Does Red Meat Give You Colon Cancer?

Have you heard? There’s a new “red meat will kill you” study. This time, it’s colorectal cancer.

Here’s the press release.

Here’s the full study.

I covered this a couple Sundays ago in “Sunday with Sisson.” If you haven’t signed up for that, I’d recommend it. SWS is where I delve into my habits, practices, and observations, health-related and health-unrelated—stuff you won’t find on the blog. Anyway, I thought I’d expand on my response to that study here today.

How the Study Was Conducted

It’s the basic story you see with most of these observational studies. Around 175,000 or so people were asked to recall what they ate on a regular basis—a food frequency questionnaire. This is the exact questionnaire, in fact. The research team took the answers, measured some baseline characteristics of all the subjects—socioeconomic status, exercise levels, whether they smoked, education level, occupation, family history of colorectal cancer, and a few others—and then followed up with participants an average of 5.7 years later to see how many had developed colorectal cancer.

What the Study “Showed”

Those who had moderate amounts of red meat had a 20% higher chance of getting cancer.

And in the end, the increased risk was a relative risk. It wasn’t a 20% absolute increase in risk. It was a relative increase in risk. The subjects started with a 0.5% risk of getting bowel cancer. In those who ate the most processed meat and red meat, that risk increased 20%—to 0.6%!

From 0.5 to 0.6%. Sure, that’s an increase, but is it something to overhaul your entire diet for? To give up the best sources of zinc, iron, B vitamins, protein, carnosine, creatine? All that for a measly 0.1% that hasn’t even been established as causal?

Study Findings Most News Outlets Won’t Include

One head scratcher that leaps out: the link between unprocessed red meat and colon cancer was not actually statistically significant. Only processed meat was significantly linked to colon cancer.

Another head scratcher: red meat, whether processed or unprocessed, had no significant association with colorectal cancer in women. Why didn’t they highlight the fact that in women, eating red meat was completely unrelated? That’s half the world’s population. That’s you or your mom, your daughter, your grandmother, your girlfriend. And unless they were to look at the full study and read the fine print, they’d never know that red meat actually had the opposite relationship. You’d think the authors would want to mention that in the abstract or see that the press releases and media treatments highlighted that fact.

It’s probably because mentioning that red meat was neutral in women and had no statistically significant link to colon cancer in men and women would have destroyed their case for red meat as an independent carcinogen. See, carcinogens are supposed to be carcinogens. There are many meaningful differences between men and women, but a poison is a poison.

What’s the proposed mechanism for red meat triggering colon cancer in men but not in women? If they didn’t have one (and I imagine they wouldn’t have mentioned it if they did), then there’s probably something else going on.

Besides, the literature is far from unequivocal.

What Other Research Says About Red Meat and Bowel Cancer

In analyses that include consideration of cooking methods and other mitigating factors, red meat has no relationship with colon cancer.

Or what about this study, where colon cancer patients were more likely to eat red meat, but less likely to have type 2 diabetes? Should people avoid red meat and work toward getting diagnosed with type 2 diabetes?

Or how about this study, which found no difference in colorectal cancer rates between people who ate red meat-free diets and people who ate diets containing red meat? Shouldn’t the diet without any red meat at all have some effect?

Or this classic study, where rats on a bacon-based diet had the lowest rates of colon cancer. In fact, bacon protected them from colon cancer after they were dosed with a colon cancer promoter, while rats on normal “healthy” chow were not.

The Blind Spot In Red Meat Research

I don’t need to go into all the confounding factors that might predispose conventional red meat lovers to bowel cancer. Nor will I mention that it’s impossible to fully control for variables like the buns and bread and fries you eat the red meat with and the industrial seed oils it’s cooked in.

That last bit is crucial: the seed oils. It’s what nearly every cancer researcher misses. It’s not just a minor variable; it’s quite possibly the most important determinant of whether meat is carcinogenic in the colon or not. Heme iron—the compound unique to red meat that usually gets the blame for any increase in cancer—is most carcinogenic in the presence of the omega-6 fatty acid linoleic acid.

