Take the paleo diet, for example. Ask a vegan about paleo, and she would most likely shun it because of "all that meat," admonishing you to try a plant-based diet instead.

But according to the most extensive research ever done on paleo eating – the seminal research of Boyd and Konner, which extended over 25 years – the Paleo diet is 100 percent plant-based. They showed that the majority of Paleo diets studied broke down into approximately 35 percent animal foods and 65 percent plants.

In my book, 65 percent of calories come from vegetables, fruits, and nuts is a plant-based diet! What else would it be?

The old food pyramid was about 55 percent carbohydrates, and it was considered "high carb." Why on earth wouldn't a diet consisting of 65 percent plants be considered plant-based?

Yet no self-respecting vegan would consider a paleo diet plant-based because "plant-based" doesn't mean plant-based anymore. It means vegan. And that's a very different thing.

This brings us to the aforementioned book, The China Study.

So back in the 1980s, a huge observational study was undertaken in China. It was a collaboration between Cornell University, Oxford University, and the government of China. It was published in 1990 under the title, "Diet, Lifestyle and Mortality in China," with Dr. Chen Jushi (not Dr. Colin Campbell) listed as the senior author.

It's a massive tome, weighing over six pounds and containing 991 pages. It's still available on Amazon for $499.95 if you're interested.

T. Colin Campbell was one of the researchers in that study. His book, also named The China Study, is his interpretation of what the China Study actually said. It's Campbell's conclusions about the study, a decidedly vegan interpretation of the data that was collected.

As others have brilliantly demonstrated, it's entirely possible to come to a very different set of conclusions about the same data. Campbell, like Ancel Keys before him, was astonishingly good at ignoring data that didn't fit his talking points. Psychologists call this "confirmation bias."

Meanwhile, "veganism" has become a great deal more than just a fringe movement dedicated to eliminating animal products from our diet. It's become a cause, an identity, and a movement – one that demands fealty to its principles and tolerates no dissent.

As such, veganism as we now know it has lost all claim to scientific objectivity. "Plant-based" has now become a rallying cry, not a reasonable nutritional philosophy.

There's a wonderful new book called Sacred Cow, written by two of my esteemed colleagues, Robb Wolf and Diana Rogers. The book, and the documentary movie of the same name, are balanced, fair, and reasoned arguments for the role of animals in sustainable food production. And, let's be clear, you can and should eat animal products on a "plant-based" diet!

In one particularly impactful scene, the documentary interviews a former vegan who tells of her own road-to-Damascus moment:

"I realized when I was growing my own food and living a vegan lifestyle that it was impossible to grow tomatoes without killing slugs and other pests. I was following a plant-based (vegan) diet because I didn't want to kill any living thing, but I was living a lie. Plenty of living things had to die for me to consume my vegetables, and that's true for any vegan on the planet."

"Plant-based" was a useful term when it meant what it was supposed to mean: a mixed diet with a high proportion of plant foods. That would make a diet of 35% meat (paleo) most definitely a plant-based diet, but it would not make it a vegan one.

Equating "plant-based" with "vegan" makes the former term essentially useless.

There's a term in the health food industry called "greenwashing." It's when you get to label a crappy product "healthy" by using some buzzwords that everyone associates with health.

Putting the slogan "made with whole grains" on a box of sugared chocolate cereal is a perfect example of greenwashing. "Plant-based" is another.

Just because a product was "made" with whole grains doesn't mean there are any whole grains left in the processed end-product. And just because a product – be it a house cleaning solution, eye cream, or food – is plant-based doesn't mean there's anything good in it. After all, you can make some pretty nasty plant-based substances, especially if you use toxic mushrooms as raw material.

It's time to retire the buzzword "plant-based", at least as a surrogate for "healthy." In most cases, what people really mean by plant-based is "vegan."

"Vegan" and "healthy" are not identical terms. As an even cursory trip down the aisles of Whole Foods will show, it is entirely possible to make utterly disgusting and completely unhealthy products that meet the criteria for "plant-based." Sugar is inherently plant-based, and so is flour.

Doubt me? Just read the ingredients in vegan pizza.