The Link Between Meat and Cancer

August 22, 2015 in Categories: , by

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I’m sure you’ve seen more than one article pronouncing that meat causes cancer. Depending on the source, the article might have a plant-based diet lean and demonize all meat, or merely throw red meat or deli meats under the cancer bus. I know I get asked nearly daily to rebut some article or other on the subject.

red-meat-cancer-connectionBut, the truth is that there really are a lot of studies out there linking meat consumption (especially red meat) to cancer—in human populations, in animal models, and even in some controlled trials focusing on pre-cancerous changes in the human body. Hardly a month goes by without seeing at least one of these studies pop up in the headlines and make the rounds on social media. These studies seem to buoy critics of the Paleo diet and low-carb diets alike, while providing fuel for harassment from family members who just don’t get how we eat (or why).

Within the Paleo community, there is a strong tendency to dismiss these scientific studies as being irrelevant or poorly conducted. The most standard response is “But the study didn’t use grass-fed and organic meat!” and then we go on our merry way with the assumption that the results don’t apply to us (and we tell our family members so!). Then, there’s always the more general anti-science sentiments, dismissing the relevance of a study based on perceived design flaws or legitimate study limitations. As you can probably imagine, dismissing science because it doesn’t conform to our established beliefs is not something I endorse.

Studies linking meat consumption to cancer are relevant to the Paleo community and are worthy of discussion. So, let’s do that.

Researchers have uncovered several mechanisms linking cancer with components of meat that have nothing to do with an animal’s diet or antibiotic exposure, including heme iron, specific proteins, other specific molecules, and heat-induced mutagens. These are things that exist in meat whether it’s conventional or grass-fed or wild game. That means that organic grass-fed meat, while it promotes health in other ways (better fats, more micronutrients), still has the capacity to increase cancer risk. So, instead of dismissing the meat and cancer research as irrelevant, let’s take the time to objectively look at how it affects us.

But, don’t get scared over to vegetarianism just yet! When we take a closer look at these studies, we see something extraordinarily interesting: the link between meat and cancer tends to disappear once the studies adjust for vegetable intake. Even more exciting, when we examine the mechanistic links between meat and cancer, it turns out that many of the harmful (yes, legitimately harmful!) components of meat are counteracted by protective compounds in plant foods.

Said more simply: YES, meat does cause cancer! …IF you aren’t eating your veggies!

Let’s dive into the mechanistic details!

Heme

A major mechanism linking meat to cancer involves heme, the iron-containing compound that gives red meat its color (in contrast to the nonheme iron found in plant foods). Where heme becomes a problem is in your gut: the cells lining your digestive tract metabolize it into cytotoxic compounds (meaning toxic to living cells), which can then damage your colonic mucosa, cause cell proliferation, and increase fecal water toxicity—all of which raise cancer risk. Yikes! In fact, part of the reason red meat shows up linked with cancer far more often than white meat could be due to their differences in heme content: white meat (poultry and fish) contains much, much less of it.

heme-chlorophyll-badHere’s where vegetables come to the rescue! Chlorophyll, the pigment in plants that makes them green, has a molecular structure that’s very similar to heme. As a result, chlorophyll can block the metabolism of heme in your intestinal tract and prevent those toxic metabolites from forming. Instead of turning into harmful byproducts, heme ends up metabolized into inert compounds that are no longer toxic or damaging to your colon. Animal studies have demonstrated this effect in action: one study on rats showed that supplementing a heme-rich diet with chlorophyll (in the form of spinach) completely suppressed the pro-cancer effects of heme. All the more reason to eat a salad with your steak!

 

L-Carnitine and TMAO

L-carnitine is an amino acid that’s particularly abundant in red meat (another candidate for why red meat seems to disproportionately increase risk of cancer compared to other meats). When you consume L-carnitine, your intestinal bacteria metabolize it into a compound called trimethylamine (TMA). From there, the TMA enters your bloodstream and gets oxidized by your liver into yet another compound, trimethylamine-N-oxide (TMAO). This is the one we should pay attention to!

nm.3178-F1TMAO has been strongly linked to cancer and heart disease, possibly due to promoting inflammation and altering cholesterol transport. Having high levels of it in your bloodstream could feasibly be a major risk factor for some chronic diseases. So, is this the nail in the coffin for meat eaters?

