Controversial study on red and processed meat is a 'disservice to the public,' experts say

A controversial study has leading experts up in arms after it hinted that eating less red and unprocessed meat does not improve one's health, according to CNN. 

The study, published on Monday in the American College of Physicians's journal Annals of Internal Medicine, suggests that "adults continue current unprocessed red meat consumption" as a "weak recommendation" based on "low-certainty evidence." Nutritional Recommendations (NutriRECs), an organization that proclaims itself "an independent group with clinical, nutritional and public health content expertise," produced the study but has since received backlash.

"Why would you make a 'weak' recommendation about eating red and processed meat?" asked Christopher Gardner, a nutrition scientist at Stanford School of Medicine. "I'm completely flabbergasted. I'm also really worried about how dangerous this is."

The study's authors claim that dietary guidelines set forth by the U.S. and U.K. governments, World Cancer Research Fund/American Institute for Cancer Research and the World Health Organization are all based on limited observational studies that do not detail the specific effects of consuming red or processed meat.

"The organizations that produce guidelines did not conduct or access rigorous systematic reviews of the evidence, were limited in addressing conflicts of interest, and did not explicitly address population values and preferences," the authors assert in their study. 

The NutriRECS researchers said their findings, on the other hand, are based on a methodology called GRADE, otherwise known as the Grading of Recommendations, Assessment, Development and Evaluation.The methodology is meant to reduce confusion that may arise from multiple grading systems when it comes to evaluating recommendations and evidence.

"On the basis of 4 systematic reviews assessing the harms and benefits associated with red meat and processed meat consumption and 1 systematic review assessing people's health-related values and preferences on meat consumption, we suggest that individuals continue their current consumption of both unprocessed red meat and processed meat," the researchers wrote.

Some experts, however, say NutriRECS didn't properly apply GRADE, claiming instead that the measurement should be used to assess randomized clinical trials and not lifestyle studies like the ones NutriRECS referred to.

"We can't randomize people to smoke, avoid physical exercise, breathe polluted air or eat a lot of sugar or red meat and then follow them for 40 years to see if they die," Gardner said. "But that doesn't mean you have no evidence. It just means you look at the evidence in a more sophisticated way."

Furthermore, research already shows a link between processed meats such as ham, bacon, sausage, and corned beef and colorectal cancer, Oxford University epidemiologist Tim Key told CNN. 

"There's substantial evidence that processed meat can cause bowel cancer — so much so that the World Health Organization has classified it as carcinogenic since 2015," he said. 

In fact, the American Cancer Society estimates that there will be 101,420 new cases of colon cancer and 44,180 new cases of rectal cancer in the U.S. this year, many of which will most likely be linked to meat consumption

"If the takeaway from this publication is 'red and processed meats are back,' that would be a disservice to the public," nutrition scientist Dr. Alice Lichtenstein, of the Cardiovascular Nutrition Laboratory at the Human Nutrition Research Center on Aging at Tufts University, said of NutriRECS's study.

RELATED: These eight foods and drinks can contribute to cancer: 

These eight foods and drinks can contribute to cancer
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These eight foods and drinks can contribute to cancer

1. Processed meat

The World Health Organization places processed meat in the same category as tobacco smoking and asbestos when it comes to carcinogenicity. Although the three groups are not considered equally dangerous, processed meat has been proven to cause colorectal cancer. Studies show that "every 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by about 18 [percent]," the U.N. agency notes.

Research has also found a connection between processed meat and stomach cancer, but the evidence is not conclusive. 

2. Salt-cured meat or fish

Salt-cured foods tend to have high levels of nitrates and nitrites, both of which react with amines and amides to form compounds that can lead to cancer, according to the National Cancer Institute

Moreover, research shows that "the more people eat of these foods the greater their chance of developing stomach cancer," Dr. Stephanie Fay wrote for World Cancer Research Fund International

3. Pickled foods

Much like salt-cured food, pickled foods contain a strong amount of nitrate and nitrate. A 2012 survey published by the American Association for Cancer Research revealed a direct correlation between the consumption of pickled vegetables and gastric cancer. Those of East Asian descent are particularly vulnerable to the disease since their diet heavily consists of pickled foods, the study said.  

4. Grilled food

Grilling food over an open flame creates heterocyclic amines and polycyclic aromatic hydrocarbons, two types of chemicals that can cause changes in the DNA, thereby increasing the risk of cancer, the National Cancer Institute points out. Researchers determined that high consumption of well-done, fried or barbecued meats led to increased risks of colorectal, pancreatic and prostate cancer. 

5. Microwave popcorn

Microwave popcorn contains a toxic compound called diacetyl, which can cause scarring of the tiny air sacs in the lungs and has been linked to lung cancer, Eitan Yefenof of the Hebrew University of Jerusalem told Reader's Digest.

The health threat actually comes from the popcorn bags, which contain chemicals that are suspected to cause cancer, according to Healthline. Those chemicals can also be found in pizza boxes, sandwich wrappers and Teflon pans. 

6. Alcohol

Heavy consumption of alcohol increases the risk of developing cancers of the oral cavity, pharynx, larynx, esophagus, liver, breast, colon and rectum, says the National Cancer Institute. The U.S. government's Dietary Guidelines for Americans 2015-2020 defines "heavy alcohol drinking" as "having 4 or more drinks on any day or 8 or more drinks per week for women and 5 or more drinks for men in one sitting (typically in about 2 hours)." Those who drink should do so in moderation (one drink per day for women and up to two drinks per day for men). 

7. Bagels

As mouth-watering as bagels are, they're also a health risk, particularly for non-Hispanic whites. Bagels have a high glycemic index, which means that they can significantly raise blood sugar levels. Elevated blood sugar levels trigger the secretion of insulin, which, in turn, can influence the risk of lung cancer, according to a 2016 study published by the American Association for Cancer Research

8. Soda

Drinking carbonated beverages heavily can exacerbate the symptoms associated with cancer, such as gas, bloating, heartburn or reflux, according to Stacy Kennedy, a senior clinical nutritionist at Dana-Farber Cancer Institute. 

In addition, many soft drinks contain high fructose corn syrup, which can contribute to weight gain and obesity. Obesity itself has been linked to 13 different types of cancer, including breast, esophageal and endometrial cancers. 


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