Fiber 101: Soluble Fiber vs. Insoluble Fiber

By Nicole Teh

Wholegrains, vegetables, beans, oats, and fruits.

Soluble fiber, insoluble fiber, high-fiber…

Yup, we’ve all heard a gazillion times that we ought to eat more fiber. But, what, exactly, is fiber?

Long heralded as a vital part of a healthy diet, fiber (or ‘roughage’) refers to carbohydrates that the body cannot digest or absorb. It is present in all plant foods, including fruits, vegetables, grains, nuts, legumes/beans. And because it is not digested by our bodies, it passes through our stomach, intestine, colon, and out – with very little change in the digestive system.

But what’s the difference between soluble and insoluble fiber, you ask?

Soluble fiber (found in oats, beans, and fruit) dissolves or swells put into water (like oatmeal). They’re soft and gooey. Soluble fiber helps to lower total blood cholesterol levels by lowering ‘bad’ cholesterol levels. For people with diabetes, soluble fiber helps to slow down the absorption of sugar and help improve blood sugar levels.

Insoluble fiber, on the other hand, as the name suggests, does not dissolve in water. Insoluble fiber promotes the movement of material through our digestive systems, as they are not readily broken down in our intestinal tract. Commonly found in wheat bran, nuts, and vegetable like cauliflower, they can be your best friends in times of (constipation) troubles.

So why should we increase our fiber intake? Reasons aplenty. Primarily, though, fiber helps to keep us full while helping to pull toxins our of our bodies while also helping to maintain steady blood sugar levels.

Thinking of increasing your fiber intake? Do so slowly to allow the natural bacteria in our digestive systems to adjust to the change. Adding too much too quickly can promote intestinal gas and bloating.