In one study, feeding heme iron to rats promoted colon cancer only when fed alongside high-linoleic acid safflower oil. Feeding MUFA-rich and far more oxidatively-stable olive oil alongside the heme prevented the colon carcinogenesis.

Another study had similar results, finding that meats containing medium to high amounts of heme—beef and beef blood sausage—promoted carcinogenic conditions in the colon when the fat sources were linoleic acid-rich corn and soybean oil.

And most recently is this paper. Mice were split into three groups. One group got heme iron plus omega-6 PUFA (from safflower oil). One group got heme iron plus omega-3 PUFA (from fish oil). The third group got heme iron plus saturated fat (from fully hydrogenated coconut oil, which contains zero PUFA). To determine the carcinogenicity of each feeding regimen, the researchers analyzed the effect the animals’ fecal water (which is exactly what it sounds like) had on colon cells. The fecal water of both PUFA groups was full of carcinogenic indicators and lipid oxidation byproducts, and exposing colonic epithelial cells to fecal water from PUFA-fed mice was toxic. The coconut oil-derived fecal water had no markers of toxicity or lipid oxidation.

I never see these (animal) studies cited in observational studies of meat and colon cancer. I think that’s a huge blindspot, and it’s one of the reasons I rarely put any stock in these scary-sounding studies.

That’s it for today, folks. Thanks for reading. Now go enjoy a steak.

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References:

Bylsma LC, Alexander DD. A review and meta-analysis of prospective studies of red and processed meat, meat cooking methods, heme iron, heterocyclic amines and prostate cancer. Nutr J. 2015;14:125.

Alsheridah N, Akhtar S. Diet, obesity and colorectal carcinoma risk: results from a national cancer registry-based middle-eastern study. BMC Cancer. 2018;18(1):1227.

Rada-fernandez de jauregui D, Evans CEL, Jones P, Greenwood DC, Hancock N, Cade JE. Common dietary patterns and risk of cancers of the colon and rectum: Analysis from the United Kingdom Women’s Cohort Study (UKWCS). Int J Cancer. 2018;143(4):773-781.

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Weekly Link Love — Edition 26


Research of the Week

Scientists generate speech from brain recordings.

In the U.S., sedentary behavior has remained stable or gotten more prevalent.

Visualizing coffee might be enough (not buying this one).

Pigs who eat chicken generate more lipid oxidation products than pigs who eat beef.

When we sleep, our brain distinguishes between important and unimportant sounds.

Thinking of your future self as similar to your present self produces better outcomes.

20 minutes of nature is enough.

New Primal Blueprint Podcasts

Episode 330: Gary E. Foresman, MD: Host Elle Russ chats with Dr. Foresman about heart disease, statins, and more.

Episode 331: Brad Kearns and Brian McAndrew Talk Carnivore and Balance: Host Brad Kearns chats with Primal video whiz Brian McAndrew about carnivory and balancing being strict with being happy.

Health Coach Radio Episode 9: Lauren Schwab: Lauren has mastered the art of the wellness retreat, not an easy task.

Each week, select Mark’s Daily Apple blog posts are prepared as Primal Blueprint Podcasts. Need to catch up on reading, but don’t have the time? Prefer to listen to articles while on the go? Check out the new blog post podcasts below, and subscribe to the Primal Blueprint Podcast here so you never miss an episode.

Media, Schmedia

First they came for the hot dogs and bologna, and I was silent….

Salt limits get even lower.

Interesting Blog Posts

How a knee bone that almost disappeared is coming back.

A novel tactic for getting teens to spurn junk food.

Lowering cholesterol with psyllium at every meal: one experience.

Hilarious.

Social Notes

If you’ve had success with the Primal Blueprint, Keto Reset, or any of the advice offered on this site, send in your success story. All submissions will receive a discount code for use on Primal Blueprint or Primal Kitchen.

