Fiber and its Benefits

Fiber and its Benefits 

We’ve all been asked the question “how much fiber do you eat?” by doctors, nutritionists, dietitians, family members, and/or friends.  The topic usually comes up when you’re having some kind of problem in the bathroom and need some advice to find relief.  But what is fiber? Where do you get it? How much do you need? What are the benefits? There’s two types?

All these questions will be answered right here and now in the quickest way possible to save you all from hours of internet searches and endless contemplation.

What is Fiber?

Fiber is a part of plants that cannot be digested by the human body, which allows it to remain mostly intact while it passes through the GI tract.  Many of you have probably heard of soluble and insoluble fiber and may be wondering “whats the difference?”  Basically, it comes down to how the fiber acts in relation to water.

Soluble fiber:  Soluble fiber absorbs water and swells inside the GI tract.  This can slow down transit time and carry pathogens, fat, and cholesterol out of the body.

Insoluble fiber:  Insoluble fiber does not absorb water so it is said to add “bulk” to stools.  Insoluble fiber decreases transit time and makes stool elimination more simple. 

Sources of Fiber

Fiber can be found in many types of foods, but different foods usually have different types of fiber in different amounts.

Soluble fiber: Oatmeal and oat bran, beans ( black, pinto, kidney, navy, lima, and many more), all fruits and vegetables (especially oranges, avocados, brussel sprouts, and sweet potatoes), and nuts.

Insoluble fiber:  Whole grains (foods that say whole wheat or whole grain), vegetables (especially leafy greens, onions, bell peppers), popcorn, beans, and most fruits (especially raspberries). 

Benefits

We started this conversation by talking about fiber helping out with bathroom related issues. It is true that fiber, both soluble and insoluble, can decrease problematic evacuation.  It is also true that insoluble fiber is seen to be more beneficial for this purpose than soluble fiber.  But surely there are more benefits of fiber than that right?  Correct!

People who consume enough fiber have been shown to have lower risks of certain cancers, diabetes, obesity, and many other medical complications

Cancer:  Studies have shown that increasing fiber intake decreases ones risk for colorectal, ovarian, prostate, and lung cancer.  People who have the highest intakes of fiber generally have the lowest risk for these types of cancer(when only fiber consumption is taken into account)¹.  

Diabetes:  Fiber, especially fiber from whole grains, has long been shown to decrease the risk of developing type 2 diabetes.  Possible mechanisms for this are improved control of blood sugar (improved glycemic control) and body weight².

Obesity:  Fiber has also been suggested to decrease the risk for becoming obese and gaining body fat³.  Fiber slows down digestion and elicits a feeling of fullness and satiety, which can decrease immediate and post meal calorie consumption.  Foods high in fiber are sometimes very low calorie in comparison to their volume (they have a high volume to calorie ratio), which increases fullness with fewer calories consumed.  This is especially true of fruits and vegetables. 

Amounts needed

 **These values are based on total fiber.  No specific recommendations for insoluble fiber intake currently exist.

In conclusion, fiber is important.  It helps stave off constipation and can decrease your risk for certain medical conditions.  There are two types of fiber, but you should only worry about your total fiber intake unless otherwise directed by your medical doctor or dietitian.

Written by Anthony Scornavacco.  If you missed his post on Iron, please go back and read it here.

References

1. Kunzmann AT, Coleman HG, Huang WY, Kitahara CM, Cantwell MM, Berndt SI: Dietary fiber intake and risk of colorectal cancer and incident and recurrent adenoma in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Am J Clin Nutr 2015;102:881-890.

2. Meyer KA, Kushi LH, Jacobs DR Jr, Slavin J, Sellers TA, Folsom AR. Carbohydrates, dietary fiber, and incident type 2 diabetes in older women. Am J Clin Nutr 2000;71:921-930

3. Liu S, Willett WC, Manson JE, Hu FB, Rosner B, Colditz G. Relation between changes in intakes of dietary fiber and grain products and changes in weight and development of obesity among middle-aged women. Am J Clin Nutr 2003;78:920-927