There are two types of fiber (soluble and insoluble), and for optimal gut health, it is best not to distinguish between them overly much and to simply focus on a diet high in fiber overall.

noli's read

Dr. Bulsiewicz highlights a classic distinction in nutrition here, while encouraging a simplified approach. Research widely confirms that soluble fibers (which form a gel) and insoluble fibers (which add bulk) play complementary roles for transit and the microbiota, as indicated by various observational studies and reviews on digestive health. The idea that it is unnecessary to obsess over the exact ratio between the two is consistent with current public health recommendations. Most plant-based food sources naturally contain a mixture of both, making technical separation often superfluous for the general public. There is no exaggeration here; the message prioritizes long-term adherence to a plant-rich diet rather than a sometimes discouraging mathematical precision. The approach is supported by the scientific consensus, which advocates for a diversity of fiber sources rather than targeted supplementation.

the sources

1. 1Reynolds A et al. 2019