The gut microbiome has become a hot topic in health and nutrition. Made up of trillions of microorganisms including bacteria and fungi, the gut microbiome has a huge influence on our overall health. And what we eat is a major factor in supporting or hurting the health of our guts.
As scientists learn more about how the gut microbiome works, it’s become clear that plant foods are beneficial for gut health. In fact, Tim Spector, a leading expert on gut health, recommends eating 30 different plant foods a week. Vegetables and fruits are important, but seeds, nuts, and spices count too.
Plants are full of fiber
In a new episode of The Fit Vegan Podcast, gastroenterologist Dr Angie Sadeghi talked about what makes plant foods so good for gut health. One of her key messages was that fiber is crucial for fuelling the microbiome and repairing the gut. You should eat around 30g of fiber a day, but most people eat too little. Fiber can’t be obtained from animal products — for that you need plants like whole grains, vegetables, and pulses.
Eating lots of plants foods helps create gut microbes that specialize in breaking down fiber. When these microbes ferment dietary fiber, they produce short-chain fatty acids. These help to lower inflammation, maintain the gut barrier function, and support the immune system.
Research shows that dietary fiber from some types of plant foods may be more beneficial than others. Prebiotic fiber, found in foods including chicory root, garlic, onions, and beans, is the type that feeds the “good” gut bacteria that we want more of. While general fiber from sources like potatoes and fruit is still good for you, it doesn’t have much impact on the type of bacteria in the gut microbiome.
Plants provide complex carbs
Carbohydrates are an important part of a healthy diet. According to Dr Sadeghi, eating whole, nutrient-dense carbs, helps maintain the protective layers of the gut, preventing inflammation and intestinal permeability, known as leaky gut. This can contribute to the development of conditions such as celiac disease, Crohn’s disease, and irritable bowel syndrome.
Along with fiber, complex carbohydrates found in foods such as sweet potatoes and bananas provide starches. Resistant starches in particular have recently emerged as playing an important role in gut health. Resistant starches don’t break down in the small intestine, but move on to the large intestine where microbes ferment them. Like the fermentation of fiber, this process produces short-chain fatty acids, including ones linked to lowered risk of colorectal cancer.
By contrast, avoiding carbs or only eating simple carbs will produce harmful byproducts in the gut as it’s forced to digest protein inefficiently, according to Dr Sadeghi.
Plants increase microbe diversity
The more types of plants you eat, the more diverse your gut microbiome will be. This is why Tim Spector recommends 30 kinds of plants a week.
According to the research behind the recommendation, gut bacteria have different properties such as enzymes that means their reaction to different carbs vary. “A diet containing various types of dietary fibers and resistant starches likely supports a more diverse microbial community,” the research says.
Plant promote beneficial species
Eating more types of plants also helps to encourage the growth of beneficial microbes that have anti-inflammatory properties and boost the immune system.
Each species of microbe has its own preferences regarding prebiotics and polyphenols, the bioactive compounds found in plant foods. Polyphenols promote beneficial bacteria. This means that the more types of plants you eat, the more variety of compounds you’re providing for your gut microbes and the more you fuel the good bugs.
Eating different colored plants contribute to this too, as they contain different polyphenols. This is even true of the same foods in different colors, such as red and yellow peppers.