Myth 7: The more fiber you eat, the better.

Truth Not all fibers are equally beneficial. Consider the source.

Yogurt doesn’t naturally come with fiber, yet the grocery aisles now boast fiber-supplemented yogurt, along with cereals, energy bars, even water. What’s the deal?

Fiber is a fad-food component right now, and manufacturers are isolating specific types of fiber and adding them to packaged foods to take advantage. But the science isn’t entirely clear yet: Just as we’re learning more about different types of fat, research is showing how complex fiber is as well. We now know that different fibers have different functions (wheat bran helps move foods along; oat bran lowers cholesterol; inulin supports healthy gut bacteria). Some experts are skeptical that the so-called faux-fiber foods offer the same beneficial effect as naturally fiber-rich ones like whole grains, vegetables, fruits, and legumes.