Brown sugar doesn't contain any FODMAPs and should be tolerated by most people.
Brown sugar is a sucrose sugar product with a distinctive brown color due to the presence of molasses. It is either an unrefined or partially refined soft sugar consisting of sugar crystals with some residual molasses content (natural brown sugar), or it is produced by the addition of molasses to refined white sugar (commercial brown sugar).
Commercial brown sugar contains 3.5% molasses (light brown sugar) to 6.5% molasses (dark brown sugar) based on total volume. Based on total weight, regular commercial brown sugar contains up to 10% molasses. The product is naturally moist from the hygroscopic nature of the molasses and is often labeled as "soft." The product may undergo processing to give a product that flows better for industrial handling. The addition of dyes or other chemicals may be permitted in some areas or for industrial products.
One hundred grams of brown sugar contains 377 Calories (nutrition table), as opposed to 387 Calories in white sugar (link to nutrition table). However, brown sugar packs more densely than white sugar due to the smaller crystal size and may have more calories when measured by volume.
Any minerals present in brown sugar come from the molasses added to the white sugar. In a 100-gram reference amount, brown sugar contains 15% of the Daily Value for iron, with no other vitamins or minerals in significant content.