Diana Rodgers and Robb Wolf have built careers learning about nutrition and food systems, then teaching others what they’ve learned. They’ve distilled a lot of that acquired wisdom in their book Sacred Cow. I’m assessing the book from several perspectives–
- Is Sacred Cow a good book to recommend to the average person? It is and I will, although the nutrition section had too many acronyms without a crib sheet. I largely agreed with the practical “Eat Like a Nutrivore” chapter, which is what a lot of readers will want to use to change their lives. Diana’s and Robb’s listing of their daily diets are almost entirely things I would eat, except maybe for the sweet potatoes. There are a couple of caveats, which I’ll discuss below.
- Was it worthwhile for me to read, since I’m a biologist who has researched a lot of this and created a website about nutrition? Yes, I learned some biology I didn’t already know, plus some very interesting concepts, like green/blue/gray water.
- Did it cover all the biology I would have liked? No, it missed some important science, but what they did cover was reasonably accurate. They do make some assumptions about a future of cheap energy I don’t agree with. That’s ironic, because what they advocate will be very, very important for the future I envision.
The book begins by presenting the provocative claim that meat has been made a scapegoat for nutrition and food supply problems of the Industrial (what I call the Hydrocarbon) Age. They talk a bit about human biology and evolution. They point out that the human digestive tract structure, with a small colon, shorter large intestine, and a larger small intestine, is best suited to higher nutrient density foods. To digest the leafy and fibrous parts of plants, one needs a large colin like our cousins the gorillas. The discussion of what our body structure implies regarding a human-optimal diet is good. The discussion of our evolutionary past is not strong, but none of the other authors whose work I’ve read do any better. Genus Homo evolved as persistence hunters, which they don’t mention. Here’s an overview of our lineage’s evolution– http://www.nutritionequation.org/biology/people-a-new-animal/. While I agree that humans are omnivores, the evidence from the mammoth kill sites indicates we used to eat an awful lot of meat. That’s discussed in Pat Shipman’s The Invaders: How Humans and Their Dogs Drove Neanderthals to Extinction.
The chapter on whether we’re eating too much meat (they say we’re not..) moves into a well reasoned discussion of protein requirements. I learned a bit there. In the chapter that asks the question “Does Meat Cause Chronic Disease?” there’s an excellent exposition of the problems with correlational studies, which aren’t causational studies, even though they are often treated as such. They do a good job of demonstrating that there are no valid studies linking meat consumption to disease. I liked their take on the work of Ancel Keys, a researcher whose fixed ideas and strong will drove poor research and acceptance of that work by others. Keys was intent on proving that eating fat from meat made you fat and sick, and on getting policies instituted at the national level that supported his ideas. Not only did he present correlation as causation, he cherry-picked which results to present.
Modern, less biased researchers, most notably Dr. Richard Johnson and his small army of collaborators, have demonstrated a true mechanism by which the real villain, the sugar fructose, can cause obesity, diabetes, heart disease, high blood stokes, and other pathologies that are collectively termed metabolic syndrome. Diana and Robb do not discuss the role of sugar in metabolic syndrome. From my communications with Diana, I don’t think they were aware of Johnson’s work. In fairness, I should say that other writers on the topic usually point to the glucose/insulin hypothesis relative metabolic syndrome. Johnson et al’s fructose/vasopressin hypothesis is a better fit with a detailed mechanism elucidated. Either way, their discussion of problems caused by processed foods, while good and valid, misses the point that it’s the sugar in those food-like substances causing metabolic syndrome. Other writers have pointed out that when Senator McGovern’s Select Committee on Nutrition and Human Needs published the Dietary Goals for the United States in 1977, it resulted in the low fat diet recommendations. That drove the USDA’s misguided nutrition programs, and instant creation of a processed food industry. Specifically, the processing removed the fat, replacing it with sugar to make the food palatable. Here’s my discussion of that transition– http://www.nutritionequation.org/society/good-intentions-bad-policy/.