Got named one of Healthline’s “Best Men’s Health Blogs.”

I hope this guy follows me.

Everything Else

If you’re not eating whole rattlesnakes, you can’t call yourself paleo.

Human composting up for a vote in Washington state.

A man’s beer-only fast for Lent ends up working out.

“The sudden passionate happiness which the natural world can occasionally trigger in us,” Michael McCarthy writes, “may well be the most serious business of all.”

“So I had a piece of salmon and my brain felt like a computer rebooting.”

Things I’m Up to and Interested In

This is awkward: Using CRISPR to edit DNA also causes off-target RNA alterations.

Article I found interesting: Neuronal life after death.

Video I enjoyed: 3 pro soccer players vs 100 kids.

I’m not surprised: Wildlife-friendly agriculture increases yield.

Why everyone needs to lift: Having muscle protects against progression from healthy to metabolically unhealthy.

Question I’m Asking

What’s the best book you’ve read in the past year?

Another Question I’m Curious About

What would you do with a bunch of extra arugula?

Recipe Corner

Time Capsule

One year ago (Apr 21– Apr 27)

Comment of the Week

“I don’t think we should be drinking teas grown in ‘Shady Conditions’…
all kidding aside, magnesium works well for me until about after 5pm, and then it wires me up and I can’t sleep.”

– You haven’t had tea grown in places with gunshots going off, discarded syringes littering the ground, and human fecal matter smeared everywhere? It’s the best, nocona!

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Dear Mark: What Breaks a Fast Followup

For today’s edition of Dear Mark, I’m answering a round of questions drawn from the comment section of the “What Breaks a Fast” post. You folks had tons of follow-up questions about whether other types of foods or compounds break a fast. Does a teaspoon of honey? Does elevated insulin from BCAAs? Does coconut milk? Does pure prebiotic fiber? What about longer fasts—are they recommended? And how about unsweetened cocoa powder? What explains my ability to predict your questions? Do sausages break a fast? Does liquor? How should you exercise?

Let’s dig right in:

Hey, what about honey? 1 tsp in morning tea?

A teaspoon or less of honey is fine and won’t negate the benefits of fasting. I alternate between doing collagen coffee and coffee with cream and teaspoon of sugar (which was my typical morning coffee for over a decade). No reasonable person should fear a teaspoon of sugar or honey.

For what it’s worth, honey isn’t “just” sugar. It elicits a more beneficial (or less negative) metabolic response than other forms of sugar.

I’m shocked about the BCAA. I used to fast and take BCAA’s (yes, to continue dynamic exercise). I used to find it extremely difficult to fast compared to now when I fast without taking them. Does that mean that the insulin response made fastic more difficult?

It’s possible. Insulin impairs lipolysis—the release of stored body fat into circulation for energy usage—and the success of fasting depends on lipolysis. Without lipolysis, you can’t access all that stored energy.

Thank you very much for this info!! I am a butter-coffee-for-breakfast drinker, and I always worry about the ingredients breaking a fast. Could you please comment on coconut milk (in the can)? I love putting that in my coffee/breakfast.
Thanks.

Coconut milk is a less concentrated source of medium chain triglycerides, or MCTs (as in MCT oil). MCTs convert directly to ketones, making MCT oil and to a lesser extent coconut oil or coconut milk a potential “boost” for fasting. Still, energy is energy, and any energy you take in is energy you won’t be pulling from your body.

I find MCTs and coconut to be more useful when someone is just getting the hang of fasting or ketosis—as a nice boost to get things moving in the right direction.

Keep your coconut milk under a tablespoon and you’ll be fine.

Does prebiotic (resistant starch) fiber break a fast? Acacia senegal or potato starch? Thanks!

No. If you’re worried, test your postprandial blood sugar after eating the fiber.

Great input Mark as someone 3days into a 7day water fast with electrolytes of course what’s your view on longer fasts.

