"Have you ever wondered what's the truth about meat? Is it really as bad as many people think?
"When I teach critical thinking and how to analyze research, I point out that despite what we think is true, if an exception exists (and I don't mean an individual, but an entire culture) then what we believe is simply not true."In the third paragraph of her article, Merritt writes:
"....Mostly, though, what we tend to do is ignore what we disagree with, disregard science and keep marching forward with our beliefs, incorrect or not. Keep this in mind as we look at what's true and false about meat."
With all this Ms. Merritt tries to convince the reader that she has superb critical faculties, a strong grasp of the science of meat and health, and never ignores findings that she finds disagreeable and readily changes her views to accord with evidence. Let's see if she lives up to her own promise.
First, Ms. Merritt states that "how we eat meat now is inflammatory" which she attributes to an imbalanced intake of essential fatty acids. In the course of this paragraph, she says:
"Just so you know, arachidonic acid is a necessary Omega-6 fatty acid..."Thereby she implies that we have a dietary requirement for arachidonic acid (AA), which is absolutely false. While AA is biologically essential, adult humans have no dietary requirement for AA because the body can produce all AA required from linoleic acid, which is according to the Institute of Medicine Food and Nutrition Board "the only n-6 polyunsaturated fatty acid that is an essential fatty acid," and abundantly supplied by plants.
|Source: Dietary Reference Intakes|
Then she states:
"An analysis of a Paleolithic culture (who did not have the level of inflammatory disease that we now have) shows an AA intake that is double ours. So, again, what's wrong with us or our meat that gives us a different result? Guesses, anyone?"Leaving aside her flippancy, apparently, in her view, this article she cites:
Kuipers, Remko S., et al. "Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet." British Journal of Nutrition 104.11 (2010): 1666-1687.
counts as an "analysis of a Paleolithic culture (who did not have the level of inflammatory disease that we now have)."
Contrary to her suggestion, this was not an "analysis of a Paleolithic culture." According to the authors, stated right in the abstract:
"The objective of the present study was to reconstruct multiple Paleolithic diets to estimate the ranges of nutrient intakes upon which humanity evolved."The words "reconstruct multiple Paleolithic diets" and "to estimate" tells you right off that this paper is speculative, not factual, more aligned with science fiction than epidemiology. It did not report the actual dietary intake of any actual Paleolithic culture. So of course this imaginary Paleolithic culture eating multiple imaginary diets can be as high in AA and as free of inflammatory diseases as you like. Fiction has no limits.
Further, no actual Paleolithic culture has ever been or ever will be surveyed for inflammatory diseases. Paleolithic cultures existed in Paleolithic times, i.e. between 2.6 million and 10,000 years ago. No one knows what the incidence of inflammatory diseases was in true Paleolithic cultures. Modern African hunter-gatherers are not Paleolithic cultures. They have tools (e.g. bow and arrow) that Paleolithic people did not have. The relative freedom from modern inflammatory degenerative diseases among some modern hunter-gatherer tribes has a lot to do with the fact that they rarely had food surpluses, carried loads of blood draining parasites (reducing inflammatory iron levels), had short lifespans (died before the age at which cardiovascular disease or cancer starts to take lives), and, in many cases, ate meat infrequently.
After giving a few paragraphs over to a mostly correct discussion of the carcinogens produced in meat by high temperature cooking, Merritt addresses the environmental impact of raising cattle, suggesting that grass-fed animals produce less carbon emissions than kitchen waste in landfills:
"Conventionally raised animals in feed lots eat an enormous amount of grains, instead of grass, changing it's nutritional profile for the worse, and driving a structure that requires a lot of farming. Much of the carbon footprint worldwide from cow products comes from clear-cutting rain forests to create grazing lands, which we don't do here, and we import very little from those countries. It's actually not cow farts that cause methane, but cow burps, but again, landfills easily lead for methane production and it's actually mostly from kitchen waste."Merritt does not provide a single citation for this claim that landfills and kitchen waste produce more methane than livestock. Johnson and Johnson published an article in the Journal of Animal Science entitled "Methane Emissions from Cattle" in 1995. Note that this is from a publication friendly to the livestock industry. It only took me about 10 minutes to find this peer-reviewed paper through an online search. It contains the following table:
According to Johnson and Johnson, landfills contribute 30 million metric tons of methane per year, while livestock and manure together contribute 90 million metric tons, or 3 times the contribution of landfills. Yes, Ms. Merritt, "we" do tend to ignore what "we" disagree with, disregard science and keep marching forward with "our" beliefs, incorrect or not, don't "we"?
