Does Meat Cause Cancer?

Tweet about this on TwitterPin on PinterestShare on LinkedInShare on Google+Share on FacebookBuffer this pageDigg thisEmail this to someoneFlattr the authorShare on StumbleUponShare on Reddit

According to a report released today, processed meat is carcinogenic (cancer causing – see the definition below for more detail). After considering more than 800 studies examining the association between meat and cancer, the World Health Organization’s International Agency for Research on Cancer (IARC) Working Group classified processed meats as Group 1, carcinogenic. They based this on convincing evidence from population based studies that eating processed meats causes colorectal cancer. Yet the results aren’t as crystal clear as they seem.

What is Red Meat and Processed Meat?

Red meat – unprocessed mammalian muscle meat – beef, pork, veal, lamb, mutton, horse or goat meat, including minced or frozen meat

Processed meat – meat that is transformed through salting, curing, fermenting, smoking or other processes to preserve the meat and enhance flavor. Processed meats can include other meats or meat byproducts such as blood. Hot dogs, sausages, corn beef, beef jerky and canned meat are all examples of processed meat.

Carcinogenic – compounds that are carcinogenic “do not cause cancer at all times, under all circumstances. Some may only cause cancer in people who have a certain genetic makeup. Some of these agents may lead to cancer after only a very small exposure, while others might require intense exposure over many years,” states the American Cancer Society.

What they Found

Processed Meat:
Though they considered 800 studies, their conclusions were drawn upon 18 cohort studies (this is when scientists follow a group of people that don’t have the disease – in this case cancer – over time to see who does and who doesn’t develop cancer). Twelve of the 18 studies reported positive associations between processed meat consumption and colorectal cancer. Six out of 9 case-control studies (where they look at the diet of people with cancer and compare it to the diet of people without cancer) reported a positive association and a meta-analysis (statistical approach to combining results from several studies) of 10 cohort studies reported a statistically significant dose-response relationship with an 18% increase in risk for every 50 gram (1.5 oz. or about the size of ½ of a deck of cards) of processed meat eaten daily. Yet Dr. Kurt Straif, Head of the IARC Monographs Programme stated “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.” Recent estimates suggest approximately 34,000 cancer deaths per year can be attributed to diets high in processed meats.

Red Meat:
The Working Group classified red meat as “probably carcinogenic to humans” while stating there is “limited evidence in human beings for the carcinogenicity of the consumption of red meat.” If those two statements sound like they contradict each other, here’s why:

The largest body of data they found was from 14 cohort studies (where they follow a group of people that don’t have the disease – in this case cancer – over time to see who does and who doesn’t develop cancer). Seven of the 14 studies showed higher consumption of red meat (as compared to lower consumption of red meat) was positively associated with colorectal cancer. Seven out of 15 case-control studies (where they look at the diet of people with cancer and compare that to the diet of people without cancer) found higher consumption of red meat was positively associated with colorectal cancer compared to lower intake of red meat. “No association was seen in  several high quality studies.” The author suggests that bias and confounding couldn’t be ruled out (other diet and lifestyle variables may have affected the results.

What Makes Processed Meat Carcinogenic?

When meat, fish, or poultry (chicken, turkey, ducks, geese) are cooked over high temperatures, chemical compounds that are known or suspected carcinogens (cancer causing) including N-nitroso-compounds (NOC), polycyclic aromatic hydrocarbons (PAH), advanced glycation end products (AGEs) and heterocyclic aromatic amines (HCA) are formed. High and dry heat including frying, grilling and barbecuing are the worst combination for the production of these chemicals. The 2-page report mentions some of these compounds as “mechanistic evidence” supporting their conclusions while also stating that we don’t know how cancer risk is increased by processed and red meat. (The full report won’t come out for several months).

N-nitroso-compounds (NOC) are found in nitrate-cured meats, smoked foods (fish or meat), malt in beer and whiskey production, pickled vegetables and foods stored under humidity leading to fungi that generate nitrosamines.

Polycyclic aromatic hydrocarbons (PAH) are formed when fat and juices from meat grilled over an open flame drip onto the fire, resulting in flames, and PAHs adhering to the surface of the meat. Smoking meats also leads to the formation of PAHs. PAHs are also found in air pollution.

Advanced glycation end products (AGEs) are harmful compounds formed during dry heat cooking. Though many foods contain AGEs, meats fried or cooked over dry heat have significantly more AGEs than any other food. AGEs accumulate in the human body, affect cell functioning and may contribute to insulin resistance, type 2 diabetes and, as the name implies, aging.

