Several years ago, a respectable scientist wanted to research nutrition, specifically the nutrients available in raw food vs. cooked food. And he discovered that nutritionists had *never* done that research.
So he set himself to find out the differences between raw foods, when raw foods were mechanically processed, and when they were cooked. The difference between raw and mp foods and cooked was surprising.
He discovered that raw foods do not surrender their nutrients easily. He noted that for this reason, herbivores, like gorillas, must eat almost constantly to get the nutrition they need.
For people on a raw food diet, and most vegetarians, this almost guarantees that they are malnourished, even deprived of at least some essential nutrients. Which is typically hard to even detect until they enter a deficiency state and damage is already taking place.
The cell wall of the plants inhibit nutrient uptake.
Cooking breaks down that cell wall to enough of a degree that the nutrients inside can then be digested.