Important Foods for Better Gut Health (and What to Limit)

The best foods for gut health are fermented foods like yogurt and kefir, fiber-rich plants like oats, beans, bananas and leafy greens, and nuts, seeds and berries. They feed your helpful gut bacteria and support a healthy gut lining. The main things to limit are alcohol, added sugar and heavily processed foods.

Why does gut health matter for training?

Your gut does a lot more than digest food. It is closely tied to your immune system, your energy and how you feel day to day. When digestion is off, training, recovery and fat loss all get harder. I have had clients who could not figure out why they felt flat in every session until I helped them clean up what they were eating.

I am not saying the gut fixes everything. But it is one of the first places I look when someone feels run down despite doing the work.

Which fermented foods help your gut?

Fermented foods contain live bacteria and can increase the variety of microbes in your gut. In a Stanford study, people who ate more fermented foods for 10 weeks had a more diverse gut microbiome and lower markers of inflammation (Wastyk et al., 2021).

My go-to options:

• Plain Greek yogurt. Look for “live and active cultures” on the label, and pick unsweetened versions.
• Kefir. A drinkable fermented milk with a wider range of strains than most yogurt. In one study, kefir improved lactose digestion in adults who usually have trouble with dairy (Hertzler and Clancy, 2003).
• Sauerkraut, kimchi and other fermented vegetables, as long as they are refrigerated and unpasteurized.

If you are thinking about probiotic supplements, the NIH has a good overview of what the evidence does and does not support (NCCIH). Food is where I start.

Which high-fiber foods feed good bacteria?

Your gut bacteria live on fiber that your body cannot digest on its own. Certain fibers, called prebiotics, are especially good at feeding helpful microbes (Holscher, 2017).

Good sources:

• Bananas, especially slightly green ones, which contain resistant starch
• Oats and brown rice, which provide soluble fiber
• Beans, lentils and chickpeas
• Onions, garlic and leeks
• Leafy greens and other vegetables

If you are eating very little fiber now, add it slowly over a couple of weeks and drink more water. Jumping straight to a huge amount usually means bloating.

Which foods help calm inflammation?

• Nuts and seeds. Almonds, walnuts and sunflower seeds give you fiber, healthy fats and vitamin E. In a large study of adults, people who ate more nuts and seeds had lower levels of inflammatory markers like C-reactive protein (Jiang et al., 2006). That study shows a link, not proof of cause, but it lines up with what I see.
• Berries and leafy greens. They are packed with fiber and plant compounds called polyphenols.

What should you limit for better gut health?

• Alcohol. Heavy drinking can damage the gut lining and increase gut-related inflammation (Bishehsari et al., 2017). I cover the training side in alcohol consumption weakens your immune system.
• Ultra-processed foods. Some food additives may be a problem. In a controlled feeding study, the emulsifier carboxymethylcellulose changed the gut bacteria of healthy adults in a short time (Chassaing et al., 2022). More on this in why ultra-processed foods will always be a problem.
• Added sugar. Large amounts crowd out the fiber-rich foods your gut bacteria need.
• Processed meats. Bacon, deli meat and hot dogs are easy to overdo. I keep them occasional.

How do you start improving your gut health today?

Here is the simple reset I give clients:

1. Add one fermented food and one high-fiber food to each meal.
2. Track bloating, energy and digestion for 7 days.
3. Cut out most ultra-processed food and added sugar for 30 days.
4. Bring foods back one at a time and notice how you feel.

Ask yourself a few honest questions while you do it. How many of your meals include fiber or a fermented food? How often do you eat processed or sugary foods? Do you crash after certain meals?

For more on what to eat around training, read what are the worst foods to eat before a workout and my post on good versus bad gut bacteria.