Sushi is considered a healthy food because it is generally low in fat but it is an unbalanced food which is also low in protein and vegetables. The largest component is rice. For an occasional meal that is fine but before we decide to add this to our list of foods we can consume, we have to investigate each of the parts that make up the whole.
Rice is low Fodmap but when it is prepared for sushi, sushi vinegar is added. Many commercial sushi vinegars contain high fructose corn syrup, so if fructose is a trigger for you, you will need to check the ingredients of the rice component before purchasing. If you make the sushi yourself, you can use ordinary sugar instead. The brown rice option is always the healthier choice because the inclusion of the rice fibre slows down the absorption of the sugars in the rice.
Nori, which is wrapped around the rice, is a dried, edible seaweed, which is low Fodmap so we do not need to worry about this component of sushi.
You will need to analyze the fillings and choose according to your Fodmap triggers. Avocado contains sorbitol but is okay in small amounts, which is all you get in a sushi roll anyway. Avoid any of the mashed foods like tuna, which could easily contain onion or garlic, which are high Fodmap and cause issues even in small amounts for some. Any protein meat that looks marinated, for example in teriyaki sauce, should be avoided because they could contain high Fodmap ingredients. The cleaner and simpler the filling, the safer it will be as long as it is naturally low Fodmap.
This can vary from person to person but remember we should eat more frequent smaller meals to avoid irritating our hypersensitive digestive systems. I would eat only three pieces for a meal, but those who have a higher need for calories, could be fine with six.
Any food that is made of many parts has to be analyzed in the same way. You need to be able to put a tick beside each individual ingredient before deciding it is safe to consume.