June 22, 2016 Dr. Neal Barnard ,
Mariana C. Stern, Ph.D., a co-author of the World Health Organization report that declared processed meats carcinogenic to humans, says that physicians should recommend that patients avoid processed meats. In this excerpt from the upcoming summer issue of Good Medicine magazine, Dr. Stern discusses the link between meat and cancer, the impact of the WHO report, and her single most important piece of nutrition advice.
Dr. Stern will discuss her research on nutrition and cancer at the Physicians Committee’s International Conference on Nutrition in Medicine on July 29-30, 2016, in Washington, D.C. Register to attend at ICNM16.org.
How does meat increase cancer risk?
Several mechanisms have been postulated. One is the presence of heme iron in red meats. This is a component of the protein that transports oxygen in blood. Meats are rich in this protein, as muscle requires a lot of oxygen. In excess, heme iron is known to cause damage in tissues, and can also help in the formation of carcinogens called nitrosamines in the intestines. These nitrosamines can also form in meats that have been treated with nitrates, like bacon or cold cuts, or inside our intestines when diets are high in red meat and there are sources of nitrates. Another mechanism is the formation of a group of carcinogens called heterocyclic aromatic amines that naturally form in red meat when it is cooked at high temperature. Components in the meat can react at high temperature to form these powerful carcinogens.
It is still not clear which of these mechanisms is the most important. There is a chance that different combinations of these may be at play in different people.
Do particular meats increase the risk for particular cancers?
To date, the evidence is strongest for an association between red meats (muscle meat from cows, lambs, pigs, sheep, and horses) and colorectal, pancreas, and prostate cancer. Whereas there is evidence that red meat may also increase risk of other cancers, the evidence is still inconclusive. The evidence is very strong for processed meats and colorectal cancer, and also strong for stomach cancer. Again, there is evidence that processed meats may also increase risk of other cancers, such as breast cancer, but the evidence is still inconclusive.
You were a co-author of the World Health Organization monograph that led to the classification of processed meats as a Group 1 carcinogen. How do you think the report has influenced processed meat consumption?
There is definitively more awareness. I find that many people who had never heard that processed meats might be bad for us now know this and perhaps are starting to make different choices, or at least know that they should not eat processed meats every day. Unfortunately, this knowledge does not cut across our society, as not all people keep up with the scientific knowledge that trickles to the media. In the scientific community, there is more interest on this topic, more validation, which hopefully may translate into more support for new funded studies to understand the role of processed meats on cancer further.
Do you think policy changes should be enacted to protect people from processed meats?
Yes, I think the public should be informed of the known risks of consuming processed meats, so that they can make informed choices. Processed meats are still an affordable staple in many people’s diets, the aisles in supermarkets offering processed foods are very big, and particularly worrisome is the role of processed meats in children’s diets. They make convenient and affordable lunch and snack options. Parents should know the risks associated with processed meats and learn to make alternative choices.
Should physicians recommend that their patients avoid processed meats?
I think so. Diets high in red meat may contribute to heart disease, diabetes, and cancer. Processed meats are now established sources of carcinogens. There are many benefits associated with increasing fruits and vegetables and reducing red meats—and clear benefits from reducing processed meats, given their salt, fat, and carcinogen content. A healthy diet should be part of the conversation between a physician and a patient.
What foods help reduce cancer risk?
Fruits, vegetables, legumes, grains, and nuts. We know diets high in fiber are protective against the development of several cancers, and other diseases as well. We also know of many vitamins and other chemicals present in fruits, vegetables, and nuts that have many beneficial effects reducing inflammation, preventing damage to our DNA, and overall reducing cancer risk.
What is the single most important piece of nutrition advice you wish everyone knew?
Do not trust all information posted online about nutrition and health. Go to the most reputable sources. For knowledge about nutrition and cancer this would include the Physicians Committee, the American Cancer Society, the American Institute of Cancer Research, and the World Health Organization, among others. Epidemiological or experimental studies on diet and cancer are published every day. The press likes them, and they make for great stories, so they appear in the media very quickly. Not all meet the most rigorous scientific standards. And even if they do, the variability across the population is so large that epidemiologists never rely on one single study to make definitive conclusions. We rely on systematic reviews conducted by experts using rigorous methods.
