The role of dietary fiber is getting a whole lot of attention in both medical and nutrition research. It’s the ‘pre-biotic’ on which pro-biotics feed to do their magic. And it seems like magic when you learn that around 70% of our immune system is generated by molecules produced by the microbiome in the gut.
Indigestible dietary fiber plays that role, and if you’re limiting carbs you don’t want to be eliminating dietary fiber as well. Avoiding or even eliminating simple carbs is probably a fine idea, even a necessary idea if you’re dealing with high blood sugar. But avoiding complex carbs isn’t wise. In fact long term I’d say it’s a very bad idea.
Some age related illnesses could be worsened by chronic low grade inflammation. Animal proteins and fats are known to induce an inflammatory response. Crohn’s, IBS, some forms of arthritis may connected to this. And possibly hypertension. By contrast some food plants are known to have anti-inflammatory properties. Plants with phytochemicals. And the (inedible) kale plant among other cruciferous vegetables.