Not so fast! An important study on this topic was published in 2013 in Nature Medicine, and sheds light on what’s really going on. This paper had quite a few components (discussed in detail in a fascinating blog post by Jeff Leach of the Human Food Project), but one of the most interesting has to do with gut bacteria. Basically, it turns out that the bacteria group Prevotella is a key mediator between L-carnitine consumption and having high TMAO levels in your blood. In this study, the researchers found that participants with gut microbiomes dominated by Prevotella were the ones who produced the most TMA (and therefore TMAO, after it reached the liver) from the L-carnitine they ate. Those with microbiomes high in Bacteroides rather than Prevotella saw dramatically less conversion into TMA and TMAO.

Guess what Prevotella loves to snack on? Grains! It just so happens that people with high Prevotella levels tend to be those eating grain-based diets (especially whole grain), since this bacterial group specializes in fermenting the type of polysaccharides abundant in grain products. (For instance, we see extremely high levels of Prevotella in populations in rural Africa that rely on cereals like millet and sorghum.) At the same time, Prevotella doesn’t seem to be associated with a high intake of non-grain plant sources, such as fruit and vegetables.

So, is it really the red meat that’s a problem… or is it the meat in the context of a grain-rich diet? Based on the evidence we have so far, it seems that grains (and the bacteria that love to eat them) are a mandatory part of the L-carnitine-to-TMAO pathway. Ditch the grains, and your gut will become a more hospitable place for red meat!

Neu5GC

Another lesser-known mechanism behind the meat and cancer link involves a sialic acid molecule called Neu5GC, which is found abundantly in red meat. The human body can’t produce Neu5GC (instead, we make a different sialic acid molecule called Neu5AC), but we can incorporate Neu5GC into our cell membranes if we ingest it from food. There’s just one problem: since Neu5GC is a foreign molecule, our bodies can launch an immune response against the Neu5GC we’ve incorporated, leading to the production of antibodies and inflammation. That process appears to be involved in raising cancer risk. (In fact, mice studies designed to simulate what happens in the human body are showing that after long-term exposure, Neu5GC accumulates in tumors and significantly raises the number of carcinomas that form.)

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The question then becomes why do we form antibodies against Neu5GC at all? Not everyone does, and it may be something that happens in an over-stimulated or dysfunctional immune system, similar to the way we form antibodies against our own tissues in autoimmune disease. In this case, nutrient sufficiency, gut health, adequate sleep, stress management and activity are all important inputs to prioritize (all discussed in detail in The Paleo Approach). And it is thus no surprise that nutrient deficiency, gut dysbiosis, poor sleep, high stress and inactivity have all been linked to increased cancer risk.

Do vegetables play a role here too? Unfortunately, that’s something researchers are still exploring—and we can’t say yet how vegetable intake influences the potential Neu5GC-cancer connection. But, we do know from a giant range of studies that vegetables exert cancer-protective properties through a number of pathways, and every study that corrects for vegetable intake finds the meat and cancer link to disappear. High vegetable intake benefits the immune system in many ways too. So, we can make an educated guess at this point and say that whatever risk Neu5GC may create, vegetables appear to negate it.

Mutagens from Cooking

623-06122235cOkay, a juicy steak on the grill tastes amazing. I think we can all agree on that. But, what’s not amazing is the molecular effect high-temperature cooking has on meat. Harsh cooking methods like grilling and frying can generate compounds called heterocyclic amines, or HAs (formed from reactions between amino acids and creatine in muscle meat) and polycyclic aromatic hydrocarbons, or PAHs (formed when meat drippings hit open fire and cause PAH-containing flames to rise up, in turn coating the meat with PAHs). Both of these compounds are known to be mutagenic, causing changes in DNA that may increase your risk of cancer. Plenty of animal experiments and human population studies point towards HAs and PAHs being major players in the cancer correlations we see with meat.

Although we’re not 100% sure how dramatically HAs and PAHs raise cancer risk in humans (it’s really hard to measure people’s exact intake and correlate it with disease incidence over time), it’s safe to say these compounds aren’t harmless, and we should try to minimize our exposure to them. One way to do that, of course, is to stick with gentle cooking methods (hello, crockpot!) instead of charring our meat to smithereens. But, guess what else can counteract meat mutagens? It probably won’t come as a surprise that the answer, again, is vegetables!

