Book Review: "The Human Diet: Its Origins and Evolution"

Book Review: "The Human Diet: Its Origins and Evolution"

I recently read this book after discovering it on another health site. It's a compilation of chapters written by several researchers in the fields of comparative biology, paleontology, archaeology and zoology. It's sometimes used as a textbook. 

I've learned some interesting things, but overall it was pretty disappointing. The format is disjointed, with no logical flow between chapters. I also would not call it comprehensive, which is one of the things I look for in a textbook. Here are some of the interesting points:

• Humans in industrial societies are the only mammals to commonly develop hypertension, and are the only free-living primates to become overweight.
• The adoption of grains as a primary source of calories correlated with a major decrease in stature, decrease in oral health, decrease in bone density, and other problems. This is true for wheat, rice, corn and other grains.
• Cranial capacity has also declined 11% since the late paleolithic, correlating with a decrease in the consumption of animal foods and an increase in grains.
• According to carbon isotope ratios of teeth, corn did not play a major role in the diet of native Americans until 800 AD. Over 15% of the teeth of post-corn South American cultures showed tooth decay, compared with less than 5% for pre-corn cultures (many of which were already agricultural, just not eating corn).
• Childhood mortality seems to be similar among hunter-gatherers and non-industrial agriculturists and pastoralists.
• Women may have played a key role in food procurement through foraging. This is illustrated by a group of modern hunter-gatherers called the Hadza. While men most often hunt, which supplies important nutrients intermittently, women provide a steady stream of calories by foraging for tubers.
• We have probably been eating starchy tubers for between 1.5 and 2 million years, which precedes our species. Around that time, digging tools, (controversial) evidence of controlled fire and changes in digestive anatomy all point to use of tubers and cooked food in general. Tubers make sense because they are a source of calories that is much more easily exploited than wild grains in most places.
• Our trajectory as a species has been to consume a diet with more calories per unit fiber. As compared to chimps, who eat leaves and fruit all day and thus eat a lot of fiber to get enough calories, our species and its recent ancestors ate a diet much lower in fiber.
• Homo sapiens has always eaten meat.

The downside is that some chapters have a distinct low-fat slant. One chapter attempted to determine the optimal diet for humans by comparing ours to the diets of wild chimps and other primates. Of course, we eat more fat than a chimp, but I don't think that gets us anywhere. Especially since one of our closest relatives, the neanderthal, was practically a carnivore.
They consider the diet composition of modern hunter-gatherers that eat low-fat diets, but don't include data on others with high-fat diets like the Inuit. 

There's some good information in the book, if you're willing to dig through a lot of esoteric data on the isotope ratios of extinct hominids and that sort of thing.

Book Review: Blood Sugar 101

Book Review: Blood Sugar 101

I just finished reading "Blood Sugar 101" by Jenny Ruhl. It's a quick read, and very informative. Ruhl is a diabetic who has taken treatment into her own hands, using the scientific literature and her blood glucose monitor to understand blood sugar control and its relationship to health. The book challenges some commonly held ideas about diabetes, such as the notion that diabetics always deteriorate.

She begins by explaining in detail how blood glucose is controlled by the body. The pancreas releases basal amounts of insulin to make glucose available to tissues between meals. It also releases insulin in response to carbohydrate intake (primarily) in two bursts, phase I and phase II. Phase I is a rapid response that causes tissues to absorb most of the glucose from a meal, and is released in proportion to the amount of carbohydrate in preceding meals. Phase II cleans up what's left. 

In a person with a healthy pancreas, insulin secretion will keep blood glucose under about 130 mg/dL even under a heavy carbohydrate load. The implications of this are really interesting. Namely, that blood glucose levels will not be very different between a person who eats little carbohydrate, and one who eats a lot, as long as the latter has a burly pancreas and insulin-sensitive tissues.

Most Americans don't have such good control however, hence the usefulness of low-carbohydrate diets. This begs the question of why we lose blood sugar control. Insulin resistance seems like a good candidate, maybe preceded by leptin resistance. As you may have noticed, I'm starting to think the carbohydrate per se is not the primary insult. It's probably something else about the diet or lifestyle that causes carbohydrate insensitivity. Grain lectins are a good candidate in my opinion, as well as inactivity. 

Diabetics can have blood glucose up to 500 mg/dL, that remains elevated long after it would have returned to baseline in a healthy person. Ruhl asserts that elevated blood sugar is toxic, and causes not only diabetic complications but perhaps also cancer and heart disease. 

