“I’ve heard from friends that cooking vegetables destroys all of the enzymes. Should I consider a raw food diet?”
Raw-foodists eat a diet that consists completely (or mostly) of foods—such as vegetables, fruits, nuts, seeds, and sprouted legumes—that are uncooked. That’s not to say there’s no processing involved. Some warming is allowed, although food can’t be heated above a certain temperature or its natural enzymes are destroyed (more about that later). Most raw-foodists are vegan, but others do eat raw eggs and raw cheese made from raw, or unpasteurized, milk. With all the peeling, chopping, extracting, blending, dehydrating, soaking, fermenting, and grinding that goes on, raw-foodists can spend more time in the kitchen than people who actually cook their meals.
And raw-foodism (aka rawism, live diet, or living diet) is no longer a fringe category in the diet world: A whole new wave of converts has embraced this approach to health and wellness. It’s not new, of course; the history of raw-foodism is too long and colorful to get into here, but its proponents included the English Romantic poet Percy Bysshe Shelley and Swiss physician (and creator of muesli) Maximilian Bircher-Benner, who founded a lifestyle reform movement based on raw food in the late-19th century.
There are many different degrees and versions of a raw foods diet, but, in general, it is rich in fiber, vitamins, minerals, and phytochemicals. Many foods, in fact, are more nutritious when eaten raw, as heat degrades some key players, including vitamins C and B6. Since all highly processed food—i.e., the stuff that fills most supermarket shelves—is off limits, you’re eliminating the saturated fat, trans fats, sugar, sodium, and extra calories that can get you in a boatload of trouble. That alone is huge, in my book. That said, though, raw-foodists, especially those who are vegans or fruitarians, really need to make sure they get enough vitamin B12, calcium, iron, and omega-3 fatty acids.
And, unfortunately, several principles of raw-foodism are based on misunderstandings about basic human biology and nutrition. I don’t have the space or time to go into all of them here, but there are a couple of biggies. One of the major misconceptions is that a raw foods diet is the most “natural” way to eat.
Think about it: We all know the marketing buzzword natural is essentially meaningless, right? Aside from what it signifies on cereal boxes and packages of chicken parts (“precisely nothing” is the correct answer), as I mentioned in a recent column on the Paleo Diet, early humans survived and thrived on many different diets. And just a few years ago, renowned Harvard primatologist Richard Wrangham made the compelling case that learning to cook food was the catalyst in human evolution. In Catching Fire: How Cooking Made Us Human, he argued that cooked food, with its high caloric density and high digestibility, enabled us to evolve our large brains and made us the species we are today. “Fossil evidence indicates that this dependence arose not just some tens of thousands of years ago, or even a few hundred thousand,” he wrote, “but right back at the beginning of our time on Earth, at the start of evolution.” We’ve had plenty of time to adapt, in other words.
Raw food diets have often been reported in nonindustrialized societies. Perhaps the most famous example of this occurred in the 1940s, when nutritionist Edward Howell (more about him in a minute) popularized the notion that the traditional Inuit diet was dominated by raw foods. Upon further study, however, that and other, similar, claims have been found to be exaggerated or false. Inuit men on the hunt would eat raw fish, for instance, and some soft (i.e., spreadable) foods such as blubber and liver were preferred raw, but a substantial cooked meal was the norm at night.
One benefit of cooking, by the way, is that it breaks apart cell walls in foods to release carotenoids that are otherwise unavailable. The carotenoid lycopene, for instance, is four to five times higher in cooked tomatoes than in fresh. As far as spinach goes, cooking both increases the lutein and beta-carotene and reduces the chemicals that inhibit the absorption of calcium and iron. Of course, boiling vegetables to death is going to have a negative impact on their nutrients, and overindulging in char-blackened red meat—which contains carcinogenic compounds called heterocyclic amines—may increase risk for some cancers. But that’s where different cooking techniques come in handy: Steam, sauté, quick-braise, or stir-fry veggies, and perhaps slap fish on the grill instead of a steak.
Another fallacy revolves around enzymes, a special type of protein. All living organisms contain thousands of different enzymes, and each one triggers a very specific biochemical reaction. Central to raw-foodism is the near-mystical belief that the enzymes in raw food carry a “life force” that leads to increased vitality and other health benefits. This sciencey-sounding theory stems from the aforementioned Edward Howell, whose sources from the 1920s and ’30s were invalidated long ago. It is perfectly true that cooking destroys the enzymes in food, but you know what? It doesn’t matter.
First, the enzymes in plants are for the plants. They help with germination, photosynthesis, respiration, decomposition, and so on. They cannot help with any human body functions, including digestion. Our bodies produce their own digestive enzymes for that, about 22 of them. Second, the hydrochloric acid your stomach produces to break down food is so concentrated that one drop will eat a hole in a piece of wood. Very few of the enzymes in raw foods make it through that acid bath into the intestines, where nutrients are absorbed. Don’t believe me? Want to see my sources? Pick up any high-school biology textbook.
So what’s the take-away? Because many foods are more nutritious when eaten raw, it’s a smart idea to work them into your daily routine; raw nuts and cruciferous vegetables like kale, broccoli, and cabbage are a great place to start. And a diet that includes lots of plants, whether raw or cooked, is undeniably healthful. But the more outlandish raw-foodism claims are not borne out by legitimate science.