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Resistant Starch, Fiber, and Short Chain Fatty Acids 

A deeper dive into gut health! 

If you are trying to optimize your gut health, then you likely know that getting adequate fiber is important for the gut microbiome and motility. However, what you may not be as familiar with is the role that resistant starch and short-chain fatty acids play in the gut microbiome and how they too are beneficial for gut health. This post explains the benefits of fiber, resistant starch, short-chain fatty acids, and how to incorporate these nutrients into your diet.

Let’s recap: Starch and Fiber 

Before we jump into talking about resistant starch and fiber, it is important to understand starch and fiber as it is easy to confuse the two. 

Starch (a type of carbohydrate) is made up of glucose molecules (sugar) joined together and is broken down into individual glucose units in the stomach upon consumption and then is further broken down in the small intestine later in digestion. Starchy foods contain fiber which helps slow the breakdown and release of the food’s glucose molecules (sugar) into the bloodstream. Starchy foods include potatoes, corn, rice, pasta, etc.

Fiber is a type of carbohydrate that the body cannot break down and is found in plant-based foods like fruits, veggies, whole grains, beans, nuts and seeds, etc. There are two types of fiber soluble and insoluble, both of which have benefits and are digested by the body differently. 

In general, fiber has numerous health benefits:

  • Helps promote satiety and reduce cravings
  • Improves blood-sugar balance
  • Weight management 
  • Aids in detoxification (may help balance cholesterol and other hormones) 
  • Helps to regulate bowel movements
  • Aids in a healthy gut microbiome
  • Decreases risk of colorectal cancer

The majority of adults in the United States do not get adequate fiber with the recommendation that women get at least 25 grams and men get at least 38 grams of fiber per day (FYI the average American gets 10-15 grams a day!). Check out this post to learn more about fiber!

What is resistant starch?

Resistant Starch is a form of starch that resists digestion until it reaches the large intestine where it is converted into short-chain fatty acids (SCFAs – more on this later!). Because resistant starch is not broken down right away like starchy foods and is converted to SCFAs it does not spike blood sugar as much and has numerous health benefits. Resistant starch is found in foods that are cooked and cooled (ideally overnight) like potatoes, oats, rice, etc. (note they can be reheated when served!) and in plantains and green bananas. 

Benefits of Resistant Starch: 

  • Helps feed the gut bacteria 
  • Helps stabilize blood sugar (has a lower glycemic index than non-resistant starch)
  • Improves digestive health and motility 
  • May decrease inflammation

To incorporate more resistant starch in your diet, we recommend prepping carbohydrates ahead of time. This may look like making a big batch of overnight oats, rice, or potatoes at the beginning of the week and then placing them in the fridge (letting them cool overnight) so that the resistant starch can develop and you can reap the health benefits without the hassle of trying to prep these foods before a meal and  forgetting last minute to let them cool. 

Short Chain Fatty Acids (SCFAS)

SCFAS is produced by the fermentation of fiber and resistant starch in our colon. SCFAS act as prebiotics for our gut, meaning that they feed our probiotics (the beneficial bacteria), to support a healthy gut microbiome and boast numerous health benefits. In fact, measuring the number of SCFAs (there are three main SCFAS: acetate, butyrate, and propionate) in our stool via a stool test can be a great marker of our gut health!

Benefits of SCFAs:

  • Promotes gut health
  • Helps strengthen and repair the gut lining
  • Aids in immune system regulation (remember that 70 % of the immune system is in the gut)
  • May enhance energy and mood (perhaps through the gut-brain connection!
  • Improves digestion 
  • Reduces risk of colon cancer and IBD

If you seek these health benefits, we recommend eating tons of veggies, fruits, nuts and seeds, beans and legumes, and cooled starches to get adequate amounts of fiber and resistant starch. 

Unfortunately, some conditions may negatively affect the production of SCFAs including the use of antibiotics, chronic constipation, a low fiber diet, and uncontrolled Type II diabetes. 

A day of eating to increase fiber, resistant starch and promote SCFA production

To help put this pattern of eating into perspective, below you will find a day of eating to increase the consumption of fiber and resistant starch to promote SCFA production and therefore a healthier gut microbiome. 

Breakfast: Overnight oats with apple, cinnamon, walnuts, chia seeds, and protein powder of choice

Lunch: Big salad with arugula, shredded carrots, cucumber, tomatoes, roasted chickpeas, and parsley in a lemon olive oil garlic salt, and pepper dressing

Snack: Sweet potato toast (using previously cooked and cooled sweet potato) with avocado and a sunny-side-up egg

Dinner: Wild-caught salmon topped with lemon and dill, with asparagus and quinoa (cooked and cooled)

Dessert: Berries with homemade coconut whipped cream

The Bottom Line

Fiber and resistant starch are key to promoting a healthy gut lining and microbiome by their role in the production of SCFAs, as well as overall health. The best way to increase fiber consumption is through eating a variety of fruit, vegetables, nuts and seeds, and beans and legumes while the best way to increase resistant starch is through the consumption of cooked and cooled starches. 

Want to learn more or work on the health of your gut microbiome? Click here to work with us!

Written by Alison Richman MS, RDN