Multiple studies have shown that indoles, a class of phytochemicals abundant in cooked or crushed/chewed crucifers (like broccoli, cauliflower, Brussels sprouts, and cabbage), can suppress the tumors induced by PAHs and HAs, as well as totally change the way your body metabolizes these mutagens to make them less harmful. One study found that feeding people a diet containing 500 grams of crucifers per day (in the form of broccoli and Brussels sprouts) reduced the formation of toxic metabolites from a particularly dangerous HA called 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (try saying THAT five times fast!). Basically, it looks like we can protect ourselves from some of the damage these mutagens cause by making sure we eat plenty of cruciferous vegetables. Let’s fire up the barbecue! (and make a shaved Brussels salad!)

But What About the Inuit?

A common argument for the claim that red meat can cause cancer when you don’t eat enough plant foods is, “What about the Inuit?” After all, didn’t they stay cancer-free on a diet that was nothing but meat?

Actually, this is a myth! The Inuit (on their traditional diet) definitely had a huge intake of animal foods, but they also went to great lengths to gather amazingly nutrient-dense plants whenever they were available (as well as preserve them for year-round use). Those included kelp, algae, and other seaweeds (which are super high in chlorophyll), plankton from whales’ stomachs, fireweed, sorrel grass, flower blossoms preserved in seal oil, mosses, a variety of berries, ground nuts, lichens, willow leaves, sourdock, scurvygrass, roseroot, numerous other weeds and greens, tubers, starchy corms (which the Inuit collected from caches made by tundra mice and voles), and the partially digested stomach contents of caribou and other land animals (considered a delicacy, and usually consisting of a variety of lichens, blueberry leaves and shoots, horsetails, grasses, birch, willow, and other plants the animals had grazed on). Whew! That’s quite a list. And, many of those wild foods have a much higher micronutrient content than the cultivated vegetables we get from the store, so a little went a long way.

cueillettePlus, the Inuit traditionally fermented large quantities of their greens, berries, and roots as a way of preserving them. If you’ve read my posts on fermentation (check out my latest one here!), you know that fermented foods can have major anti-cancer properties, and might offset the increased risk from red meat by shifting the gut microbiome and protecting the colon from dangerous precancerous mutations.

What’s more, we can’t rule out the possibility that the Inuit evolved a unique gut ecology that helps them cope with their diet. We already know they evolved a genetic CPT1A mutation that prevents most Inuit from entering ketosis, something not found in those of us descended from non-arctic populations. Could something similar have happened with the Inuit gut microbiome? It’s definitely possible.

Bottom line: despite a high meat intake, the Inuit were also eating a huge variety of protective plant foods (and receiving the perks of fermentation), so they really don’t invalidate the red meat and cancer connection.

Does This Mean It’s Better to Be Vegetarian?

Not at all! The point of this post isn’t to scare you away from meat, but to emphasize that both plant foods and animal foods play an important (and symbiotic) role in the human diet. Without the protective effects of plant foods, some components of animal products—meat, in this case—can become legitimately harmful and raise your risk of diseases like cancer. But, animal products play an equally valuable role for our health, providing nutrients that are low or absent from plant foods (like B12, preformed vitamin A, zinc, highly absorbable iron, easiest-to-digest protein, and complete protein).

The danger comes when we have an imbalance between our intake of plant foods and animal products—tilting too far in the direction of either carnivore or vegan. The key is to enjoy nutrient-dense items from both the plant and animal kingdoms that lead to healthy gut flora, an excellent micronutrient status, and happy taste buds.

While a meat-heavy diet may increase cancer risk, eating lots of veggies mitigates it. When you eat both meat and a variety of vegetables (at least 5 veggie servings a day), the rationale for concerns falls short.

Yes, I just concluded what other Paleo peeps have been saying all along: meat is an essential component of a healthy diet for optimal health. But, I think it’s important to emphasize that a detailed reading of the science emphasizes just how important it is for high vegetable consumption to be another essential component of said healthy diet for optimal health.

So go ahead and eat that steak, just steam some broccoli and make a salad to go with it.

dsc_0178Citations

Balder HF, et al. “Heme and chlorophyll intake and risk of colorectal cancer in the Netherlands cohort study.” Cancer Epidemiol Biomarkers Prev. 2006 Apr;15(4):717-25.

