Why Is Processed Meat So Dangerous?
What makes some meats likely to cause cancer? And are some meats okay? Continue reading →
Consuming processed meats, like bacon and sausage, may increase the risk of colon cancer in humans, according to a new report by the World Health Organization, and eating unprocessed red meat may spike the chance of getting other types of cancers.
Beef jerky, bologna and their meaty cousins were dubbed Group 1 carcinogens by the WHO experts, who cited "sufficient evidence" that processed meat causes colon cancer.
Tobacco, asbestos and formaldehyde also fall into Group 1.
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Fresh red meat, like beef or lamb, was dubbed a Group 2A carcinogen, or "probably carcinogenic to humans." Other substances in this category include glyphosate, which is found in many commercial weedkillers, and ultraviolet radiation.
"For an individual, the risk of developing colorectal cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed," said WHO expert Kurt Straif, reports the New York Times. "In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance."
The formal review tallied data from 800 studies that looked at the relationship between meat consumption and over a dozen different cancers. The conclusion: eating 50 grams of processed meat each day increases colon cancer risk by 18 percent.
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Fifty grams isn't that much: It equals roughly 1.5 ounces.
Why is processed meat so dangerous?
Carcinogens are most likely introduced in processed meats during the actual act of processing, including curing, smoking or grilling.
Here's what happens: Compounds called heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are formed when meats come in contact with high temperatures. HCAs and PAHs have been shown to change human DNA in ways that set the stage for cancer, according to the National Cancer Institute (NCI).
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PAHs develop when fat and juices from the meat drip down onto the open flame, reacting with the fire and causing flames that contain PAH. The PAH then sticks to the meat. (This can also happen when meats are smoked.)
HCAs develop when the different macronutrients in meats react with each other when exposed to high temps.
Grilling or pan frying meat over 300 degrees will trigger HCAs, and the longer you grill or fry, the more HCAs develop. PAHs appear anytime a meat is charred.
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Previous large-scale epidemiological studies have shown a link between diets high in well-done, fried and barbecued meats and colon, pancreatic and colon cancer, adds NCI.
Is some meat okay?
The case against fresh red meat, however, is more complicated than the WHO report implies.
For one, the nutritional profile of meat is almost completely dependent on what the animal has eaten during its lifespan.
"Grass-fed, pastured beef and grain-fed beef are so vastly different in their nutritional values, that they cannot realistically be considered the same food source," writes oncologist Colin Champ.
Meat from animals that have been grass-fed are rich in inflammation-cooling omega-3 fats. They're also higher in conjugated linoleic acid (CLA), a substance that has been shown to confer a protective property against cancer, reports the Mayo Clinic.
There is significantly less CLA in grain-fed beef, and significantly more inflammation-promoting (and thereby cancer-promoting) omega-6 fats.
What's more, noted the WHO experts, "no clear association was seen in several of the high quality studies" between fresh red meat consumption and cancer risk, reports the Wall Street Journal. They also pointed out how tricky it was to control for other factors, like smoking or physical inactivity, that can play a role in cancer risk.
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The best advice for concerned meat eaters might be to heed the familiar mantra: "Consider the source."
"The nutritional benefit (or detrimental effect) of a hotdog full of processed meat and nitrates is NOT THE SAME as grass-fed beef," continued Champ. "All meat is not created equal, so to study industrially produced meat products and apply that data to free-range, grass-fed meat is scientifically false."
Those who are considering cutting down on meat in light of the findings might adopt a slightly altered mantra: "Consider the alternative." Replacing meat with heaps of sugary candy might be equally as damaging. Replacing it with vegetables will do a body good.
"A characteristic of the American dietary that has persisted throughout years has been its abundance." This sentence is no less true today than when it was
published in the American Journal of Clinical Nutrition in 1959
. That abundance, however, comes with a cost: Americans eat too much. That excess consumption and often poor nutrition has brought with it a multitude of life-changing and often life-threatening diseases and conditions, including obesity, diabetes, heart disease, cancer and more. Although the number of Americans who are overweight or obese has been on a steady climb since the middle of the 20th century,
a recent report by the New York Times suggests
that efforts to abate this health crisis might be gaining ground thanks to a shift in public attitudes. For the first time since the federal government began tracking dietary intake over more than four decades of data collecting, the daily calorie intake of the average American showed a sustained decline. Read on to see how the American diet has changed since the middle of the 20th century.
While calorie counts have been on the downswing, calorie intake is still far above where it once stood. Americans' daily average caloric intake is over 500 calories higher than it was in 1970, when the average hovered around 2,169 calories per day. What does a more than 20 percent increase in caloric intake mean for the average American? Consider that a pound a fat contains 3,500 calories. Assuming that even a quarter of those calories represent excess energy beyond what's needed for daily maintenance levels, that translates into a pound of stored fat gained every month, or 12 additional pounds per year. Portion sizes have seen a similar increase over time.