There is the misconception that “everything gives cancer, so why worry about one dietary item or another, they will all cause cancer anyway!” This is not true. To date, there are only a handful of dietary items that have been consistently and solidly linked to cancer. Red meat is one of them, so we should take this seriously. Meat does not need to be the main staple of our diet, and it is not the only source of protein for kids and adults to be strong and healthy. We should give a more prominent role to plant-based foods, which when part of a balanced diet can provide all the essential nutrients we need to grow and stay healthy and strong, and also provide us with many disease- and cancer-fighting nutrients.
In the Western diet, we have grown used to the idea of having meat as the main food item on our plate and everything else on the side. Many people still think that without meat they cannot be healthy. We need to reverse our thinking and make plant-based foods the center of our plate.
June 17, 2016 Dr. Neal Barnard ,
“Where do you get your protein?” It’s probably the No. 1 question vegetarians and vegans get about their diets.
But why? In the United States today, protein deficiency is virtually nonexistent. In fact, most Americans are actually getting twice the protein their bodies really need.
The protein myth is one of many topics that Marta Zaraska tackles in her book Meathooked—an exploration of our cultural addiction to meat. As Ms. Zaraska explains, “it’s extremely hard to succumb to [protein deficiency] in the West unless you are truly starving, an AIDS patient, or a drug addict.” Most of us, she explains, only need 0.8 grams of protein per kilogram of body weight each day—that’s about 50 grams for someone who weighs 150 pounds—which most people achieve easily.
But you wouldn’t know that if you get your nutrition advice from the headlines—which constantly push high-protein diets. In spite of the fact that we now eat more meat than ever—about 125 pounds per person every year—and collectively consume more than one million chickens per hour, we still strive for more protein. The more, the better.
But when it comes to protein, evidence shows that more isn’t actually better. A long-term study published in 2014 found that diets rich in animal protein are linked to a fivefold increase in risk of death from diabetes and a fourfold increase in risk of death from cancer—risk factors that are comparable to smoking. And for the first time, the Dietary Guidelines for Americans now urge certain groups of Americans—namely men and teenage boys—to reduce their overall consumption of high-protein foods, like meat and eggs, to improve their health.
So what makes high-protein diets so dangerous? Part of the reason may be that high-protein foods, like meat, dairy products, and eggs, are also rich in fat, saturated fat, and cholesterol.
A healthful plant-based diet, on the other hand, easily provides all the protein our bodies need, without any of the health risks. All foods, including fruits and vegetables, contain protein, while certain plant-based foods, like whole grains, beans, nuts, lentils, tofu, and quinoa pack an extra protein punch.
So worrying about protein isn’t necessary—a recent study even found that 90 percent of the world’s countries and territories exceed protein requirements.
The real deficiencies in the standard American diet? Nine in 10 Americans don’t eat enough vegetables, while a whopping 97 percent of us fail to meet daily recommendations for fiber—a nutrient that can help control weight, lower cholesterol, and even fight off cancer. A recent study published in The Journal of Gerontology even found that fiber may be the key to successful aging.
Considering the current epidemics of heart disease, type 2 diabetes, and obesity, we should stop counting grams of protein and start asking: Where do you get your fiber?
June 13, 2016 Dr. Neal Barnard ,
Iowa Sen. Joni Ernst introduced legislation this week to ban “Meatless Mondays” from the military. Sen. Ernst—who represents the No. 2 meat-producing state—says that “our men and women in uniform should have the option to consume the protein they need, including meat, on a daily basis.” But banning Meatless Mondays and promoting the protein myth is a disservice to service members, increasing their risk for obesity, diabetes, and early death.
The military has seen a 61 percent rise in obesity since 2002, according to the nonprofit Mission: Readiness. Protein from meat is one of the causes. A recent study found that people who ate large quantities of protein and a small amount of carbohydrates were almost twice as likely to gain more than 10 percent of their body weight and experienced a 59 percent increase in all-cause mortality during the study.