"And we don't take into account the transport and production of our vegetables. This study pointed out that 'long-distance air transport, deep-freezing, and some horticultural practices for producing fresh vegetables may lead to environmental burdens for vegetarian foods exceeding those of locally produced organic meat.'"
Merritt refers to this study as the source for her quotation:
It is deeply ironic that Merritt selectively quotes only the last sentence from the abstract of this study and ignores the context, which reads as follows:
Let me emphasize the sentence that is most relevant and inconvenient to Merritt's beliefs:
"Assessment suggests that on average the complete life cycle environmental impact of nonvegetarian meals may be roughly a factor 1.5–2 higher than the effect of vegetarian meals in which meat has been replaced by vegetable protein."Merritt warned us:
"Mostly, though, what 'we' tend to do is ignore what 'we' disagree with, disregard science and keep marching forward with 'our' beliefs, incorrect or not."Next Merritt takes on another claim she dislikes:
"What about the claim that animal protein causes cancer? If that was true, then the traditional Inuit would have had rampant cancer (instead of their .01% rate) because they ate mostly animal protein and fat, as the permafrost kept them from planting vegetables."In keeping with her suggestion to engage in critical thinking, I noticed that Merritt did not provide any scientific reference given to support this claim about the Inuit, something I expect from people who claim to be teaching critical thinking. This could very well be because there is no evidence to support this claim. No traditional Inuit group was ever properly evaluated by modern epidemiological methods for cancer incidence.
Moreover, most scientists are aware that cancer is caused by mutagens that disturb DNA replication. Due to the absence of data indicating that animal protein is mutagenic in and of itself, scientists tend to avoid the claim that "animal protein causes cancer" and prefer to investigate whether or not meat-eating promotes and therefore increases the risk of cancer tumor development. This means that Merritt has created a straw man –– "animal protein causes cancer" –– that has few if any scientific defenders.
However, as pointed out by Travis at Healthy Longevity, the observation of higher risk of cancer among populations eating high meat diets is well documented as far back as 1908. In The Natural History of Cancer William Roger Williams reviewed the medical literature and documents providing evidence from a large number of global populations before the widespread practice of grain-feeding animals, i.e. this data pertained to people eating wild and grass-fed animal products. The data showed that nations with meat-based diets had a significantly higher incidence of cancer compared to nations consuming primarily plant-based diets. Williams also noted that within nations with meat-based diets as the norm, groups that largely abstained from animal foods, such as nuns, monks, slaves and prison inmates had a reduced incidence of cancer.
Williams also reported on the cancer rates of the Argentina Pampas region inhabited by the Gaucho, a nomadic population that subsisted predominantly on organic pasture-raised animal foods:
"Cancer is commoner in Argentina which comprises the Pampas region inhabited by the Gauchos, who for months subsist entirely on beef, and never touch salt than in other parts of South America. On the other hand, among the natives of Egypt, who are of vegetarian habits, and consume immense quantities of salt, cancer is almost unknown."This pattern has not changed in more than 100 years. The positive link between meat consumption and cancer is supported by a very large body of epidemiological and experimental data. Both the American Institute for Cancer Research and the World Cancer Research Fund recommend avoiding or limiting meat to reduce cancer risk.
As for the Inuit, a fact sheet put out by the Inuit themselves states that
- Lung cancer rates among the Inuit are the highest in the world and rising,
- Death rate from strokes is twice as high among Inuit as among all Canadians,
- Inuit women have a COPD death rate 10 times that of Canadian women,
- Cancer is the second leading cause of death among the Inuit, and incidence rates are rising,
- Compared to the general Canadian population, Inuit have a higher incidence of lung, liver, oesophageal, nasopharyngeal, and salivary cancers, but lower rates of breast, prostate, and endometrial cancers, and
- Inuit life expectancy is 13 years less than the general Canadian population and this gap is not closing.
Since breast and prostate cancers are age-related and Inuits tend not to live to the ages at which these cancers manifest, it is hardly surprising that they rarely manifest these cancers. However, some preserved mummies of pre-contact Inuit show evidence of death from nasopharyngeal carcinoma. If cancer was extremely rare among Inuit, as claimed by Merritt, the chances of even one individual with evidence of cancer being preserved would be astronomical. The fact that cases have been found indicates that cancer was not rare among them. The idea that cancer was rare in Inuit at any point in time lacks scientific evidence base.
