Cutting Out Bacon, Sausage and Hot Dogs May Reduce Risk of Breast Cancer Interview with:
"bacon&eggs" by ilaria is licensed under CC BY 2.0
Maryam Farvid, Ph.D., Research Scientist  

Department of Nutrition
Harvard T.H. Chan School of Public Health
Boston, MA 02115 What is the background for this study? What are the main findings?

Response: Prior prospective studies on red and processed meat consumption with risk of breast cancer have produced inconsistent results.

Current meta-analysis of 15 prospective studies shows that women who eat a high amount of processed meat each day may have a higher risk of breast cancer than those who don’t eat or have a low intake in their diet.  Continue reading

Does Red Meat Really Increase Risk of Heart Disease? Interview with:

Wayne W. Campbell PhD Center on Aging and the Life Course Purdue University

Dr. Wayne Campbell

Wayne W. Campbell PhD
Center on Aging and the Life Course
Purdue University What is the background for this study?

Response: Organizations that promote healthy eating often recommend consuming no more than 3.5-4.5 2-3 ounce servings of red meat per week. This recommendation is mainly based on data from epidemiological studies that observe a cohort of peoples’ eating habits over time and relate those habits to whether or not they experience a cardiovascular event, such as a heart attack or stroke, or cardiovascular-related death.

These studies show associations between dietary choices and health but are unable to determine if a dietary choice is actually causing the disease. Randomized controlled clinical trials are able to determine causality by isolating one dietary variable to see the effects of that variable on certain health risk factors. Therefore, our lab compiled data from randomized controlled trials assessing the consumption of ≤ vs >3.5 servings of total red meat per week on blood lipids and lipoproteins and blood pressures, since these are common measures taken by clinicians to determine the risk for developing cardiovascular disease.

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Study Links Red Meat To Inflammation and Tumor Formation Interview with:
Annie Samraj and  Ajit Varki MDDr. Annie Samraj MD
Postdoc Fellow
Varki Lab and

Ajit VAjit Varki MD Distinguished Professor of Medicine and Cellular & Molecular Medicine Co-Director, Center for Academic Research and Training in Anthropogeny (CARTA) Co-Director, Glycobiology Research and Training Center (GRTC)  University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0687.arki MD
Distinguished Professor of Medicine and Cellular & Molecular Medicine , Co-Director, Center for Academic Research and Training in Anthropogeny, Co-Director, Glycobiology Research and Training Center
University of California, San Diego, La Jolla, CA

Medical Research: What is the background for this study? What are the main findings?

Dr. Varki: For the past decade, there has been increasing evidence that people who consume red meat (beef, pork, lamb) are at a higher risk for certain kinds of cancers. Although red meat is a high quality source of protein, iron and vitamins, too much consumption may be harmful to humans. While there are other hypotheses under consideration, we focused on a non-human sugar molecule called Neu5Gc in red meat that could explain the link to cancer risk.

We extensively studied various foods and concluded that red meat (particularly beef) is rich in Neu5Gc. In contrast poultry, fish steaks and hen eggs have little or no Neu5Gc. From previous studies, we knew that animal-derived Neu5Gc could be incorporated into human tissues. In this study, we hypothesized that eating red meat could lead to inflammation if the body’s immune system targets the foreign Neu5Gc. Chronic inflammation is also known to instigate or promote tumor progression.

To test this hypothesis, we used mice engineered to be similar to humans in that they lacked Neu5Gc, and also produced antibodies against it. When these mice were fed Neu5Gc, they developed systemic inflammation. Tumor formation increased fivefold and Neu5Gc accumulated in the tumors, proving the hypothesis. None of the various control groups of mice showed this effect.