Heterocyclic aromatic amines (HCA) are formed when amino acids, sugars and creatine react at high temperatures. When meat, fish, pork and poultry are cooked at higher temperatures for a longer period of time, more HCAs are formed.

HCAs and PAHs must be metabolized by specific enzymes (a process called bioactivation) before they can damage DNA. Yet the activity of these enzymes varies between people and therefore, one’s risk of developing cancer due to HCA and PAH exposure depends on how they metabolize these compounds.

What this Report Does Not Tell Us

IARC Working Groups examine if exposure to a specific food or compound could cause cancer but does not tell us how likely we are to get cancer. Also, there are many known human carcinogens (UV light – including the UV light in those LEDs lights used to set gel nails, alcohol, the mineral oil you use on wood cutting boards and more) – some many cause cancer after little exposure while others take a lifetime of exposure. Many factors influence the development of cancer including age, gender, family history, and other lifestyle factors (tobacco and alcohol use, weight, diet, physical activity).

How Much Processed & Red Meat is Too Much?

Cancer is a complex disease and no single food causes, cures or prevents cancer. However, as stated by the American Institute for Cancer Research (AICR):

  • A modest amount of red meat does not raise colorectal cancer risk.
  • Eating more than 18 ounces of cooked red meat per week increases the risk of  colorectal cancer.
  • Eating small amounts of processed meat regularly increases risk (of colorectal cancer).

AICR recommends avoiding processed meats and eating no more than 18 ounces of red meat per week (3 oz. = about the amount in a deck of cards). I also suggest making potentially better choices (see the infographic below and the 2nd to last paragraph of this blog post). What about HCAs, PAHs and other compounds? Here’s how you can decrease your intake of these compounds:

cooking meat
Where does meat processed without nitrates fit in? We don’t know. If they are processed without nitrates then they should  presumably contain few to no NOCs making them a better choice than meats processed with nitrates. However, I couldn’t find a single study comparing the compounds in meats produced without nitrates to their counterparts produced with nitrates.

If you aren’t preparing your food at home, take a close look at how it was prepared and cooked so you can minimize your intake of these compounds. If you don’t plan on cutting out processed meats, at the very least, limit your intake of sausage, ham, bacon, hot dogs, pepperoni, pastrami, bologna, corned beef, deli/luncheon meats, salami, nitrite-treated meat or meat products as well as meat preserved by smoking, curing or salting, all of which could increase your risk of cancer.

Disclosures: None, I have no connection to any red meat commodity boards, stock in red or processed meat companies (though I should look up the shorts or consider buying on a dip) or emotional connection to cows, pigs, horses, red or processed meats 🙂

References:
National Cancer Institute. 
American Institute for Cancer Research
Medline Plus.
Nutr Cancer 2008;60(2):131–144.
J Food Sci 2008;73(6):T100-5.
Cancer Sci 2010;101(2):508-16.
Cancer Epidemiol Biomarkers Prev 2012;21(6):905-15.
Int J Cancer 2014;134(1):125-35.
J Am Diet Assoc 2010;110(6):911-16.
Curr Diab Rep 2014;14(1):453.
Ann N Y Acad Sci 2005;1043:533-44.

Why “Avoid Processed Foods” is Bad Advice

Tweet about this on TwitterPin on PinterestShare on LinkedInShare on Google+Share on FacebookBuffer this pageDigg thisEmail this to someoneFlattr the authorShare on StumbleUponShare on Reddit

Countless internet blogs preach about the dangers of processed food, how eating a diet with processed food will make you gain weight and your health will suffer. Yet anyone who writes this nonsense doesn’t understand the real definition of processed foods (and I bet large sums of money they eat many processed foods) and the benefits they provide.

A processed food is “any food other than a raw agricultural commodity (“food that is in its raw or natural state, including all fruits that are washed, colored, or otherwise treated in their unpeeled natural form prior to marketing”) and includes any raw agricultural commodity that has been subject to processing, such as canning, cooking, freezing, dehydration, or milling (1, 2).” Fruits, vegetables, beans, legumes, livestock – these are all agricultural commodities. And therefore, all of the following are processed foods: frozen broccoli, frozen chicken breast, dried beans, dried pumpkins seeds. Who in their right mind would dare say any of these foods are harmful or will make you pack on the pounds? Someone who has no clue what they are talking about. Not to mention there are many reasons why processed food are healthy:

Versatility

If you want to get a wide array of nutrients and healthy plant compounds (such as antioxidants) you should eat a wide variety of foods. If you take all processed foods out of your diet you’ll only eat what is in season and hasn’t been altered.

