Behavioral Nutrition: An Evolutionary Perspective


By Curtis T. Cripe

According to Dr. Michael Murray (Murray, 2005), the human body is designed to eat both plant and animal foods. There are indications we evolved to digest primarily plant foods. This is based upon the structure of the human gastrointestinal tract, as well as the composition of our teeth. We have twenty molars, which are perfect for crushing and grinding plant foods, along with eight front incisors, which are used for biting into fruits and vegetables. The front four canine teeth are designed for meat eating. The human jaws swing vertically and horizontally allowing us to tear and crush. Teeth of carnivore's jaws swing only vertically. Other evidence supporting the human body's preference for plant foods is based on the long length of the intestinal tract. Carnivores have a short bowel, while herbivores have a bowel length proportionally to humans.

According to Murray (Murray, 2005), Drs. Burkitt and Trowell are credited with much of the link between diet and chronic disease. They based their work on extensive studies examining diseases in various populations. Burkitt and Trowell formulated the following sequence of events concerning nutrition:

First stage: Cultures that consume traditional diets consisting of whole, or unprocessed foods, typically have low levels of chronic diseases, such as heart disease, diabetes, and cancer.

Second stage: Cultures eating a more "Western" diet, experience a sharp rise in the number of individuals with obesity and diabetes.

Third stage: Cultures that abandon their traditional diets, experience conditions once quite rare become extremely common. These include conditions such as constipation, hemorrhoids, varicose veins and appendicitis.

Fourth stage: Upon full Westernization of a culture's diet, other chronic degenerative or potentially lengthy diseases, including; heart disease, cancer, osteoarthritis, rheumatoid arthritis, and gout, become extremely common.

During the twentieth century, food consumption patterns in the U.S. changed dramatically (Murray, 2005). There were significant increases in the consumption of meat, fats and oils, and sugars and sweeteners in conjunction with a decreased consumption of non-citrus fruits, vegetables, and whole-grain products. The biggest change in the last hundred years of human nutrition was the switch from a diet high in complex carbohydrates, such as those found naturally in grains and vegetables to a tremendous and dramatic increase in the number of calories consumed in the form of simple sugars. High consumption of refined sugars is linked to many chronic diseases, including obesity, diabetes, heart disease, and cancer. Total dietary fat intake has increased from 32 percent of calories in 1909 to 43 percent of calories by the end of the 20th century. Carbohydrate intake dropped from 57 percent to 46 percent and protein intake has remained fairly stable at about 11 percent. Compounding these detrimental changes are the individual food choices. These changes led Murray to introduce the Optimal Health Food Pyramid.

The Optimal Health Food Pyramid (OHFP) (Murray, 2005) includes the best aspects from the two most healthful diets ever studied: the traditional Mediterranean diet and the traditional Asian diet. The OHFP attempts to clearly define what the healthy components are that lie within categories, as well as stress the importance of regular consumption of vegetable oils as part of a healthy diet. The OHFP also stresses which foods to avoid, entirely.

These include:

  • Refined white flour products such as breads, pastas, cakes, muffins and pretzels
  • Refined sugar-loaded products such as cereals, candies and baked goods
  • Processed foods that contain empty calories (sugar and fat) and/or salt, which includes canned soups, theater-style popcorn, and potato chips
  • Margarine, butter and shortening
  • Smoked and cured meats, which includes bacon, hot dogs, smoked luncheon meats, sausages, ham and Spam
  • Meats cooked at extremely high temperatures or cooked to well done
  • Heavily sweetened or artificially sweetened soft drinks, flavored drinks and teas, chips and doughnuts

Foods that need to be included in the OHFP include vegetables: Five to seven servings daily.

Vegetables provide us the broadest range of nutrients in any food class (Murray, 2005). They are rich sources of vitamins, minerals, carbohydrates and protein, as well as they provide high quantities of cancer-fighting phytochemicals. According to Murray (Murray, 2005), the word "vegetable" is Latin, vegetare, meaning "to enliven or animate." Vegetables should be the main focus of any health-promoting diet, since it gives us life. It is very important not to overcook vegetables, since this will result in the loss of important nutrients. Light steaming, baking and quick stir-frying are the best ways to cook vegetables.

There are three vegetable categories:

  1. Green, leafy and cruciferous
  2. Low-glycemic
  3. Starchy.

The OHFP stresses we should eat a variety of vegetable from each category daily.

Each one vegetable serving equals: 1 cup of raw leafy vegetables (such as lettuce or spinach);1/2 cup raw, non-leafy, cooked vegetables, or fresh vegetable juice.

According to the OHFP, an individual should eat two to four servings of green, leafy and cruciferous vegetables a day; two to three servings of low-glycemic vegetables a day; and one to two servings of starchy vegetables each day.

