Essential Foods and Their Functions

Essential Foods and Their Functions

You may have read the Quick List of Necessary Foods. Now we will take a closer look at the functions of the necessary and essential nutritional elements: carbohydrates, fats, proteins, vitamins, minerals and water, foods needed, servings needed and signs of nutritional deficiency and toxicity of some vitamins and minerals. There was a good reason for Mother to say, “Eat your _______!”

The following is adapted from my lectures to student nurses regarding clinical nutrition.  Much of the nutritional information presented here and elsewhere in this book is adapted from Understanding Normal and Clinical Nutrition, 2nd Edition, by Whitney, Cataldo, and Rolfes, West Publishing Co. It is now available in the 6th Edition of 2001.

Also used is a favorite paperback book, Nutrition and Vitamin Therapy, by Michael Lesser, M.D., published by Bantam Books and Mary Dan Eades’ book, The Doctor’s Complete Guide to Vitamins and Minerals, copyright by The Philip Lief Group, Inc. and published by Dell Publishing, in which she gives recommendations for dietary and supplementary treatment of numerous conditions, to be used in consultation with your physician.

You may be interested in Dr. Lesser’s 2002 book written with Colleen Kapklein, The Brain Chemistry Diet: The Personalized Prescription for Balancing Mood, Relieving Stress and Conquering Depression Based on Your Personality Profile.

If, by reading the following, you become convinced that you need vitamin and mineral therapy, you may refer to Dr Lesser and Colleen Kapklein’s book or to Mary Dan Eades’ book which was insulinupdated in 2000.


We must have energy for the body to function properly.  The energy is best supplied by the “carbohydrates,” that is, starches and sugars.

The most useful carbohydrates are the starches (bread, potatoes, dried beans, whole grain foods, cooked carrots, peas, corn, squash, pastas).  Starches also are called “complex carbohydrates.”  They provide stability in the production of glucose, a “simple carbohydrate.”

Glucose, sometimes called “blood sugar”, is used by the body to produce energy.  It is the “fuel” the body needs to run on just as your car needs gasoline.  Your brain uses about 20% of the body’s blood sugar, glucose.  If you have too little blood glucose at any one time, your heart, kidneys, and lungs will be given priority in order to sustain processes essential to life.  As the brain receives less glucose, your intellectual, emotional, and physical functioning progressively deteriorates.  You may faint, go into coma, and if the blood glucose level goes low enough, you can die.

Insulin is needed to process carbohydrates into energy.  When blood sugar goes up abruptly, as it does after eating refined sugar snacks and fruit, it stimulates a sharp increase in the insulin supply, then the blood sugar level falls quickly.  The excess insulin will often lower the blood sugar level to the point that the person feels weak, irritable, “fuzzy headed” or “light headed.”  These are symptoms of “functional hypoglycemia” which can be controlled by eating balanced meals at least three times a day and eating protein with starchy snacks.  Avoid simple sugar snacks such as candy, coffee with or without sugar, and fruit and fruit juices between meals. And if you do choose one of the latter, be sure to have some protein, such as a cheese stick or some nuts with your snack.

a minimum of two servings of whole grains such as whole wheat bread (unless allergic to wheat).  A serving is one slice of a regular loaf of bread or 1/2 cup cooked grains or starchy vegetables.
The starches–bread, whole grains, potatoes, cooked carrots, peas, dried beans, and corn–provide “staying power.”  Cooking increases the calories available in the foods by changing some of the indigestible fiber to starch and sugar. Diabetics may need to avoid potatoes.  Corn is a frequent offender as an allergenic food.
Eating starchy foods in preference to sweet foods helps keep the blood sugar at an even level with fewer dips and highs.  If you are a person who avoids starchy foods you are, unknowingly, “begging for trouble” sooner or later, as you fail to meet the body’s needs for a steady supply of energy for all the body’s life- processes.  If the word “starch” gives you a negative view of these foods, call them by their more technical name, “complex carbohydrates,” instead.  By either name they are staples of good nutrition.

Starches are needed for stable blood sugar levels and to prevent cravings and subsequent bingeing. Whole grains, and fresh and frozen “starchy” vegetables with the peelings intact, also offer high levels of vitamins,  minerals. and fiber.

