Books

01.16.14

In Defense of the Paleo Diet

Critics of America’s most popular new diet aren’t entirely wrong, but look closely at their three biggest criticisms and you see why you should still be experimenting with a paleo diet says Chris Kresser, author Your Personal Paleo Code.

The Paleo diet has exploded in popularity over the past several years. It’s not unusual to see a Paleo book on the New York Times bestseller list, and by now you’ve either heard of it, know someone who is doing it, or perhaps are doing it yourself. But while the Paleo diet has rapidly gained a foothold in the public consciousness, it has also been criticized in the media. I outline below the three most common critiques and explain why they don’t invalidate the fundamental premise of the Paleo approach.

What the critics say:

“Human evolution didn’t stop in the Paleolithic, so there’s no reason we should follow a Paleo diet.”

What the science says:

It’s true that evolution didn’t stop in the Paleolithic. In fact, some scientists have argued that it’s occurring at a rate 100 times faster than the average over six million years of hominid evolution, and that as much as ten percent of the human genome shows evidence of recent genetic selection. These changes do affect tolerance to some agricultural foods. For example, although humans had only been able to digest lactose—the sugar in milk—during infancy and childhood, 8,000 years ago a genetic mutation arose  that allowed them to digest it into adulthood.

But it’s important to note that these genetic changes are relatively simple and crude, and they only affect some people. Two-thirds of the population still cannot digest lactose as adults, and nearly one in ten people are intolerant to gluten, a protein in wheat and other grains. Agricultural foods like grains and dairy are still far more likely to cause problems for people than the Paleolithic foods we’ve been eating for hundreds of thousands of generations. When was the last time you heard of someone with a sweet potato, broccoli, or blueberry intolerance?

In my book, Your Personal Paleo Code, I argue that the Paleo diet should be used as a starting point because it removes the foods people are most likely to react to. From there, you can reintroduce some of the “grey area” foods like dairy and grains to see how you tolerate them.

What the critics say:

“The Paleo diet is dangerous because it permits red meat, which clogs our arteries and shortens our lifespan.”

What the science says:

Early studies did seem to suggest that eating red meat increased the risk of heart disease and cancer. However, these studies were problematic because of something called the “healthy user bias.” This is a fancy way of saying that people who engage in behaviors perceived to be unhealthy (whether they are or not) are more likely to engage in other unhealthy behaviors. In studies linking red meat consumption to heart disease and cancer, those who ate more red meat also tended to exercise less, smoke more, eat fewer vegetables, and eat more sugar and processed foods. How can we determine whether it’s the increased intake of red meat or all of these other factors that are contributing to disease?

Though I agree with some parts of the Paleo critiques, they don’t invalidate the basic concept behind the Paleo approach: that there hasn’t been enough time for humans to fully adapt to the modern, industrial diet and lifestyle we’re following today

One way is to reduce the influence of these factors. More recent higher-quality studies have attempted to do just that—and they’ve found no association between red meat consumption and heart disease or cancer. For example, a huge study with over 1.2 million participants found no relationship between fresh (unprocessed) red meat intake and heart disease. Another study in the prestigious journal Obesity Reviews found no evidence to support a link between red meat and colorectal cancer. Finally, a study on vegetarians and omnivores who shop in health food stores found no difference in lifespan between the two groups.

What the critics say:

“There’s no evidence to support the Paleo diet.”

What the science says:

There are, in fact, several lines of evidence that support a Paleo diet and lifestyle:

Archeological evidence. By studying fossil remains, archeologists have determined that there was a significant decline in health when our hunter-gatherer ancestors shifted to an agricultural diet and lifestyle.

Anthropological evidence. Anthropological studies of contemporary hunter-gatherer cultures indicate that they were remarkably lean and fit, superior to us in nearly every measure of health and fitness, and virtually free of the chronic, inflammatory diseases that are so commonplace today. When these cultures adopt a modern diet and lifestyle, they develop these diseases at rates similar to industrialized populations.

Biochemical evidence. Studies on the nutrient content of common foods suggest that Paleo is a remarkably nutrient-dense diet. This is important because suboptimal intake of any of the 40 nutrients the body requires to function will contribute to disease and shorten lifespan.

Clinical evidence. There are already several clinical studies of the Paleo diet with promising results, including positive changes in weight, waist circumference, C-reactive protein (a marker of inflammation), blood sugar, blood pressure, insulin sensitivity, and lipid markers like LDL cholesterol, triglycerides, and HDL.

As you can see, though I agree with some parts of the Paleo critiques, they don’t invalidate the basic concept behind the Paleo approach: that there hasn’t been enough time for humans to fully adapt to the modern, industrial diet and lifestyle we’re following today, and that our health is suffering as a result. Thankfully, the fact that Paleo was the most Googled diet in 2013 suggests that people aren’t taking the critics too seriously, and they’re more likely to trust the dramatic results their friends or family members have experienced than what they read in newspapers or magazines or watch on TV.