Heart attack incidence is strongly associated with A1C level, which is a rough measure of average blood sugar over the past couple of months. It makes sense, although most of the data she cites is correlative. They might have seen the same relationship if they had compared heart attack risk to fasting insulin level or insulin resistance. It's difficult to nail down blood sugar as the causative agent. More information from animal studies would have been helpful.

Probably the most important thing I took from the book is that the first thing to deteriorate is glucose tolerance, or the ability to pack post-meal glucose into the tissues. It's often a result of insulin resistance, although autoimmune processes seem to be a factor for some people. Doctors often use fasting glucose to diagnose diabetes and pre-diabetes, but typically you are far gone by the time your fasting glucose is elevated! 

I like that she advocates a low-carbohydrate diet for diabetics, and lambasts the ADA for its continued support of high-carbohydrate diets.

Paleopathology at the Origins of Agriculture

Paleopathology at the Origins of Agriculture

In April of 1982, archaeologists from around the globe converged on Plattsburgh, New York for a research symposium. Their goal:

...[to use] data from human skeletal analysis and paleopathology [the study of ancient diseases] to measure the impact on human health of the Neolithic Revolution and antecedent changes in prehistoric hunter-gatherer food economies. The symposium developed out of our perception that many widely debated theories about the origins of agriculture had testable but untested implications concerning human health and nutrition and our belief that recent advances in techniques of skeletal analysis, and the recent explosive increase in data available in this field, permitted valid tests of many of these propositions.

In other words, they got together to see what happened to human health as populations adopted agriculture. They were kind enough to publish the data presented at the symposium in the bookPaleopathology at the Origins of Agriculture, edited by the erudite Drs. Mark Nathan Cohen and George J. Armelagos. It appears to be out of print, but luckily I have access to an excellent university library.

There are some major limitations to studying human health by looking at bones. The most obvious is that any soft tissue pathology will have been erased by time. Nevertheless, you can learn a lot from a skeleton. Here are the main health indicators discussed in the book:

• Mortality. Archaeologists are able to judge a person's approximate age at death, and if the number of skeletons is large enough, they can paint a rough picture of the life expectancy and infant mortality of a population.
• General growth. Total height, bone thickness, dental crowding, and pelvic and skull shape are all indicators of relative nutrition and health. This is particularly true in a genetically stable population. Pelvic depth is sensitive to nutrition and determines the size of the birth canal in women.
• Episodic stress. Bones and teeth carry markers of temporary "stress", most often due to starvation or malnutrition. Enamel hypoplasia, horizontal bands of thinned enamel on the teeth, is probably the most reliable marker. Harris lines, bands of increased density in long bones that may be caused by temporary growth arrest, are another type.
• Porotic hyperostosis and cribra orbitalia. These are both skull deformities that are caused by iron deficiency anemia, and are rather creepy to look at. They're typically caused by malnutrition, but can also result from parasites.
• Periosteal reactions. These are bone lesions resulting from infections.
• Physical trauma, such as fractures.
• Degenerative bone conditions, such as arthritis.
• Isotopes and trace elements. These can sometimes yield information about the nutritional status, diet composition and diet quality of populations.
• Dental pathology. My favorite! This category includes cavities, periodontal disease, missing teeth, abscesses, tooth wear, and excessive dental plaque.

The book presents data from 19 regions of the globe, representing Africa, Asia, the Middle East, Europe, South America, with a particular focus on North America. I'll kick things off with a fairly representative description of health in the upper Paleolithic in the Eastern Mediterranean. The term "Paleolithic" refers to the period from the invention of stone tools by hominids 2.5 million years ago, to the invention of agriculture roughly 10,000 years ago. The upper Paleolithic lasted from about 40,000 to 10,000 years ago. From page 59:

In Upper Paleolithic times nutritional health was excellent. The evidence consists of extremely tall stature from plentiful calories and protein (and some microevolutionary selection?); maximum skull base height from plentiful protein, vitamin D, and sunlight in early childhood; and very good teeth and large pelvic depth from adequate protein and vitamins in later childhood and adolescence...
Adult longevity, at 35 years for males and 30 years for females, implies fair to good general health...
There is no clear evidence for any endemic disease.

