With all that said, here's what you should know about lactose in cheese if you're looking to eat it and not feel like garbage.
Here's what determines the amount of lactose in cheese.
Cheese is actually quite low in lactose compared to dairy products like milk, cream, and yogurt. Most contain less than 2 grams per serving (1 ounce), which is far less than the 12 to 13 grams of lactose you get in one serving (1 cup) of milk. Of course, most people don't just eat 1 ounce of cheese in one sitting, so keep in mind that eating the better part of a cheese plate will probably mean you're having way more than just 2 grams of lactose.
Interestingly, the cheesemaking process contributes to the amount of lactose. Every cheese goes through a slightly different process, but in general, making cheese basically involves removing whey (the liquid part) from milk and then acidifying and salting the remaining curd, says Andy Hatch, cheesemaker and owner at Uplands Cheese. "The manner in which each of these three steps occurs will determine the character of the resulting cheese," including how much lactose is or isn't in it, Hatch says.
For example, soft cheeses like brie as well as hard ones like cheddar or Monterey Jack are low in lactose, but they go through two totally different processes, he says. Harder cheeses have the whey drained out of the cheese vat before the curds are packed into cheese forms for pressing. But softer cheeses, like brie and Camembert, don't have their whey removed until after the curds are put into cheese forms, where "they will slowly drip out of the newly formed cheeses," Hatch says.
"Approximately 97 percent of the lactose [in cheese] is actually lost as the whey drains during the cheesemaking process," Cathy Strange, global executive coordinator of specialty product innovation and development at Whole Foods Market, tells SELF. Exactly when the whey is removed—whether at the beginning or the end—doesn't really impact the amount of lactose a cheese will end up with.
What really determines that is the next step, fermentation, which begins as soon as lactic acid bacteria (which can be naturally occurring or added) starts metabolizing the milk's lactose and turning it into lactic acid. This can begin at any time during the process depending on how a cheesemaker manipulates certain conditions, like temperature, moisture, and salt, Hatch explains. And, he adds, fermentation can happen before whey is drained and after it's all gone—it will only stop when all the available lactose has been converted into lactic acid.
These are the cheeses that are generally lower in lactose.
Aged cheeses, both hard and soft—like Parmesan or brie—contain so little lactose that it's virtually undetectable, Sasson says. In fact, things like cheddar and blue cheese can have as little as 0.1 grams of lactose per serving, though it will vary depending on the specific product, brand, or recipe. The key here is the extended aging and fermenting process, which can last for decades in some cases.