According to my nutrition instructor, Dr. Virginia Stucky (who devised the exchange system for diabetics to use), you need a minimum of two slices of whole wheat bread to supply your daily needs for some of the B Vitamins, and more if you have high levels of stress.

A minimum of 3 to 6 servings of starches daily is needed while losing weight depending on body size and activity.  Your weight loss should not be more than two pounds a week.  If you lose more than that, you need more starches to maintain health while losing weight. The number and size of servings can be adjusted to help maintain your weight at a healthful level. People who are active in athletics, sports, and manual labor may need as many as 11 servings depending on body size.

One thousand to twelve hundred calories are required each day in order to have the nutrients necessary to keep a person from getting sick.  This amount of nutrients is called the recommended daily allowance (RDA).  As your caloric needs increase over 1000-1200 calories, nutritional recommendations are to increase the amount of vegetables, fruits, and grains in your diet, rather than meats.  This will increase your intake of vitamins, minerals, and fiber, with less increase in fats than you have when you increase your meat allowance.

A serving equals 1/2 cup cooked for starchy vegetables, or 1 cup raw vegetables.
The fresh, raw, green, leafy vegetables such as kale, lettuce, spinach, and broccoli and even tomatoes can be eaten in quantities as desired without excessive calories.  Carrots are very high in Vitamin A and can be eaten in moderation.  They contribute Vitamin A which is absorbed by the body when oil is present.  This implies that you would be wise to eat a salad with oil in the dressing.  As we’ll explain when talking about fats, one tablespoon of oil is needed by the body each day in order to function properly.
Supplementing the diet with Vitamin A or eating extremely large amounts of highly potent vitamin A foods can result in toxicity, since Vitamin A can be stored in the body.  One sign of toxicity is jaundice, a “yellowing” of the skin and “whites” of the eyes.

Raw vegetables are high in fiber that in recent years has been associated with protection from some kinds of gastro-intestinal problems, including cancer, and with a lower incidence of hardening of the arteries.   These benefits are in addition to smoothing out blood sugar levels as mentioned earlier.  Raw vegetables in general are low in calories and rich in vitamins and minerals.  If you tire of raw vegetable salads with oil dressing, your tablespoon of oil may be used with raw vegetables for a delightful “stir fry” meal for variety’s sake.  Raw vegetable serving sizes (1 cup) may double the size of a serving of cooked vegetables (1/2 cup)so, depending on the vegetable, you may need to reduce the amount for cooking.

Cooked vegetables have more of the fiber converted to starch.  Fiber has been associated with health, especially of the gastro-intestinal tract.  Cooking most vegetables may not appreciably decrease the fiber content, but it does make it more digestible.  Cooked dried beans and legumes provide four (4) times the amount of fiber as the same serving size of other vegetables and are a good source of minerals.  So you see, some vegetables are much more rich in fiber than others.  In general we might say that the more fiber, the less “juicy” the vegetables are in their natural state.

The starchy vegetables mentioned earlier (corn, potatoes, peas, dried beans, legumes), of course, are not as low in calories as are green beans, cabbage, cauliflower, broccoli, asparagus, celery, bean sprouts, brussel sprouts, greens, tomatoes, onions, and zucchini.  These low calorie vegetables and fruits such as grapefruit, strawberries, and lemons can be used in larger amounts as desired and tolerated.

Vegetables also offer Vitamin C and minerals that make them desirable components of the daily food selection. To some extent, vegetables and fruits offer similar vitamins and minerals, that is why the minimum amounts of vegetables and fruits seem confusing.

To be specific and clear, AS A MINIMUM, you need 1 citrus fruit (for Vitamin C), 1 green or yellow vegetable (for Vitamin A), and two or three other fruits or vegetables daily.

One serving equals a small (2 inches in width) orange or apple or 1/2 grapefruit or 1/2 cup juice, or half a medium sized banana.

We need at least one citrus fruit a day and two or more other fruits (or vegetables).  Citrus fruits are especially important to our health by providing Vitamin C.  We’ll talk about Vitamin C in more detail when we talk about the vitamins we need.  If a person is allergic to citrus fruits, a supplemental form of Vitamin C may be necessary.  Citrus fruits are the sour or acidic fruits.  Oranges, grapefruit, lemons, limes, and tangerines are most common.  Kiwi is another acidic fruit high in Vitamin C.

