Food for Thought — October

What do you need to know about fiber and your gut microbiome?
An image of a gut drawn on a chalboard and surrounded by food including nuts, broccoli, bananas, carrots and oranges.

This monthly feature was written by Nutrition Sciences Services Practice Manager Kaitlin Poillon and Assistant Clinical Professor and Director of the Center for Nutrition & Performance Nyree Dardarian from Drexel’s nutrition counseling and the Department of Nutrition Services in the College of Nursing & Health Professions.

The gut microbiome is comprised of trillions of micro-organisms, also known as microbiota, in the human gastrointestinal (GI) tract. The composition of the microbiota and its effect on health is determined by many factors, diet included. Fiber is a key nutrient in the development of a healthy gut microbiome.

Why fiber you may ask? Well, fiber acts as the “food” that gut microbiota feed on to produce increased amounts of good bacteria in the gut. This leads to the accumulation of short-chain fatty acids (SCFAs) and other metabolic by-products that are critical to human health.

In a study published in the American Society for Microbiology, Volume 6, Number 2, a two-week diet intervention was conducted in healthy young adults to examine the impact of fiber consumption on the gut microbiome. The high-fiber diet, consisting of about 25 grams per day, altered the gut microbiome of the participants, increasing the amount of known fiber-degrading microbes. It is concluded that this increase led to a higher production of SCFAs in the gut, positively impacting the gut microbiome and the health of the participants.

Fiber is found mostly in whole fruits and vegetables along with whole grains, beans, legumes, lentils, nuts and seeds. To ensure you are getting enough fiber daily, it is crucial to include at least five servings of whole fruits and vegetables as well as consume whole grains (whole wheat breads and pastas, brown rice, quinoa, farro, millet, barley, bulgur and oatmeal) at least half of the time. Increasing your fiber intake is recommended to be a gradual process to prevent any GI distress, and you will want to make sure you are staying hydrated to help with digestion. See below for a high-fiber sample meal plan.

Sample Meal Plan with Approximately 30–35 Grams of Fiber

Breakfast: 1 cup oatmeal, 1 sliced banana and 2 tablespoons crunchy peanut butter. Drink: 16 ounces water.

Lunch: Mixed greens salad – 2 cups spring mix, ½ cup cherry tomatoes, ½ cup diced carrots, 3-ounce grilled chicken breast, ¼ cup quinoa and 3 tablespoons Italian dressing. Drink: 16 ounces water.

Snack: 1 apple and ¼ cup almonds. Drink: 16 ounces water.

Dinner: 3-ounce salmon filet, 1 cup broccoli and ¼ cup brown rice. Drink: 16 ounces water.

Snack: 1 cup vanilla Greek yogurt and 2/3 cup granola. Drink: 16 ounces water.

For more meal plan and nutrition tips, sign up for a one-on-one nutrition counseling session at Drexel University today by emailing Your health can’t wait!