Chapters 5 & 6, which explore the nutritional qualities of meat, especially beef, and plant derived foods, are strong and useful. I learned (or was reminded) that heme iron from meats is absorbed and used well, while the iron from plant sources is not. They do a very good exposition of all the deficiency diseases possible from a diet solely based on plants without supplementation. In contrast, there are and were groups of people who survived and thrived on diets of mostly or entirely animals or animal products. This makes the point that if supplementation is necessary that suggests we didn’t evolve eating a diet of strictly plants. They point out that plants do provide many useful nutrients and minerals. They do not advocate, or practice, a diet narrowly focussed on meat or animal products like eggs and cheeses.
Part II, the Environmental Case for Better Meat, is a great set of lessons in applied ecology and honest environmental analysis, perhaps the strongest section of the book. They cite a study making the very believable claim that 80% of the world’s 3,170 gigatons of carbon is stored in the soil. About 60% of that soil is covered by grasslands of varying levels of aridity. If a grassland is plowed into row crops, vast amounts of carbon are released, and the soil itself tends to erode away. They point out that grasses have evolved to regrow after their above ground parts are eaten. In fact the grassland deteriorates if that doesn’t happen. We can’t eat that grass. Only herbivores, in particular ruminants like cattle and bison, have digestive tracts that can turn cellulose and other plants materials into nutrients we can use. For proper grassland maintenance, the ruminants must be kept in groups and regularly moved to new pasture, mimicking their behavior when they faced threats from predators. If left to their own devices, the grazers tend to stay in one place eating preferred plants until those are gone, not just trimmed down. While keeping as much land area as possible grassland with ruminants is optimal relative carbon storage, if crops are grown there are practices like no-till farming which dramatically reduce carbon emissions. If grazing animals can be added to that system, consuming crop wastes and other plants with proper management practices, all the better.
Of course what’s easiest for current industrial farming operations in the United States is to use energy and petrochemicals derived from cheap oil and natural gas to plant hundreds to thousands of acres of government subsidized commodity crops like corn, wheat, and soybeans on bare dirt tilled with giant tractors. Then drench those acres with the fossil fuel derived ammonia, herbicides, pesticides, plus mined phosphorus. The commodity crops have been bred to maximize yield under those conditions. Diana and Robb explain this well, clearly showing that what drives the Concentrated Animal Feeding Operations (CAFO) many of us find disturbing ecologically, nutritionally, and ethically is the industrial scale production of those commodity crops using the cheap oil. They do point out that cattle get 87% of their lifetime nutrition from grass, even if they are finished (final weight gain…) on corn in a feedlot. Pigs and chickens on the other hand spend their lives in captivity, being fed corn and byproducts of industrial farming. They spelled out that on pre-industrial farms, which had tilled land, fallow land, and pasture land, the cattle ate the grass and crop waste, while the chickens and pigs ate the wastes from the cows and humans. The manure from the animals was mixed back into the soil to provide nitrogen for the plants, rather than using external inputs.
DIana and Robb do the most thorough job of debunking spurious claims regarding the high Green House Gas (GHG) production and high water use by cattle I’ve seen so far. I was well aware that the GHG claims had been debunked by others and retracted by the UN agency making them. Sacred Cow’s detailed discussion of methodical problems and flat misstatements is very useful for understanding the details. They introduced the concept of Green/Blue/Gray water. Green water is essentially what falls from the sky. That water would fall on a pasture whether cows ate the grass or not. Blue water is surface and subsurface waters that are diverted and/or pumped to water crops and people. Gray water is what drains away with some load of chemicals/materials it acquired in the field or in our water systems. That can cause the huge dead zones in the oceans where rivers like the Mississippi empty out.