Cooked and dried fruits have higher calorie counts than fresh fruits and lose some of their vitamins.  If you discard the peels and cooking juices of fruits or vegetables you also lose much of the mineral content, so be sure to wash them, keep them and USE them.

Refined white sugar offers only energy.  It has none of the vitamins and few minerals needed by the body.  That is why sugar is called, “Empty Calories.”  Excess energy is stored in the body as fat.
Other kinds of “sugar” that have vitamins and minerals associated with them are “fruit sugar” (fructose) and “milk sugar” (lactose).

When you eat a fruit, the sugar causes the same response in the body as refined sugar, the quick “high” or “pick-me-up,” and a few minutes later, a lower blood sugar than you started with due to the action of insulin.  Therefore, if you are subject to “low blood sugar” (hypoglycemia) you will feel better if you have a little protein or starchy food with your fruit snacks.  When you take milk as a snack, the protein and fat (or protein if skim milk) will prevent the drop in blood sugar.

I like the way sugar is explained in the following:

“Sugars in your diet can be naturally occurring or added. Naturally occurring sugars are found naturally in foods such as fruit (fructose) and milk (lactose). Added sugars are sugars and syrups put in foods during preparation or processing, or added at the table.Nutrition – Examples of Typical High-Sugar Beverages (spot)

Foods Containing Added Sugars

The major sources of added sugars are regular soft drinks, sugars, candy, cakes, cookies, pies and fruit drinks (fruitades and fruit punch); dairy desserts and milk products (ice cream, sweetened yogurt and sweetened milk); and other grains (cinnamon toast and honey-nut waffles).

The hidden ingredient with many different names

To figure out if a packaged food contains added sugars, and how much, you have to be a bit of a detective. On the Nutrition Facts panel, the line for sugars contains both the natural and added types as total grams of sugar. There are four calories in each gram, so if a product has 15 grams of sugar per serving, that’s 60 calories just from the sugar alone, not counting the other ingredients.

To tell if a processed food contains added sugars, you need to look at the list of ingredients. Sugar has many other names. Besides those ending in “ose,” such as maltose or sucrose, other names for sugar include high fructose corn syrup, molasses, cane sugar, corn sweetener, raw sugar, syrup, honey or fruit juice concentrates. Check here for more information about reading food labels.”

The article goes on to list many ways to reduce sugar in your diet.


The blood-brain barrier is a fatty barrier that functions as a “strainer” to keep toxins, heavy metals, and poisons out of the brain while letting essentials flow in and out..

Fat eaten in a meal also signals the  brain’s hunger control mechanism, “I’m satisfied now,” so that cravings are satisfied and constant nibbling or gorging is not desired or necessary.  Overeating or bingeing can be related to deficiencies of other nutrients and to “emotional deficiencies” also.

A person who “fasts,” or who vomits, after eating more than they wanted, and those who rapidly gulp down large quantities of food, can “disable” the appetite control mechanism.  Establishing a pattern of balanced food intake that includes three or four small meals a day, or three meals and two to three snacks, can restore the mechanism.  Small bites of food chewed slowly and thoroughly improves digestion and increases the time needed to consume a meal.  This also gives you time to “savor” the food, and your body time to register that your needs are met and signal the brain, “I’m satisfied.”

The above eating pattern, careful selection of foods, and inclusion of exercise in the day’s activities can control the weight, assuming that the person does not over-eat out of frustration over other issues of daily living.  If not medical care may be necessary for other conditions that affect weight.  As we age, the frequent decline in activity and natural decline in metabolic rate tends to result in increased body weight as fat.  To counteract this, we need to pay close attention to meeting our nutritional needs while reducing our calorie consumption.

Stored fat is difficult to break down and does not eliminate the need for oil in our daily intake.  Stored fat is needed only in moderation to protect body organs and tissues, especially the nerves and brain, and to help insulate us from cold temperatures.  Feminine curves, which some people find pleasing, require fat.  Remember that being “overweight” does not mean that you can safely eliminate oils or fats from your daily food selection.

