Most people believe that raw foods are better for you than cooked ones. The basis of this is often bound up in myths of what people think constitutes our “natural diet”, particularly given the popularity in recent years of diets like the paleo diet and the raw food movement. The assumption is that, since fruit and vegetables are naturally in a raw state, and before the invention of fire our ancestors ate food raw, this is a more “natural” state, and therefore better, way to eat food.
That said, the average lifespan of someone in the Paleolithic period was about 33 yrs. You would have been lucky to make it to 40. Sure, some of them probably got eaten by saber toothed tigers and infant mortality was high and what-not, but diet was certainly not uniform around the world. What about the Inuit, who have survived mostly on whale blubber?
So is raw food really that much better for you? And, here’s what I really want to focus on:
What if you are allergic to raw fruit and vegetables?
If you’re like me and have oral allergy syndrome and can’t eat certain fresh fruits and vegetables, you might be wondering if cooking, boiling or steaming destroys the nutrients in foods. You might be worried about eating a balanced diet if you’re allergic to most raw foods.
The good news is that the nutrients in many vegetables actually improve with cooking, steaming, sauteing, and yes, even microwaving.
The thing about oral allergy syndrome fruits and vegetables is that most of them can be safely had by most people if they are peeled and/or cooked, boiled or steamed. The heating process helps to destroy the allergen-proteins and make the foods safer to eat. And for those of you who worry that heating foods might destroy the nutrients, fear not. In many cases heating helps release nutrients.
But before I tell you all about that I have to tell you that I'm not thrilled about the raw food movement. I'm happy for you all, really, that you can turn a handful of dates and seeds and nuts into healthy energy bars and that you can shred some zucchini and slap some raw tomatoes on it and call it pasta. That's awesome. Am I jealous? Yes. A little bit.
But if I hear one more smug raw foodie tell me that if I just ate more raw fruit and vegetables and nuts maybe I would be healthier and my allergies would get better, I'ma gonna get angry.
Sure, cuz if someone was deathly allergic to peanuts, you would suggest they ate a jar of peanut butter to heal themselves.
As if I caused my allergies by not eating healthy.
Thank you but I've endured enough blame for my allergies over the years. There is plenty of research to suggest that allergies are actually determined as early as in the womb, and that all kinds of external factors such pollution, pesticides, antibiotics and more can imbalance the immune system and cause allergies later in life.
If you don't believe me, you can read all about it in my new book Living with Oral Allergy Syndrome: A Gluten and Meat-Free Cookbook for Wheat, Soy, Nut, Fresh Fruit and Vegetable Allergies (you can read the first 22 pages on my blog, or you can Order from Amazon.com here.) The book includes 10 pages on the potential causes of hay fever, food allergies and oral allergy syndrome, and 5 chapters of healthy recipes for cooked fruits and vegetables and non-OAS related foods.
Anyway, on to the heating.
Steaming vegetables helps fight cancer and heart disease
For example, a study from 2008 found that steaming vegetables significantly improved the in vitro bile acid binding of collard greens, kale, mustard greens, broccoli, green bell pepper, and cabbage compared to their raw form. In vitro bile acid binding has been related to lowering the risk of heart disease and cancer, and bile acid helps the body to utilize of cholesterol and reduce fat absorption. 
In the case of carrots, courgettes and broccoli, an overall increase in antioxidant was found in steamed vegetables over raw. This likely because the steaming softened the vegetables and increased the ability of compounds to be extracted and be converted into "more antioxidant chemical species."  I'm assuming these are good species, as opposed to the alien kind that Sigourney Weaver has been known to battle.
Interestingly, microwaving vegetables has also been shown to improve the in vitro acid binding of certain vegetables. Kale, mustard greens, broccoli and cabbage had the most improvement when microwaved without added water, while collard greens and bell peppers were better off with a small amount of added water. 
Another study found that in the case of pepper, squash, green beans, peas, leek, broccoli and spinach their total total antioxidant activity either increased or remained unchanged after microwaving. 
