In my experience, I can say that most people do need an
extra fiber supplementation to their everyday diet - no matter if they are on keto or not.
The Journal of Nutrition 146, no. 2 (2016): 306 - 317; Thompson, S. V., et al. «Effects of isolated
soluble fiber supplementation on body weight, glycemia, and insulinemia in adults with overweight and obesity: A systematic review and meta - analysis of randomized controlled trials.»
Since modern diets are typically low in fiber and high in carbs and saturated fat,
adequate fiber supplementation is highly recommended, not only to aid digestion, but also to support cardiovascular health.
Fiber supplementation is also frequently suggested in treatment plans.
But for people with poor nutrition,
fiber supplementation may be an option.