Four servings of the good oils and fats (nuts, seeds, and vegetable oils) are included in the OHFP. This includes daily servings of nuts and seeds, especially those providing monounsaturated and medium-chain fatty acids, which contain beneficial oils. Regular consumption of nuts has been shown to improve blood sugar regulation and lower the risk for diabetes, heart disease, obesity, and cancer (Murray, 2005). The better oils are canola, flaxseed, macadamia or olive oil. These can be used to replace butter, margarine and shortening for cooking or salad dressings. The OHFP recommends avoiding using safflower, sunflower, soy and corn oil because they contain too much omega-6 fatty acid, which can feed into inflammatory pathways in the body. The OHFP suggests at least one serving of nuts or seeds (one serving equals 1/4 cup) and 3 tablespoons of the healthy oils per day.

The OHFP suggest we have three to five servings of whole grains daily. The OHFP choice of whole-grain products includes whole-grain breads, wholegrain flour products and brown rice (Murray, 2005). Over processed counterparts include white bread, white flour products and white rice. Whole grains provide substantially more nutrients and health-promoting properties and are a major source of complex carbohydrates, dietary fiber, magnesium and other minerals and B vitamins. Protein content and quality of whole grains is also greater than that of refined grains. Diets rich in whole grains have been shown to be helpful in the prevention and treatment of diabetes, heart disease, and cancer.

The OHFP diet includes two to three servings of beans daily as a mainstay. Beans are in most diets of the world and are second only to grains in supplying calories and protein to the world's population. Beans supply about the same total calories as grains, but usually provide two to four times as much protein and are a richer source of soluble fiber. This lowers cholesterol and stabilizes blood sugar levels (Murray, 2005).

The OHFP diet recommends three to four servings of fruit daily. Fruits are a rich source of many beneficial nutrients. Regular fruit consumption has been shown to offer significant protection against chronic degenerative diseases, including cancer, heart disease, cataracts, diabetes and stroke (Murray, 2005).

The OHFP diet recommends two to three servings daily of high quality protein. Fish consumption, in particular, has shown tremendous protection against heart disease and cancer because of the high content of omega-3 fatty acids in fish. Smaller species of fatty fish, such as wild salmon, mackerel, herring, and sardines help avoid mercury, PCBs and other environmental toxins because they have less accumulation than farmed fish.

The OHFP diet suggests limiting red meat (beef, veal, or lamb) consumption. This limitation should be no more than two servings per month with the leanest cuts possible to be chosen. Chicken and turkey can also be used as protein, with the choice of the white meat (breast) to reduce fat intake. Eggs are also a very good source of high-quality protein and, if produced by free-range hens and fed flaxseed meal, are rich in beneficial omega-3 fatty acids.

Many people are allergic to milk or lack the enzymes necessary to digest dairy products, so consumption should be limited to no more than one or two servings per day. Even though dairy foods are rich in protein and calcium, they are also high in fat and calories. Dairy foods can also contain accumulations of agricultural chemicals and hormones if not organically produced. Fermented dairy products such as yogurt, kefir and acidophilus-fortified milk are preferred over milk due to their content of beneficial bacteria.

The Optimal Health Food Pyramid and the dietary guidelines given reflect the current scientific ideal diet for most people and is based upon a 2,OOO-calorie-a-day diet (Murray, 2005).

Safe Eating

Concern about the safety of food and water is a shared by many individuals. These concerns include fear of deadly bacteria such as E. coli, as well as the effects that food additives, pesticides, pollutants, food irradiation and genetically modified foods have on the body. There are more than 250 different organisms that are capable of causing food borne illness, including a variety of bacteria, viruses, and parasites (Murray, 2005). Poisoning can occur due to ingestion of harmful toxins or chemicals from organisms that have contaminated the food. This includes such things as botulism. Clostridium botulinum grows in foods and produces a powerful paralytic toxin and can produce illness even if the bacteria are no longer there. Most of the common microorganisms that cause food-borne infections are those present in the intestinal tracts of healthy animals. Meat and poultry can become contaminated when slaughtered if there is contact with intestinal contents. Fresh fruits and vegetables can be contaminated if they are washed or irrigated with water that is contaminated with animal manure or human sewage. The most common causes of food-borne infections are the bacteria Campylobacter, Salmonella and E. coli, and the calici viruses, also known as the Norwalk and Norwalk-like viruses. The most common sources are from undercooked meat and poultry, raw eggs, unpasteurized milk, and raw shellfish.

Campylobacter is a bacterial pathogen that causes fever, diarrhea and abdominal cramps. It is the most commonly identified bacterial cause of diarrhea illness in the world. This bacterium lives in the intestines of healthy birds. Most raw poultry meat has Campylobacter on it. The most frequent source of this infection is undercooked chicken or other food that has been contaminated with juices dripping from raw chicken.

