11 Gut-Microbiome Superstars That Are Better Than Probiotics (and Where to Find Them)

5. Resistant-Starch Foods — Green Bananas & Cooked-Cooled Potatoes

Resistant starch is a form of carbohydrate that resists digestion in the small intestine and arrives in the colon where microbes ferment it into beneficial short-chain fatty acids. Foods higher in resistant starch include slightly underripe (green) bananas and potatoes that have been cooked, cooled and then eaten cold or gently reheated. Nutrition experts like Lauren Manaker, RDN, highlight underripe bananas as an easy, portable source of resistant starch that supports the microbiome. A simple approach is to include one small green banana in a smoothie or snack rotation, or enjoy chilled potato salad made from cooked-cooled potatoes a couple of times weekly. Start modestly, since resistant starch can produce gas initially; a gradual increase over two weeks helps the gut adapt. You can find green bananas at most grocery stores and prepare cooled potato dishes at home for better control. For those with blood sugar concerns, balance portions and pair resistant-starch foods with protein and healthy fats to blunt glucose spikes. Resistant starch is a practical tool for feeding beneficial microbes without supplements.

6. Oats — Beta-Glucan for Microbial and Barrier Support

Oats provide beta-glucan, a soluble fiber that functions as a prebiotic and supports both the microbiome and gut barrier health. Beta-glucan is linked to increased beneficial bacteria and may help moderate blood sugar and cholesterol, making oats a multi-benefit choice for older adults and anyone focused on steady nutrition. Try one serving—about half a cup cooked—each morning as porridge, overnight oats, or added to smoothies. Preparing oats with milk or plant-based milk and topping them with nuts and berries adds healthy fats and polyphenols for broader microbial support. Buy whole or steel-cut oats from grocery stores and bulk bins for better texture and nutrition versus highly processed instant varieties. Those with celiac disease should buy certified gluten-free oats to avoid cross-contamination. Dietitians often recommend oats as a gentle, everyday prebiotic that fits many eating patterns and supports long-term microbiome health.