Gut health is still up there as one of the hottest health topics today, and I don't think this will be changing any time soon. We are only just scratching the surface in terms of our knowledge in this area, making it a really exciting time to be working in health. Just like anything else, variety is important when we are feeding our bodies. As much as I am a fan of bone broth and sauerkraut, don't be afraid to branch out into some other wonderfully supportive foods. Here are four underrated foods that work wonders to support gut health.Cabbage really is an incredible vegetable. Aside from being the base of most sauerkraut and kimchi recipes - which have amazing digestive benefits, it is also high in an amino acid called L-glutamine. L-glutamine is a primary fuel for our gut cells, providing them with the nourishment they need to heal and prevent digestive disorders. And if you've ever finished a serve of cabbage rolls and wondered why you were in such a good mood - here's a possible explanation. L-glutamine is a precursor for GABA, or gamma aminobutyric acid - a major relaxing neurotransmitter. More specifically, glutamine is converted to glutamate, which is then converted to GABA.Low levels of GABA may be associated with stress, anxiety, depression, insomnia, muscle spasms, hypertension and dry skin. Low levels may also impact your digestive system, as GABA stimulates the secretion of digestive enzymes to assist with the digestion and absorption of food. Go cabbage!What is lovely about the fibre in apples is the particular relationship it has with the other phytonutrients that lie within. Three grams of fibre may not seem like a huge amount (we used to think that it was higher), but the combination of the soluble fibre and the other phytonutrients in the apple create an impact typically seen with much higher levels of fibre. This tells us that eating the whole apple is important to achieve the maximum health benefits, and that when all nutrients within the apple are consumed together as a whole, the impact is greater than each constituent on its own.Polyphenols such as quercetin are another gut loving component of apples. Most polyphenols pass through the upper gut to the colon where they feed our gut bacteria and influence a reduction in intestinal inflammation - win! They also act as a prebiotic fibre and resistant starch, nourishing our gut microbiome by modulating the gut microbiota, increasing bifidobacteria and protecting against chronic and digestive disease. Double win!!Kombucha seems to be stealing all the probiotic drink limelight these days. Don't get me wrong - it's fabulous stuff, but if you're ready to mix it up then perhaps the ‘champagne of milks' might be worth a try?Kefir involves a community of around thirty different types of microbes, well represented by various lactobacillus species, all ready to lend their special gifts to your gut. When we drink kefir, it coats the digestive tract in a thin layer of mucus, laying down a bed for the friendly bacteria to colonise and protect against pathogenic bacteria. It is both a prebiotic and a probiotic - a synbiotic, meaning that it contains both the good bacteria, but also their survival kit for their new life in the gut.As if that wasn't enough, kefir is packed with nutrients, including calcium, potassium, magnesium, and zinc, among others, and has an antibacterial effect that works towards protecting against gastrointestinal disorders and vaginal infections. Kefir can be made using a base of cow's milk or coconut milk, and those with lactose intolerance are often able to happily drink kefir as the hungry bacteria consume most of the lactose during the fermentation process. There are also enzymes to aid in the digestion of the milk, which are not present in the unfermented product. The one draw back - it is a little sour. Try adding some to smoothies to introduce yourself to the taste, and I'm sure the benefits will win you over!The final star food is a form of starchy fibre called resistant starch. It can't be digested in the small intestine, and passes through to the colon where it is then fermented by bacteria. Foods like legumes (lentils, beans), peas, wholegrains and cooked and cooled starchy foods are high in resistant starch, and they behave very differently in the body to a normal starch.This process of fermentation produces metabolites, short-chain fatty acids, gases and small amounts of organic acids and alcohols. These metabolites, particularly the short-chain fatty acid butyrate, are important food and energy sources for our gorgeous enterocytes - the cells that line the gut wall, therefore enabling them to perform at their best.Not only that, these metabolites seem to have protective effects against DNA damage to the cells and the development of colon cancer, help to regulate metabolism, optimise the secretion of hormones, and reduce the pH of the large intestine. Resistant starch also seems to improve the function and quantity of our healthy gut bacteria themselves. We know that our gut microbiota play a significant role in our immunity, detoxification processes, brain function and inflammation. More and more studies are revealing links between suboptimal gut bacteria and inflammatory bowel disease, obesity, mental illness, diabetes, and other chronic diseases, so it makes sense to keep them as happy and healthy as we can.