Re-Assessing Nutrition, Part 2 (“Correlation does not equal causation” only goes so far)

At times, nutrition can seem like economics: get 3 nutritionists in a room, and you’re going to get 6 different opinions.

Anyone with an opinion can cite one or more studies that give them credibility. If you want to eat a high-fat/high protein diet, there are studies that appear to support you. If you want a low-fat/high-carb diet, there are plenty of studies that appear to support you. If you want something in between, there are studies that appear to support you.

The problem is that when we assess the question–“what is the best dietary regimen”–we often don’t qualify it appropriately. The proper question is, “What is the best dietary regimen for my given activity level and health situation?

We also have to qualify it–as economists do–by indicating ceteris paribus (all things being equal). This is because some people have food allergies, others have metabolic issues, others have Type 1 Diabetes, and so forth. Dietary needs can vary. This is perhaps the main factor that makes the field of nutrition a difficult one.

Given that a third of Americans are obese, the common question is, “What is the best dietary regimen for getting off these #$%! pounds???”

If you have heart ailments, a better question may be, “What is the best dietary regimen for keeping my ticker tocking?”

If you are an athlete, the question might be, “What dietary regimen puts me in the best position to get my best performance?”

For me, the proper question is, “What is the best dietary regimen that minimizes my risks of cancer, heart disease, and dementia?”

In the world of sports–especially those that require high endurance–the science is indicative of high complex carbs/low-moderate protein/low-moderate fat. In the endurance world, vegans are not uncommon. While weightlifters and bodybuilders are still steeped in protein-mania–and science appears to support that approach in those sports that are dependent on strength–the rest of the sports world is not as big on steak and eggs as was the case 30 years ago.

But what if you are not a full-time athlete? What if you don’t run marathons? What if you’re only getting a couple hours of cardio per week? What if you just want to stay healthy, keep the excess pounds off, keep autoimmune diseases in check (i.e. arthritis) and mitigate your risk of cancer?

What if you’re like me: you want to do all those things, but still do the occasional 100-mile bike ride, or half-marathon, or half-Ironman?

It’s fair to ask what the science says about all of this.

Enter two excellent reads–Prevent and Reverse Heart Disease, by Caldwell Esselstyn, MD and The China Study, by T. Colin Campbell.

Esselstyn did his own 20-year study while he was a surgeon at the Cleveland Clinic. He took a set of patients with advanced heart disease–many of them had already had bypass surgery and/or angoplasty–and put them on a strict vegan diet. He monitored the results over a 20 year period. The results were breathtaking: those patients overwhelmingly were able to avoid further cardiac incidents, and in many cases the heart disease was even reversed.

The skeptics, however, can look at Esselstyn’s work and punch holes in it: (a) there was no “control” group, (b) it’s only one isolated study, (c) perhaps Esselstyn was personally biased.

Even then, the results are what they are. It’s a Cleveland Clinic study. Esselstyn’s credentials are impeccable. Any bias-centered criticism of Esselstyn would have to be balanced against his record of intellectual integrity as a physician.


(a) Esselstyn has provided ACTIONABLE INTELLIGENCE for those who have heart disease and wish to avoid future surgeries and/or premature death.
(b) Esselstyn has provided ACTIONABLE INTELLIGENCE for those who wish to mitigate their risks of heart disease and complications thereof.

And that’s what we’re all about here: ACTIONABLE INTELLIGENCE.

And that brings me to Campbell and The China Study (TCS).

In TCS, Campbell makes a more comprehensive case for a vegan nutritional regimen. He begins by highlighting his scientific work, analyzing carcinogens (aflatoxin), and nutritional approaches in various undeveloped nations. It was in the course of studying the dynamics of aflatoxin that Campbell stumbled into the dilemmas between plant versus animal proteins. His first two chapters are foundational in this respect.

As Campbell made his case for the vegan approach–highlighting links between animal-based diets and a myriad of ailments–the skeptic in me often screamed, “Correlation does not equal causation!” Everyone with a bare-bones-basic knowledge of statistics knows that.

Unfortunately, while that statement is indeed true, it only goes so far. And every physician worth a penny knows that.

Want an example? Type 2 Diabetes.

While we have a plethora of scientific evidence correlating obesity with Type 2 Diabetes, we still have not verified conclusively that obesity causes Type 2 Diabetes. At the same time, (a) every good physician in America will tell diabetes patients to get their weight down and keep it down; and (b) when a Type 2 Diabetic drops the pounds, the diabetes usually goes away.

