Have you ever had wagyu beef? Wagyu is the breed of cattle from which the infamous kobe beef is derived: highly marbled, impossibly tender. I mean, this stuff is ridiculous. I’ve had wagyu steak that you could cut with your fork, no knife required. It can actually be too melt-in-your-mouth tender for me. I’m not saying I like meat tough and stringy, but I like to know I’m actually eating something’s muscle tissue. At PrimalCon 2011 , the wagyu steaks were grass-fed , grilled perfectly, and not overly tender or excessively marbled. Just great. I suspect they were a wagyu-angus crossbreed, which is true for most wagyu raised in the US. I can get behind wagyu like that.
So why am I talking about wagyu beef (why not?) and what does all have to do with “human interference factor”? Well, last week I happened across an interesting science story in a newspaper. It was your typical science reporting – kind of vague and prone to make broad proclamations based on limited evidence – but the study being referenced got my attention. In it, Australian researchers compared the postprandial inflammatory markers  of patients after eating either 100 grams of wild kangaroo meat or 100 grams of Australian wagyu beef.
C-reactive protein and interleukin-6 were the main markers studied. CRP  is a general assessment of systemic inflammation , and chronically elevated CRP is strongly linked with metabolic syndrome, heart disease, cancer, obesity, and lots of other fun stuff. You basically want your CRP as low as possible. IL-6 is an inflammatory cytokine  that the body makes during the inflammatory response using tissue omega-6 fat . It can be useful in the right quantities, but harmful in excess (like, in folks with too much omega-6 in their diet and body tissues). After eating wild kangaroo meat, CRP and IL-6 levels were unchanged in subjects, while eating the wagyu spiked both IL-6 and CRP levels. One hour after eating wagyu, CRP was “significantly” spiked, and after two hours it had dropped to an “insignificant” elevation. The researchers called this evidence of a “low-grade, systemic, immune reaction” to “new” or “modern” meat. In other words, the meat with a high “human interference factor” was more inflammatory than the wild food.
Human interference factor refers to the amount and type of artifice used in the raising of an animal for food. Was the animal raised in a manner closely congruent with its wild nature, or did a human tinker with the feed ratios and living conditions in a way that conflicted with the animal’s nature? Obviously, there are varying degrees of HIF, some of which are necessary if we want regular access to animal products without having to hunt , fish, or forage. Domestication of livestock is the most basic interference we can run, and it can be done well. Joel Salatin  is a proponent of rotational grazing, which involves moving the herd of cattle to a new patch of pasture every day. This attempts to mimic the nomadic nature of wild ruminants by giving them access to fresh vegetation each day and preventing overgrazing in a single area. It’s a type of HIF, but a gentle type that pretty closely resembles nature and produces healthy animal fat and protein. Now, what about Australian wagyu? What kind of HIF is involved with wagyu production? Quite a bit.
First, the feed. All Australian cattle get a good amount of pasture time, but the wagyu are shifted onto intensive grain-feeding for the last 200-500 days of their lives. They typically receive a mix of corn, wheat, alfalfa, and barley grains, whereas many standard Australian cattle finish out their lives on grass. So the meat in the study was certainly grain-finished, and intensively so. Grain is a pretty unnatural diet for cattle. A diet of cultivated corn and wheat is highly unnatural and only possible with human interference.
Second, the genetic stock. Wagyu is a selectively bred strain of cattle, genetically predisposed to develop greater marbling with higher amounts of unsaturated fatty acids (both monounsaturated and polyunsaturated) and lower levels of saturated fat. These traits were no accident; they were cultivated over centuries. Most other cows (even feedlot cows) have higher levels of saturated  and monounsaturated fat, with very little polyunsaturated fat .
Third, the living conditions. Australian wagyu live the latter part of their lives in the feedlot, which isn’t the traditional norm for ruminants.
Overall, wagyu is a breed with some novel nutritional characteristics that you won’t encounter much in the wild. But you know what? This isn’t just about the wagyu. It’s about the human intervention, and it’s about whether animal products raised with a high level of HIF deserve greater scrutiny.
Human interference was a problem, this time, but what about with other animal products, like eggs? Researchers from Tel Aviv  looked at the fatty acid composition of conventional eggs from hens fed typical hen stuff: soy, corn (and its oil), sunflower, and safflower. In other words, hens that lived on omega-6 and whose tissues were imbued with the stuff. They then gathered a group of new hens, yet to lay eggs. These innocent, feathered maidens hadn’t eaten the typical omega-6 fare growing up, so their tissues were largely free of omega-6 fatty acids. Instead of corn and soy feed, these hens ate wheat, barley, and sorghum, plus an antioxidant blend. Eggs from both groups were fed to human subjects at a rate of two eggs a day per person for several weeks. At the end, people eating the conventional eggs had 40% more oxidized LDL than people eating the eggs low in omega-6. Oxidized serum LDL is strongly associated with atherosclerosis (and it’s probably a causative relationship).
HIF mattered with eggs, but in a different way. Both groups of hens experienced HIF. For the conventional group, human interference did what you’d expect: crammed the birds full of grains and fats they’d never encounter in a wild setting, resulting in nutritionally poor, downright unhealthy eggs that you’d be better off avoiding altogether. For the experimental group, however, HIF was mild, gentle. It maintained and supported the animal’s nature, rather than stifled and perverted it. Selectively using modern grains  and antioxidant  supplementation, it promoted and enabled an “ancestral” level of omega-6 in the animals’ tissue and in the eggs themselves. Both rearing methods were “unnatural” and only possible with human ingenuity, but the experimental method was a perfect example of positive human interference. It was interference designed to achieve the natural, ancestral endpoint, and it worked. Pastured and wild chickens eat wild plants, seeds, bugs, and grain (most of which contain various antioxidant phytochemicals and low levels of omega-6); the experimental hen diet recognized this and got to a similar place using slightly contrived methods.
I don’t think eating is supposed to be a stressful, inflammatory experience that induces a systemic immune response. I don’t think eating two eggs a day for a couple weeks is supposed to oxidize your LDL . That the wagyu meal was stressful on a clinical level and that the omega-6 enriched eggs negatively affected blood lipids  both suggest that human interference factor is a valuable tool for making good food choices. Meaning, how we raise food, even if we mean well but especially when we try to circumvent or ignore the realities of that animal’s evolutionary past, can negatively affect how that food interacts with our metabolism. But, as grass-fed beef , pastured eggs , and this whole Primal Blueprint  thing have all shown, when an animal is raised in a manner congruent with its nature, good things generally happen. Health, fatty acid profile , flavor (have you tasted a longterm Primal eater? tender and delicious!), micronutrient density (we’re also fairly high in selenium), and plenty of parameters that we have yet to even understand or identify, all improve.
And that’s the crux of this stuff: there’s a lot we don’t know. We’re still learning – we’ll always be learning, if we’re doing it right – and we need tools to which we can refer in times of uncertainty. I mean, you gotta eat something today. What’s it gonna be? How are you going to decide? Are those pastured eggs worth a couple extra bucks a dozen? To me, yeah. I defer to nature and prefer foods with a low human interference factor. It’s worked well so far. But you have to decide for yourself.
Human interference factor appears to be a budding area of study, so this is a topic I’ll be revisiting as I become aware of more research.
What do you folks think? Is human interference factor a good heuristic for determining the safety and suitability of animal foods? If I’ve missed an example that shows something different, let me know! Thanks for reading.