Bennett J & Rowley S. “Chapter 5: Gathering.” Uqalurait: An Oral History of Nunavut. 2004: McGill-Queen’s University Press. pp. 84–85.

Clement FJ, et al. “A Selective Sweep on a Deleterious Mutation in CPT1A in Arctic Populations.” Am J Hum Genet. 2014 Oct 23;95(5):584-589.

De Filippo C, et al. “Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa.” Proc Natl Acad Sci U S A. 2010 Aug 17;107(33):14691-6.

Kang DW, et al. “Reduced incidence of Prevotella and other fermenters in intestinal microflora of autistic children.” PLoS One. 2013 Jul 3;8(7):e68322.

Kuhnlein H & Turner N. “Traditional Plant Foods of Canadian Indigenous Peoples: Nutrition, Botany and Use.” (Food and Nutrition in History and Anthropology). 2001: Taylor and Francis.

Murray S, et al. “Effect of cruciferous vegetable consumption on heterocyclic aromatic amine metabolism in man.” Carcinogenesis (2001) 22 (9): 1413-1420.

Price W. “Chapter 5: Isolated and Modernized Eskimos.” Nutrition and Physical Degeneration. 1939: Paul B. Hoeber, Inc.

Koeth RA, et al. “Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis.” Nat Med. 2013 May;19(5):576-85.

Samraj AN, et al. “A red meat-derived glycan promotes inflammation and cancer progression.” PNAS January 13, 2015 vol. 112 no. 2 542-547.

Tangvoranuntakul P, et al. “Human uptake and incorporation of an immunogenic nonhuman dietary sialic acid.” Proc Natl Acad Sci U S A. 2003 Oct 14; 100(21): 12045–12050.

de Vogel J, et al. “Green vegetables, red meat and colon cancer: chlorophyll prevents the cytotoxic and hyperproliferative effects of haem in rat colon.” Carcinogenesis 2005;26:387–93.

Walters D, et al. “Cruciferous vegetable consumption alters the metabolism of the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in humans.” Carcinogenesis 2004;25(9):1659-1669.

Wattenberg L & Loub W. “Inhibition of Polycyclic Aromatic Hydrocarbon-induced Neoplasia by Naturally Occurring Indoles.” Cancer Res (1978) 38: 1410.

Wu GD, et al. “Linking long-term dietary patterns with gut microbial enterotypes.” Science. 2011 Oct 7;334(6052):105-8.

Comments

Thank you so much for this Sarah! I’ve always supported a “high meat” diet when someone asks me about the meat and cancer connection. I usually point out that the North American standard diet is not “high meat” it’s high grain, and it’s the grains that are contributing to the high cancer rates. Switch out the grains for greens, and there goes the meat – cancer connection! You have validated my argument 🙂

This is a fantastic article! What great analysis. Will definitely be referring everyone to this post. Must have taken so much time and work. Thank you for sharing this with us! I learned a lot =)

so what happens with a diet consisting of mostly grains and mostly vegetables, wouldn’t the vegetables cancel out the bad effects of the grains?

As I understand it, grains, especially whole grains, contain high amounts of phytic acid. If not properly prepared by soaking or fermenting, this “anti-nutrient” inhibits our bodies’ uptake of vital nutrients from the foods we eat including vegetables. This could be a reason why a diet high in vegetables but also high in grains may not be as healthy.

Thanks for summing all of this up! P.S. I am hoping that now that you have been diagnosed with fibromyalgia that you will write a post that focuses on that topic. I’ve been a sufferer for going on 5 years now, and I’d love to see what your thoughts are on current research relating to that particular illness. For example, I understand that nightshade vegetables may be problematic in arthritis, but fibromyalgia is a different beast, and I’m confused as to whether the same mechanism applies. Here’s to hopin’ and wishin’ for a post on fibro! 🙂

Just found you here on line. I am very interested in this as some of the things that you talked about sound very familiar to me! Believe me, what I know of what is going on in my body I dearly hate. I don’t think that any one is too old to learn new “tricks.” I don’t really think that eating correctly is a trick. It is a necessity for good health. I confess that I have been very negligent about what I eat! I am paying a high price for my stupidity. I would really like to change how I am eating (wrongly) and change to the right way. I truly believe that just because I am a Senior citizen is not a reason to teach and old dog new tricks.. In other words—HELP! ! ! ! ! !