Salmonella is another bacterium that is widespread in the intestines of birds, reptiles and mammals. It spreads to humans by a variety of different foods of animal origin. Salmonellosis typically includes fever, diarrhea and abdominal cramps. It can invade the bloodstream and cause life-threatening infections in individuals with poor health.

E. coli is a bacterial pathogen that is found in cattle and similar animals. Humans can become ill when consuming food or water that has been contaminated with even microscopic amounts of cow feces. The illness is often severe, provoking bloody diarrhea and painful abdominal cramps, without much fever.

Calicivirus, or Norwalk-like virus, is a common cause of food borne illness, but is rarely diagnosed because laboratory tests are not widely available. It causes acute gastrointestinal illness, usually with more vomiting than diarrhea and resolves within two days. It is believed to spread primarily from one infected person to another.

To reduce risk of suffering a food borne illness one should cook meat, poultry and eggs thoroughly. Avoid contaminating foods by washing hands, utensils and cutting boards after they have been in contact with raw meat or poultry and before touching another food. Also wash fresh fruits and vegetables in running tap water with a soft bristle brush and mild soap. Greens should be soaked in cold water as many times as needed to get them clean.

Other Concerns

Food irradiation is the use of ionizing radiation on foods. It is used to delay ripening and extend the shelf life of fruits and destroy harmful bacteria in fresh meat, poultry and other foods.

This practice is an extremely controversial practice. On one end of the spectrum, proponents feel that food irradiation is safe and necessary in order to reduce the risk for food borne illness. Food irradiation considerably reduces losses due to spoilage. At the other end of the spectrum are concerns that irradiation produces altered food molecules, destroys most of the vitamins and alters the fatty acid structures in food. Genetically modified foods are another concern. The terms genetically modified organism (GMO) and genetically modified foods (GM foods) refer to plants or animals whose genes have been changed. For example, personally, I can eat non-GMO wheat-based products, whereas I cannot eat GMO wheat due to allergies to those products.

The FDA has approved the use of more than 2,800 different food additives. It is estimated that the per capita daily consumption of these food additives is 13 to 15 grams (Murray, 2005). Food additives are used to prevent foods spoiling or to enhance their flavor. They include such substances as preservatives, artificial colors, artificial flavorings and acidifiers. Although many synthetic food additives have been banned, a number of synthetic food additives remain in use. Many have been linked to hyperactivity and learning disabilities in children and migraine headaches. At the Crossroads Institute and Centers we see a number of children who have been diagnosed with attention issues and placed on medications, when in actuality they only had a food allergy to some form of food additives. Once this was removed so did their attention symptoms.

Pesticides are another concern, according to Murray (Murray, 2005). In the U.S., more than 1.2 billion pounds of pesticides and herbicides are sprayed on or added to crops each year, in which more than 98 percent of it is absorbed into the air, water, soil or food supply. Major long-term health risks include potential cancer and birth defects. The major health risks of acute intoxication of these chemicals include vomiting, diarrhea, blurred vision, tremors, convulsions and nerve damage.

There are seven important principles that help avoid diet-related diseases and assist in maintaining good health (Murray, 2005):

  1. Eat a "rainbow" assortment of fruits and vegetables.
  2. Reduce your exposure to pesticides.
  3. Eat to regulate your blood sugar level.
  4. Do not over consume meat and other animal foods.
  5. Eat the right types of fats.
  6. Keep your salt intake low, but your potassium intake high.
  7. Drink a sufficient amount of water each day.

A diet rich in fruits and vegetables is best for preventing virtually every chronic disease (Murray, 2005). A "rainbow" of fruits and vegetables means selecting a variety of colors, including red, orange, yellow, green, blue and purple. The body will have a full spectrum of pigments with powerful antioxidant effects, as well as the nutrients it needs for optimal function and protection against disease. Pesticide-free or organic foods are the best selections. Refined sugars, white flour products and other sources of simple sugars, which are quickly absorbed into the bloodstream, thus causing a rapid rise in blood sugar, should be reduced or avoided in order to avoid the body's response to boosts of secretion of insulin by the pancreas. Limit the amount of meat consumed. The higher your intake of meat and other animal products, the higher your risk of heart disease and cancer, especially for the major cancers such as colon, breast, prostate, and lung cancer. A diet high in saturated fat and cholesterol has been linked to numerous cancers. The goal is to decrease total fat intake, especially saturated fats, trans-fatty acids and omega-6 fats, while increasing your intake of omega-3 fatty acids and monounsaturated fatty acids. It is further recommend that you reduce the amount of salt intake.


Murray, M., Pizzorno, J., Pizzorno, L. (2005) The Encyclopedia of Healing Foods. Atria Books, New York