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Let’s talk about fiber.

Lentil macro bowl with quinoa, spinach, and a sweet potato

What is it?

Fiber is the difficult to digest portion of a plant (either soluble or insoluble). It cannot be absorbed or digested by the body.

Dietary fiber refers to the undigested parts of plant based foods that are natural to the plant. It contains beta bonds and no digestive enzymes are produced by the body to break it down.

Functional fiber is the carbohydrate that is extracted from plants and added to foods (ie: gums or cellulose). You can find these in foods like granola bars that claim they are “high fiber.”

The food groups that have the highest amount of fiber are fruits, vegetables, whole grains, nuts, seeds and legumes (so basically plants!).


Why is it important?

Fiber is important as it improves laxation, reduces risk of coronary heart disease, assists in maintaining normal blood glucose levels, and feeds good gut bacteria.

The AMDR for fiber (Acceptable Macronutrient Distribution Range) for men and women is as follows:

25g/day for young adult women

38g/day for young adult men

Interesting enough there was no UL (Upper Limit) set for fiber intake as you would simply have to stop eating because you would be so full from all of the bulk in your stomach. The only time excess fiber intake could do some harm would be if you were consuming a large amount of synthetic fiber added to processed “health” foods.


What happens when you actually consume fiber?

When undigested carbohydrates enter the large intestine they are broken down (fermented) by bacteria in the large intestine which produces short chain fatty acids (acetic, propionic and butyric acids), lactic acid, methane, hydrogen and carbon dioxide. These short chain fatty acids provide fuel for the gut cells. It is important to have a healthy diverse gut as this can help your body to fight off bad bacteria (infections, yeast, etc.) and the gut is where almost 90% of all diseases begin. So keeping your gut fueled and happy will keep you healthy!


What can you do to increase your fiber consumption?

You can eat more whole fruits, vegetables, legumes, nuts, seeds and whole grains.

Lentil orzo salad with fresh veggies

If you want to see how much fiber is in the foods you are eating you can use this chart from the University of Michigan or just about any macro tracker (like MyFitnessPal) will have the fiber content on your foods as well! Just remember this is all a rough estimate as plants are never the same exact size!

An instant increase in any food group will cause some side effects then will normalize with time, if you are going to increase fiber it is important to increase slowly by day- not all at once to reduce side effects. It is also extremely important to be drinking plenty of fluids as they will help increase laxation whereas if you are not getting enough fluids you will find yourself ‘backed up.”

There are actually some diseases associated with low fiber intake ranging from diverticulosis, constipation, heart disease, some cancer, and obesity. This is why eating more fiber can be a means of prevention and general rule of good health.

Hope you enjoyed this quick lesson about fiber intake! Now go and eat some plants!


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What is a Registered Dietitian?

A food and nutrition expert who can work in a wide variety of employment settings, including health care, business and industry, community/public health, education, research, government agencies and private practice. RDNs are accredited health professionals that must meet state and government regulations to maintain their credential in addition to completing continuing education. RDNs can practice something called Medical Nutrition Therapy to improve the health of those who suffer from chronic diseases. 

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