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Variety in the diet is one of the basic concepts of good nutrition, with universal agreement among nutritionists and food scientists. As will be demonstrated in the discussion that follows, a varied diet offers the individual an opportunity to consume all the vital nutrients that contribute to good health, and reduces the incidence of food allergies, intolerances, and other health problems. Yet, in developed countries, the trend is toward less and less true variety as the food base continues to narrow. This trend can be traced to agricultural and marketing practices beyond the control of food shoppers, as well as to individual consumer choices based on preference or economic necessity. For millions of years, hunter-gatherers ranged great distances and had a varied diet including foods from animal sources, wild berries and fruits, seasonal vegetables, nuts and seeds, and edible roots.
In the United States an estimated 90 percent of our historic fruit and vegetable varieties have vanished.…
Even today, some nomadic peoples search widely for a variety of foods in deserts, tundras, and forests. In the last 10,000 to 20,000 years, with the establishment of stable agriculture, the majority of humans became reliant on domesticated crops and livestock. Dairy foods and cultivated grains were added to their diets. This system, centered on family farms, worked well until the early twentieth century. Then, it was gradually replaced by industrialized agriculture, whose hallmarks include monoculture, restricted seed choices, and limited livestock varieties. Today, the patenting of living organisms also reduces the availability of certain species to farmers and consumers.
Industrially raised animals also have decreased variety in their diets, and this may affect their nutritional profiles. Pastured poultry eat a diversity of insects and plants, but caged ones have a limited diet consisting largely of grains and soy. Similarly, pastured livestock eat a variety of grasses, but feedlot animals have a restricted diet that often includes processed corn or wheat. Also, there are less-apparent trends that serve to further narrow the food base.
Formerly, numerous species of wild fish were readily available to consumers, both at fish markets and in restaurants. People in coastal areas had greater access to ocean finfish and shellfish; and those living inland could easily obtain fresh water species, as well as other varieties shipped to their regions. Restaurants often served “catch of the day” from a variety of species. Today, however, with the increasing scarcity of wild fish and the dwindling supply of some species, we have become dependent on aquaculture to meet growing consumer interest in fish consumption.
However, fish farming limits the variety of fish available, as only a few species can be reared economically. Farmed fish are fed foods not normally in their diet, such as corn, other grains, or soybeans. Both the flavor and nutritional profile of such fish differ markedly from that of their wild counterparts. This is especially true for salmon.
Restaurant practices also contribute to the narrowing food base. Even full-service restaurants offer only a limited number of vegetables, fruits, whole grains, and animal-sourced foods. Fast food restaurants have even more restricted menus. Limited offerings are consumed daily by many children, not only on fast-food premises but at school cafeterias, starting in elementary school, and even at some children’s hospitals and museums. Coffee shops; pancake, crepe, or doughnut eateries; and vending machines limit food choices and fail to provide nutrient-dense foods.
The illusion of variety
In the marketplace, many food products that appear to differ are actually manufactured from the same ingredients. They differ merely in form, texture, or taste. For examples, dozens of pasta products vary in shape but are made from the same dough. Numerous dry cereals, differing in flavor and appearance, are manufactured from similar ingredients, such as wheat, soy, or corn. Extrusion equipment can produce any form the processor desires. By offering numerous versions of the same product, manufacturers obtain more shelf space. With an expanded display, more products are sold.
Fractionation of foods is another technique used by food processors that provides consumers with the illusion of variety and results in greater profitability for producers. For example, fluid milk is available as whole milk, reduced-fat milk containing different percentages of fat, and skim milk. The dairy industry profits by selling milk fat separately, in products such as cream and butter, and at the same time generates propaganda about the alleged health hazards of fat. In reality, the fractionated milk is imbalanced, as components of milk fat are necessary to digest nutrients in the remaining fluid.
Similarly, grains are fractionated, to the further detriment of consumers. Processors sell the bran, middlings, and germ separate from the flour, which by then is depleted of vital nutrients, including zinc. In the whole grain, zinc buffers the toxic effects of cadmium that may be present. During the refining process, the zinc is removed, but the cadmium remains. No longer buffered, the cadmium can wreak havoc on our health.
The alarming pace of food biodiversity loss and ecosystem degradation makes a compelling case for re-examining food systems and diets
Food allergies and intolerances
It is not surprising that the major allergenic foods in developed countries are those eaten most frequently. As dietary variety declines, repeated consumption of the foods that remain sets the stage for allergenicity. If a reaction is severe, the offending food may need to be avoided completely, thus narrowing the food base further. If the reaction is not severe, food rotation may be sufficient to avoid symptoms.
The major food allergens in developed countries include wheat, beef, corn, shellfish, soy, peanuts, and dairy products. Soy, formerly a minor food in the Western diet, came into prominence as a meat substitute in 1973, at a time of rising meat prices. Since then, its use has increased greatly, both as a whole legume and in its numerous fractionated forms. As a result, soy has become a major allergen.
Patterns of allergenicity differ regionally. Beef, eaten extensively in the northern, midwestern, and western regions of the United States, is a major allergen in those areas; pork, eaten widely in the southern states, is a common allergen there.