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Only Processed Red Meat Linked to Shorter Survival

Andrea Bellavia From the Unit of Nutritional Epidemiology and the Unit of Biostatistics Institute of Environmental Medicine Karolinska Institutet, Stockholm, Interview with:
Andrea Bellavia
From the Unit of Nutritional Epidemiology and the Unit of Biostatistics
Institute of Environmental Medicine
Karolinska Institutet, Stockholm, Sweden

Medical Research: What are the main findings of the study?

Dr. Bellavia: By evaluating together the consumption of processed and fresh red meat, we observed that processed red meat consumption was associated with shorter life, implying a potential negative effect on health. On the other hand, consumption of only fresh red meat was not associated with either shorter or longer survival. Therefore, the main finding of this work is that the negative effects of red meat consumption might only be due to meat processing, which counteract the positive effects of the beneficial nutrients of meat.
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Processesed Red Meat Linked To Higher Risk Of Heart Failure Interview with:
Dr inz. Joanna Kaluza
Department of Human Nutrition
Warsaw University of Life Sciences – SGGW

Medical Research: What are the main findings of the study?

Response: The most important finding of my study is the fact that processed red meat consumption, but not unprocessed red meat, increases a risk of Heart Failure incidence and Heart Failure mortality.

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Breast Cancer: Study Finds Red Meat May Increase Risk Interview with Dr. Maryam Farvid MSc, Ph.D. Takemi fellow, and Associate Interview with
Dr. Maryam Farvid MSc, Ph.D.
Takemi fellow, and Associate Arofessor

Senior author: Prof Walter Willett
Department of Nutrition, Harvard School of Public Health,
Boston, MA,

MedicalResearch: What are the main findings of the study?

Dr. Farvid: Compared to women who had one serving per week red meat, those who consumed 1.5 serving per day red meat had a 22 percent higher risk of breast cancer. Red meat intake is associated with breast cancer risk in a dose-response manner. Each additional serving/day increase in total red meat was associated with a 13% increase in risk of breast cancer. Furthermore, each additional serving/day of poultry was associated with a 25% lower risk of postmenopausal breast cancer. Substituting one serving/day of legumes for one serving/day of red meat was associated with a 15% lower risk of breast cancer, substituting one serving/day of poultry for one serving/day of red meat was associated with a 17% lower risk of breast cancer overall, and substituting one serving/day of combined legumes, nuts, poultry, and fish for one serving/day of red meat was associated with a 14% lower risk of breast cancer.

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Limiting Red Meat May Reduce Diabetes Risk An Pan, PhD

Research Associate, Dept Nutrition
655 Huntington Avenue Building 2, Room 351
Boston, Massachusetts 02115

Changes in Red Meat Consumption and Subsequent Risk of Type 2 Diabetes Mellitus: Three Cohorts of US Men and Women What are the main findings of the study?


— Compared with people who did not change their intake of red meat, those who increased it by as little as half a serving a day (about 1.5 ounces) over a four-year period had a 48% increased risk of developing type 2 diabetes in the subsequent 4 years.

— People who decreased their intake by half a serving a day over four years did not have an acute reduced risk in the next four years compared to people who did not change their intake, but had a reduced risk of developing the disease by 14% in the entire follow-up period, suggesting a prolonged effect.

— The findings included both processed meat such as lunch meat and hot dogs and unprocessed meats such as hamburger, steak and pork. And the association was generally stronger for processed red meat compared to unprocessed red meat.

— Adjusting for weight modestly reduced the association between red meat consumption and diabetes suggesting that weight gain played a role in the development of the disease.

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Consumption of red processed meat may increase risk of type 2 diabetes

Boston, MA – A new study by Harvard School of Public Health (HSPH) researchers finds a strong association between the consumption of red meat—particularly when the meat is processed—and an increased risk of type 2 diabetes. The study also shows that replacing red meat with healthier proteins, such as low-fat dairy, nuts, or whole grains, can significantly lower the risk.

The study, led by An Pan, research fellow in the HSPH Department of Nutrition, will be published online in the American Journal of Clinical Nutrition on August 10, 2011 and will appear in the October print edition.

