Feeding Your Gut

There is a large and diverse variety of microorganisms (microbes, bacteria, protozoa, fungi) living in your gut, called the gut microbiome. While this might seem alarming, many of these microbes are actually beneficial for your health. These gut microbes:

• build resistance to disease

• synthesize essential nutrients, such as vitamin K2, which is important for bone health

• create by-products, such as short-chain fatty acids that support digestive health.

A healthy gut microbiome influences digestion, immunity, metabolism, mood, brain health and risk of chronic disease. I cover the gut-brain connection in a previous article.

The foods we eat – and don’t eat – have a major impact on the microbial composition in the gut. The microbes in our gut like to eat lots of diverse, high-fiber plant foods. Highly processed foods (often full of unhealthy fats, artificial sweeteners, and added sugar) are less likely to keep beneficial microbes around. Instead, they can invite in unhealthy bacteria which can lead to dysbiosis - an imbalance of bad bacteria in the gut microbiota.

One of the world's leading experts on gut health, Dr. Will Bulsiewicz, recommends in his awesome book, Fiber Fueled, to consume at least 30 different plant foods per week. That's not 30 servings. It's 30 different types of plants - vegetables, fruits, legumes, whole grains, nuts, seeds, herbs and spices. That may sound like a ton, but you could get 10-15 different species in one salad alone. Throw a few different herbs and spices on any ordinary dish and you got several more. It's not as hard as you think, as long as you stock your fridge and cabinets with lots of this awesome stuff.

“The single greatest predictor of a healthy gut microbiome is the diversity of plants in one’s diet.” - Dr. Will Bulsiewicz

Diets rich in whole grains and a variety of fruits and vegetables increase microbial diversity, leading to positive health outcomes, such as improved metabolic and immune function. By making food choices that allow gut microbes to flourish, you’ll naturally “crowd out” those processed foods that are less beneficial. Plus, the gut microbiome begins to change within just a few days of making dietary shifts – so it’s never too late to start feeding your microbes well!

So what are the best foods to feed a healthy gut?

Dietary Fiber

Fiber is important for heart, digestive and metabolic health, helping with cholesterol, blood sugar control, and regular bowel movements. It comes in two forms: dietary fiber, naturally found in plants, and functional fiber, which is added to foods. Dietary fiber is further divided into two kinds:

Dietary Fiber	Benefits	Sources
Insoluble Fiber	Does not dissolve in water and helps add bulk to stools and supports digestion.	Brown rice, nuts, pears, strawberries, wheat bran, whole grain bread, whole-wheat flour, vegetables with edible skins (zucchini, potatoes, carrots, eggplant, cucumbers, sweet potatoes)
Soluble Fiber	Does dissolve in water; lowers cholesterol and steadies blood sugar by slowing digestion.	Apples, berries, barley, beans, citrus fruits, dates, jicama, leeks, oatmeal

Most plant foods contain both types, but in different amounts and locations—for example, pears have more insoluble fiber than soluble, and potato skins are richer in insoluble fiber while the flesh contains more soluble fiber.

The USDA recommends 38 grams of dietary fiber per day for men, and 25 grams for women. After the age of 50, this drops down to 30 grams for men, and 21 grams for women.

Both classes of dietary fiber remain undigested until reaching the large intestine, where microbes jump into action and “digest,” or ferment, the fiber. Insoluble fiber is poorly fermented in the large intestine, while soluble fiber provides microbiota-accessible carbohydrates (MACs), which are easily fermented by microbes.

Prebiotics

Prebiotics are a type of dietary fiber and are non-digestible food ingredients that feed the probiotics in your gut. In doing so, they play a large role in influencing the types of microbes available, thereby increasing health outcomes. Prebiotics have been linked to improved immune function, nervous system health, skin health, cardiovascular health and bone health.

All soluble fibers are prebiotics, and there are several types: fructans (including fructo-oligosaccharides [FOS] and inulin); galacto-oligosaccharides (GOS); resistant starch; and pectic oligosaccharides (POS), or pectin. The chart below provides a list of foods that contain these prebiotics.