The allergenicity of corn, soy, and wheat is exacerbated in humans by the use of these ingredients in feed eaten by livestock and farmed fish. As a result of this practice, people have difficulty avoiding these allergenic foods. Moreover, the animals themselves suffer digestive and other health problems from consuming these feeds, which are alien to their digestive tracts.
Food intolerances further limit dietary variety. The most common of these are difficulties in digesting lactose and gluten. Lactose intolerance results from a lack of sufficient lactase, an enzyme needed to digest the primary milk sugar, lactose. This is distinctly different from milk allergy, a condition in which all dairy products from the offending species must be avoided. The degree of lactose intolerance varies on a scale; some individuals can tolerate milk in small amounts, especially if it is consumed with other foods. Lactose-intolerant individuals may tolerate fermented milk products, such as yogurt or kefir, as fermentation reduces the lactose in such foods. Often, whole milk is tolerated better than fat-reduced milks. In order to overcome the “skinny” texture and taste of fat-reduced and skim milks, nonfat milk solids may be added for “body.” This practice results in even higher levels of lactose in these products.
Celiac disease or nontropical sprue, once known as “wasting disease,” is an autoimmune disorder that requires a lifetime of total avoidance of gluten-containing grains. Non-celiac individuals who are gluten intolerant also need to avoid or limit its consumption.
In recent years, gluten has become a hot topic. Some people with digestive problems have concluded, without any evidence, that gluten is the culprit, even though their digestive difficulties may be caused by many other factors. The food industry has exploited this concern and profitably produces numerous products without gluten. The phrases “gluten free” and “no gluten” are used to promote products that never have contained gluten.
Exclusion of gluten-containing grains from the diet can narrow the food base, but, strangely, it may also have an opposite effect. Some nongluten grains, such as millet, quinoa, and amaranth, which are gaining popularity among Americans, beneficially add variety.
The growth of farmers markets and community-supported agriculture (CSA) has increased our access to fresh locally grown and raised foods. Moreover, local organic farmers keep their soil in good tilth with the time-honored practices of rotating crops and using cover crops, mulch, compost, and soil amendments. These enterprises are beneficial by providing alternatives to large-scale, industrialized agriculture and reducing energy use for transportation and distribution. They afford opportunities for conversation between producers and consumers.
However, eating only foods grown locally—attempted by extreme locovores—limits the food base by excluding species that are not grown in the area. Tropical fruits, for example, would be excluded in many regions. In the northern parts of the United States, both the variety of produce and the length of the growing season are more limited than in the warmer southern areas. Despite its drawbacks, globalization of the food supply does offer a greater variety of foods than would have been available in any one location.
Moreover, extreme locovorism can limit the availability of nutrients. If the soil in an area is unsuitable for agriculture (for example, dangerously high in selenium or low in calcium), excesses or deficiencies of nutrients will be found in crops grown in that area, as well as in livestock raised there. Consuming foods grown or raised on a variety of soils offers the opportunity to obtain a more balanced nutrient profile.
Consumption of a variety of fruits and vegetables also allows us to benefit from the synergistic effects of phytochemicals with powerful antioxidant and anticarcinogenic activities. Eating a diversity of these foods may reduce the incidence of certain types of cancers. The official recommendation to eat five to ten servings of fruits and vegetables daily should encourage consumption of a greater variety of these foods.
Veganism: A Current Mania
Humans have the capacity to obtain nourishment efficiently from a wide diversity of foods. We are structured physiologically to be omnivorous. Some of our teeth are suited to tear flesh foods, and others are suited to chew. Creatures that are dependent mainly on a single food for sustenance are much more vulnerable to dietary stressors. Examples are pandas, which are dependent on bamboo; koalas, whose diet consists almost entirely of eucalyptus leaves; and monarch butterflies, which are reliant on milkweed.
In developing countries, human vegetarianism has often resulted from scarcities of foods from animal sources, but it is usually based on deliberate ethical, religious, or environmental considerations in developed nations. The trend in the developed world encompasses a range of vegetarian lifestyles: Some individuals shun red meats; others, all meats. Some also eliminate fish, eggs, and dairy foods.
At the far end of the continuum are the vegans and fruitarians. The red-meat abstainers have a far wider selection of foods than the vegans and fruitarians, whose food bases are precariously limited. Despite this peril, veganism is currently trendy. Eventually, its shortcomings will produce malnutrition and lead to health problems.
The raw food fad
With the discovery of fire, early humans came to enjoy the comforts of the hearth. Also, importantly, fire made some foods safer and expanded the food base. Inedible roots and tubers, after being cooked, became digestible. Later in our history, cooked domesticated legumes and grains also contributed nourishment.
The current fad of the all-raw food diet can severely limit the food base. Most foods from animal sources may be eliminated. Many vegetables that are commonly cooked, such as potatoes and brassicas (e.g., Brussels sprouts), may be shunned. Legumes and whole grains, unless they are sprouted, are off limits, as they require cooking.