Pan, senior author Frank Hu, professor of nutrition and epidemiology at HSPH, and colleagues analyzed questionnaire responses from 37,083 men followed for 20 years in the Health Professionals Follow-Up Study; 79,570 women followed for 28 years in the Nurses’ Health Study I; and 87,504 women followed for 14 years in the Nurses’ Health Study II. They also conducted an updated meta-analysis, combining data from their new study with data from existing studies that included a total of 442,101 participants, 28,228 of whom developed type 2 diabetes during the study. After adjusting for age, body mass index (BMI), and other lifestyle and dietary risk factors, the researchers found that a daily 100-gram serving of unprocessed red meat (about the size of a deck of cards) was associated with a 19% increased risk of type 2 diabetes. They also found that one daily serving of half that quantity of processed meat—50 grams (for example, one hot dog or sausage or two slices of bacon)—was associated with a 51% increased risk.

“Clearly, the results from this study have huge public health implications given the rising type 2 diabetes epidemic and increasing consumption of red meats worldwide,” said Hu. “The good news is that such troubling risk factors can be offset by swapping red meat for a healthier protein.”

The researchers found that, for an individual who eats one daily serving of red meat, substituting one serving of nuts per day was associated with a 21% lower risk of type 2 diabetes; substituting low-fat dairy, a 17% lower risk; and substituting whole grains, a 23% lower risk.

Based on these results, the researchers advise that consumption of processed red meat—like hot dogs, bacon, sausage, and deli meats, which generally have high levels of sodium and nitrites—should be minimized and unprocessed red meat should be reduced. If possible, they add, red meat should be replaced with healthier choices, such as nuts, whole grains, low-fat dairy products, fish, or beans.

Worldwide, diabetes has reached epidemic levels, affecting nearly 350 million adults. In the U.S. alone, more than 11% of adults over age 20—25.6 million people—have the disease, according to the Centers for Disease Control and Prevention. Most have type 2 diabetes, which is primarily linked to obesity, physical inactivity, and an unhealthy diet.

Previous studies have indicated that eating processed red meats increases the risk of developing type 2 diabetes. Risks from unprocessed meats have been less clear. For instance, in 2010, HSPH researchers found no clear evidence of an association between eating unprocessed meats and increased risk for either coronary heart disease or type 2 diabetes, but that study was based on smaller samples than the current study, and the researchers recommended further study of unprocessed meats. Another HSPH study in 2010 linked eating red meat with an increased risk of heart disease—which is strongly linked to diabetes—but did not distinguish between processed and unprocessed red meats.

This new study—the largest of its kind in terms of sample size and follow-up years—finds that both unprocessed and processed meats pose a type 2 diabetes risk, thus helping to clarify the issue. In addition, this study is among the first to estimate the risk reduction associated with substituting healthier protein choices for red meat.

“Our study clearly shows that eating both unprocessed and processed red meat—particularly processed—is associated with an increased risk of type 2 diabetes,” said Pan. He noted that the 2010 U.S. dietary guidelines continue to lump red meat together with fish, poultry, eggs, nuts, seeds, beans, and soy products in the “protein foods” group. But since red meat appears to have significant negative health effects—increased risk of diabetes, cardiovascular disease, and even total mortality, as suggested by several recent studies—Pan suggested the guidelines should distinguish red meat from healthier protein sources and promote the latter instead.


Support for the study was provided by the National Institutes of Health’s National Institute of Diabetes and Digestive and Kidney Diseases and the National Heart, Lung, and Blood Institute.

“Red Meat Consumption and Risk of Type 2 Diabetes: 3 Cohorts of U.S. Adults and an Updated Meta-Analysis,” An Pan, Qi Sun, Adam M. Bernstein, Matthias B. Schulze, JoAnn E. Manson, Walter C. Willett, and Frank B. Hu, American Journal of Clinical Nutrition, online August 10, 2011.