Cooking and Nutrition: Easy Does It

July 1, 2017 - 2 minutes read

All cooking has an impact on the nutritional content of food. Sometimes this is positive—for example, the beneficial antioxidants found in carrots and tomatoes are released during heating. But, in general, heating food degrades its nutritional value, often by:

  1. denaturing proteins, which limits their accessibility to the body
  2. hydrolyzing carbohydrates, creating simple sugars (those “bad carbs”)
  3. destroying some vitaminsVitamins C and B12 are especially sensitive to heat; low- or deficient Vitamin B12 levels are surprisingly common in industrialized nations like the U.S.

The ideal way to heat food is gently and evenly. This preserves vitamins, and does minimal damage to other essential nutrients—and can even increase antioxidant levels: A 2006 study found that gently cooking broccoli didn’t just preserve its delicate Vitamin C, but also increased the antioxidant levels, making it even healthier than raw broccoli.

Because microwave ovens heat unevenly, most people tend to “nuke the heck” out of everything.  Not only does this lead to unsightly chili detonations in the microwave, but it also badly overheats some portions while leaving others dead cold.

The Scourge of Uneven Heat

This isn’t just a matter of being wary of burns or a mouthful of cold spaghetti. We already know that overheated food can lose nutritional value, but the real health risks came from those cold spots:

Microwaving prepared chicken dinners lead to multiple multi-state salmonella outbreaks in 2007 and 2008, sickening hundreds. A more subtle, but likely more widespread issue: The lectins naturally present in some foods (such as the kidney beans in the aforementioned chili) don’t break down if the food isn’t heated sufficiently and evenly.

These carbohydrate-binding proteins interact with the cell membranes in your digestive tract. They contribute to persistent allergic reactions in some sensitive individuals (lectins are often the culprit behind peoples’ mysterious “gluten” allergies), but can trigger mild to intense gastrointestinal distress in almost anyone  In fact, some lectins—like those found in those red kidney beans—are actually made up to five times more potent when under-heated, and have resulted in hospitalizations.


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