Would l-carnitine supplements also pose a risk, then? Sorry if the answer to that seems obvious, but I am currently taking l-carnitine after an amino acids test (NutrEval) showed I have a problem metabolizing fats, and I was not aware of it possibly being harmful!

I would like to second Marina’s question – I’ve been taking l-carnitine supplements as I also don’t metabolize fatty acids as was discovered via an ion test from my functional med dr. I’ve been following a paleo diet also for the past 2.5 years.
Any response/opinion/thought on her and my question would be very appreciated!

Oh, fabulous, fascinating article! Yes, like Rebecca, I tend to point out to people that the problem (with the diet and with the studies) is the grains. This is a great resource for all of us who are hoping to educate and empower people on their road to health. Thankyou!

Dónde cónsigo libros con verdaderas recetas paleolítica para perder peso, vivo en México en la hermosa ciudad de pachuca hidalgo muy cercas del D.F.,

DONDE CONSIGO LIBROS DE DIETAS PALEOLÍTICA EN ESPAÑOL PARA PERDER PESO, QUIERO RECUPERAR MI PESO POR INSTRUCCIONES DEL ONCOLOGO LO TENGO QUE HACER AYÚDAME POR FAVOR ESPERO A LA BREVEDAD POSIBLE RESPUESTA FAVORABLE GRACIAS

I found your article very interesting as paleo diet is the current fab diet.My husband & I have had one hell of a ill health journey over the past 2yrs.We both have a balanced diet of meats ,veg & fruit.no alcohol or junk food.My mother is 92yrs of age & has influenced my healthy diet.After having 2 brain & thyroid scans,a battery of blood tests, consultating 15 drs including 7 specialists to no avail 6mths later a diligent holistic Gp gave me a diagnosis of vitamin B12 deficiency in 2 visits.Since then I have diagnosed 10 other persons.I believe like American author of Could it be B12 ? There is an epidemic worldwide of misdiagnosis due to drs not recognising symptons of a vital nerve supporting vitamin.Vegetarians,vegans ,persons taking anti acid meds ,OCP .metformin,Dilantin,PPI ,lap banding surgery are at high risk of Vitamin B12 levels being depleted.if not detected early & treated with a simple vitamin this deficiency leads to autism,anaemia,hearing &memory loss,permanent nerve damage & disability,dementia & death.

Hi Sarah. Thank you for another valuable post. My question is I love to use my pressure cooking to cook nutrient full casseroles but does this super high pressure cooking negatively affect meat like grilling/frying? Kind regards Karen 🙂

Absolutely amazing article! !!! I love that your research steers people into the right direction and shoes them a proactive way to eat to get the most benefits on a microbial level and have a ballanced diet that does good not harm. So user friendly. Love your work.

Thanks for showing that meat causes cancer and plants don’t. Amazing that doctors will still recommend people eat cancer causing foods and that your followers will agree – all because they like to hear good things about their bad habits.

i can’t find the study right now, but i read one a couple years back that showed that the human body treats seal meat more like a carbohydrate
see if you can find that one

Mktaylor, if you read the abstract, there is no mention of the quality of food these people consumed. I am always surprised when people compare a vegetarian diet against the general omnivore population, the latter of which are people who consume animals raised in horrific, industrial settings and fed highly unnatural diets. These animals are themselves sick, and how on earth would consuming them cause anything but sickness in humans. When we start parsing out risk of consuming wild and conscientiously-raised animal foods vs. eating conventionally raised foods, we will have some answers to your question–except, we already do.

Numerous physicians and surgeons living on what was the frontier in the 1800s and early 1900s lived among indigenous people that still consumed their traditional omnivorous diets. The incidence of cancer was next to zero (far lower than contemporary vegan people). This held up with populations from North America, South America, Africa, and Asia. While people immediately raise concerns about hunter-gatherer longevity and the diagnostic tools available at the time, keep in mind that it is a myth that hunter-gatherers lived short lives. Research demonstrates many individuals lived into their late 60s, 70s, 80s, and even early 90s. Also, those frontier physicians did find cancer in the “white people”, raised in civilization, living on the frontier.

None of these studies (such as you posted a link to) are worth much to me because they only demonstrate that eating industrially produced food is harmful. Do we need studies to demonstrate this? Best wishes to you.

