Cooking Food

Put Your Food to the Fire: Eating cooked food is one of the driving forces that made us human

“Whenever we cook we become practical chemists, drawing on the accumulated knowledge of generations, and transforming what the Earth has offered us into more concentrated forms of pleasure and nourishment.”

– Harold McGee from On Food and Cooking

 

Broiled, boiled, baked, sautéed or fried, cooked food (and cooking that food) likely forms an integral part of your daily diet, and is probably deeply ingrained in your traditions, memories, and maybe even your social life. Despite this, if you ask most Americans what is healthier—a cooked carrot or a raw one—most will likely say the raw carrot. Cooking is often seen as an unnecessary, or even unhealthy practice, one that came along as a sort of luxury for making food taste better. But cooking has been practiced by every known human society and is thought to date back nearly 2 million years. Why is cooking so deeply ingrained in our human psyche? Is it possible that cooking, a practice so uniquely human, is what made us human in the first place? Could cooking food offer advantages beyond mere taste? This is the theory that primatologist, professor, and author Richard Wrangham proposes in his book, Catching Fire: How Cooking Made Us Human (Basic Books, 2010). According to Wrangham, cooking offered early humans an evolutionary advantage, propelling us to the upright walking, large brained, computer using humans we are today. And there is reason to believe that it continues to offer advantages to modern humans.

Besides making food tastier, cooking offers other advantages. It makes food safer by killing bacteria that could potentially harm us. It allows tough foods, like raw meat and densely fibrous vegetables to be cut, mashed, and chewed. But most importantly, Wrangham argues, cooking increases the amount of energy our bodies can obtain from food. His theory is that cooking made food more digestible, allowing more energy to be obtained from less food, which allowed the digestive tract to shrink and the brain to grow.

Digestion is a very energetically expensive process. Cooking is a sort of predigestion, initiating the breakdown of food and thus requiring less energy not only to eat the food, but also to finish the process of digestion once food is ingested. A shift to eating more cooked food would have allowed for more nutrients to be absorbed from less food, essentially making us more efficient eaters. Proportionally speaking the human gut is 60 percent smaller than a primate’s[i] and this smaller digestive tract saves us at least 10 percent of our daily energy expenditure.[ii] Although eating meat is often credited as the factor that allowed for the massive growth of our ancestors’ brains, cooking may have created the perfect synergy, freeing up more energy to fuel this brain growth.

Beyond the benefits that cooking would have offered our early ancestors there are some pretty significant benefits it offers modern humans as well. One major argument for eating raw foods is that cooking kills the nutrients in food. While this may be true for some nutrients, like vitamin C, which is particularly susceptible to heat, cooking actually enhances the availability of certain nutrients, and depending on the cooking method, has little effect on others. For example, the availability of alpha and beta-carotene in carrots and spinach is improved when the veggies are steamed. The same is true of lycopene, which is found in higher levels in cooked tomatoes versus raw tomatoes.[iii] Cooking also improves nutrient absorption by breaking down the fibers in food, allowing for the release of the nutrients. We all know vegetables and fruits are good sources of vitamins, minerals, and other beneficial nutrients, but what many don’t realize is that the digestive tract has to access those nutrients through a fibrous matrix. While fiber is beneficial to the human digestive tract, it is not broken down or absorbed and offers little in the way of nutrients or energy. Aside from very thorough mashing/puréeing or chewing (think about how much time an ape spends chewing each day!) cooking is our best means for breaking down this fiber, allowing for better access to the nutrients inside. In terms of nutrient acquisition, the net gain obtained from cooking is greater than the minor losses caused by it.

For the same reason that breaking down the fiber improves access to nutrients, it can also greatly improve overall digestion. For the millions of Americans that suffer from gas and bloating, as well as those with chronic loose stool or diarrhea, cooking can be a real lifesaver. The simple act of cooking hard to digest foods like vegetables, and the proper soaking and cooking of beans, can do wonders to improve digestibility and comfort.