Check out the post I wrote on long fasts. Potentially beneficial but the risks accumulate the longer you go. You just have to be even more careful and methodical.

How about unsweetened cocoa?

A tablespoon runs just over 12 calories (depending on the brand; some cocoa powders contain more fat and thus more calories), with around a gram of net carbs and a gram of fat. Also a nice source of potassium and magnesium, along with a ton of polyphenols which can have fasting-mimicking effects on their own.

Eating enough unsweetened cocoa powder to knock you out of your fast would be incredibly repulsive. Probably impossible.

Cocoa is definitely a nice addition.

Okay it’s almost creepy the way Sisson answers my questions before I even ask them! I was wondering about this yesterday and then this post popped up in my inbox.

How does he do that…? ?

Kraft-Heinz has a strong relationship with Google and Amazon, and the Kraft acquisition gave me access to Alexa/Google Home datasets and the ability to predict what my readers are wondering about.

Just kidding, though it’s scarily not out of the realm of possibility anymore.

What about a small snack of paleo sausages, smoked or dried? So meat and fat (beef, pork or lamb), and some spices. Maybe 100g worth.

Well, that’s a legit snack bordering on a small meal. That will break the fast, but it’s not all for naught. There is the whole “fasting-mimicking diet,” where you eating very few calories for several days out of the week and retain many if not most of the benefits of full-on fasting.

Let’s just say if you ate a small snack of paleo sausages on your “fasting” days, you’d still be way ahead of 99% of people.

But do try a full-on fast at least once. You might surprise yourself.

Great post! What about alcohol? Specifically, a shot or 2 of liquor. I would assume beer and wine would break a fast, but what about whiskey or tequila?

When alcohol enters the system, utilization of all other energy sources is suspended until the alcohol is burned. Back in 1999, researchers did a study where they gave fasting adult men the equivalent of a couple shots of liquor. They stopped releasing stored body fat, stopped burning body fat, and began burning way more acetate (a product of ethanol metabolism). They didn’t exactly “break” the fast, but all the metabolic trajectories we love about fasting took a big pause.

Good morning Mark,
How does one exercise in the morning while fasting? When to eat?

You can exercise any way you like, but I change how I train based on when I’m going to break the fast with food.

If I’m going to break the fast with a meal right after, I train any way I like. I’ll do sprints, HIIT, weights, anything.

If I’m going to keep fasting after the workout, I like to stick to strength training and low-intensity movement (walking, hiking, standup paddling). The strength training is essential during a fast because it’s an anabolic signal to your muscles—move it or lose it. Simply lifting heavy things during a fast can stave off muscle loss.

That’s it for today, folks. Stay tuned later this week for “What Breaks a Fast: Supplements Edition.”

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19 Keto Soups

Thanks to the good folks at Paleohacks for today’s recipe.

There’s nothing quite like cozying up on the couch with a warm bowl of rich and hearty soup. Unfortunately, hearty soup recipes often rely on high-carb ingredients like potatoes, rice, and noodles to achieve comfort food status.

Luckily, we know tons of Paleo-friendly soup recipes that fuel your body and nourish your belly – all while keeping you in ketosis. Think fat bomb hamburger soup loaded with veggies and beef, or a velvety, dairy-free celeriac soup with chorizo, sage crisps and walnuts. If you’re craving takeout, there’s keto-friendly hot and sour soup, or if you need something that takes hardly any effort, we have a go-to chipotle chicken soup you can make right in a slow cooker. Whatever you crave, there’s a healthy soup to enjoy this fall. Check out these 23 keto-friendly snacks to keep you going between meals.

This low-carb hamburger soup is loaded with healthy fats to keep your body in ketosis, thanks to the addition of buttery organic red palm oil.

Celeriac, also known as celery root, is a hearty root vegetable ideal for a smooth, creamy soup. In fact, it’s the perfect replacement for high-carb potatoes!

Craving creamy beef stroganoff without the carbs? Try this soup! It’s chock-full of umami steak and mushrooms, made velvety smooth with silky coconut cream.