If all these foods are removed from the diet, what is left to eat? Salad fixings, fruits, nuts, and seeds remain. Even certain fruits, such as plantain and rhubarb, require cooking. In some instances, we obtain greater amounts of specific nutrients from cooked than from raw vegetables or fruits. Examples are carotenoids from carrots and lycopene from tomatoes. Furthermore, specific antinutrients in foods such as beans and spinach are deactivated by cooking. Despite all these limitations, some restaurants cater to patrons who desire an all-raw food menu. Some misguided parents who attempt to raise their children on an all-raw food diet are dismayed to find that their children become malnourished.
The gut is regarded as the second brain, with good reason. It contains a distinct nervous system with hundreds of millions of neurons, and with taste receptors formerly believed to be present solely in the mouth. It also contains various microorganisms, numbering in the trillions, that affect both the immune and digestive systems. In a healthy gut, beneficial microorganisms overpower and hold in check any pathogenic ones present. However, for individuals consuming the standard American diet (SAD), both the number of species and the populations of beneficial microorganisms are low, compared with those found in the guts of individuals on more diversified, nourishing diets.
Study of the human microbiome has begun relatively recently, and intriguing information is being discovered. For example, it has been assumed that synthetic sweeteners merely pass through the digestive tract, with no effect on the gut. In a landmark research article published in Nature, three synthetic sweeteners were reported to adversely affect the gut microbiome in mice and humans. The tested sweeteners, saccharin, aspartame, and sucralose, also induced high glucose levels in the blood and triggered metabolic changes associated with obesity and diabetes. If these findings are confirmed by additional studies, they will have profound implications. Numerous food additives, pesticide residues, heavy metals, and pharmaceuticals, officially deemed safe at established levels, will need to be tested to ascertain their effects on the microbiome.
Currently, even less is known about the microbiota of other animals, plants, and soils than has been learned about our own. Substantial research on how the use of chemical fertilizers in agriculture may affect plant and soil microorganisms is needed. Beneficial creatures such as earthworms are visible in organically treated soils but absent in chemically treated ones. Similarly, numerous beneficial microorganisms present in organically treated soils may be reduced or absent in those that been treated chemically. The term “living soil,” used by Lady Eve Balfour in her classic 1943 book on organic agriculture, now can be seen to take on new meaning.
To summarize, numerous agricultural practices contribute to an ever-narrowing food base. In addition, our dietary habits can contribute to the trend. As educated consumers, we have the ability to make better choices, selecting a varied diet of healthy foods, and even trying unfamiliar ones.
About the Author
Beatrice Trum Hunter, MA, has written more than 30 books on food and environmental issues, frequently before widespread public awareness. She was food editor of Consumers’ Research magazine for more than two decades. She is an honorary board member of the Price-Pottenger Nutrition Foundation, and has been the recipient of many awards, including the Jonathan Forman Award of the Society for Clinical Ecology, the New Hampshire Society for Preventive Dentistry, and the Donon Pepper Humanitarian Award.
- Suez J, Korem T, Zeevi D, et al. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. 2014; 514(7521):181-186. doi:10.1038/nature13793. Published online September 17, 2014.
- Balfour E. The Living Soil. London: Faber and Faber; 1943.
Biodiversity in Peril
The escalating threat to biodiversity, particularly as it affects food sources, is receiving increasing attention. The following excerpts provide additional insights into the situation. – Editors
Food varieties extinction is happening all over the world – and it’s happening fast. In the United States an estimated 90 percent of our historic fruit and vegetable varieties have vanished.… In the Philippines thousands of varieties of rice once thrived; now only up to a hundred are grown there. In China 90 percent of the wheat varieties cultivated just a century ago have disappeared. Experts estimate that we have lost more than half of the world’s food varieties over the past century. As for the 8,000 known livestock breeds, 1,600 are endangered or already extinct.
– Charles Siebert, Food Ark, National Geographic, July 2011; http://ngm.nationalgeographic.com/2011/07/food-ark/siebert-text/1
“Over the past 50 years, we are seeing that diets around the world are changing and they are becoming more similar – what we call the ‘globalised diet,’” Colin Khoury, a scientist from the Colombia-based International Center for Tropical Agriculture, said. “This diet is composed of big, major crops such as wheat, rice, potatoes and sugar.”…
He added that while these food crops played a major role in tackling global hunger, the decline in crop diversity in the globalised diet limited the ability to supplement the energy-dense part of the diet with nutrient-rich food.
– Mark Kinver, Crop Diversity Threatens Food Security, BBC News Science & Environment, March 3, 2014; http://www.bbc.com/news/science-environment-26382067
The alarming pace of food biodiversity loss and ecosystem degradation makes a compelling case for re-examining food systems and diets.… Simplification of diets, low in variety but high in energy, contributes to the escalating problems of obesity and chronic disease, which are increasingly found alongside micronutrient deficiencies and undernourishment, particularly in poor areas of the developing world. Biodiversity plays a key role in ensuring dietary adequacy, because nutrient contents between foods and among varieties/cultivars/breeds of the same food can differ dramatically.
– Food and Agriculture Organization of the United Nations, Biodiversity: Nutrition; www.fao.org/biodiversity/cross-sectoral-issues/nutrition/en
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Published in the Price-Pottenger Journal of Health and Healing
Spring 2015 | Volume 41, Number 4
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