The level of skeletal (including cranial and pelvic) development Paleolithic groups exhibited has remained unmatched throughout the history of agriculture. There may be exceptions but the trend is clear. Cranial capacity was 11% higher in the upper Paleolithic. You can see the pelvic data in this table taken from Paleopathology at the Origins of Agriculture. 

There's so much information in this book, the best I can do is quote pieces of the editor's summary and add a few remarks of my own. One of the most interesting things I learned from the book is that the diet of many hunter-gatherer groups changed at the end of the upper Paleolithic, foreshadowing the shift to agriculture. From pages 566-568:

During the upper Paleolithic stage, subsistence seems focused on relatively easily available foods of high nutritional value, such as large herd animals and migratory fish. Some plant foods seem to have been eaten, but they appear not to have been quantitatively important in the diet. Storage of foods appears early in many sequences, even during the Paleolithic, apparently to save seasonal surpluses for consumption during seasons of low productivity.

As hunting and gathering economies evolve during the Mesolithic [period of transition between hunting/gathering and agriculture], subsistence is expanded by exploitation of increasing numbers of species and by increasingly heavy exploitation of the more abundant and productive plant species. The inclusion of significant amounts of plant food in prehistoric diets seems to correlate with increased use of food processing tools, apparently to improve their taste and digestibility. As [Dr. Mark Nathan] Cohen suggests, there is an increasing focus through time on a few starchy plants of high productivity and storability. This process of subsistence intensification occurs even in regions where native agriculture never developed. In California, for example, as hunting-gathering populations grew, subsistence changed from an early pattern of reliance on game and varied plant resources to to one with increasing emphasis on collection of a few species of starchy seeds and nuts.

...As [Dr. Cohen] predicts, evolutionary change in prehistoric subsistence has moved in the direction of higher carrying capacity foods, not toward foods of higher-quality nutrition or greater reliability. Early nonagricultural diets appear to have been high in minerals, protein, vitamins, and trace nutrients, but relatively low in starch. In the development toward agriculture there is a growing emphasis on starchy, highly caloric food of high productivity and storability, changes that are not favorable to nutritional quality but that would have acted to increase carrying capacity, as Cohen's theory suggests.

Very interesting.

One of the interesting things I learned from the book is that Mesolithic populations, groups that were halfway between farming and hunting-gathering, were generally as healthy as hunter-gatherers: 

...it seems clear that seasonal and periodic physiological stress regularly affected most prehistoric hunting-gathering populations, as evidenced by the presence of enamel hypoplasias and Harris lines. What also seems clear is that severe and chronic stress, with high frequency of hypoplasias, infectious disease lesions, pathologies related to iron-deficiency anemia, and high mortality rates, is not characteristic of these early populations. There is no evidence of frequent, severe malnutrition, so the diet must have been adequate in calories and other nutrients most of the time. During the Mesolithic, the proportion of starch in the diet rose, to judge from the increased occurrence of certain dental diseases [with exceptions to be noted later], but not enough to create an impoverished diet... There is a possible slight tendency for Paleolithic people to be healthier and taller than Mesolithic people, but there is no apparent trend toward increasing physiological stress during the mesolithic.

Cultures that adopted intensive agriculture typically showed a marked decline in health indicators. This is particularly true of dental health, which usually became quite poor.

Stress, however, does not seem to have become common and widespread until after the development of high degrees of sedentism, population density, and reliance on intensive agriculture. At this stage in all regions the incidence of physiological stress increases greatly, and average mortality rates increase appreciably. Most of these agricultural populations have high frequencies of porotic hyperostosis and cribra orbitalia, and there is a substantial increase in the number and severity of enamel hypoplasias and pathologies associated with infectious disease. Stature in many populations appears to have been considerably lower than would be expected if genetically-determined maxima had been reached, which suggests that the growth arrests documented by pathologies were causing stunting... Incidence of carbohydrate-related tooth disease increases, apparently because subsistence by this time is characterized by a heavy emphasis on a few starchy food crops.

Infectious disease increased upon agricultural intensification:

Most [studies] conclude that infection was a more common and more serious problem for farmers than for their hunting and gathering forebears; and most suggest that this resulted from some combination of increasing sedentism, larger population aggregates, and the well-established synergism between infection and malnutrition.