This is not the time or place to get into the microwave debate, I'm just relating a study here! Microwave or not as you please. My suggestion, though, is that if you do microwave it's better to use glass containers and never plastic, or plastic wrap, as these can leach creepy chemicals into your food.
Sauteing is even better than steaming for many veggies
Surprise! Contrary to popular belief, compared to raw or steamed vegetables, sauteing significantly improved in vitro bile acid binding in mustard greens, kale, broccoli, cabbage and green bell pepper. Collard greens, on the other hand, did better with steaming. 
But don't worry, if you happen to prefer your collard greens sauteed over steamed. Sauteing is still better than boiling. One study found that although a short boil with collard greens improved in vitro bile acid binding, sauteing was a better method of preparing them. 
The scientists in these studies have even said that:
Eating sauteed/steamed/microwaved vegetables can help keep dietary fat low and potentially lower the risk of premature degenerative diseases.  In some of the above noted cases cooking is preferred "to preserve the nutritional and physicochemical qualities". 
Of course, greens aren't necessarily the only vegetables that are more nutritious when cooked or heated, but the point is that it doesn't really matter if you can't eat them raw. If you know that there are certain vegetables that you can safely eat when they've been heated or cooked, then don't worry about loss of nutrients. The important thing is to try to get your veggies any way you can!
So the raw foodies can keep their fancy date balls that I can't eat without my throat swelling. I'm going to feel pretty good tonight when I saute up a batch of kale and eat it with a side of brown rice from my freezer.
Looking for more research like this? Check out my new book Living with Oral Allergy Syndrome: A Gluten and Meat-Free Cookbook Wheat, Soy, Nut, Fresh Fruit and Vegetable Allergies or Order from Amazon.com here to get it in time for Christmas!
* Please note as always, I'm not a medical practitioner and the posts on this site are not meant to replace the advice of a doctor. Most fruits and vegetables are safer for people with OAS to eat after they've been cooked or processed, but everyone is different and some may still react to some foods, so it's always a good idea to check with your doctor before trying foods you might be allergic to. Kahlon, Talwinder S., Rebecca R. Milczarek, and Mei-Chin M. Chiu. "In Vitro Bile Acid Binding of Mustard Greens, Kale, Broccoli, Cabbage and Green Bell Pepper Improves with Sautéing Compared with Raw or Other Methods of Preparation." Food and Nutrition 3 (2012): 951-958.
 Kahlon, Talwinder Singh, Mei-Chen M. Chiu, and Mary H. Chapman. "Steam cooking significantly improves in vitro bile acid binding of collard greens, kale, mustard greens, broccoli, green bell pepper, and cabbage." Nutrition research 28, no. 6 (2008): 351-357. Link to abstract: http://www.sciencedirect.com/science/article/pii/S027153170800064X
 Miglio, Cristiana, Emma Chiavaro, Attilio Visconti, Vincenzo Fogliano, and Nicoletta Pellegrini. "Effects of different cooking methods on nutritional and physicochemical characteristics of selected vegetables." Journal of Agricultural and Food Chemistry 56, no. 1 (2007): 139-147.
 Kahlon, Talwinder S., Rebecca R. Milczarek, and Mei-Chin M. Chill. "In Vitro bile acid binding of kale, mustard greens, broccoli, cabbage and green bell pepper improves with microwave cooking." Vegetos-An International Journal of Plant Research 25, no. 2 (2012): 29-36. Link to abstract: http://www.indianjournals.com/ijor.aspx?target=ijor:vetos&volume=25&issue=2&article=004
 Turkmen, Nihal, Ferda Sari, and Y. Sedat Velioglu. "The effect of cooking methods on total phenolics and antioxidant activity of selected green vegetables." Food chemistry 93, no. 4 (2005): 713-718. Link to abstract: http://www.sciencedirect.com/science/article/pii/S0308814605000531
 Clifford, Alexander, and Paul Dawson. "Culinary Method Affects the Antioxidant Activity of Collard Greens (Brassica oleracea)." Journal of Food Research 1, no. 4 (2012): p66.
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