Dairy products
Lactose is a water-soluble molecule. Therefore fat percentage and the curdling process have an impact on which foods may be tolerated. After the curdling process, lactose is found in the water portion (along with whey and casein) but is not found in the fat portion. Dairy products which are "fat reduced" or "fat free" generally have a slightly higher lactose percentage. Additionally, low fat dairy foods also often have various dairy derivatives such as milk solids added to them to enhance sweetness, increasing the lactose content.
Milk. Human milk has the highest lactose percentage at around 9%. Unprocessed cow milk has 4.7% lactose. Unprocessed milk from other bovids contains similar lactose percentages (goat milk 4.1%,[51] buffalo 4.86%,[52] yak 4.93%,[53] sheep milk 4.6%)
Butter. The butter-making process separates the majority of milk's water components from the fat components. Lactose, being a water soluble molecule, will still be present in small quantities in the butter unless it is also fermented to produce cultured butter.
Yogurt, Frozen Yogurt and kefir. People can be more tolerant of traditionally made yogurt than milk, because it contains lactase enzyme produced by the bacterial cultures used to make the yogurt. Frozen yogurt, if cultured similarly to its unfrozen counterpart, will contain similarly reduced lactose levels. However, many commercial brands contain milk solids, increasing the lactose content.[54]
Cheeses. Traditionally made hard cheese (such as Emmental) and soft ripened cheeses may create less reaction than the equivalent amount of milk because of the processes involved. Fermentation and higher fat content contribute to lesser amounts of lactose. Traditionally made Emmental or Cheddar might contain 10% of the lactose found in whole milk. In addition, the traditional aging methods of cheese (over 2 years) reduces their lactose content to practically nothing. [55] Commercial cheese brands, however, are generally manufactured by modern processes that do not have the same lactose reducing properties, and as no regulations mandate what qualifies as an "aged" cheese, this description does not provide any indication of whether the process used significantly reduced lactose.
Sour cream if made in the traditional way, may be tolerable, but most modern brands add milk solids. Consult labels.[56]
Examples of lactose levels in foods. As scientific consensus has not been reached concerning lactose percentage analysis methods [57] (non-hydrated form or the mono-hydrated form), and considering that dairy content varies greatly according to labeling practices, geography and manufacturing processes, lactose numbers may not be very reliable. The following are examples of lactose levels in foods which commonly set off symptoms. These quantities are to be treated as guidelines only.
)
