Dairy and FODMAPs: 49 foods rated

Cream cheese is a fresh cheese that was never drained hard and never aged, so the lactose is still in it. It is also spread thickly rather than grated thinly, which doubles the practical difference from a hard cheese.

Evaporated milk has had about half its water boiled off, so the lactose per spoonful is roughly double that of milk. It is used in coffee and in cooking by the tablespoon rather than the glass, which is the only thing keeping the dose manageable.

Fresh whole milk is unconcentrated and unfermented, which means nothing has reduced its lactose - no drying, no draining, no culture. It sits at the top of the dairy range by default rather than by any property of its own.

Goat milk carries essentially as much lactose as cow milk - the difference is a fraction of a percent. People switch to it expecting relief and do not get it. What is genuinely different is the protein and the fat globule size, which is another question entirely.

Mascarpone is made from cream rather than milk, and fat displaces the water where lactose lives - so per gram it carries less than cream cheese does. It is eaten in dessert quantities, which puts the serving back where the concentration saved it.

Milk is the reference point for the D of the acronym. Lactose is a disaccharide, and it needs lactase to be split before it can be absorbed - an enzyme most of the world's adults stop making. A glass is well over the threshold, and unlike the other FODMAP families there is a genuine fix: lactase-treated milk is the same milk with the sugar already split.

Milk powder is milk with the water removed entirely, which makes it about eight times the lactose of liquid milk by weight. It hides in biscuits, sauces, chocolate and instant drinks, where nobody reads it as a serving of milk.

Ricotta is made FROM whey - the liquid a cheesemaker drains off - so it keeps the lactose that draining removed from the cheese beside it. That is why one fresh Italian cheese is high here and mozzarella, made from the curd, is low. Same dairy, opposite halves.

Sheep milk carries slightly more lactose than cow milk, not less, and it is much richer in solids overall - so a smaller volume delivers the same dose. It is the milk most often assumed to be gentler and the one that measures highest.

Skim milk powder is the most lactose-dense dairy ingredient there is: the water is gone and so is the fat, leaving the sugar and the protein. It is the standard cheap filler in processed food, and a small percentage of a recipe is still a large percentage of a milk.

Skimmed milk carries marginally MORE lactose per hundred millilitres than whole, not less - removing the fat concentrates everything in the water phase, and lactose lives there. Choosing skimmed to be gentler on the gut works against you on this axis.

Skyr is strained hard, which removes whey and with it lactose - but it is also concentrated, so what remains is packed into less volume. The two effects work against each other, and a normal pot still lands above the threshold.

Sweetened condensed milk concentrates the lactose and then adds sucrose on top - roughly half the tin is sugar by weight. Two FODMAP questions arrive together, and the sweetness masks how much milk sugar is underneath it.

• Tuck C et al., J Hum Nutr Diet 31 (2018), FODMAP content of common plant-based and processed foods
• USDA FoodData Central, the national nutrient database, queried for the sugar profile

Whole milk carries the same lactose as skimmed - the fat changes the calories, not the sugar. What the fat does change is the speed: a fattier milk empties from the stomach more slowly, so the same lactose arrives more gradually. That helps some people and is not a reason to expect a different level.

Yogurt: yoghurt cultures eat some of the lactose but not most of it - a few hours of fermentation is not the weeks a hard cheese gets. The bacteria also carry their own lactase into the gut, which helps a little. Neither effect is enough to bring a standard pot below the threshold.

Buttermilk is cultured, and the bacteria have worked on the lactose for longer than a yoghurt gets - which is why it sits a level lower. Traditional buttermilk, the liquid left after churning butter, is lower still than the cultured product sold under the same name.

Whey is the liquid the lactose left in when the curd was drained - so it holds what the cheese gave up. It is where ricotta comes from, and it is the reason a cheese and its by-product sit on opposite sides of this axis.

Whey protein is where the label matters more than the food. An ISOLATE has been filtered until almost no lactose remains and is effectively low; a CONCENTRATE keeps a good deal of it. Both are sold in the same tubs to the same people, and the word on the front is the whole answer.

Buffalo mozzarella is a fresh cheese, and fresh cheeses are low for a different reason from aged ones: the lactose left with the whey when the curd was drained, rather than being eaten over time. Removal beats fermentation here, and it happens in an afternoon rather than a season.

Cream is low because it is mostly fat, so the lactose per spoonful is small.

• USDA FoodData Central, the national nutrient database, queried for the sugar profile

Creme fraiche is low because it is mostly fat, and lactose lives in the water phase.

Edam is low because the lactose is gone, eaten by the starter bacteria over weeks of ripening. Lactose is the D of the acronym, and an aged cheese has almost none left - which is why hard cheese is one of the few dairy foods a low-FODMAP diet keeps.

Emmental is low because the lactose is gone, eaten by the starter bacteria over weeks of ripening. Lactose is the D of the acronym, and an aged cheese has almost none left - which is why hard cheese is one of the few dairy foods a low-FODMAP diet keeps.

Feta is not quite a fresh cheese - the curd is drained, then ripened weeks in brine - but it is low for the same family of reasons: the lactose left with the whey at draining, and the brining weeks let the bacteria work on what little remained. Removal first, a short ripening second, and the answer stays low.

Goat cheese is a fresh cheese, and fresh cheeses are low for a different reason from aged ones: the lactose left with the whey when the curd was drained, rather than being eaten over time. Removal beats fermentation here, and it happens in an afternoon rather than a season.

• USDA FoodData Central, the national nutrient database, queried for the sugar profile

Grated mozzarella is a fresh cheese, and fresh cheeses are low for a different reason from aged ones: the lactose left with the whey when the curd was drained, rather than being eaten over time. Removal beats fermentation here, and it happens in an afternoon rather than a season.

Greek yogurt is low because it is strained, so much of the lactose left with the whey.

Halloumi is a fresh cheese, and fresh cheeses are low for a different reason from aged ones: the lactose left with the whey when the curd was drained, rather than being eaten over time. Removal beats fermentation here, and it happens in an afternoon rather than a season.

Hard cheese is low because the lactose is gone, eaten by the starter bacteria over weeks of ripening. Lactose is the D of the acronym, and an aged cheese has almost none left - which is why hard cheese is one of the few dairy foods a low-FODMAP diet keeps.

Kefir is low because it is fermented longer than yoghurt, by a culture that eats more of its FODMAP.

Mozzarella is a fresh cheese, and fresh cheeses are low for a different reason from aged ones: the lactose left with the whey when the curd was drained, rather than being eaten over time. Removal beats fermentation here, and it happens in an afternoon rather than a season.

Paneer is a fresh cheese, and fresh cheeses are low for a different reason from aged ones: the lactose left with the whey when the curd was drained, rather than being eaten over time. Removal beats fermentation here, and it happens in an afternoon rather than a season.