Skip the takeout and make this Chinese mainstay soup at home. This healthy version is made with thin slices of pork tenderloin and gets its characteristic tang from gut-healthy apple cider vinegar.

This simple and satisfying butternut squash soup is spiced with fall flavors like cinnamon, nutmeg and thyme. Try blending in some cauliflower to make it even thicker.

Who doesn’t love those super simple recipes where all you have to do is dump everything in the slow cooker? Let your crockpot do all the work in this flavorful chipotle chicken soup recipe.

You might not typically think of salmon as soup-worthy, but this recipe will convert you. Use seafood broth to boost that savory, comforting factor.

Garnish this smoky, Spanish-inspired soup with diced avocado, and get ready to warm up quick.

This gorgeously-colored soup is loaded with anti-inflammatory turmeric, juicy chicken thighs, and tons of veggies. It’s good for you all-around.

A drizzle of nutty tahini and a scattering of crispy bacon on this asparagus soup makes for a work of art.

Feeling under the weather? Get the classic fix with this herb-filled chicken soup, made right in the crockpot.

What is it about this spinach and mushroom soup that makes it feel like “a hug in a bowl”? It’s loaded with health-boosting ingredients, like bone broth, collagen peptides, coconut vinegar, nutritional yeast and ghee.

Do you have a freezer full of frozen seafood like fish and shrimp? This is the soup you need to cook up tonight. Enjoy succulent seafood in a rich, creamy tomato broth.

Cassidy’s Craveable Creations | Meatball Soup

Spinach-packed beef meatballs are surrounded by veggies like zucchini, tomatoes and carrots in a rich broth of tomatoes, stock and balsamic vinegar.

Go Greek with this tangy lemon chicken soup with hearty kale and cauliflower rice.

Why slave over finicky cabbage rolls when you can get the same flavor and texture in soup form?

This autumnal pumpkin soup is loaded with warming spices like cinnamon, ginger, and nutmeg.

Bacon and cauliflower are the perfect couple in this creamy, chowder-like soup.

Boost your go-to tomato basil soup with thick slices of Italian sausage for a meal you can enjoy on its own. If you’re feeling particularly indulgent, serve with this cauliflower grilled cheese for dunking!

Thanks again to Paleohacks for today’s recipe. Have a great Sunday, everyone.

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2 Meat, 2 Pepper Chili

Thanks to the good folks at Paleohacks for today’s recipe.

This rich keto chili is made with two types of beef and slow cooked in bone broth for stick-to-your-ribs heartiness. This rich and simple crockpot recipe combines sirloin steak, ground bison, sweet bell peppers, and smoky ancho chiles for a recipe that is anything but ordinary. Best of all, this chili can be prepped ahead of time for a meal that reheats in a pinch throughout a busy week.

The stock for this chili is made from bone broth, or slow-simmered beef bones. When bones simmer in water overnight, they release their amino acids into the liquid, creating a liquid golden broth full of gut-healing collagen. We love this potent and flavorful bone broth recipe with leeks and rosemary, but you can also purchase plain bone broth online or in most grocery stores if you’re in a pinch.

Most of the flavor in this chili comes from dried ancho chiles. These are made from smoked poblano peppers, condensing their sweetness and adding a complexity to chili that raw pepper alone can’t match. This pepper is not spicy, making it one the whole family can enjoy. You can find dried ancho chiles in the ethnic foods aisle of most grocery stores.

Lean ground bison and tender chunks of sirloin beef are browned in a skillet before being added to the crockpot. This gives them a chance to caramelize, deepening the flavor of the chili. Both grass-fed beef and bison are rich in omega-3 fatty acids and contain more free-radical fighting antioxidants like vitamin-E than their factory-farm counterparts.

Get started by heating ghee in a large skillet over medium heat. Add onions and garlic. Sauté for 5 minutes, then pour them into the crockpot. Next, turn up the heat to medium-high and add the diced steak and ground bison to the skillet to brown for seven or eight minutes. Drain and discard any fat, then pour the meat over the onions in the crockpot.