There are some apparent exceptions to the trend of declining health with the adoption of intensive agriculture. In my observation, they fall into two general categories. In the first, health improves upon the transition to agriculture because the hunter-gatherer population was unhealthy to begin with. This is due to living in a marginal environment or eating a diet with a high proportion of wild plant seeds. In the second category, the culture adopted rice. Rice is associated with less of a decline in health, and in some cases an increase in overall health, than other grains such as wheat and corn. In chapter 21 of the book Ancient Health: Bioarchaeological Interpretations of the Human Past, Drs. Michelle T Douglas and Michael Pietrusewsky state that "rice appears to be less cariogenic [cavity-promoting] than other grains such as maize [corn]."

One pathology that seems to have decreased with the adoption of agriculture is arthritis. The authors speculate that it may have more to do with strenuous activity than other aspects of the lifestyle such as diet. Another interpretation is that the hunter-gatherers appeared to have a higher arthritis rate because of their longer lifespans:

The arthritis data are also complicated by the fact that the hunter-gatherers discussed commonly displayed higher average ages at death than did the farming populations from the same region. The hunter-gatherers would therefore be expected to display more arthritis as a function of age even if their workloads were comparable [to farmers].

In any case, it appears arthritis is normal for human beings and not a modern degenerative disease. 

And the final word:

Taken as a whole, these indicators fairly clearly suggest an overall decline in the quality-- and probably in the length-- of human life associated with the adoption of agriculture.

Book Review: Dangerous Grains

Book Review: Dangerous Grains

Dangerous Grains is about the health hazards of gluten grains. It's co-written by James Braly, an M.D. who specializes in food allergies, and Ron Hoggan, a celiac patient who has written widely on the subject. 

Celiac disease is a degeneration of the intestinal lining caused by exposure to gluten. Gluten sensitivity is a broader term that encompasses any of the numerous symptoms that can occur throughout the body when susceptible people eat gluten. The term gluten sensitivity includes celiac disease. Gluten is a protein found in wheat, its close relatives (kamut, spelt, triticale), barley and rye. Wheat is the most concentrated source. 

Dangerous Grains is a good overview of the mountain of data on celiac disease and gluten sensitivity that few people outside the field are familiar with. For example, did you know: 

• An estimated one percent of the U.S. population suffers from celiac disease.
• Approximately 12 percent of the US population may suffer from gluten sensitivity, according to blood antibody tests.
• Gluten can damage nearly any part of the body, including the brain, the digestive tract, the skin and the pancreas. Sometimes gastrointestinal symptoms are absent.
• Both celiac and other forms of gluten sensitivity increase the risk of a large number of diseases, such as type 1 diabetes and cancer, often dramatically.
• The majority of people with gluten sensitivity are not diagnosed.
• Most doctors don't realize how common gluten sensitivity is, so they rarely test for it.
• Celiac disease and other symptoms of gluten sensitivity are easily reversed by avoiding gluten.

That's an enormous disease burden coming from a single type of food. I suspect the true incidence may actually be higher, although it's difficult to be sure. 

Dangerous Grains also discusses the opioid-like peptides released from gluten during digestion. Opioids are powerful drugs, such as heroin and morphine, that were originally derived from the poppy seed pod. They are strong suppressors of the immune system and quite addictive. There are no data that conclusively prove the opioid-like peptides in gluten cause immune suppression or addiction to wheat, but there are some interesting coincidences and anecdotes. Celiac patients are at an increased risk of cancer, particularly digestive tract cancer, which suggests that the immune system is compromised. Heroin addicts are also at increased risk of cancer. Furthermore, celiac patients often suffer from abnormal food cravings. 

I know several people who have benefited greatly from removing gluten from their diets. Anyone who has digestive problems, from gas to acid reflux, or any other mysterious health problem, owes it to themselves to try a gluten-free diet for a month. Gluten consumption has increased quite a bit in the U.S. in the last 30 years, mostly due to an increase in the consumption of processed wheat snacks. I believe it's partly to blame for our declining health. Wheat has more gluten than any other grain. Avoiding wheat and all its derivatives is a keystone of my health philosophy. 

Another notable change that Sally Fallon and others have pointed out is that today's bread isn't made the same way our grandparents made it. Quick-rise yeast allows bread to be fermented for as little as 3 hours, whereas it was formerly fermented for 8 hours or more. This allowed the gluten to be partially broken down by the microorganisms in the dough. Some gluten-sensitive people report that they can eat well-fermented sourdough wheat bread without symptoms. I think these ideas are plausible, but they remain anecdotes to me at this point. Until research shows that gluten-sensitive people can do well eating sourdough wheat bread in the long term, I'll be avoiding it. I have no reason to believe I'm gluten sensitive myself, but through my reading I've been convinced that wheat, at least how we eat it today, is probably not healthy for anyone.

