Animal-based Diets and Human Health
Eating animal-based products has serious health consequences, yet it is widely believed that meat, dairy, and egg products are essential dietary requirements. In order to improve health it is important to understand not only the dangers of consuming products from Concentrated Animal Feeding Operations (CAFOs), but also the reality of the supposed benefits we get from consuming animal-based products.
Dangerous Drug Use in CAFOs
Drugs are widely used on factory farms as farmers want to get as many animals as possible to market weight in the shortest amount of time. The use of growth-enhancing drugs as well as antibiotics enable the animals to reach slaughter weight more quickly and to survive the unsanitary and confined conditions of the factory farm.
Antibiotic use has become a common practice in the industry, and livestock in the U.S. consume over 5 million kilograms (around 12 million pounds) of antibiotics each year.1 Eating products from animals who have been administered antibiotics has serious consequences. Studies have shown a clear link between consuming products from animals that were given antibiotics in their feed and antibiotic resistance in humans. This poses a serious public health issue, as antibiotic drugs such as penicillin, tetracycline, and erythromycin are commonly used to treat disease.
In the U.S. dairy industry, a genetically engineered growth hormone called recombinant bovine growth hormone (rBGH) is commonly used to increase milk production. In 2007, nearly 43 percent of large-scale dairy operations used rBGH,2 even though it has been shown that humans who consume milk products from cows treated with rBGH have a higher risk of developing breast, colon, prostate, and other cancers. Due to these potential health risks and some animal welfare issues, such as treated cows experiencing mastitis (udder infections) and reproductive problems, the rBGH growth hormone has never been allowed in the EU or Canada. Israel, Japan and Australia have also banned the use of rBGH, while the U.S. dairy industry continues to use it heavily.
Between 1995 and 2000, 70 percent of chicken producers in the U.S. were using arsenic-laced feed to prevent disease and promote growth.3 Chronic exposure to arsenic has been shown to increase the risks of several types of cancer, cardiovascular disease, and diabetes in humans. In October 2013, after a four-year-long campaign by the Center for Food Safety, the FDA announced that it will ban three of the four commonly used arsenic-laced drugs in animal feed. The companies responsible for putting these drugs on the market had largely voluntarily withdrawn the three drugs from the market several years ago after studies showed levels of arsenic in chicken that exceeded amounts that occur naturally. The use of the fourth drug nitarsone remains permissible.
E. coli (Escherichia coli O157:H7)
More than half of feedlot cattle carry the intestinal bacteria strain E. coli O157, and ingesting as few as ten of these microbes can cause a fatal infection in humans. It is prevalent at such a high level because these cows cannot escape their own waste in the confined, unsanitary conditions in which they live. These microbes should be killed off by the acidic content of the human stomach, but because cattle are fed corn, their stomachs are unnaturally acidified, and the E. coli can now withstand the acidity of a human stomach. Fortunately, there is a solution, and by switching a cow's diet from corn to hay a few days before slaughter, the presence of E. coli in manure has been shown to be reduced by as much as 70 percent.4 Unfortunately, the industry forgoes this diet change because it is expensive and inconvenient. Furthermore, partially due to the use of antibiotics in farmed animals, some people are resistant to the drugs used to fight infections brought on by exposure to E. coli.
Mad Cow Disease
Mad cow disease (bovine spongiform encephalopathy, BSE) is also a result of factory farm operations and causes serious public health issues. In humans, it is known as Creutzfeldt-Jakob disease (CJD), or, in the young, variant CJD. Most foodborne illnesses can be prevented by thoroughly cooking meat; however, mad cow disease, which causes dementia and is ultimately fatal in humans, is not one of them. Mad cow disease spreads when cattle are fed nervous system parts of other infected cattle. The FDA banned the use of certain animal proteins from cattle feed in 1997, but the use of blood products in feed were still permissible.5 In 2008, with the "enhanced feed rule" the FDA amended the rule to ban the use of brains and spinal cords of cattle 30 months of age or older from all animal feed.6 The USDA has reduced testing for mad cow disease since 2006 by over 90 percent because they claimed that tests were too expensive to conduct and detection of infected cows was rare.7 However, in April 2012 a cow tested positive in California for this very fatal disease.
See Contaminated Food for further information about foodborne illnesses.
First Glimpse of the Relationship between Meat Consumption and Disease
It was during the First World War that scientists began to realize that meat consumption and disease may be connected. The Danish government responded to the possibility of a food shortage during the war by feeding the grain originally destined for livestock directly to the people. The government had very strict food restrictions during October 1917 to October 1918 and the nation consumed essentially a vegetarian diet for this year. The death rate from disease was 34 percent lower during this year than the average for the preceding 18 years.8
Scientists, intrigued with the findings of a correlation between meat consumption and death rates, conducted similar research during World War II. Consistent with the statistics from the First World War, scientists found countries that were forced to cut meat consumption during the Second World War had lower death rates from disease during this time.
