At the fromagerie, we often have people say they can't eat cheese because they are lactose intolerant. These same people invariably tell me that they can eat those made from goat's or sheep's milk. Really? And why would that be true? All milks have lactose, but most of the lactose in cheese is either drained away with the whey or converted to lactic acid during the aging process leaving little or no lactose. So how could this be true
and what is the issue here? Is there any science to back this up? Is cow's milk harder on the body than goat's or sheep's milk?
Lactose
intolerance is very common in adults and not dangerous, but milk
allergies are more serious and broad reaching. Understanding the root cause of the problem is necessary because while symptoms associated with lactose intolerance are similar to those of dairy allergies; it is how & to what the body reacts that is different. It is important to note that a person can be lactose intolerant and also have sensitivity to dairy proteins, i.e., be allergic, but these two maladies are not necessarily coexistent. In the case of lactose intolerance it is the milk sugars (lactose) that cause the hypersensitivity whereas in a milk allergies, it is the milk proteins.
There are different make ups of milk proteins (casein) in all of the milk types. It is the major protein in cow's milk alpha-s1-casein protein, not present in sheep or goat milk, which is to blame for the adverse reaction. The body's immune system attacks them as if they were an invader rather than breaking them down. Since these milk proteins are present in any related milk product, anyone with an allergy to the proteins is susceptible to varying degrees of allergic reaction. And as milk proteins are the main building block of any cheese, for someone with a milk allergy, eating cheese is pretty much impossible.
Those with lactose intolerance have a different problem. Lactose intolerant people cannot digest lactose (milk sugars) which is different than milk proteins. The body is incapable of metabolizing lactose because of a lack of the enzyme lactase in the small intestines (known as lactase deficiency). As enzymes help the body absorb foods, not having enough lactase means these sugars stay intact and the intestinal bacteria have a feeding frenzy. So when products containing high levels of lactose are ingested, gas is produced in the intestines and violà, discomfort ensues.
According to Wikipedia, milk from buffalo has 4.86% lactose, yak 4.93%, unprocessed cow milk 4.7%, goat milk 4.7% and sheep milk 4.6%. So when someone says they are lactose intolerant to cow's milk, the same intolerance to sheep and goat's milk should exist, right? Well, while these milks contain the same level of lactose, it is thought that goat & sheep milk are more easily digested than cow's milk because they do not contain the same concentrations of casein (milk proteins). Therefore, there is a strong possibility that folks who can drink non-cow milks with no problem, in reality have an allergy as opposed to being lactose intolerant.
So what about cheese? Well, in the case of cheese, it comes down to how much actual lactose is still present in the finished product. Because lactose is a water-soluble molecule, higher fat percentages, fermentation, the curdling process and aging have an impact on the amount of lactose that remains in a cheese product. To begin with, in the early hours of the life of a traditionally produced cheese, most of the lactose present in any milk passes into the whey, which is drained off. The bit that remains in the cheese curd is converted into lactic acid during the ripening process and disperses as the water content evaporates and the milk proteins become more concentrated.
The longer the aging, the less lactose is present in the curd. Not true of milk proteins obviously as the pate is made is primarily made up of these proteins. Traditional, aged hard cheeses have only about 10% of the lactose that is found in the original whole milk. For instance, a 24 month old Emmental or Comté, both cow's milk cheeses, have practically no lactose remaining. So theoretically, even if one is lactose intolerant, one will have problems with fresh and minimally aged cow milk cheese like camembert but not have problems eating long aged cow's milk cheeses.
So why is it that these folks seem to be able to deal with the other milk types? In buffalo, goat & sheep milk cheeses; the basic milks have smaller fat globules to begin with, which do not clump together in the same was as in cow's milk, thus making the milk naturally homogenized and in general produce a more dense cheese. Assuming you do not have a major protein related allergy, these two factors in conjunction contribute to a higher digestibility of these milks and their respective cheeses.
None of this is 100% applicable to commercial cheese, i.e., those manufactured by modern processes. Here these processes generally do not have the same lactose reducing properties, in part due to the elimination of so called 'good bacteria' during the milk pasteurization process and/or the length of aging.
Another culprit which might be part of this digestive problem can be found in an additive, Lysozyme (additive E1105). The additive is an anti-microbial enzyme which is extracted from fresh chicken egg white and is used for its antibacterial properties primarily in the manufacture of industrial cheeses. Although it is not always the case, people allergic to eggs (different than dairy) may also be allergic to lysozyme; therefore they often present the same symptoms as someone with a milk allergy. So the rule of thumb for people with egg white allergies might be to avoid commercially made cheeses all together. Not to fear however, because the use of lysozyme is not allowed in the production of French AOC cheeses (interestingly most being made from raw milk).
With all this information, it would seem that people with lactose intolerance should be able to eat any, and I would say any traditionally made, milk type cheeses that have been long-aged. No scientific tests have been done to prove this that I can find, so I always try to enlist willing subjects to try a beautiful 24 month old Comté or Beaufort to see if what happens. If they still report having a problem, then in my opinion, they are more likely to have a milk allergy than being lactose intolerant.