Dear Sarah,

Great article. Thank you for your work. There is even more to this “red meat causes cancer” story that could be discussed (I realize your article here can only be so long before people stop reading it). Of interest perhaps:

“omnivory—as commonly practiced in the United States—likely does produce higher rates of cancer, in part through the quality of animal foods ingested (as noted in the previous paragraph) but also through the kinds of animal foods ingested. People in affluent countries tend to focus on lean muscle meats, specific cuts that lack connective tissue (including skin and cartilage). This dietary focus on tender cuts of meat provides an imbalance of certain amino acids, specifically, more methionine and less glycine (glycine is an amino acid well represented in connective tissue, skin, cartilage, and organ meats). High intake of methionine is associated with increased production of insulin-like growth factor-1 (IGF-1), a hormone that promotes cell growth throughout the body, including cancer cells. Therefore, omnivory as commonly practiced by domesticated humans, does appear to increase cancer rates. Restricting dietary methionine has been shown to reverse this trend, but so can increased consumption of glycine-rich foods—both are which balance out the methionine to glycine ratio). In other words, a healthy balance of amino acids, which are consumed when the animals are more fully utilized, does not demonstrate higher incidence of cancer (and explains, in part, why meat consumption in hunter-gatherers did not result in cancer). While many Americans will not want to consume certain cuts of meat that contain connective tissue, the skin of poultry, bone broths, and animal gelatin are easy ways to incorporate glycine in the diet. Emulating hunter-gatherer diets is sometimes as easy as consuming poultry with the skin (which also adds much flavor and nutrition and prevents the meat from drying out). While there is very important information for omnivores in this paragraph, part of the telling of this story is to demonstrate that blanket statements like “red meat cause cancer” should really be refined to read “red meat from unhealthy animals in diets that focus on tender cuts can cause an increased incidence of cancer”. In other words, we do not need to turn to veganism to prevent cancer, instead, we can also utilize time-honored methods of consuming animal foods (such as full utilization) to maintain health.”

Can you just stop eating meat for the animals! I was paleo for years until discovered vegan life style. Stop animal cruelty! Dont tell me your grassfed cow is happy when being chopped for your dinner. I seen it with my own eyes how they slaughter pigs and cows so you can include them in your paleo diet. Also research why humans should not eat pork! Please do! Peace to all of you, but stop animal cruelty!

I still don’t understand why the message isn’t just to eat plants and forget the meat altogether. There’s no downside to eating a plant-based diet, and it’s much more humane and sustainable for our planet. Whether you think eating meat is toxic or not, no one, or real study, is saying eating more plants or all plants is a bad thing. Give up the dead animals already, there’s really much more to enjoy out there

Thank you for a well written and well researched article! It was fantastic:)
I do however have concerns that you did not even touch on the artificial additives found in PRESERVED meats! They are a very important factor to consider when choosing which types of meats to eat.

Artificial additives are in most everything these days and I believe they do a great deal more damage than people realise.

I worry that a lot of paleo followers rely heavily on bacon in their day to day lives and I have witnessed many, who believe that “the more meat the better” and will happily sit down to plates full of preserved ham and bacon, with not a vege in sight:(

I therefore, think it was a point that should have been examined in this article also.

But I found all the info provided on the metabolism of meat and veg fascinating and thank you again for a great article.

Does anyone see the flaw here. It’s kinda like cutting your arm over and over again. Sure if you don’t protect/clean your body (as the antioxidants from veggies do) your gonna get an infection. But because we can prove with science that cleaning a wound and bandaging is beneficial does it make sense to put your body in that line of fire just because you know of a backup plan. It makes much more sense to just not cut yourself. As it makes more sense to just consume veggies and grains. Obviously with a plant based whole food diet , grains encouraging TMAO is non existent as you are not consuming the harmful substance to begin with. Just something to think about.

That actually makes the argument going the other way as well. If the issue is the interaction between grains and red meat, why not just avoid the grains completely as the harmful substance since they do not have any added benefit over the animal foods. They are harder on your body, both during digestions and dealing with effects after if consumed as a major portion of calories, plus they do not have any micro-nutrient advantage over meats.

Another excellent article Sarah. I agree with the comment above that paleo eaters eat too much meat, and this article explains how that’s a problem. Not to mention, our paleo ancestors could not realistically have eaten as much meat as I see advocated on many paelo sites. I think paleo’s go too far to the low-carb side too and my instinct tells me that traditional diets, both ancient and more recent have relied heavily on starchy tubers as fillers to nutrient-rich veggies and meats. Love the insight into the Inuit diet – you’re right, no one mentions anything but whales and seals.