Of course, protein is an important nutrient required for the building, maintenance, and repair of tissues in the body. But replacing protein from animal products with a variety of grains, legumes, and vegetables can provide all of the essential amino acids our bodies require—without the risks associated with meat and dairy products.
In fact, switching from beef to beans can actually reduce diabetes risk. A recent study found that those who consumed the highest amount of animal protein increased their risk for type 2 diabetes by 13 percent, but found that participants who replaced 5 percent of their protein intake with vegetable protein, including potatoes, legumes, and grains, decreased their risk for diabetes by 23 percent.
Meatless meals can also mitigate the risk for early death. Another study found that people younger than 65 who ate the most animal protein had a 74 percent increased risk for death from any cause and a four-fold increase in death related to cancer. Risks for death were diminished or absent when protein sources were plant-derived.
If Sen. Joni Ernst really wanted what’s best for our military members, she’d mandate Meatless Mondays, instead of increasing their mortality risk with meat.
June 9, 2016 Dr. Neal Barnard ,
Our fight against obesity has become a war on sugar. Next week, Philadelphia’s city council will have a final vote to determine whether the city will become one of the first in the nation to adopt a soda tax. Meanwhile, tempers are flaring in Baltimore over a proposed bill that would require health warnings on advertisements for sugary beverages—a measure San Francisco is set to adopt next month.
When it comes to public health, these proposals are all a step in the right direction— there are no health benefits to drinking soda. But these regulations alone are not going to solve our ever-growing obesity epidemic.
Sugar has long taken the blame for our growing waistlines. But over the past two decades, sugar consumption has actually dropped by 14 percent, while sales of sugary, full-calorie sodas have dipped by 25 percent. Still, obesity rates continue to surge.
A study released this week in the Journal of the American Medical Association found that more Americans than ever are now obese. By the end of 2014, obesity prevalence stood at 35 percent for men and an all-time high 40 percent for women.
It’s time to stop blaming sugar. When it comes to weight problems, sugar-sweetened beverages and other sweets distract from the main culprits fueling obesity: our appetite for meat and cheese.
In 2012, Americans collectively consumed 52.2 billion pounds of meat. And every year, the average American individually eats about 270 pounds. Compared to just a century ago, that’s nearly 150 more pounds per person each year. At the same time, cheese consumption has soared from just four pounds per person in 1909 to 36 pounds today, making it the No. 1 source of saturated fat in Americans’ diets. In addition to fat, meat and cheese are loaded with cholesterol and packed with calories.
Epidemiological studies consistently show that populations who base their diets on fruits, vegetables, whole grains, and legumes are the healthiest and slimmest on the planet. Two major review studies released last year analyzed the diets of thousands of people and confirmed that vegetarian and vegan diets are best for weight control. Similarly, a 2015 clinical study found that participants assigned to completely meat-free diets lost more weight, compared with those following the pesco-vegetarian, semi-vegetarian, and omnivorous diets.
To truly turn the obesity epidemic around, we must move these high-fat foods from the center of our plates and start basing our diets on nutrient-dense plant-based foods.
June 8, 2016 Dr. Neal Barnard ,
It took five years. But Aaron Rodgers, who plays for the National Football League’s Green Bay Packers, finally got our message that Cheese Can Sack Your Health. In 2011, we posted this billboard near Lambeau Field in Green Bay, Wis., where the Packers play.
This week Rodgers told ESPN that he has followed “more of a vegan diet” since his knee surgery in January. He told ESPN: “Through your eating, you can reduce inflammation because if you do research, you learn the different foods you eat can actually increase the inflammation in your body and especially in certain parts of your body.” You can find out more about the dangers of cheese and how to break your addiction here.
To learn more about plant-based diets for athletes, join us for our International Conference on Nutrition in Medicine on July 29-30 in Washington, D.C., where ultraendurance athlete Rich Roll will present Nutrition to Power Athletic Performance.
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