I'm not aware of any truly healthy traditional culture that eats wheat as a staple. As a matter of fact, white wheat flour has left a trail of destruction around the globe wherever it has gone. Polished rice does not have such a destructive effect, so it's not simply the fact that it's a refined carbohydrate. Hundreds, if not thousands of cultures throughout the world have lost their robust good health upon abandoning their traditional foods in favor of white flour and sugar. The medical and anthropological literature are peppered with these stories. 

Overall, the book is well written and accessible to a broad audience. I recommend it to anyone who has health problems or who is healthy and wants to stay that way!

Book Review: The Primal Blueprint

Book Review: The Primal Blueprint

Mark Sisson has been a central figure in the evolutionary health community since he began his weblog Mark's Daily Apple in 2006. He and his staff have been posting daily on his blog ever since. He has also written several other books, edited the Optimum Health newsletter, competed as a high-level endurance athlete, and served on the International Triathlon Union as the anti-doping chairman, all of which you can read about on his biography page. Mark is a practice-what-you-preach kind of guy, and if physical appearance means anything, he's on to something.

In 2009, Mark published his long-awaited book The Primal Blueprint. He self-published the book, which has advantages and disadvantages. The big advantage is that you aren't subject to the sometimes onerous demands of publishers, who attempt to maximize sales at Barnes and Noble. The front cover sports a simple picture of Mark, rather than a sunbaked swimsuit model, and the back cover offers no ridiculous claims of instant beauty and fat loss.

The drawback of self-publishing is it's more difficult to break into a wider market. That's why Mark has asked me to publish my review of his book today. He's trying to push it up in the Amazon.com rankings so that it gets a broader exposure. If you've been thinking about buying Mark's book, now is a good time to do it. If you order it from Amazon.com on March 17th, Mark is offering to sweeten the deal with some freebies on his site Mark's Daily Apple. Full disclosure: I'm not getting anything out of this, I'm simply mentioning it because I was reviewing Mark's book anyway and I thought some readers might enjoy it.

The Primal Blueprint is not a weight loss or diet book, it's a lifestyle program with an evolutionary slant. Mark uses the example of historical and contemporary hunter-gatherers as a model, and attempts to apply those lessons to life in the 21st century. He does it in a way that's empowering accessible to nearly everyone. To illustrate his points, he uses the example of an archetypal hunter-gatherer called Grok, and his 21st century mirror image, the Korg family.

The diet section will be familiar to anyone who has read about "paleolithic"-type diets. He advocates eating meats including organs, seafood, eggs, nuts, abundant vegetables, and fruit. He also suggests avoiding grains, legumes, dairy (although he's not very militant about this one), processed food in general, and reducing carbohydrate to less than 150 grams per day. I like his diet suggestions because they focus on real food. Mark is not a drill sergeant. He tries to create a plan that will be sustainable in the long run, by staying positive and allowing for cheats.

We part ways on the issue of carbohydrate. He suggests that eating more than 150 grams of carbohydrate per day leads to fat gain and disease, whereas I feel that position is untenable in light of what we know of non-industrial cultures (including some relatively high-carbohydrate hunter-gatherers). Although carbohydrate restriction (or at least wheat and sugar restriction) does have its place in treating obesity and metabolic dysfunction in modern populations, ultimately I don't think it's necessary for the prevention of those same problems, and it can even be counterproductive in some cases. Mark does acknowledge that refined carbohydrates are the main culprits.

The book's diet section also recommends nutritional supplements, including a multivitamin/mineral, antioxidant supplement, probiotics, protein powder and fish oil. I'm not a big proponent of supplementation. I'm also a bit of a hypocrite because I do take small doses of fish oil (when I haven't had seafood recently), and vitamin D in wintertime. But I can't get behind protein powders and antioxidant supplements.

Mark's suggestions for exercise, sun exposure, sleep and stress management make good sense to me. In a nutshell: do all three, but keep the exercise varied and don't overdo it. As a former high-level endurance athlete, he has a lot of credibility here. He puts everything in a format that's practical, accessible and empowering.