Prebiotic	Sources
Fructans	Artichokes, asparagus, chicory root, dates, fennel, figs, functional food products with inulin (ex. high-fiber granola bars), garlic, kidney beans, onions, plums, ripe bananas, watermelon, wheat
Galacto-oligosaccharides (GOS)	Cashews, chia seeds, legumes, pistachios, seaweed-derived products, soybeans
Resistant starch	Cashews, cassava, green bananas, potato starch, potatoes (cooked and cooled), tiger nuts
Pectic oligosaccharides (POS)	Apples, apricots, cherries, citrus fruit (especially the peel), pectin used as a thickener in commercial foods as well as jams and jellies

Probiotics

Probiotic means “for life” in Greek – a fitting name considering how supportive these beneficial microorganisms are for overall health and quality of life. Probiotics may occur naturally in food (e.g., lacto-fermented vegetables), be added to food (ex. cereals fortified with probiotics), or be formulated into dietary supplements.

The main health benefits of probiotics include:

• Digestive Health - supports regular bowel movements adn may relieve symptoms of irritable bowel syndrome

• Gut Microbiome Balance - restore beneficial bacteria after antibiotic use or illness; reduce the growth of harmful microbes

• Metabolic Health - Supports better blood sugar regulation, lowers bad cholesterol and lowers blood pressure.

• Disease Prevention - stimulates immune cells and enhances the boyd' defense against infection.

• Emotional Well-Being - supports a healthy gut-brain connection through the growth of neurotransmitters.

Strain names identify probiotics and include information on the genus, species (and subspecies, if applicable), and alphanumeric designation. Probiotics aren’t “one size fits all,” and certain strains may be more effective than others for some health concerns. For instance, research has found that Bifidobacterium longum is anti-inflammatory, while B. bifidum supports immune function.

Probiotics in kefir

Fermentation occurs when microorganisms change starches or sugars into another substance, such as an acid or alcohol. Because probiotics are created during the process, fermented foods naturally contain many strains of beneficial microbes and are a way to consume probiotics without supplementation. Fermented foods can be found at local farmers’ markets and health food stores. Read labels carefully to be sure you’re getting the real deal – make sure the microbes are still intact. For example, canned sauerkraut pasteurized at high temperatures won’t provide the same probiotic benefits that unpasteurized, raw sauerkraut will.

Below is a list of common fermented foods, along with what to look for and how to enjoy them. Not everyone can tolerate fermented foods, so if you're new to these foods, start slowly with small portions and see how you feel. It’s natural to experience some bloating or slight changes in bowel habits when first starting! Over time, you will get a sense of how your body reacts and which foods and portions work best for you!

Fermented Foods	What To Look For	How To Enjoy
Kefir	Organic, no or low sugar options, indicates the product contains live cultures	In smoothies, with granola or simply on its own
Kimchi	Labeled as naturally fermented, raw and organic	As a condiment, in a stir-fry, noodle bowls or on eggs
Kombucha	Raw, unpasteurized options in dark bottle	As an alternative to alcohol, soda or other sugar-sweetened beverages
Miso	Organic, non-GMO	In homemade dressings, sauces and soups
Pickles	Labeled as naturally fermented, organic and raw (should not indicate preparation with vinegar)	In salads or sandwiches, or simply on their own
Sauerkraut	Organic, unpasteurized and raw indicates the product contains live cultures	As a condiment or side dish with eggs, vegetable dishes or sandwiches
Tempeh	Organic, non-GMO	As a meat substitute
Yogurt	Organic, no or low sugar options, indicates the product contains live cultures	In smoothies, or on its own with fruit, nuts or granola

Short-Chain Fatty Acids

When the MACs in prebiotics are fermented in the large intestine, short-chain fatty acids (SCFAs) are formed. These beneficial by-products are an energy source for the cells in the colon and have proven health benefits (including immune and metabolism support). They are also important for building intestinal mucosa, or the lining of the gut. It’s interesting to note that SCFAs allow for cross-feeding – that is, for one bacteria to feed off another’s energy source. In other words, SCFAs play a role in helping other species in the gut survive The SCFAs include:

• Butyrate - A major energy source for epithelial cells in the colon, butyrate is anti-inflammatory and has anticancer properties. It is found as a dietary supplement and is naturally available from foods like butter and cream.

• Acetate - The main SCFA in the colon, acetate can help with cholesterol synthesis and is found in fermented foods, vinegar, and dietary supplements.

• Propionate - This SCFA helps produce glucose in the liver and has been linked to the

  production of the hormones that regulate appetite. It’s found in cheese, fermented foods, and dietary supplements.

Note: All of this information is for general information only and applies to most people. However, we're all unique creatures and please exercise caution if you have any food sensitivities. If you're unsure, please talk to a licensed healthcare professional or registered dietician to get properly tested.