Another benefit of cooking is its ability to break down naturally occurring anti-nutrients, which can interfere with nutrient absorption. Over time, plants have developed chemicals, or anti-nutrients, which work in a myriad of ways to protect them from being eaten—a sort of built in pest-control if you will. Some examples of these anti-nutrients include phytates that block mineral absorption, lectins that damage the intestinal lining, protease inhibitors that interfere with protein digestion, and goitrogens that interfere with thyroid function.[iv] In nearly all cases, cooking reduces these anti-nutrients at least somewhat, and more extensive preparation methods such as soaking, sprouting, and fermenting (really just an extension of cooking) generally reduce them even more.[v][vi] [vii] [viii]

Long before we had modern scientific methods for testing the pros and cons of cooking food, humans seemed to have an intuitive sense about the benefit of cooked foods. For example, take Ayurveda, the 5,000-year-old traditional healing practice in India. In Ayurveda, digestion is governed by agni, or the digestive fire. Eating too many raw or cold foods can extinguish this “fire” making digestion less efficient and reducing the nutrients that can be obtained from food. Likewise, Traditional Chinese Medicine (TCM) views the process of digestion as one dependant on healthy digestive fire, a process driven by heat and warmth. Although raw foods do have their place in TCM, too much cold or raw food weakens the digestive fire and wastes valuable body energy in the process of raising the temperature of the food for the digestive process to efficiently work.[ix] In both of these traditional healing modalities consuming cooked food is an integral part of health, and is especially healing for those recovering from malnutrition, digestive disturbances, and illness.

Cooking most certainly shaped modern humans and is clearly good for our health, however it is important to mention that some cooking methods are better than others. First, let’s be clear that overcooking any food is not good—boiling a vegetable until it is pale and flavorless is not only unappetizing, but a good way to lose valuable nutrients. Heating oil to high temperatures damages the healthy fats in the oil and grilling meat until it is charred creates dangerous and potentially carcinogenic compounds. Learn to rely on cooking methods such as steaming, low- to medium heat sautéing, braising, baking, roasting, and broiling at moderate temperatures. Grilling is also a fantastic way to cook your food (and get back to your Paleolithic roots!), just be sure to add antioxidants to the mix to minimize the formation of harmful compounds. For example, use a spice rub with turmeric or rosemary or add antioxidant-rich fruit, like the cherry burger recipe below. And take care not to char your food—those blackened bits are full of unhealthy compounds.

Eating cooked food fuels your digestive fire and nourishes your body, but even more fundamentally, it has been one of the driving forces that made us uniquely human. The next time you are savoring the rich flavors and textures that cooking created, take a minute to appreciate that you are participating in a unique experience shared by all of humankind!

 

References

[i] Watzke H. The Brain in Your Gut. July 2010. TED Talk. www.ted.com. Accessed December 18, 2012.

[ii] Wrangham R. Catching Fire: How Cooking Made Us Human. New York, NY: Basic Books; 2009.

[iii] Mateljan G. The World’s Healthiest Foods. n.p. (2007).

[iv] Daniel K. Plants Bite Back. The Weston A. Price Foundation. www.westonaprice.org. March 29, 2010. Accessed March 19, 2013.

[v]Sisson M. The Low Down on Lectins. Mark’s Daily Apple. www.marksdailyapple.com June 4, 2012. Accessed March 13, 2013.

[vi] Mateljan G. The World’s Healthiest Foods. n.p. (2007).

[vii] Fallon S, Enig MG. Nourishing Traditions. Washington, DC: New Trends Publishing; 2001.

[viii] Anti-Nutrients and Their Removal. Nebraska Dry Bean Commission, Dept. of Food Science and Tech at UNL. www.drybean.unl.edu Accessed March 13, 2013.

[ix] Tan A. Cooked vs. Raw Food: A TCM Perspective on Cooked vs. Raw Foods. Straight Bamboo TCM Clinic Website. http://straightbamboo.com/articles/cooked-vs-raw/  Accessed February 20, 2013.