IBS affects both the brain and the gut, so experiencing pain and cramps in the lower abdomen, excessive gas and bloating, as well as diarrhea and constipation are all very common. Pain and cramps are often linked to excessive gut muscle contractions and an oversensitivity of the gut. Gas and bloating are likely due to problems with bacteria in the gut, or perhaps the gut is simply less able to tolerate and transport gas. As for diarrhea and constipation, these occur when the normal bowel movement rhythm is disrupted, either by speeding up or slowing down the gut muscle contractions. Diarrhea happens when the muscles contract more than they need to, while constipation is caused by the muscles contracting less than they should.
People with IBS may also find that they’re more sensitive to FODMAP foods, which stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. FODMAPs can cause inflammation and irritation in the gut, lead to intestinal gas, and trigger other IBS signs and symptoms. This is because they increase the amount of water going into the gut and the gut bacteria then causes them to ferment. High-FODMAP foods include things such as garlic and onion, lentils and beans, almonds and cashews, and avocados. Trading in these foods for a low-FODMAP diet may therefore help improve symptoms of IBS.
Stress and fatigue are strongly linked to IBS, which is likely due to psychological distress since the nervous system controls the gut and is also responsible for responding to psychological stress. One study found that those with IBS experienced greater changes in the stress hormone cortisol when given a public speaking task, and over half of people with IBS report fatigue. Poor sleep quality is related to more severe gastrointestinal symptoms and interestingly enough, the intensity of IBS symptoms seems to predict the severity of fatigue. In the same way that stress and fatigue are symptoms of IBS, they can also act as triggers for a whole list of symptoms.
Joint pain and brain fog are often experienced by people with IBS, possibly due to increased inflammation in the body and intestinal gas and bloating, respectively. Joint pain refers to any discomfort, pain, or inflammation arising from a joint, while brain fog is a state of foggy thinking, mental confusion, impaired judgement, and difficulty concentrating. Additional common symptoms of IBS include farting, passing mucus from the anus, tiredness or lack of energy, nausea, backache, problems peeing, and being unable to control bowel movements on occasion.
In general, dietary modifications, stress-reducing therapies, and certain medications can help reduce or eliminate symptoms of IBS. Symptoms may be better or worse on certain days, the latter of which is referred to as a flare-up, and can be triggered by food or drink. There is no single diet or medicine that works for all IBS sufferers, but things such as cooking homemade meals with fresh ingredients, keeping a food diary to identify triggers, finding ways to relax, getting plenty of exercise, and eating slowly may all help. In addition, not delaying or skipping meals, staying away from alcohol and fizzy drinks, and cutting down on fatty, spicy, or processed foods may be beneficial.
Resources:
https://www.medicalnewstoday.com/articles/324259.php
https://www.healthline.com/nutrition/9-signs-and-symptoms-of-ibs#section9
https://www.nhs.uk/conditions/irritable-bowel-syndrome-ibs/diet-lifestyle-and-medicines/