Value

Dried beans, oatmeal and rice are processed foods that are very affordable. All cost pennies per serving (about 15 cents for a serving of brown rice). Canned and frozen fruits and vegetables are another great example of affordable foods that are picked at their peak of ripeness, preserving nutrition value and flavor. In addition, 100% juice is a bargain, thanks to food processing.

Concord Grapes
Concord Grapes
Welch's 100% Grape Juice made with Concord Grapes
Welch’s 100% Grape Juice made with Concord Grapes

A few weeks ago I had the opportunity to see a Concord grape farm – where they grow and   process the grapes into Welch’s 100% Grape Juice made from Concord Grapes. Nothing is wasted during this process. The Concord grapes are crushed – skin, seeds and all (so more of the grape is in the bottle) – and heated to release healthy polyphenols (plant based compounds) straight from the grape into the juice. In fact, 40 whole Concord grapes are in every 8 oz. serving of Welch’s 100% Grape Juice made from Concord Grapes. This is important because over a decade of research indicates that, thanks to the Concord grape, 100% grape juice made from these grapes helps support a healthy heart. Because the Concord grape harvest season is very short, lasting approximately 12 weeks, juice processing delivers the benefits of Concord grapes to us year round.

I consider all of these processed foods a good nutrition bargain. Plus, you may end up with less food waste, thanks to a longer shelf life, if you buy canned and frozen produce and poultry as well as 100% juice.

Convenience

In between long days and traveling, there are days I like meals that take me 5 minutes or less to throw together (not to mention if I’m hungry I want to eat asap). Frozen and canned foods allow me to do this. Steamed vegetables? They take about 7 minutes in my stovetop steamer. Canned? Less than 1 minute to open the can (because sometimes I don’t even heat them up). Frozen chicken breast? Perfect, I don’t have to go by the grocery store late at night if there is nothing in my fridge.

So the next time you hear someone say you should eat fewer processed foods, ask them to define “processed food.” And if you read it in a blog, move on to nutrition advice grounded in science.

Disclosure: I am an advisory board member of family-farmer owned Welch’s.

1) 21 U.S.C. United States Code, 2010 Edition, Title 21 – Food and Drugs. Chapter 9 – Federal Food, Drug, and Cosmetic Act, Subchapter II – Definitions.

2) SEC. 201. [21 U.S.C. 321]. CHAPTER II—DEFINITIONS 1.

Is Organic Food Better for You (nutrition, fewer pesticides)?

Tweet about this on TwitterPin on PinterestShare on LinkedInShare on Google+Share on FacebookBuffer this pageDigg thisEmail this to someoneFlattr the authorShare on StumbleUponShare on Reddit

If you saw the recent press about organic food (MSNBC’s headline: “Organic food no more nutritious than non-organic”), you may be left wondering if conventional is best after all. But,  you’ll want to take a close look at this debate before making up your mind. A recent review of the published research on organic and non-organic foods (including veggies, fruit, meat, poultry, eggs and milk), out of Stanford University and published in the Annals of Internal Medicine, found that organic options may not vary from their conventional counterparts when it comes to nutrition. However, they found consuming organic may lower your exposure to pesticides (though your risk for exceeding allowed government limits, even in conventional foods, is small). E coli contamination risk didn’t differ between organic or conventional chicken and bacterial contamination of chicken and pork was common regardless of farming method (organic or conventional). However, they found the risk of picking up antibiotic-resistant bacteria in your pork or chicken was higher if you chose the conventional kind vs. organic. And finally, some studies didn’t define the criteria they used to determine what foods qualified as organic (strange! – check this link for more about organic labeling).

Two more things to keep in mind. “Natural” does not mean organic. And, organic does not always mean pesticide and chemical free. It means the food is free from synthetic pesticides and fertilizers. Organic farmers can use pesticides derived from natural sources. If you really want to become an informed consumer, you’ll go straight to the source on organic farming. And if you want to know what’s in your food, buy local and ask the farmer what they use to keep the pests away or better yet, get out there and start planting your own garden.

Here’s my bottom line on organics:

  • It’s a personal choice
  • Eat more fruits and vegetables, regardless of whether or not they are organic
  • Wash your produce regardless of whether it is organic or conventional (do you know how many unclean hands may have touched that piece of fruit?)
  • If it comes down to price, choose better quality food overall – weigh the nutrition value of the food, your feelings on pesticides and how far you need to stretch your food dollar

If you have a strong opinion on this subject, leave a comment and let me know!