For The Love Of Food

by | Aug 5, 2011

For The Love of Food

Welcome to Friday’s For The Love of Food, Summer Tomato’s weekly link roundup.

Many must-read articles this week, including the juice on processed OJ, the truth about factory farming and antibiotic resistance and the latest demolition of our favorite vegan propaganda book, The China Study.

Want to see all my favorite links? Be sure to follow me on on Digg. I also share links on Twitter (@summertomato) and the Summer Tomato Facebook fan page. I’m very active on all these sites and would love to connect with you.

Links of the week

What inspired you this week?

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Book Review: Good Calories, Bad Calories

by | Jan 6, 2010

good calories bad calories cover

Good nutrition advice is not easy to come by, but we have to start somewhere.

It is probably obvious to most of you that public education on diet and health is vastly inadequate. We learn virtually nothing in school, and what they do manage to pass on is less-than-useful or just simply wrong.

Advice changes from year to year, sometimes drastically.

Everyone claims to be a nutrition expert, but very few people are actually trained enough to understand the complex and sometimes contradictory findings made by scientists in the field.

But although there are few sources you can trust, some books do stand out as valuable for understanding the basics of health and nutrition. Good Calories, Bad Calories by Gary Taubes is by far the most thorough I’ve found, and is essential reading for anyone who has an honest desire or need to understand how diet impacts health.

Taubes makes a detailed and compelling case that refined carbohydrates are the primary cause of weight gain and “diseases of civilization” such as heart disease, hypertension and diabetes. In my view, any honest and opened-minded scientist would have to largely agree with him.

GradeAGood Calories, Bad Calories is 468 pages and contains over 100 additional pages of references, which is nothing short of astonishing. Taubes explores every aspect of the science behind weight control including the most puzzling and frequently ignored evidence, which he argues is the most important.

Scientists depend on statistics, but have a tendency to ignore outliers which can make data difficult to interpret. Taubes instead points to these anomalies as evidence of flawed or incomplete theories, and suggests that isolated populations (outliers) such as the Inuit and Maasai tribes actually help the most in explaining diet-related health patterns.

Taubes argues extensively (sometimes a bit heavy-handedly) against lazy scientific thinking that relies too heavily on conventional wisdom and the appeal of simple ideas. This point is a major theme of the book and is exemplified by chapter 2, “The Inadequacy of Lesser Evidence.” He goes to great lengths to explain how our tendency not to scrutinize established theories breeds scientific closed-mindedness and can perpetuate flawed ideas for decades.

Ultimately Taubes uses this argument to directly challenge one of the most prevailing health theories in Western civilization: the cholesterol–heart disease hypothesis.

Taubes provides hundreds of pages of data and analysis to make the point that total cholesterol is not a good predictor of heart disease or mortality. Specifically LDL cholesterol is only loosely associated with heart disease (at best) and HDL cholesterol (the higher the better) is a much better indication of vascular health. (Read more: How To Raise Your HDL Cholesterol)

Once this basic premise of health is thrown into question, Taubes carries you through the logic of why a high-fat diet cannot be responsible for heart disease (remember the Inuit) and instead presents why quickly digesting carbohydrates are the most likely culprit.

Fundamental to this argument is the tie between heart disease and type 2 diabetes (along with other “disease of civilization” or metabolic syndrome), which are both inextricably linked to carbohydrate consumption. The logical conclusion from his analysis is that all calories are not created equal, despite what we are told daily by the nutrition community and the media. Understanding the logic behind this argument can fundamentally change the way you approach food and is the best reason to read Good Calories, Bad Calories.

Despite this, Taubes’ book is rarely the first I recommend to people who come to me for nutrition advice. There are a few reasons for this, but the main one is that Good Calories, Bad Calories is not an easy read. I’m a scientist and nutrition data junkie, and this book still took me months to get through (I normally read 4-5 per month). For your average eater, a book like this can quickly become a burden and many people will give up before getting to the good part (about half way through it starts to pick up substantially).

In the first few chapters I was put off by the book’s almost defensive tone. A large part of the first section is dedicated to discrediting the character of a pioneering scientist and father of the dietary fat–heart disease hypothesis, Ancel Keyes. Presumably this depiction is intended as background so the reader understands why Keyes so aggressively disseminates a theory that isn’t fully proven. However, I found the extensive character attack unbecoming for a book espousing science and experimental data, and it seemed unnecessary.

Another reason I resist recommending this book as nutrition advice is that it doesn’t offer much in the way of actual advice. Taubes certainly provides compelling evidence that carbohydrates are best avoided and that dietary fat is safer than presumed, but how much of this knowledge can be translated directly to daily life isn’t clear. For practical advice, I prefer Michael Pollan’s In Defense of Food (based largely on the same data).