Add the ancho chiles, tomatoes, bone broth and dried herbs to the crockpot, then cover and set to low heat for six hours. Add a chopped green bell pepper to the crockpot for the last hour of cooking to help keep it crisp. Ladle the chili into bowls and garnish with freshly chopped cilantro.

Looking for more keto recipes? Check out these 23 paleo and keto-friendly snacks.

Time In the Kitchen: 10 minutes

Cook Time: 6 hours, 15 minutes

Servings: 6

Tools:

  • Large skillet
  • Crockpot

Ingredients:

  • 1 tbsp ghee
  • 1 small white onion, chopped
  • 1 tsp minced garlic
  • 1/2 lb sirloin steak, cubed
  • 1 lb ground bison
  • 2 medium, dried ancho chili peppers, finely chopped
  • 2 (14.5 oz) cans diced tomatoes
  • 2 cups beef or bison bone broth
  • 2 tbsp cumin
  • 1 tsp oregano
  • 1 tsp smoked paprika
  • 1/2 tsp sea salt
  • 1 green bell pepper, chopped
  • Chopped cilantro, for serving

Instructions:

1. Heat ghee in a skillet over medium heat. Add the onions and garlic and sauté for 5 minutes, stirring occasionally. Pour the onions into the crockpot and return skillet to the stovetop.

2. Add the diced steak and ground bison to the skillet and turn the heat up to medium-high. Brown the meat for 7-8 minutes, stirring occasionally. Drain and discard any fat. Pour the meat into the crockpot.

3. Add the ancho chiles, tomatoes, bone broth, cumin, oregano, paprika and sea salt to the crockpot. Cover and set to low heat for 5 hours.

4. Add the bell pepper to the crockpot and cook on low heat for one more hour.

5. Ladle the chili into bowls and garnish with cilantro.

Nutritional Info:

  • Calories: 257
  • Carbs: 4.7 grams
  • Fat: 11 grams
  • Protein: 34 grams

Thanks again to Paleohacks for today’s recipe. Have a great Sunday, everyone.

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Instant Pot Oxtail Stew

People don’t talk about oxtail stew these days, but it’s a true Primal-worthy classic. With an arguably richer taste than beef and more succulent feel when cooked for stew or soup, oxtail might just become a new favorite. But the real difference (and reason behind the appealing stewed texture) is the ample connective tissue—an incredible source of collagen for the benefit of skin, hair, joint health, performance and more. (Since we used bone broth here in lieu of water or regular stock, this recipe is one of the best you can make for collagen content.) You’ll enjoy warming up with this gelatinous, flavorful and hearty dish on a late winter night. And you might consider making an extra batch: it tastes even better the next day.

Time In the Kitchen: 25 minutes (plus cook time)

Servings: 4

Ingredients:

  • 2 pounds grass-fed oxtail
  • 1 1/4 cup beef bone broth
  • 1/4 cup Primal Kitchen® Barbecue Sauce
  • 1 lb. small red potatoes (about 6), cut into bite-size pieces
  • 4 large carrots, cut into 1-inch-thick slices
  • 1 large onion, cut into bite-size pieces
  • 2 slices nitrate-free bacon, cut into 1-inch pieces
  • Salt and pepper to taste

Instructions:

Heat Instant Pot on Saute and crisp chopped bacon. Remove and drain on paper towel.

Season oxtail and sear on all sides in bacon fat (3 min per side).

Add in other ingredients and cook 45 minutes on Manual High (Sealed). Let vent 15 minutes.

For slow cooker: cook bacon and sear oxtail in separate pan. Then cook all ingredients in slow cooker on low for 8 hours.

Nutritional Information (per serving):

  • Calories: 719 
  • Net Carbs: 24.6 grams
  • Fat: 36 grams
  • Protein: 67 grams

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