The most common argument used to attack the benefits of a diet that includes animal proteins is the notion that ‘the evidence shows vegetarianism is better.’ Here’s why that’s all wrong.

“The Big Fat Surprise” Part IV.

  • Monday: An interview with author Nina Teicholz, noting that the decades-long claim that foods with fat are unhealthy has little basis in science.
  • Tuesday: Science and common sense took a beating 40 years ago, as official nutritional policy converged around an “eat less fat” prescription.
  • Wednesday: Understanding the fatal flaws in the research that led Americans to cut back on animal foods in the mistaken belief it would lead to better health.
  • Today: A promising way for industry to leverage positive change in how people relate to all the media reports indicting meat-eating and livestock production — it’s called positioning.

It can be awfully frustrating trying to respond to industry critics who criminalize “industrial agriculture” and who demonize the consumption of animals foods is the way they always trot out study after study headlining meat’s (alleged) role in “causing” obesity, heart disease, cancer or diabetes.

I’ve had about a million such “discussions” myself over the years, and inevitably, it comes down to a “diet vs. diet” comparison, wherein veggie advocates start reciting evidence for the superiority — culinary and nutritionally — of plant-based foods over meat, milk and eggs.

There is a very effective way to refute such positioning, however, and author Nina Teicholz does an elegant job of explaining exactly that, especially in her chapter analyzing the rise to prominence of the Mediterranean diet.

With all the attention that diet’s “branding” has received, the hundreds of cookbooks published, the litany of famous chefs utilizing its basic components — and the appeal of what would seem to be an idyllic life on a Greek island (although the Eurocrisis has scotched that fantasy) — it would be a rare person living under the proverbial rock who did not know that the diet emphasizes vegetables, whole grains and cheese, while limiting poultry and seafood and along with virtually excluding meat and milk.

But it does include olive oil. Lots of olive oil.

As it grew in popularity during the 1990s, the Mediterranean diet was perfect for chefs creating those fancy pasta-veggies-and-meat bowls swimming in some spicy sauce. Which is pretty much the entire menu at Olive Garden.

Plus, vegetarian believers could point to the longevity that Greeks seem to enjoy as ammo to berate Americans gorging themselves on “hunks of animal flesh.” It was the perfect foil to what could be broadly characterized as the “Western Diet.” And since by exclusion anyone following the diet would not be eating a whole lot of processed products and fast-foods, there are undeniable health benefits for its adherents.

In fact, nutrition researcher Ancel Keys, who authored the infamous Seven Countries study that spawned the whole low-fat movement (and it’s worth the price of “The Big Fat Surprise” just to understand how he single-handedly altered the course of USDA’s official nutrition guidance), so admired not only the diet but the lifestyle and the landscape of the Mediterranean region that he actually built himself a villa near Naples, Italy, as a second home. His outsized influence in promoting the Mediterranean diet helped give it prominence and provided culinary coherence to the low-fat gospel.

Only one problem. It turns out that the Greeks, the Italians and the residents of the island of Crete who actually lived on the diet were consuming 40 percent or more of their daily calories from fat, thanks to the liberal amounts of olive oil added to every meal. That ran totally counter to the official recommendations that limited fat calories to 20 percent of the total diet.

That didn’t stop its advocates, Teicholz writes, including Walter Willett, a medical doctor and Professor of Epidemiology and Nutrition at Harvard University School of Public Health, who simply altered USDA’s 1990s version Food Pyramid to include an entire level on the pyramid labeled “Olives Oil and Olives.”

Like it was a separate food group.

Much of the buzz over the Mediterranean diet was actually fueled by marketing funded through European governments and commodity groups. “Spain and Greece supported olive oil promotions,” Teicholz writes, “and the European Union reportedly spent a $215 million over roughly a decade on olive-oil-related public relations, including scientific ‘bulletins’ about olive oil.”

That kind of change can leverage a lot of people’s dietary choices.

Ultimately, the fat calories in the Mediterranean diet mattered less to its advocates than its reliance on carbohydrates, rather than animal protein, for the majority of its meals. And as a restaurant entrée, a seafood-and-pasta dish does make for a nice alternative to chicken and burgers. People don’t eat “nutrition,” they eat food, and when you listen to the vegetarian preachers, that’s one of the applause lines in their sermons: Vegetarian meals taste great! Who needs meat?

Clues vs. proof

Now, here’s the key point to be made about the Mediterranean diet and virtually every other vegetarian alternative — and it’s also the most compelling argument against an insistence that we shouldn’t be eating meat: The healthfulness of a low-fat diet has not been demonstrated scientifically. The effectiveness of such diets has only been researched in epidemiological studies.

Here’s why that matters. A scientific study that would “prove” the impact of any diet would need to create a significantly sized study group and a similarly large control group, both of which must be matched in terms of gender, age, health status, preexisting conditions, etc. Then the study group would eat the recommended diet over a period of years, while the control group would eat some other diet for the same time period. Then the researchers compare outcomes.

You can see that such a set-up would be almost impossible. A majority of people wouldn’t stick to a restrictive diet, and there would be a raft of variables — the amount of exercise, stress levels, genetic predispositions — that could never be controlled. With food and lifestyles, the best that research can provide are associations, parallels, suppositions to be drawn from even the most rigorous dataset — because they’re based on epidemiology, not experimentation.

Epidemiological studies are based on observed patterns among a defined population. Such studies are important for tracking disease outbreaks, for defining emerging risk factors and for detailing the scope of medical or health-related outcomes.

In other words, epidemiology quantifies what happened, it doesn’t explain why. That requires scientific experiments set up under highly controlled conditions, so that confounding variables are excluded and only the effect of the intervention being studied is recorded. And that’s just not possible when it comes to people and food.

So whenever some self-appointed health guru claims that their preferred diet has been “proven” to accelerate weight loss/provide a fantastic energy boost/protect you from disease, their evidence comes from observing cultures, lifestyles and dietary patterns, not as the result of scientific studies replicated under controlled conditions.

Science provides a cause-and-effect explanation for whatever phenomena being studied. Epidemiology gives us, at best, clues about how certain variables are associated. The latter is an excellent tool for quantifying outcomes; it’s a lot less useful in “proving” what foods we should be eating to stay healthy.

Remember that next time you’re having a conversation with someone who insists that, “The evidence proves that vegetarians . . . [fill in the blank: “live longer/look better/stay healthier”] than meat-eaters.

They don’t have proof, merely some clues.

Tomorrow: The final installment of a review of “the Big Fat Surprise” review provides a compilation of talking points from the book to refute the veggie advocates and promote the industry.

The opinions expressed in this commentary are solely those of Dan Murphy, a veteran food-industry journalist and commentator.