Fiber: does heat treatment of products destroy dietary fibers?

There is a common myth that any heat treatment of vegetables, fruits, and grains completely destroys the beneficial dietary fiber in them. From a chemical point of view, this is not true. The very structure of complex carbohydrates that make up plant fibers is quite resistant to high temperatures during normal boiling, baking, or stewing. Fiber does not disappear from a product without a trace when heated.

However, heat treatment changes the physical properties of fiber, making it softer and breaking down the rigid cell walls of plants. That is why boiled carrots or baked apples are digested much easier and faster than their raw counterparts. For people with a sensitive stomach or gastrointestinal diseases, such processing is a salvation, as it reduces mechanical irritation of the intestinal mucosa.

One should also take into account the factor of water-soluble substance loss, which can pass into the broth when boiling products in a large amount of water. If you drain the water after cooking vegetables, some of the useful trace elements go away with it, although the insoluble fibers themselves remain in the bulk of the product. To minimize these losses, it is better to prefer steaming, baking in the oven, or stewing in a small amount of sauce.

Thus, heat-treated foods remain a valuable source of fiber and are great for the daily diet. The combination of raw and cooked vegetables and fruits allows you to get maximum benefits without the risk of getting abdominal discomfort. The main thing is to avoid deep frying, which adds extra harmful fats to dishes and nullifies all the benefits of plant foods.