According to the U.S. Department of Health & Human Services
, in the last two decades alone, food portions in American restaurants have doubled or in some cases tripled. Portion sizes began increasing in the 1970s and rose sharply in the 1980s. Many food portions greatly exceed USDA and FDA standard servings,
according to a study published in the American Journal of Public Health
. "The largest excess over USDA standards (700 percent) occurred in the cookie category, but cooked pasta, muffins, steaks and bagels exceeded USDA standards by 480 percent, 333 percent, 224 percent and 195 percent, respectively," the study found.
According to the U.S. Department of Agriculture (PDF)
, between the 1950s and 2000, Americans consumed on average 39 percent more refined sugars. Consumption of corn sweeteners, with high-fructose corn syrup leading the charge, octupled. On average, Americans consume an estimated 156 pounds -- yes, pounds -- of added sugar per capita every year. Excessive sugar intake can lead to all kinds of negative health outcomes, including but not limited to dental problems, obesity, diabetes, liver failure and more. These concerns are what led the
Food and Drug Administration (FDA) recently to propose
a change in food labeling that would recommend the daily intake of calories from added sugars not exceed 10 percent of total consumption. More than 70 percent of U.S. adults get over 10 percent of their daily calories from sugar.
Americans aren't just eating more sugars than they used to; we're also drinking more.
According to the Harvard School of Public Health
, before the 1950s, the standard soft drink size was 6.5 ounces. That decade, manufacturers started selling larger sizes, and by 1960 the 12-ounce can was everywhere. Fast forward 30 years, and 20-ounce bottles are ubiquitous. Today, single-use soft drinks can reach up to 64 ounces and have up to 700 calories. Since the 1970s, sugary drinks have grown from 4 percent of Americans' daily calorie intake to 9 percent. A quarter of Americans get at least 200 calories a day from soft drinks. Teens and children are particularly high consumers, too. Sugar drinks are the top calorie source for teenagers, and are consumed daily by an estimated 91 percent of children.
Beginning in 1980, when USDA issued the first federal dietary guidelines implicating fats and cholesterol as a major source of Americans' health woes, particularly heart disease, the food industry began shifting formulas in their products that moved away from saturated fat and toward vegetable oils and carbohydrates. Low-fat diets became all the rage, with a bevy of product lines offering low-fat alternatives. What happened after Americans got turned on to low-fat foods? They got even fatter and less healthy. Foods may not have had as much saturated fat, but they made that up with an increase in sugar and refined grains, which kept calorie counts the same. The switch to hydrogenated vegetable oils and margarines also only increased health risks. Heart disease is still the number one killer in the United States, and we also have rising numbers of diabetes and obesity to contend with. In fact, despite numerous studies since the 1990s showing that low fat diets are ineffective at best and harmful at worst, the government continues to recommend a low fat diet.
Go to the snack aisle of any supermarket or convenience store in the United States, and you'll find a wide array of potential options to satisfy any junk food craving. What do all of these foods have in common? They're all made of refined grains, in addition to other nutritionally deficient ingredients. Refined grains do not offer the same nutritional benefits as whole grains. The process by which refined grains are produced removes fiber, iron, vitamins and other nutrients,
according to the American Heart Association
. Examples of refined grains include white flour, corn flour and white rice. Not only have Americans turned to unhealthier grains for a greater share of their calories; modern wheat is also less nutritious than heritage grain varieties.
As Americans increasingly eat out at restaurants more and consume more processed foods, salt intake has steadily increased across all age groups. The average American between ages 20 and 74 consumed close to 1,500 mg more sodium per day in 2006 than in 1971,
according to the Institute of Medicine of the National Academies
. The Centers for Disease Control and Prevention (CDC) recommends everyone ages 2 and up consume less than 2,300 mg per day, which is about a teaspoon a day. Some people with certain health risks, such as diabetes or high blood pressure, should limit that further to 1,500 mg per day. Eating too much salt increases water intake in the body, which leads to high blood pressure. Kidneys work overtime to deal with the excess sodium, and the increased blood volume puts a strain on the heart and blood vessels. At worst, a lifetime of a sodium surplus could lead to heart failure or stroke,
according to the Harvard School of Public Health
In 1929, presidential candidate Herbert Hoover ran under the slogan "a chicken in every pot and a car in every garage." These items might seem common enough today, but Hoover was basically promising what were then considered luxuries to every American household. At the time of Hoover's campaign, "the few chickens raised for meat were sold directly to high-end restaurants, first-class dining cars, and luxury caterers,"
according to the Smithsonian Museum of American History
. Chickens were instead kept for their eggs, which are a valuable source of protein and other nutrients. Egg consumption peaked mid-century, and has been in decline ever since. The overblown connection between cholesterol in eggs and heart disease certainly contributed to Americans turning their back on eggs. But a decline in prices of another protein source, specifically chicken, also contributed to eggs falling out of favor. In the last half of the 20th century, poultry consumption went up more than three-fold, according to USDA data. Red-meat consumption saw a steady decline over the same period, with Americans eating roughly 10 percent fewer pounds per capita every year.