I think The Primal Blueprint is a useful book for a person who wants to maintain or improve her health. Although we disagree on the issue of carbohydrate, the diet and lifestyle advice is solid and will definitely be a vast improvement over what the average person is doing. The Primal Blueprint is not an academic book, nor does it attempt to be. It doesn't contain many references (although it does contain some), and it won't satisfy someone looking for an in-depth discussion of the scientific literature. However, it's perfect for someone who's getting started and needs guidance, or who simply wants a more comprehensive source than reading blog snippets. It would make a great gift for that family member or friend who's been asking how you stay in such good shape.

Book Review: The End of Overeating

Book Review: The End of Overeating

The End of Overeating was written based on the personal journey of Dr. David A. Kessler (MD) to understand the obesity epidemic, and treat his own obesity in the process.  Dr. Kessler was the FDA commissioner under presidents George HW Bush and Bill Clinton.  He is known for his efforts to regulate cigarettes, and his involvement in modernizing Nutrition Facts labels on packaged food.  He was also the dean of Yale medical school for six years-- a very accomplished person. 

Dr. Kessler's book focuses on 1) the ability of food with a high palatability/reward value to cause overeating and obesity, 2) the systematic efforts of the food industry to maximize food palatability/reward to increase sales in a competitive market, and 3) what to do about it.  He has not only done a lot of reading on the subject, but has also participated directly in food reward research himself, so he has real credibility.  The End of Overeating is not the usual diet book. 

As you may realize if you've been following this blog for a while, I think food reward is a major determinant of food intake and a contributing factor to obesity.  It's great to see a book that tackles the topic in the popular press, making it accessible to nearly anyone. 

Dr. Kessler starts out by making the case that sugar, salt and fat cause overeating, and that much of the food industry is based around finding novel ways of packing more of these three ingredients into food to maximize palatability.  He repeats an idea that is common in the food reward literature, that reward and pleasure circuits in the brain override circuits that are designed to stabilize body fat stores (body fat homeostasis), establishing a higher 'settling point'.  I have a minor quibble with this; my belief is that excessive reward may partially override homeostatic circuitry, but it also re-regulates it to defend body fatness at a higher level (a hypothesis shared by certain other obesity researchers).  This may be one of the reasons why overweight/obese people 'defend' a higher fat mass, making weight loss difficult and often destined for failure.

A second problem is that Dr. Kessler didn't do a good job of clearly defining reward and palatability.  He seems to confuse palatability with reward at times:

In everyday language, we call food palatable if it has an agreeable taste.  But when scientists say a food is palatable, they are referring primarily to its capacity to stimulate the appetite and prompt us to eat more.  Palatability does involve taste, of course, but, crucially, it also involves the motivation to pursue that taste.  It is the reason we want more.

Actually, I believe the first sentence had it right.  Palatability is the hedonic, or pleasure value of food.  The motivation to pursue food, "the reason we want more", is due to the reward or reinforcing value of the food.  As far as I know, those are the accepted scientific definitions, although some people do use the term reward more broadly to include hedonic value*.  The two concepts are admittedly easy to confuse, because they overlap and in practice often travel together.  I have to believe that Dr. Kessler understands what reward and palatability are, but he does not convey that understanding effectively in the book. 

Another quibble I have is that he focuses too persistently on sugar, fat and salt.  These are clearly major reward factors, but so are calorie density, certain textures, free glutamate, starch and a few others.  In addition, many other cues (particularly flavors) become rewarding as they are associated with those factors.  Some of these are mentioned or implied (except starch, a major omission in my opinion), but the book is focused primarily on sugar, fat and salt throughout.  I suspect he wanted to keep it simple for clarity's sake, but that decision did sacrifice some amount of completeness. 

The book goes into considerable detail about the remarkable science of food engineering by processed food manufacturers.  The goal, as one executive bluntly put it for Dr. Kessler, "is to get you hooked", by creating food stimuli that stimulate reward circuits as much as possible.  It's a science and an art, where refined ingredients and synthetic flavorings are the palette they use to paint foods.  One of the great strengths of the book is the large number of interviews Kessler did with food industry executives-- and the candid information they provided.  The End of Overeating is worth the cover price for that alone. 

In the latter part of the book, Kessler provides practical advice for fat loss based on the food reward ideas.  It mostly revolves around learning how to wean yourself off junk food, using an approach similar to drug rehab strategies.  I think there are a lot of useful ideas there, but some people may need a more focused and comprehensive strategy to regain leanness in my opinion.

A final gentle critique is that the book is not very focused or well organized.  It often rambles on with long study descriptions, quotes and redundant information.  I think it would have been more effective if it were a concise and focused 200 pages (the book was 320).  It would have benefited from a thorough and assertive editor.

