Our gut is the main connection between the outside world and our body’s cells. Bacteria and their byproducts in the gut interact with immune cells located in the lining of our small and large intestine. These immune cells can become ‘switched on’ when the gut is imbalanced, producing compounds that lead to inflammation in the body and nervous system.
Studies have found people with anxiety and depression often have elevated levels of these inflammatory markers, and that these markers – when increased – can trigger a worsening of symptoms. Inflammation in the gut can also cause the neurotransmitter serotonin to be converted into a substance called kynurenic acid. Serotonin is a neurotransmitter that may help reduce symptoms of anxiety and depression, but when converted into kynurenic acid it can have the OPPOSITE effect, increasing symptoms. Reducing inflammation can, therefore, help restore normal serotonin levels.
Our gut is home to millions of bacteria. Some are good for us, some are bad for us, some are neutral, and some can become bad when out of balance. This imbalance in the gut is termed Dysbiosis.
Studies have found that people with anxiety and depression often have lower levels of beneficial gut bacteria such as faecal bacterium prausnitzii and bacteria from the bifido group. These bacteria are important as they produce compounds such as butyrate which have an anti-inflammatory effect. This helps to reduce leaky gut and the absorption of LPS (see below), as well as to produce key vitamins such as folate and vitamin B12 needed to manufacture our ‘feel good’ neurotransmitters such as serotonin and dopamine.
Thankfully, changing our diets can help this. The modern industrial world diet of refined sugars, carbohydrates and excess poor quality fats can cause a WORSENING of dysbiosis, whereas a whole food diet based on the foods our ancestors ate, rich in plant compounds and fibres, seems to help the growth of beneficial gut flora, and indeed, is associated with much better mental health.
Certain bacteria produce a compound in their cell wall called Lipopolysaccharide, or LPS for short. Small amounts of LPS in the gut is normal, but when there are high amounts, or when the gut wall is ‘leaky’, then fragments of LPS can get into the bloodstream and cause problems.
In particular, LPS triggers a low grade ongoing inflammatory response in the body. In the brain, this can affect serotonin levels leading to anxiety and depression. It can also amplify cortisol levels leading to a greater stress response in our bodies. LPS, when injected into animals, can stimulate almost immediate symptoms of anxiety and depression.
Certain bacteria in the gut produce more LPS than others and these include the Proteobacteria. These bacteria can overgrow when the diet is too high in poor quality fats and proteins and too low in fibres and plant compounds. Stress can increase absorption of LPS, and it is thought that this may be part of the reason some people will get a flare-up in symptoms of anxiety and depression. Small Intestinal Bacterial Overgrowth (SIBO), a condition where excess bacteria live in the small intestine, can also lead to high levels of LPS.
Low levels of nutrients such as Zinc, Magnesium, B12, B6, Folate and Iron are associated with poorer mental health and an increase in symptoms of anxiety and depression. Additionally, studies have found that even when people are on medication for anxiety such as SSRI’s, the medication will not work as well (or even at all) if the person is low in these nutrients.
For many people, having a nutrient-rich diet or supplements won’t always help, and this can be because they are actually experiencing some degree of nutrient malabsorption. Dysbiosis, inflammation, small intestinal bacterial overgrowth (SIBO), coeliac disease (gluten reactivity), inflammatory bowel disease, and common issues such as fructose malabsorption and lactose intolerance are all associated with a decrease in absorption of many of these beneficial nutrients.
Many medications decrease nutrient absorption, too, including antacids, proton pump inhibitors, the contraceptive pill, some fibre supplements, and pain-relieving agents such as NSAIDs like ibuprofen and aspirin. Thankfully, targeted dietary strategies can manage many of these issues, and it is very important you speak with your practitioner about the right gut health diet for you!
A diet rich in plant-based fibres and polyphenols (pigments that give fruit and veg their vibrant colours) can increase good bacteria as well as decrease bad bacteria in the gut addressing dysbiosis.
In particular plant foods with a blue, black or purple colour are really good at feeding bifidobacteria e.g. blueberries, purple carrots, black sesame seeds, black tahini, and purple sweet potato.
Foods that can feed faecal bacterium include onion, garlic, leek, beetroot, dandelion root and many legumes if well cooked (and tolerated). If you find you are reacting to these foods, see your Merge practitioner about how we can help this!
Whilst feeding the good, it’s also important not to feed the bad! Excess dairy fats, refined sugars, trans fats, and excessive amounts of proteins can feed proteobacteria, increasing LPS levels. We need a balance of fats, proteins and plant foods in our diet.
My advice to patients is to keep it simple – imagine your plate as having a serve of protein no bigger than the palm of your hand, a serve of whole food carbs no bigger than a clenched fist and fill the rest of the plate with varied coloured veggies. Stick to traditional fats and oils in the diet, and avoid added sugars.
Studies have found that eating foods rich in living bacteria can help improve the diversity of good bugs and provide food for existing gut bacteria. These include traditional fermented foods such as sauerkraut, kimchi, kefir, yoghurt, kombucha and lacto-fermented pickles.
Research has found that when these foods are added to the diet, stress and anxiety symptoms can sometimes improve. An exciting new area of research is also looking at supplementing with specific probiotic strains to help manage anxiety and mental health symptoms – these have been called ‘psychobiotics’.
At this point in time, we still need more research, so speak to your practitioner about what might be right for you; however, strains that have shown some benefit include L. Helveticus R00B2 and B. Longum R0175 in anxiety and depression, L. Plantarum 299V in reducing kynurenic acid and improving cognitive function, and B. Longum 1714 in reducing the stress response.
It is important to note that the strain number at the end of the description is important when choosing probiotics – a B. Longum of a different strain may have entirely different effects, so please see your practitioner to discuss the best probiotic for you and in the meantime enjoy all those traditional fermented foods!
Underlying untreated conditions such as coeliac disease, fructose malabsorption, lactose intolerance, inflammatory bowel disease and SIBO (amongst many others) can all affect nutrient absorption, so it is very important to get these conditions screened for and treated if you suspect they may be contributing to anxiety.
Sometimes this may require medical tests or trial periods on elimination diets, which can be risky to attempt on your own, so it is very important to seek help from one of our practitioners to get expert advice on this. If you are experiencing increased anxiety and notice you also have a lot of gut symptoms such as constipation, bloating, diarrhoea, IBS, intestinal discomfort, reflux and heartburn, or generally do not feel like your digestion is at its best, why not come in and see us and to find out if your gut health is linked to your anxiety.