Scientifically I also have a few issues with Good Calories, Bad Calories. First, the vast majority of the experiments Taubes cites are early diet studies, many from the turn of the century. While these experiments are clearly important, most of them do not reflect long-term (more than 6 months), real life dietary habits. These studies were also almost entirely dependent upon self-reported dietary intake, which is known to be quite inaccurate.

Much of Taubes’ argument about calories is based on the premise that overweight people eat the same amount or less than lean people. This was once thought to be the case, but recently more thorough studies have shown that overweight and obese people do indeed eat more. The problem is that all people (both lean and obese) are poor judges of food intake, and this discrepancy is largest with the biggest meals consumed. This means people who eat the largest meals tend to underestimate their calories the most, and meal size is correlated with body weight.

This does not mean that I disagree entirely with Taubes’ theory on calories. I was more convinced by the rodent studies he presented where dietary intake was tightly controlled and measured. In some of these, obese animals did seem to eat the same or less than leaner animals (always be careful reading too much into rodent data). Interestingly, the difference in body weight was always accounted for by differences in physical activity, a point I find extremely fascinating.

Since mice obviously do not exercise for the purpose of fitting into skinny jeans, the activity differences observed between obese and lean mice is clearly a fundamental change in metabolism (balance of energy use and intake). If this is true and can be manipulated by diet composition rather than voluntary exercise (which causes overeating), as Taubes suggests, this has tremendous implications for treating obesity and disease through selective diets and metabolic manipulation. I think Taubes makes a strong case for this and it is a point that should be taken very seriously by the scientific community.

My final issue with the book is how the data was presented to seemingly support a diet of almost entirely meat and animal products. While Taubes does not come out directly and say “the healthiest diet is 100% meat,” people without a knack for thinking like a scientist can easily come away with this impression (I’ve seen it).

[note: My guess is this is why I get so many emails from people asking me to help them choose between this book and The China Study (click for review), which both come off as scientific but also as diametric opposites. Personally I do not see a huge conflict between the data presented in the two books, but see it as an issue of interpretation. On this point, my vote goes to Taubes for his superior logic and reasoning.]

My own interpretation of the data presented in this book, however, is not that all carbohydrates are the enemy, but rather that quickly digesting (processed) carbs are the real problem. Taubes never refutes this as far as I could tell, though he does glorify meat-based diets (again remember the Inuit) as the best for optimal nutrition, while belittling the case for a balanced diet. But there is an important difference between saying “meat is good” and “all plants are bad,” which he never directly asserts.

Yet many people still take from this book that a protein and fat-based diet is the healthiest option, which is a flawed interpretation. Vegan diets with no animal products whatsoever can be perfectly healthy, as can largely meat-based diets, and that both are perfectly legitimate is a point that is easily forgotten by the end of Good Calories, Bad Calories.

But while the value of eating plants is an important question for the practical implications of Taubes’ theory of calories, it is not fundamental it.

Summary

Taubes’ meticulous research and overly-thorough analysis represent both the strengths and weaknesses of this book. His case for the role of metabolism in health and obesity, and against the dogma that “a calorie is a calorie” is a tremendous contribution to the field of nutrition. However, this depth can make Good Calories, Bad Calories cumbersome and difficult to read.

Final Grade: A

What did you think of Good Calories, Bad Calories?


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Summer Tomato Book Review: The China Study

by | May 6, 2009

the-china-studyIn the first official book review at Summer Tomato I examine Dr. Colin Campbell’s The China Study. Several readers have asked about this book since I wrote last week about who you can trust for diet advice, so I think it is a perfect subject for my first review.

The China Study was published in 2006 and branded itself as “The most comprehensive study of nutrition ever conducted.” It is written by Colin Campbell, PhD, a highly accomplished scientist that has worked for decades in the fields of nutrition and disease research. It was co-authored by his own son, Thomas Campbell.

Clearly both these men care deeply about health and nutrition and believe the information they provide can relieve a huge proportion of the world’s suffering. Their sincerity is apparent and, given the current dietary trends in Western culture, I am sure their recommendations would help the vast majority of people become healthier. Yet there are several logical flaws in The China Study that prevent me from giving it an A grade. Overall, however, The China Study offers a compelling view of nutrition and health from one of the leaders in the field and is worth reading.

gradebMy biggest disappointment with The China Study is how little of the book is devoted to the study itself–a large ecological-style research project, conducted by Dr. Campbell and his colleagues, examining the relationship between diet and health in rural China. As a scientist, I am a bit of a data junkie and always most impressed by strong statistics and rigorous logic.

UPDATE: [Denis Minger has taken it upon herself to re-analyzed the data from The China Study, and makes it pretty clear that Campbell vastly overstates his case. I agree with everything Denise writes, and every educated person who cares about these findings should read her analysis.]