Overall however, I liked the book.  It contains a lot of good information and practical advice from a credible source, and to my knowledge it's the only book focused on food reward in the popular press.  I recommend it to anyone who wants to expand their knowledge on food reward, and the manner in which the processed food and restaurant industries employ it.  I've added it to my list of recommended books in the sidebar.

Melissa McEwen also commented on The End of Overeating here.  


*By this definition, reward has a hedonic (pleasure) component, a motivational component, and a learning component.  Researchers sometimes call the motivational and hedonic elements "wanting" and "liking", respectively (1).  I may switch to this definition at some point, because it's widely accepted and easier than saying "reward" and "palatability" separately every time I want to mention these ideas.

Book Review: Salt, Sugar, Fat

Book Review: Salt, Sugar, Fat

Michael Moss is a Pulitzer prize-winning journalist who has made a career writing about the US food system.  In his latest book, Salt, Sugar, Fat: How the Food Giants Hooked Us, he attempts to explain how the processed food industry has been so successful at increasing its control over US "stomach share".  Although the book doesn't focus on the obesity epidemic, the relevance is obvious.  Salt, Sugar, Fat is required reading for anyone who wants to understand why obesity is becoming more common in the US and throughout the world.

The greatest strength of Salt, Sugar, Fat is its detailed insider perspective on the workings of the processed food industry.  Similar to Dr. David Kessler's book The End of Overeating, Moss interviewed a number of high-level current and former food industry executives, as well as industry and academic scientists, who were remarkably candid in explaining how the food industry gets people to buy its food.  He also dove deeply into historical records that explain how the processed food industry became the behemoth it is today.

In contrast to The End of Overeating, Moss places a greater emphasis on advertising and societal changes that have driven the demand for processed food, rather than focusing exclusively on the palatability/reward value of the food itself (and the cues that make us crave it).  The picture that emerges is that the processed food industry is an extremely sophisticated system that uses every tool in its tool belt (including quite a bit of science) to get you to purchase and consume its food.  Companies do what they can to exploit the hard-wired food selection systems in our brains.

Rather than demonizing the processed food industry, for most of the book Moss takes a fairly balanced view of its motives and actions (though he does demonize at certain times).  One of the most interesting and unexpected aspects of the book is the seemingly sincere efforts some processed food manufacturers have made to try to improve the public health impact of their products, including imposing limits on the salt, sugar, and fat content of their foods.  Nevertheless, as Moss relates, the free market dictates that these efforts typically fail or are eviscerated, because companies that impose constraints on their products are quickly out-competed by companies that don't.  Adding insult to injury, publicly traded companies are savaged by Wall street investors if they attempt to consider anything other than profit in their recipes and marketing.

Part 1: Sugar

Part 1 begins with an exploration of a phenomenon that we all intuitively recognize: people like sugar, and they seek it out.  To put that into scientific terms, sugar is palatable and rewarding.  As Moss explains in a chapter titled "exploiting the biology of the child", this is particularly true of children, who have a hard-wired preference for sugar from birth.

The title of chapter two is also particularly telling: "how do you get people to crave?"  This chapter is about the highly scientific efforts to determine the "bliss point" for combinations of sugar, flavorings, and other ingredients that maximize the enjoyment and "craveability" (reward value) of soda and other foods-- ultimately driving purchase and consumption behaviors.

The next few chapter launch into a fascinating history of the US cereal industry, from its modest roots with John Harvey Kellogg's unsweetened corn flakes, to his brother Will's betrayal by turning corn flakes into a sweetened cereal and ultimately founding Kellogg foods, to the modern cereal market in which some cereals are more than half sugar by weight.  

Also in this part comes one of Moss's scientific errors.  He states that the late Harvard physiologist Dr. Jean Mayer is "credited with discovering how the desire to eat is controlled by the amount of glucose in the blood and by the brain's hypothalamus, both of which are greatly influenced by sugar".  Dr. Mayer was a proponent of the "glucostatic hypothesis of appetite", in other words, that appetite is regulated primarily by blood glucose concentration (and/or glucose utilization), and that food intake subserves glucose homeostasis.  Although Dr. Mayer made a number of important contributions to the understanding of food intake and blood glucose regulation by the brain, many of which still stand today, the glucostatic hypothesis was largely discarded decades ago because it is too simplistic and it doesn't square with a number of basic observations (1).  Furthermore, I'm not sure what Moss meant when he wrote that blood glucose and the hypothalamus are "greatly influenced by sugar".  On a gram-for-gram basis, starch influences blood glucose more than sucrose, and as far as I know sugar itself has not been shown to have any special effects on the hypothalamus relative to other types of carbohydrate.