As I have previously discussed at length, cardiovascular disease, cancer, and obesity are endemic among Mongols living on grass fed animal flesh.
Merritt presents the Inuit as evidence against the link between meat-consumption and cancer, yet it is clear that she never took time to find out whether the claim that the Inuit rarely had cancer has an adequate evidence base. It does not. The idea that Inuits or other groups living on grass-fed animal flesh had low rates of diet-related cancers is not supported by sufficient quality evidence.
Finally, Merritt tries her hand at proving that humans need to eat meat with this sentence:
"Despite what you might read on the Internet regarding being healthy as a vegan/vegetarian, there is negligible amounts of B12 in the soil, you don't convert beta-carotene to vitamin A nearly as well as you might think, vitamin D2 (found in plants) is not as effective as D3, etc."Once again, right when evidence support is required, I notice a lack of any references documenting the implication that B12, vitamin A, and vitamin D deficiencies are unique to people who abstain from meat consumption.
Vitamin B12 is a microbial product, not an animal product. The USDA has reported results of Tufts University research indicating that meat consumption does not provide much protection against B12 deficiency:
"The researchers also expected to find some connection between dietary intake and plasma levels, even though other studies found no association. And they did find a connection. Supplement use dropped the percentage of volunteers in the danger zone--plasma B12 below 185 pmol/L--from 20 percent to 8. Eating fortified cereals five or more times a week or being among the highest third for dairy intake reduced, by nearly half, the percentage of volunteers in that zone--from 23 and 24 percent, respectively, to 12 and 13 percent.
"Oddly, the researchers found no association between plasma B12 levels and meat, poultry, and fish intake, even though these foods supply the bulk of B12 in the diet."[Emphasis added.]
The B12 in meat is bound to proteins making it largely unavailable to many humans. B12 is available directly from microbes that produce it in the form of supplements and fortified foods. This is more bioavailable due to it being free of animal protein binders. This is why the Institute of Medicine (IOM) recommends B12 supplementation to all people, regardless of diet, after the age of 50y.
Merritt provided no evidence to support her implication that conversion of carotenes is insufficient to meet vitamin A needs. In the text Dietary Reference Intakes, the IOM states clearly that carotenes can meet vitamin A needs.
Moreover, promoting non-specific "meat" for vitamin A misses the mark because, except for liver, animal meat is a very poor source of vitamin A activity.
- A 100 g sweet potato provides 22,000 IU of vitamin A activity – 4 times the RDA – and about 1100 retinol activity equivalents (USDAsr27:11508).
- A cup of boiled kale provides almost 18,000 IU of vitamin A activity – 3.5 times the RDA – and 885 retinol activity units (USDAsr27:11234).
- A 100 g serving of whole egg has only 540 IU of vitamin A activity – only 10% of the RDA – and only 160 retinol activity equivalents (USDAsr27:01123).
- A tablespoon of butter (14 g) has the same caloric content as the 100 g of sweet potato, but it provides only 355 IU of vitamin A activity and 97 retinol activity equivalents (USDAsr27:01001).
- A 100 g serving of grass-fed beef strip steak has so little vitamin A activity that the USDA doesn't even list it (USDAsr27:13000).
Vitamin D is not even a primarily nutritional issue, as the primary source of vitamin D for humans is sun exposure. Meat does not contain significant vitamin D. According to vitamin D expert Michael Hollick, M.D., vitamin D deficiency is pandemic among meat-eaters i.e. not unique to people who avoid animal flesh. Nor does a diet based on wild or grass-fed animal flesh provide protection against vitamin D deficiency in the absence of sun exposure. Ancient Thule people (forerunners to the Inuit) ate a meat- and seafood-based diet, and seafood can be rich in vitamin D, but according to Bishop:
"Both osteoporosis and problems with skeletal repair has been described in Thule skeletons, which suggests that a lack of vitamin D (possibly caused by a lack of sunlight) may have increased these problems."
I agree that critical thinking is necessary in nutrition, and as shown above, many of the key claims in Merritt's article whither under critical thinking scrutiny. Ironically, Ms. Merritt has written an article in which she makes many claims that really lack merit, and which perfectly illustrates one of her opening statements:
"Mostly, though, what 'we' tend to do is ignore what 'we' disagree with, disregard science and keep marching forward with 'our' beliefs, incorrect or not."