A majority of people believe that meat is the only way to get enough protein; however, plants are loaded with protein. As John McDougall, MD, explains: "Since plants are made up of structurally sound cells with enzymes and hormones, they are by nature rich sources of proteins. In fact, so rich are plants that they can meet the protein needs of the earth's largest animals: elephants, hippopotamuses, giraffes, and cows. You would be correct to deduce that the protein needs of relatively small humans can easily be met by plants."9 Society has put an unnecessary focus on protein and protein-rich diets. The World Health Organization recommends that people obtain 5 percent of their daily calories as protein. Therefore, if daily calorie requirements are met, it would be very difficult to not meet this protein requirement even on a plant-based diet. It is essentially impossible to be protein deficient unless you are food deficient.
Dairy does have bone-building effects, but it is also capable of weakening bone. Milk, which is produced by all female mammals, has been called nature's perfect food because it contains enough protein and nutrients for a given species to grow rapidly during infancy. However, humans cheat nature in the sense that we are the only species to drink another species' milk and the only species to continue to drink milk after weaning. As a result, we take away nature's perfect food for calves and compromise our own health.
Human milk is 5 percent protein, so nature in essence has determined that during the first two years of life, humans' most rapid growth period where protein requirement is the highest, a human baby needs no more than 5 percent of daily calories to be protein.10 On average, human babies will double their birth-weight in about 180 days. Cow's milk is 15 percent protein, as calves double their birth weight in just 47 days.11 In fact, cow's milk enables a 27 kilogram (60 pound) calf to become an over 270 kilogram (600 pound) cow in less than 8 months.12 Given this information, it is not surprising that cow's milk, which is three to four times richer in protein and other nutrients,13 has adverse effects when consumed by humans. Dairy products have been shown to have bone-destroying effects: bone loss and osteoporosis.14
Although it is widely believed that eggs are a healthy, nutritious, protein-packed food, the amount of cholesterol in eggs should not be overlooked. According to the National Cholesterol Education Program (NCEP), daily dietary cholesterol should not exceed 200 milligrams.15 One egg contains 6 grams of protein and 186 milligrams of cholesterol. This means that by consuming one egg a person has already nearly reached the recommended daily limit. Although there is a debate about how much the cholesterol in eggs raises cholesterol in the blood, it is clear that there is a relationship between dietary cholesterol and coronary heart disease. It is also important to note here that a whole egg is 32% protein and the white of an egg is essentially 100% protein. Infants, growing children, and adults only need about 5% of their daily calories to be from a protein source. This high concentration of protein can actually have harmful effects on the body. Furthermore, animal proteins, and those contained in egg whites in particular, are high in sulfur-containing amino acids, such as methionine. Excess dietary acids can lead to osteoporosis and increase the risks of heart attacks, strokes, dementia, and Alzheimer's disease.16
Disease Prevention through Diet
Although meat, dairy, and egg products are promoted for good nutrition, some studies are demonstrating something different. John McDougall, MD, a physician and nutrition expert, argues that meat is an ideal food for pointy-toothed carnivores such as felines, but meat actually sickens herbivores and omnivores, and this includes humans who have a meat-centered diet. Meat is high in fat, which promotes obesity, type-2 diabetes, artery damage, heart disease, and certain types of cancers. Research has also demonstrated that the consumption of both red meats and processed meats increases the risk of cancer. The American Institute for Cancer Research estimates that every 1.7 ounces of red meat consumed per day increases cancer risk by 15 percent, and every 1.7 ounces of processed meat consumed per day increases risk of colorectal cancer by 21 percent.17
Additionally, meats, dairy products, and eggs are the main source of dietary saturated fat and the only source, including fish, of dietary cholesterol.18 It has been well documented that diets high in saturated fat and cholesterol greatly increase the likelihood of heart disease and strokes. There is strong evidence of a connection between the leading causes of deaths and diet. In 2011, the CDC reported that heart disease was the leading cause of death, killing 597,689 Americans, and that strokes accounted for 129,476 deaths.19
Dairy products have the ability to raise the body's estrogen levels, they put people at a higher risk for certain types of cancer, including cancers of the breast, uterus, and prostate. The dietary acid and protein can lead to calcium excretion, which causes osteoporosis.20
2 Food and Water Watch (2010),
Factory Farm Nation: How America Turned Its Livestock Farms into Factories.
3 Stephanie Strom, "F.D.A.
Bans Three Arsenic Drugs Used in Poultry and Pig Feeds," The New York
Times, October 1, 2013.
9 John McDougall (2007),
McDougall Newsletter, Vol. 6, No. 4.
12 John McDougall (2007),
McDougall Newsletter, Vol. 6, No. 3.
15 Cleveland Clinic
Health Hub, 2013
16 John McDougall (2005),
McDougall Newsletter, Vol. 4, No. 3.
17 American Institute for Cancer Research,
Landmark Report: Excess Body Fat Causes Cancer, May 5, 2013.
19 Centers for Disease Control
Overweight and Obesity, May 4, 2013.
20 John McDougall (2007),
McDougall Newsletter, Vol. 6, No. 4.