Tim Spector, a professor of epidemiology at King’s College London, is encouraging anyone who experiences irregular bowel movements, bloating or heartburn after meals to seek medical advice. This is becasue these symptoms could be signs of poor gut health. In an interview with Fortune Well, Professor Spector explained individuals who are obese or who have diabetes, are more likely to face gut-related issues.

Stressing the importance of diet, he noted that it’s possible to have an unhealthy gut without noticeable symptoms—particularly if your diet is rich in meat and ultra-processed foods, which he strongly recommends avoiding. He said: “Not everyone has symptoms. Not everyone knows that they have problems.” Because of this, he said that eating 30 plants is something he does, and wants others to do too to ensure you have a thriving gut microbiome.

Although the number may appear large, he explained that it enables you to eat a variety of fibre-rich foods, which support a healthy gut. Spector, the founder of ZOE , also noted that there are plenty of options to help reach the target of 30, and shared an extensive list on their website.

This includes:

• asparagus

• broccoli

• cabbage

• carrots

• chicory

• eggplant

• Jerusalem artichokes

• red onion

• rocket

• spinach

• sweet potatoes

• zucchini

• apples

• avocados

• bananas

• bell peppers

• blueberries

• figs

• kiwis

• oranges

• raspberries

• tomatoes

• black beans

• broad beans

• butter beans

• chickpeas

• green beans

• kidney beans

• lentils

• peas

• pinto beans

• soybeans or edamame

• brown rice

• bulgar wheat

• oats

• quinoa

• rye flour

• whole wheat flour

• almonds

• Brazil nuts

• cashews

• pine nuts

• pistachios

• walnuts

• chia seeds

• flaxseeds

• hemp seeds

• pumpkin seeds

• sesame seeds

• sunflower seeds

• basil

• cilantro

• mint

• oregano

• parsley

• rosemary

• sage

• tarragon

• allspice

• black pepper

• cumin

• ginger

• nutmeg

• paprika

• saffron

• turmeric

In fact, speaking on the ZOE podcast, Tim said: “It may be one that people haven’t thought about as much because it’s a bit different but what I’m trying to emphasise is that any fermented food, that includes things like yoghurt, kefirs, regular sauerkraut, kimchis, misos. All of these have anti-inflammatory studies and these have been shown in multiple studies in both test tubes and in humans.

“The most recent studies often use multiple different ferments rather than just focusing on one. I think it’s really important that people learn to diversify what they’re eating because each ferment will have a different set of microbes in them.

“So yoghurts will have say three microbes and some of these more complex krauts and kimchis can have up to 20 or 30 in some kombucha so red sauerkraut is just one of an example of things that you can add to your meal tiny amounts. A real classic study in Stanford showed that when they asked volunteers to try and get five small portions a day of ferments, they could really show in two weeks a dramatic, significant reduction in inflammation levels.”