Part 2: Fat

This chapter begins with an interesting historical discussion of fat including Aristotle's view of it, followed by a small scientific error: Moss states that no taste receptor for fat has been found.  In fact, taste receptors for fat have been clearly identified in rodents, and emerging evidence is suggesting that the same may be true in humans (2, 3).  The research in humans is ongoing, but I would not state confidently at this point that no fat receptor has been found.

Part 2 touches on the neuroscience research that is used to exploit your hard-wired food selection behaviors.  This quote from Unilever scientist Dr. Francis McGlone was particularly telling:

There is not a lot to be gained from asking people why they like something, because they don't bloody know.  These are very low-level processes that drive these fundamental behaviors, and I'd gotten into [functional MRI brain] imaging because it's a good way to sort of bypass the mouth, if you like, so you can see just what neural processes are underpinning a behavior.

They are using fMRI to design ever more appealing foods, looking directly at the activation of reward/pleasure regions rather than relying on peoples' imprecise accounts of what they are feeling.  This is what consumers are up against.

In chapter 10, Moss assails the USDA for its alleged failure to effectively restrain the country's consumption of fat, and particularly saturated fat (even undermining its own nutrition guidelines by aggressively promoting cheese consumption).  I understand that opinions differ on the dietary fat and saturated fat issue, but Moss's perspective seems stuck in the 90s when he discusses the dangers of fat, cheese, and meats.  To be fair, I agree wholeheartedly that added fats and cheeses in processed foods can contribute to overeating and obesity, but I view the issue as more nuanced than the black-and-white picture Moss paints.  Moss's discussion of how we came to eat so much cheese in the US (hint: it's added liberally as an ingredient in processed foods) is very interesting.

Part 3: Salt

Salt is another palatability/reward factor that is used by processed food manufacturers to get people to purchase their food.  Without salt, many processed foods taste awful, with strong cardboard, metallic, and bitter flavors.  Chapter 12, "people love salt", contains a nice discussion of the reward value of salt, including reference to a paper titled "Salt Craving: the Psychobiology of Pathogenic Sodium Intake", which describes people who are literally addicted to salt (4):

Salt, the authors concluded, was similar in this way to "sex, voluntary exercise, fats, carbohydrates and chocolate, in its possessing addictive qualities".

Of course, most people are not literally addicted to salt, and never will be, but the fact that it can be addictive in some people emphasizes its significant reward value.  Its reward value is precisely why it is a ubiquitous additive in commercial food.

This chapter contained another scientific error, gleaned from the epidemiologist Dr. Eric Rimm, who allegedly said the following about potato chips:

"The starch is readily absorbed," he told me.  "More quickly even than a similar amount of sugar.  The starch, in turn, causes the glucose levels in the blood to spike, and this is a concern, in relation to obesity."

Really!  I don't mean to pick on Dr. Rimm specifically, because this idea is widely repeated, but it has no scientific basis.  First, potato chips have a relatively low glycemic load because they're mostly fat-- in other words, they don't spike blood glucose as much as an equivalent serving of plain potatoes or bread.  Second, increases in blood glucose if anything promote satiety, not hunger (5). Some would say that rapid glucose spikes are followed by dips, and that these dips promote hunger, but again although small post-meal dips are sometimes observed following the consumption of rapidly digested carbohydrate, these have not been convincingly linked to increased hunger or food intake.  Furthermore, these dips would be less likely to occur following potato chips than following an equivalent serving of plain potatoes or whole wheat bread, due to the smaller glycemic load of the chips.  Blood glucose spikes don't explain why potato chips favor overeating and fat gain.  People overeat potato chips because they're calorie-dense and they taste awesome.

Conclusions

Salt, Sugar, Fat is a very valuable book for anyone seeking to understand the current obesity and health crises in the affluent world.  The book's greatest strength is its in-depth insider account of how the processed food industry wins American stomach share by clever marketing, maximizing palatability/reward, and maximizing convenience.  The book's main weakness is Moss's brief but sometimes shaky scientific excursions.  Fortunately, these do not undermine the main thrust of the book.