Monosaturated (olive oil) or polyunsaturated fats are preferred.  Safflower, canola, and sunflower oils are good choices among the polyunsaturated oils.  Fish oils have been recommended to prevent cardiovascular disorders associated with high cholesterol counts in the blood and hardening of the arteries.  For many years now, the medical community has recommended avoidance of hard fats, lard and hydrogenated oils especially, and also coconut and palm oils.
Recent research indicates that butter is more healthful than margarine with “trans-fats.”

Web MD explains that small amounts of trans-fats occur naturally in some meats, such as beef, lamb and full fat dairy products however, most come from processing liquid vegetable oil to become a solid fat and if you are counting calories,The American Heart Association advises limiting saturated fat consumption to less than 7% of daily calories and trans fat consumption to less than 1%. Given that a gram of fat has 9 calories, the following are the recommended trans fat limits based on calorie intake:   1% of total calories = Trans fat limit.  Saturated fat is solid at room temperature, which is why it is also known as “solid fat.” It is mostly in animal foods, such as milk, cheese, and meat. Poultry and fish have less saturated fat than red meat. Saturated fat is also in tropical oils, such as coconut oil, palm oil, and cocoa butter. (same source).  Saturated and trans-fats both contribute to increasing levels of bad cholesterol, clogging the arteries and heart disease.

If your doctor recommends that you begin a low-fat or low-cholesterol diet, do not eliminate all fat (oil) from your food intake.  You need one tablespoon of fat, preferably vegetable oil, daily to provide the “essential fatty acids” that your body cannot make by itself!

I have had clients whose hair and skin were very dry and who were very depressed.  They said they were skimming, trimming, and removing all fat from their foods to reduce their total cholesterol, but without success.  After learning that the body makes cholesterol and cannot make the essential fatty acids, they added a tablespoon of oil daily (along with milk or calcium when deficient and one to two eggs a week) to provide a balanced daily food intake.  Subsequently, they have felt better, looked better, and lowered their blood cholesterol.

Fat is used in the absorption process to convey Vitamins A, D, E, and K from the intestines into the blood stream where the body can use them.  Foods rich in fat soluble vitamins should be eaten with some oil or butter.  We will discuss these vitamins later.

A three ounce cooked meat serving is approximately the size of a pack of cards.

Proteins provide the building blocks for growth and repair of every body tissue.  Meat, eggs, milk, cheese, nuts, and legume/grain combinations all provide proteins in large quantities as well as some fats, carbohydrates, vitamins and minerals.  Red meat should be eaten once a week for the mineral iron which is needed in the production of hemoglobin that carries oxygen to all the body tissues.  One or two eggs a week provide excellent proteins, essential fatty acids, iron, and also choline, a relative of the B vitamins  that is required for muscle activity and the memory processes of the brain.

Growing children, young adults (teens), and pregnant women need additional meat or other proteins to serve their growing bodies.  Persons who are healing from injuries, especially burns, or surgery also need additional proteins.  Those of us who do not like meat, or cannot afford to buy it, can use milk, eggs, nuts, seeds, and legume/grain combinations such as cooked dried beans, peas or lentils combined with wheat, oats or corn.  An all vegetable diet is not recommended by me and requires supplementation.

More energy is used in the process of digesting proteins than carbohydrates.  Proteins are sometimes increased in the daily food intake by persons wishing to lose weight.  This practice stresses the body systems, particularly the kidneys, and is expensive

Although proteins are essential to wellness, proteins from animal foods are not sufficient by themselves, or even with salads added, to maintain health.  Energy is needed to digest proteins, therefore, we need carbohydrates to provide energy for the work of digestion, the muscles’ work and the rest of the body’s processes in daily activities.  The legume/grain combinations of foods supply the needed carbohydrates for energy along with the proteins needed as building blocks.


Besides carbohydrates to furnish our bodies with energy, proteins to build and repair tissue, and fats to provide the regulatory hormones that tell us we’ve had enough food, we also need vitamins, minerals and water to facilitate the body processes.  Since we have already discussed carbohydrates, proteins, and fats, we will continue with vitamins, minerals, and water in subsequent articles.


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