Fiber: Villain or superhero?

If you pay attention to this kind of thing in the media, you might be confused about fiber. On the one hand, fiber is good for you and we don’t get enough; on the other hand, fiber is the culprit in many diseases and conditions of the digestive system. So where does the truth lie? As in most cases where there is polarity, the truth lies somewhere in the middle.

Let’s dig a little deeper. First, what is fiber? Fiber is a carbohydrate that is indigestible. This might sound bad but it’s not. It simply means it passes through the body. But it has an important role as it does so. One of the functions of fiber is to slow the entry of glucose into the bloodstream. There is an intricate relationship between blood glucose levels and insulin. The hormone insulin is secreted from the pancreas in response to elevated blood glucose levels, say after consuming carbohydrate. One of insulin’s many roles is the transport of glucose into the cells. 

The process looks like this: blood glucose levels are elevated by ingestion of a specific food, the pancreas responds by secreting insulin, insulin opens up the gates of cells to allow glucose to be absorbed, glucose gets absorbed into the cells, and blood glucose levels are normalized again. This is what happens when eating a wholesome, healthy diet. However, when refined flours (stripped of their natural fiber) are involved, this process is disturbed.

When you eat a wholesome, unrefined complex carbohydrate such as 12-grain bread or a green salad, the high-fiber content in this food acts as a brake, causing glucose to enter the bloodstream slowly. The result is you feel alert, awake and happy. This may sound too good to be true, but how your body responds to food has an effect on both your physical and emotional and mental well-being. But more about that another day. You have not over-secreted insulin, and therefore you do not have any excess to store as fat. As well, you get the benefit of all the nutrients such as vitamins A, B, C, iron and fiber.

So what happens when you eat processed, refined carbohydrate like a piece of pizza?  With very little fiber, the glucose from this food enters the bloodstream rapidly, which results in a state of high blood sugar or hyperglycemia. The body attempts to maintain balance by over-secreting insulin, which in turn drops the blood sugar to an exceedingly low level, creating the opposite condition called hypoglycemia.

The story doesn’t end there. Hypoglycemia is associated with irritability, headaches, confusion, cravings, and cold sweats. The response to these symptoms is usually to reach for more sweets and refined carbs within hours of consuming the pizza in an attempt to boost energy and curb cravings. At the next meal, the cycle will begin all over again. If this continues, the body will eventually over-secrete insulin and store the excess as body fat.

This process can lead to insulin resistance, which leads to obesity and Type II Diabetes. But, I started out this blog talking about fiber and I got off track. In tomorrow’s blog, I will explore how you measure insulin response and the role of fiber in the process. You won’t want to miss the exciting saga of how fiber comes to the rescue and a peek at its villainous alter-ego.