Why fiber is so important for our health

Fiber is something that I feel like doesn't get talked about nearly as much as it should, let alone given the credit it deserves! Fiber is essential for overall health.  It reduces the risk of developing some of our biggest and most common diseases, improves heart and gut health, helps with weight management, and prevents constipation.  That’s right, if you are solely depending on your morning cup of Joe to go to the bathroom, forgoing fiber-rich foods, your health and gut will thank you if you start incorporating more fiber into your diet- keeping things moving, naturally. 

So, what is fiber anyway?

Fiber is considered “roughage” or indigestible carbohydrates found in plant foods that contribute to fecal bulk.  It is a type of carbohydrate that your body can’t break down.  It comes in two forms- both of which are important for health and disease prevention.

Types of fiber

Soluble fiber

Fibers that dissolve in water and become gel-like in consistency.  They can be metabolized (fermented) by bacteria in the colon. Food examples include: Oatmeal, nuts, beans, apples, and lentils. Health benefits: decreases and stabilizes blood sugar levels, helps lower blood cholesterol levels, and delays gastric emptying (which keeps you fuller, longer!)  

Insoluble fiber

Fibers that do not dissolve in water and are not metabolized by bacteria in the colon.  This type of fiber helps with regularity, preventing constipation by helping food move through the digestive system. Commonly referred to as “bulk”.  Food examples include: brown rice, whole wheat bread, legumes, carrots, cucumbers.  Health benefits: Decreases transit time, prevents constipation, lowers risk for colon cancer and diverticular disease.

Why is it important? AKA the benefits of fiber

Prevention and maintenance of diseases

Fiber has been shown to have an inverse relationship with diverticular disease, colon cancer, diabetes and cardiovascular disease.  Meaning, the more fiber one eats, the more of a reduction in risk for these diseases.  

• Diabetes management

Fiber has been shown to positively impact blood sugar levels, blood lipids, inflammation, and body weight.  In these ways, it is an important component in diabetes management and prevention.  High fiber diets have been shown to reduce hemoglobin A1c levels (average blood glucose levels for 3 months), fasting plasma glucose, triglycerides, cholesterol levels, c-reactive protein (marker of inflammation), and body weight when compared to low fiber diets (Reynolds, AN). Fiber-rich foods also tend to be low in calories and high in nutrients, and are slow digesting- helping with the maintenance of weight. 

• Colon health

Fiber keeps things moving and flowing by helping food move through the digestive system, encouraging regular bowel movements.  This flow and decreased transit time prevents constipation and can help prevent small pouches from forming in your colon (diverticular disease).

A systematic review and meta analysis on fiber and diverticular disease showed that individuals had a 41% reduction in risk when they consumed 30g of fiber a day.  (Aune, D)

• Gut health

Fiber is intimately tied with gut health.  It literally feeds our gut bacteria and makes them thrive!  Our gut microbiome produces short chain fatty acids (SCFAs) from carbohydrate fermentation.  The SCFA butyrate, specifically, seems to play an important role with gut barrier function and maintenance.  Reduction of butyrate (via fecal testing) has been found in patients with colorectal cancer.  Deficiency in SCFA production is also associated with type 2 diabetes (Zhao, L.)  Since SFCA’s are produced in our gut by carbohydrate metabolism, it’s no wonder why there is an association between gut health, fiber intake, and disease. 

• Cholesterol lowering capabilities

While most of the above mechanisms may also contribute to a reduced risk of cardiovascular disease; soluble fiber, in particular, is directly correlated with lowering both LDL (low density lipoprotein AKA “bad cholesterol”) and total cholesterol. Both of which are common risk factors for cardiovascular disease.  Soluble fiber forms a gel-like consistency which binds cholesterol particles in your digestive system and excretes  them out of the body before they are absorbed, lowering cholesterol levels.  

To summarize, fiber can contribute to:

• Better cholesterol and blood sugar levels
• Lower risk of diseases  
• Less constipation
• Gut health
• Weight management

How much do we need?

The USDA fiber recommendation is 25 grams per day for women, and 38 grams a day for men.  The average person consumes around 15 grams a day.

How do we get it?

• 

We get fiber through a variety of fruits, vegetables, whole grains, legumes, nuts and seeds. Otherwise known as high quality, complex carbohydrates. While all plant foods contain fiber, and making sure you get a diversity for health is ideal, there are some foods worth mentioning because they pack a good bang for their buck!

• Legumes (ex, black beans, lentils, chickpeas, kidney beans)- range between 12-16 grams (g) per cup

• Avocados- 9 g per (California avocado, black skin)

• Raspberries- 9 g per cup (a great source!)

• Oats- 8 g (per cup)

• Pears- 5.5 g (per medium pear)

• Apples- 4.4 g (per medium apple)

• Carrots- 2.6 g (per carrot)

• Broccoli- 2.4 g (per medium stalk)

• Almonds- 3 g (per 1 oz)

• Chia seeds- 4 g (per 1 Tbsp) 

*Via USDAs database

Tips on incorporating more fiber into your diet

Incorporate more plant foods into your diet in which fiber is found! Adding a diversity of vegetables, fresh fruit, nuts and seeds, legumes, and whole grains to your diet is how to make it happen.

Some of my favorite ways to incorporate fiber-

• Incorporating oatmeal in your diet and adding fruit to it (remember how much a cup of raspberries was?!)

• Making smoothies with fruits and vegetables

• Adding seeds and nuts (or nut butters) to smoothies and oatmeal.  

• Adding beans/legumes to salads or making a dinner based around them.

• Having whole fruit and nuts as a snack

Another side tip

Don’t just jump into eating a full cup of beans in one sitting if you aren't used to eating a high fiber diet.  Slowly introduce and incorporate fibrous foods, spreading them throughout your day.  This will help your body and gut adapt which will help with the common complaints of someone who is not used to eating a high fiber diet (gas, bloating, cramping, etc.) Also, be sure to be drinking plenty of water to make sure things keep moving nicely. 

Resources

1. Aune D, Sen A, Norat T, Riboli E. Dietary fibre intake and the risk of diverticular disease: a systematic review and meta-analysis of prospective studies. Eur J Nutr. 2020;59(2):421-432. doi:10.1007/s00394-019-01967-w

2. Byrd-Bredbenner, Carol.  Perspectives in Nutrition. New York, McGraw Hill, 2009.

3. FoodDataCentral, US. department of agriculture, 4/1/2019, fdc.nal.usda.gov

4. Reynolds AN, Akerman AP, Mann J. Dietary fibre and whole grains in diabetes management: Systematic review and meta-analyses. PLoS Med. 2020;17(3):e1003053. Published 2020 Mar 6. doi:10.1371/journal.pmed.1003053
   
5. Zhao L, Zhang F, Ding X, et al. Gut bacteria selectively promoted by dietary fibers alleviate type 2 diabetes. Science. 2018;359(6380):1151-1156. doi:10.1126/science.aao5774