Only a single chapter in the book is specifically dedicated to the work done in China (Chapter 4), and it conveys little new information. Most of Chapter 4 is spent reiterating the links between diet and chronic diseases such as cancer, heart disease and diabetes, discoveries that did not surprise me in the least. The two most important novel findings reported in the China study are discussed below.

The China Study is divided into four major sections. The first section describes Dr. Campbell’s original research and is the part I enjoyed most. It begins by discussing his work in the Philippines where he discovered a tight link between animal protein consumption and a specific kind of liver cancer induced by aflatoxin, a dangerous poison that is sometimes found in contaminated peanuts. He follows up this work with extensive studies in his U.S. laboratory elucidating the mechanisms of cancer promotion by the main protein found in cow’s milk, casein. Dr. Campbell makes a compelling case that this protein can influence cancer development in the presence of an extremely potent carcinogen, and his work should be taken very seriously in this regard. However,  he goes on to argue that this finding can be generalized to support the view that all animal proteins promote cancer and he recommends they be completely eliminated from your diet.

This was a logical leap I was not able to make after reading through his evidence. What about the benefits of fish for the heart and brain?

As mentioned above, the final chapter of the first section describes the China study. According to the book, the Chinese consume much less fat and protein than Americans, but more fiber and iron. Nothing too surprising there. It also reports that rural Chinese have substantially less heart disease, cancer and diabetes than Americans, but in more urban areas where diets follow more Western patterns the incidences of these diseases are higher. Again, not surprising.

Two pieces of information out of the China study did pique my interest. The first is that participants in the China study reportedly consume more, not fewer calories than Westerners. This was true even for Chinese office workers who consume 30% more calories but weigh 20% less than average Americans.

Part of this difference was accounted for by differences in physical activity (even office workers in China get more exercise than we do), but not all of it. Data in the China study suggests that Chinese have a more active metabolism and burn more calories than typical Americans. Dr. Campbell argues that this is because they eat less animal protein and fat, but the China study is observational (non-intervention) and cannot prove cause and effect.

Isn’t it possible that the Chinese metabolize their food differently because it is less processed than Western food (no matter the source)? From the literature I have read, this seems like a more plausible explanation. But regardless of the reason, the data from China suggests that all calories are not created equal in terms of both health and metabolism. This argues against the dogma offered by most nutrition experts that a calorie is a calorie.

The other surprising finding from the China study is the degree to which blood cholesterol levels predict heart disease. Although most Americans assume there is some connection between blood cholesterol and heart disease, there is still debate regarding how strong this connection is. Data from the China study suggests lower total cholesterol levels decrease risk of heart disease and death. Moreover, the data suggests that optimal cholesterol levels are far below what are recommended by Western medicine (150 mg/dL to 180 mg/dL). The healthiest Chinese had total cholesterol levels from 170 mg/dL to as low as 90 mg/dL. In the China study, lower cholesterol levels were also linked to decreased rates of several cancers. However, some scientists question the validity of this data.

The second section of the book is titled “Diseases of Affluence” and discusses the role of nutrition in the various chronic diseases that plague Western culture. In the third section Dr. Campbell offers his ideal (i.e. vegan) diet. If you are not familiar with the literature on diet and nutrition Dr. Campbell does a decent job going over it, particularly with respect to the role of dairy in prostate cancer, type 1 diabetes and multiple sclerosis. However, most of this information is available in other books that are easier to follow and less dogmatic about the need to eliminate all animal protein from the diet, which even Dr. Campbell admits “has not been absolutely proven” (p. 242).

In my opinion the most incongruous part of The China Study is the fourth section titled, “Why Haven’t You Heard This Before?” Here Dr. Campbell goes into great detail explaining the ties between food industries, drug companies, our government and, sadly, our education system from K1 through post graduate medical residency. While this section of The China Study is fascinating, it dilutes the primary nutrition message of the book with a disconcerting illustration of the roles money and politics play in our education system. But despite the jumbled message, the facts provided in this final section of The China Study are eye-opening and may be the best reason to read the book. It is shocking to learn how deeply opposed to and uneducated most of the medical community is about the life-saving benefits of dietary intervention for chronic diseases. Personally I would have liked this section to be an entirely separate book, as I would recommend it more often.

To summarize, The China Study provides an interesting but not entirely compelling argument for adopting a vegan diet. It also offers a hefty dose of skepticism about who you can trust for nutrition advice, particularly when it comes to the medical community. Overall I enjoyed reading the book and, despite my criticisms, agree with most of it. I have no doubt that for the vast majority of Americans Dr. Campbell’s advice and recommendations would be immensely beneficial.

Final Grade: B

Please add your thoughts on The China Study in the comments below.

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