To comment on the animal cruelty comments – I agree it seems barbaric for intelligently evolved, empathetic beings to kill animals to eat them. Unfortunately, that is the way of this planet, this type of biological life that requires constant death to both animal and plant lives in order for other species (including us) to survive. Is the lion cruel when it kills a wildebeest for the pack? Is the bird cruel that eats a worm or bug? I don’t like it either but many people’s experience has proven to them that they cannot be physically and mentally healthy without animal flesh. Just so you know – meat eaters want peace and non-violence too but for now my consciences tells me to treat animals well during their lives, kill them quickly and as painlessly as possible, and thank them for their sacrifice like the Native American hunters did.

great article
question 1 : why you didn’t talk about link meat and rise IGF-1
question 2 : omeopatic medicine talk about rise in extracellura matrix intoxication,because of lower pH in the same ECM, all following high intake of meat

I am reading your wonderful book, now, and want to thank you so much for writing it. I appreciate how thorough it is, because I am also one of those people who needs the science behind a recommendation in order to be motivated to implement it. Marina and emr, above, both commented asking if you had any input on the supplement, acetyl l-carnitine. Usually the amounts that are supplemented are far in excess of what most people would get through diet. I take a gram a day of it, and have been taking it since 2012. I am wondering whether you believe it is likely to be safe to take, as long as we are not feeding harmful gut microbiota by violating the AIP principles. I also wonder if it could contribute to histamine intolerance (or an over all biologic amine intolerance) as it is an “amino” acid. I have significant issues with amines, and am starting to wonder whether my acetyl l-carnitine supplementation might be contributing to that, or thwarting my ability to heal from it. I am pretty afraid to stop taking it, as when I’ve cut down in the past I crash hard. Thank you for all your hard work!

The recommendations in the The Paleo Approach and the AIP diet itself are not meant to take the place of supplement recommendations from your doctor. So always discuss those things with your practitioner first. Histidine is the amino acid that is converted to histamine and can cause problems if you have a histamine intolerance, but I can’t say for certain that acetyl l-cartinine isn’t contributing to your issues. If you’re able to, an elimination approach may be the best way to test it. -Kiersten

A fost dirattcsiv pentru că vă place aspectul de blog. Cred că este destul de succes, cu excepţia pentru o deltalj. Sper ca cineva are cateva poze din spectacol. Sunt exceptate de la Facebook aşa că poate fi altfel.

What “gives red meat its color” is a dye the food industry adds to raw red meat to make it look palatable, not its heme iron. I know this because I’ve visited butcher counters where they *do not* treat the meat in that fashion, and the meat is closer to gray. You know, the actual color of corpse muscles. Chicken would also contain heme iron because chickens have red blood just like we do. When was the last time you saw a red defeathered chicken body? The meat’s light pink, because apparently that’s the color of a bird corpse’s muscles.

By the way, when either a red-meat animal or a bird is slaughtered, they’re also bled out. If they weren’t, the heme in their blood would render them rusty brown, not red like you see in the store (and, again, only with red meat, since that’s the only meat we dye). Dead blood isn’t red because dead blood isn’t oxygenated.

I’m a meat eater and I don’t mean to gross people out, but it’s the truth.

The Inuit could not possibly have been eating large amounts of plant matter year-round because the environment simply would not have allowed for it. There is reason to believe that the claim of eating gut contents is a myth, a story they told white people to troll us. And in the end, if you take a serious look at WHAT plants they were eating, IT’S STILL MOSTLY LOW-CARB, if we’re talking about digestible carb and not just volume of plant matter. Someone eating three pounds of iceberg lettuce a day isn’t eating high-carb either. Even the tubers would have been small and fibrous. The environment doesn’t lend to those plants storing huge amounts of starch, and for all I know some of it could have been resistant.

You don’t need a special adaptation to thrive on red meat. I thrive on red meat. I’m of European extraction. Africans thrive on red meat. Neither of those populations are Inuit.

I don’t know what it is with certain factions of the Paleo movement who apparently feel guilty that they’re no longer vegetarian and can’t resist knocking down meat-eating at every turn but it’s getting really tiresome.

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