Starch is found in foods such as bread, cereals, and potatoes.  Both starch and sugars are digested in the body and converted to simple sugars (mainly glucose), which are then used by the body to provide energy.

Unavailable carbohydrate includes dietary fiber or non-starch polysaccharide (NSP).   The term “unavailable” is used because the fiber can’t be digested and therefore doesn’t provide humans with energy.  However, fiber is helpful in many other ways.  Dietary fiber can be divided into two categories:  insoluble fiber and soluble fiber.

Insoluble fiber, such as the type found in wholegrain cereals and grains, and some fruits and vegetables, adds bulk to the contents of the gut, speeding its transit, and helps protect against constipation and other bowel disorders.  Soluble fiber, found in beans and lentils, fruit, vegetables, oats, barley, and rye, helps to reduce blood cholesterol levels and to regulate blood sugar levels.


Proteins are used for the growth and maintenance of body tissues and for the production of substances such as hormones and enzymes which help to control many functions within the body.   If insufficient carbohydrate and fat are available in the diet, then protein may also be used to provide the body with energy.  Proteins are made from building blocks known as amino acids.  There are 20 different amino acids.  Of the twenty, eleven amino acids can be made in the body while the other nine can only be supplied by the diet.  These nine are known as the essential amino acids.

Some foods are better providers of these amino acids than others.  All of the amino acids are found in meats and dairy foods.   Fewer of the amino acids are found in plant foods such as cereals, beans, lentils, and nuts.  However, a wide variety of protein sources in the correct amounts can work together to provide the ideal levels of the different amino acids.


Fats are essential to the human body for many reasons:

  • They provide energy
  • They are involved in forming cell membranes
  • They help provide fat-soluble vitamins such as Vitamins A, E, D and K
  • They are involved in making hormones
  • They provide insulation; keeping humans warm.
  • They provide humans with a shock-absorbing, protective layer

Fats are made from building blocks called fatty acids.  There are three types of fatty acids - saturated, monounsaturated, and polyunsaturated fatty acids.  The fat in food contains a mixture of all three fatty acids, in different proportions in different foods.  Saturated fats are found in butter, margarine, some blended cooking oils, meat, and meat products, whole milk and its products, and coconut and palm oil.  Monounsaturated fats are found in olives, olive oil, rapeseed, canola and peanut oil, avocados, and most nuts.  Polyunsaturated fats are found in fatty fish such as salmon and trout, safflower oil, seeds such as flax, hemp and sesame, and walnuts.    Both polyunsaturated fats and monounsaturated fats are considered good fats because they help lower cholesterol levels. Managing a healthy cholesterol level helps decrease the risk of heart disease.   However, too little of the good fats can result in chronic fatigue, obesity, and even heart problems.

Two polyunsaturated fatty acids, linoleic and alpha-linoleic acids cannot be made in the body and must be provided in the diet.  These are called essential fatty acids. These two families of unsaturated fatty acids undergo various different chemical reactions in the body to produce the fatty acids necessary for numerous different and important functions within the body.   More information about essential fatty acids can be found in Introduction to Natural Food Retailing, Lesson 4 - Nutritional Supplements & Therapies.

Trans fats are formed when the structure of monounsaturated and polyunsaturated fats are altered by a man-made process called hydrogenation. They are often found in a wide variety of processed & packaged foods.   Trans fatty acids found in industrially produced products have been shown to have a negative effect on risk factors for cardiovascular disease.  In late 2013, the FDA announced its preliminary determination that partially hydrogenated oils (PHOs), the primary dietary source of artificial trans fat in processed foods, are not “generally recognized as safe” for use in foods.

Vitamins, Minerals and Trace Elements

Vitamins, minerals, and trace elements are required for numerous functions within the body and deficiencies can lead to serious health problems and disease.  Since the body uses much smaller amounts of these as compared to fats, carbohydrates, and proteins, they are often referred to as micronutrients.  More complete information about micronutrients, is found in Introduction to Natural Food Retailing, Lesson 4 - Nutritional Supplements & Therapies.


Words to Remember


Organic compounds composed of two-carbon bonds that chain together to make protein. There are more than 50 amino acids in the body, but only 20 of them are found in protein, 9 of which are considered essential and need to be provided in food. The other 11 of the 20 amino acids are created by the body.


An organic compound found in foods composed of sugars, starches, cellulose, and fiber that are used by the body for energy.


A component of carbohydrate that is not digested by the body; instead dietary fiber provides bulk, helping elimination and protecting against constipation and bowel disorders, reducing blood cholesterol levels, and regulating blood sugar levels.


Fat molecules essential to human health that must be consumed in food because they cannot be manufactured in the body.


Substances found in small amounts needed by the human body for a range of physiological functions. The most commonly known micronutrients are vitamins and minerals.


A class of organic compounds composed of 20 amino acids that are required for the structure and function and regulation of the body’s tissues and organs.


Short for trans fatty acids are manufactured fats that are created through a process of hydrogenation to stabilize oils at room temperature and prevent spoilage. Science has determined that trans-fat is particularly dangerous for the human heart and may pose a risk for certain cancers.


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