In Part III, Diana and Robb tackle ethical concerns squarely. It’s a difficult topic, but I thought their discussion was balanced and nuanced. In natural ecosystems, animals perish in many ways, often unpleasant. We have the choice to use humane methods to kill the animals we eat. Diana sits on the board of Animal Welfare Approved, which works to improve living conditions and ensure humane handling techniques at slaughterhouses. One aspect of industrial farming I hadn’t considered is that small creatures perish in fairly high numbers. They ask “is a rodent life less valuable than a cow life”? I don’t want to try to paraphrase this section’s discussion. Read the book and form your own opinions.
They also discuss some of the origins of ideas regarding not eating meat. There are in fact strong religious elements. Most notably in their exposition, the Seventh Day Adventist (SDA) church’s co-founder Ellen G. White had an anti-meat vision in 1863. The SDA is still actively involved in promoting plant-only diets, often through organizations with secular sounding names. That’s their right, but that’s not based on biology. There is some discussion regarding hostility and anger by vegans toward non-vegans, like the authors. In my own experience, I’ve seen closed belief system aspects in my conversations with adherents to veganism and environmentalism that complicate rational discussions of science and its application to our welfare and our future. I can’t remember any other nutrition writers taking on this topic quite so directly.
Part IV, What We Can Do first discusses redesigning food production, then focuses on individual diet. They provide a number of recommendations for shifting agriculture towards a more sustainable model that doesn’t require outside inputs of energy and chemicals while degrading soils. Those sorts of approaches involve more active management and more people. One interesting analysis they did was to calculate how much acreage would be needed of grasslands to shift all cattle to grass without corn finishing in feedlots. It was quite doable. They talk about localizing food production. They make me want to plant edible things in our yard, not just columnar cacti.
This is where I encountered the one claim I would consider incorrect, and it’s not about food. They brush off the idea of “peak oil”, assuming high oil production indefinitely. A detailed discussion is beyond the scope of this review, but there’s no question that when oil is extracted from a “conventional” reserve like the giant field Ghawar in Suadi Arabia, that field has a production curve with a peak, then a decline. One can calculate the aggregate of all oil fields, which have been well mapped around the world. Production from conventional oil fields in the U.S. did indeed peak in the early 1970s. There are indications that worldwide conventional production plateaued circa 2005 or so. There are large “unconventional” oil reserves, most notably the enormous tar sand deposits in Canada and Venezuela, and the tightly bound oil and natural gas in sandstones in North Dakota, Texas, and elsewhere. A significant fraction of the oil in those deposits is extractable, but only at higher costs with more environmental impacts. For example, the tar sands must be cooked to extract the oil, releasing more GHGs. We will most definitely see a future in which oil gets harder to extract and more expensive, maybe fairly soon (within 10 years). Unfortunately for public understanding of the issue, the actual price of oil is not related to how much resource is left in the ground, only to how short term production capacities and storage compare to demand. One place to learn more about these topics is on industry analyst Gail Tverberg’s blog Our Finite World. Here’s her analysis of the nuanced reality of peak oil.
I bring this up in part because other writers, like economist Jeff Rubin, have projected that as oil gets harder to obtain, that will drive localization of economies and food production. That positions the Sacred Cow as a guide to success in making those shifts. Their dismissal of possible oil resource limits is thus a bit puzzling.
The final chapter, “Eat like a Nutrivore” is a pretty reasonable guide to changing diet for the better. As I expected from their discussions of tracking protein, that’s the starting point of their guide. They very strongly advocate getting away from overly processed foods. Both are Paleo Diet adherents, although they have made earlier comments to the effect that they are somewhat diet agnostic. Briefly, the Paleo Diet was invented by exercise physiologist Loren Cordain, who I’ve corresponded with. Loren promoted the idea that we should try to approximate the diet of our hunter-gatherer ancestors. That’s a reasonable approach, but it’s based on studies of extant hunter-gatherers. Until about 15,000 years ago, when we (and maybe some climate change effects) drove a lot of big herbivores like the mammoths to extinction, we ate bigger creatures more of the time, with larger fat stores, probably eating the fatty parts of the kill first. It’s likely we spent most of the time eating a diet low in carbohydrates, high in fat, with moderate protein levels. That flipped our metabolism over to “ketosis”, wherein we use ketone bodies derived from fat for normal metabolism. A number of researchers are studying how this works, perhaps most notably Jeff Volek at Ohio State, Dominic D’Agostino at University of South Florida, and Tim Noakes at University of Capetown (South Africa). I’ve interacted with all three. Jeff Volek has commented to me that the Paleo Diet is usually too high in carbohydrates to cause a flip to ketosis. Conversely, in fruit and berry season we are wired to gorge on those until they are gone. Those are high in sugars, particularly fructose. We dropped out of ketosis temporarily. What we call metabolic syndrome is a normal mechanism in vertebrates for converting those sugars into fat, which is how animals store energy. Our modern diet puts many people into extreme metabolic syndrome all the time, which causes pathology.