Correlation does not equal causation, but–if the correlation is strong enough, that constitutes ACTIONABLE INTELLIGENCE.

If dropping the pounds eliminates the diabetes, does it really matter–for your own health–if causation has not been established?

If you have the choice between eating a vegan diet or enduring painful, costly, and debilitating heart surgery, does it matter if causation has not been established?

Now some of Campbell’s proposals are controversial. For example, we have not determined that a vegan diet will keep you from getting Alzheimer’s, or Rheumatoid Arthritis, or Multiple Sclerosis.

Still, given that medical treatments for those diseases have not shown much promise, if eating less meat and jacking up the veggie intake might mitigate that risk–assuming it is a risk that you feel passionate about–then Campbell has given you ACTIONABLE INTELLIGENCE.

Correlation isn’t causation, but it is useful in forming testable hypotheses. At the very least, Campbell provides a nice basis for a myriad of such hypotheses.

Another aspect of TCS that is refreshing is the way Campbell provides insight into how the government has influenced nutrition education in ways that are harmful to Americans. While Campbell strikes me as a left-of-center type, his analysis is without respect for political parties and is more centered on the fascistic, incestuous relationship between lobbyists for the food industry, government agencies, and lawmakers. Campbell also provides a stark picture of how government influences nutrition: from the Department of Agriculture to the Department of Education, and how the food lobby has fought to stack the advisory panels with their own hired guns.

One does not have to be a vegan to appreciate the fact that the government’s recommended daily allowances are too fat-heavy and do not include enough fruits, whole grains, and vegetables. And Campbell provides an honest assessment as to why those recommendations are what they are.

At the end of the day, Campbell is no hack. He’s an honest scientist who has gone where the evidence took him. That evidence has led to many correlations, some of which have statistical significance.

We don’t have causation established, but we have the same smoking guns that appear to be showing up whenever a malady gets studied. You can decide, “Correlation does not equal causation, so I don’t care.” And that is your business. Or you can decide that you have enough inherent risk that this intel is worth acting on. That is also your business.

I would argue that it is not the government’s place to tell you what you must do, but it is on you to decide for yourself if Campbell and Esselstyn are on the money.

Maybe there’s a risk that is important to you; perhaps not. Does everyone need to go vegan? Not by a long shot. Is a total vegan approach required to mitigate the risks highlighted by Campbell? No (although Esselstyn insists on it himself.) Do we need government telling us to go vegan? No.

But if mitigating your risks of cancer, heart disease, stroke, autoimmune disorders, Type 2 Diabetes, and perhaps dementia is important, then it’s worth a look.

My only gripe with TCS: Campbell provides no vegan recipes. He does a wonderful job extolling the virtues of the vegan approach, but does a crappy job of providing a portrait of how appealing and enjoyable it can be. (Esselstyn, however, devotes a large part of his book to providing recipes.)

Campbell, however, has started a larger discussion: to what extent ought government be involved in the promotion of nutrition?

I’ll try to tackle that one next week.

6 thoughts on “Re-Assessing Nutrition, Part 2 (“Correlation does not equal causation” only goes so far)

  1. the level of gov’t involvement in nutrition is sickening and definitely not in our best interest.

    i do know that teachers observe what children bring from home to eat in their snacks and lunches, so i have always made sure to pack a healthy balance of foods in my girls’ lunches regardless of whether i know they will eat it or not. they eat healthy anyway, but i make sure to pack what the teachers would observe as ‘healthy.’

    when my Youngest had her three-year-evaluation for special ed this past year, part of that eval is a comprehensive q&a that her teachers must complete … and her teacher specifically noted that Mom sends her heathy snacks and lunches to school. this is now on her permanent record.

  2. i was reading diet info on my daughter’s most recent diagnosis just yesterday, and it stated that while the gov’t does not necessarily ‘endorse’ these diets for this diagnosis, parents still try them with great success.

    we don’t need a gov’t study to tell us what foods do to us when we eat them.

  3. @Ame
    Along those lines, in our attempts to take a more vegan approach to our diet, I’m realizing it is very difficult. So many recipes call for meat and/or dairy. It’s ingrained in us that we “need” these foods to survive.

    This will be an adventure, that’s for sure.

  4. you might want to ck out blogs for more info … there are many ‘nutrition’ blogs where they love to post recipes or answer questions

  5. you might be interested in Nourishing Traditions … a book, and many blog about it. i have a friend following this and the GAPS diet and having tremendous success in her family – both can easily be found thru googling

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