The diet they suggest is reasonable and will improve one’s health, but the gaps in the discussion relative the metabolic effects of sugar consumption and ketosis create some potential pitfalls. Those should not stop people from trying the plan. Cardiologist Dietmar and his nutritionist wife Elizabeth have created the Diet of Hope. The program assesses patients, then puts them on a medically supervised modified Atkins diet. They are closely followed for six weeks, somewhat analogous to the Diana and Robb’s 30 Day “Sustainable Nutrivore” Challenge. There is open-ended follow up. Most people who enter the program are overweight, almost always with qualifying medical conditions that trigger health insurance coverage of the program cost. The Diet of Hope has treated tens of thousands of patients with a 72% success rate measured as maintenance of weight loss after a year. The 28% who are not successful are those who cannot stick with the diet. Dietmar has warned me that if someone is taking a medication like insulin for diabetes and starts a diet that drastically drops sugar consumption, as does their program and what I can discern of the 30 day challenge, it’s important to drop medication levels so people don’t go into excessive insulin induced low blood sugar, which can be very dangerous. Diet of Hope works closely with the referring physicians, of which there are hundreds, on medication levels, especially during that first six weeks. Dietmar has told me they have vegetarians in the program, but not vegans.
Looking at Diana and Robb’s accounts of what they eat, it’s possible both are in ketosis, although they don’t actually tally their carbohydrate consumption. When someone drops their carb intake below their personal trigger level, their body starts to flip to ketosis. They dump their glycogen stores, along with some amount of water weight. The basic transition takes about 10-14 days, although the athletes I know have found it may take several weeks before things settle down and they get the performance improvements they are looking for. It’s pretty handy during a long endurance bout not to be able to get low blood sugar. I’ve run for almost 33 hours in my carby days, having to consume sugars for most of the run to keep my blood sugar up.
One concern for me with their diet plan would be the potential for phasing in and out of ketosis. My friends and acquaintances who have done carb binges, which started to drop them out of ketosis, have found it pretty unpleasant. There is a lot of variation in individual trigger levels. Those of us who have been able to do advanced endurance efforts on high carb diets before we discovered low carb, high fat nutrition have a higher trigger level, on the order of 100 grams per day. Loren Cordain’s Paleo website makes the blanket statement that the trigger level is about 50 grams/day, which he probably took from Jeff Volek and Stephen Phinney’s research on trigger levels for average non-athletes. He also says he doesn’t recommend sustained ketosis, which those of us who have been in ketosis for years find a bit puzzling. I would also comment that if a diet is too high in protein, Rick Johnson has commented that it triggers a metabolic response in the liver similar to high fructose diets. He specifically fingers the yeasts in beer. Beer belly is a form of fatty liver disease, which is also one of the components of metabolic syndrome.
Despite my caveats, I strongly recommend Sacred Cow for anyone who’s interested in diet, health, and the health of the planet. As I worked on this review, looking at the book in my Kindle reader, I was reminded how information dense it is. I may need to reread some sections, especially in the nutrients and sustainable agriculture sections, to better implant some details. That’s unusual for me. Also, I need to look at some of their interesting references, like the one tallying carbon storage worldwide.