Is lactose intolerance dangerous? I mean, in the same way as being allergic to shrimp? Is there such a thing as partial lactose intolerance? For instance, can you be intolerant of milk, but have no problems with cheese?
I’m lactose intolerant.
In my experience, it varies among people how it affects you-- some people react more severely, but I’ve never heard of it being deadly. It’s not exactly a dairy allergy, in the way that some are allergic to peanuts and whatnot-- more like a digestion problem. The stomach lacks, or has less of, the enzymes which break down dairy foods. Some races and ethnic groups have more trouble than others-- groups which did not traditionally have a lot of dairy in their diets, like Asians and Native Americans.
With me, sometimes dairy foods don’t bother me at all, other times, I’m in absolute agony. I think it depends on what I’ve eaten recently. At my worst time, I have horribly painful stomach cramps and diarrehea. Other times, just a little gas. Sometimes, I get no effects at all.
Lactose intolerance is not an allergy. An allergy involves the immune system; lactose intolerance is an inability to digest lactose and has nothing to do with the immune system. On the other hand, it is possible to be allergic to the proteins in cow’s milk.
Someone who is lactose intolerant should have no problem with natural hard cheeses, because these contain no lactose. To make cheese, you have to split the milk into the solid curds, from which cheese is made, and the liquid whey. Essentially all the lactose remains in the whey. However, processed cheeses and some soft cheeses are made by putting milk back in, and this of course will re-introduce lactose.
Some people with lactose intolerance can tolerate yogurt, some can’t. I believe, but I’m not sure, that the yogurt cultures split some (but not all) of the lactose, making it more easily digestible.
I won’t even notice a half glass of milk, milk in my cereal, or yogart. A full glass on the other hand will cause a massive stomache cramp that will take hours to recover from.
Long-time lactose intolerant here. The other posters gave good responses but were off slightly in some things so let me take another stab at it.
All mammals* can drink their mothers milk because their small intestines make the enzyme lactase that splits (digests) lactose into the simpler sugars glucose and galactose. Normally, bodies stop making lactase at about the time of weaning. This is also true for all mammals, including humans. Humans, however, have a natural mutation in a gene on chromosome 2 that never turns off the lactase-making ability. This is a dominant mutation, so it has quickly spread through cultures dominated by northern European immigrants.
One reason that it spread so quickly is that there is some evidence that lactase production helps in the bioavialability of calcium. In modern diets this isn’t a concern as it’s very easy to get all the calcium anyone needs. So lactose intolerance (LI) isn’t dangerous. Unless, of course, you continue to take it large amounts of lactose, develop chronic diarrhea and the problems that can be associated with it, like dehydration, hemorrhoids, and loss of nutrients. In twenty years of research I’ve only encountered one case in which this became a serious, life-threatening, problem for an adult, and that ended as soon as the LI was diagnosed.
Babies can develop temporary cases of LI whenever they have intestinal ailments ranging from a simple “stomach flu” (actually a GI tract infection) to surgery. These can be serious but there is no excuse for a doctor today not recognizing the problem.
Similarly, adults can have problems with their intestines that create LI. Celiac disease is a major cause, but there are literally dozens of others.
As said earlier, milk protein allergies - either to the casein protein, the whey protein, or both - also occur but have no relation to LI whatsoever. They are similar to other food allergies in the way they manifest and the symptoms they offer.
LI is a threshold ailment in most people. That is, few people even with LI manufacture zero lactase. Most still make some. So if you have a tiny bit of lactose in food then the amount of lactase in your body will be enough, and you won’t have symptoms. Go even a small bit over that threshold, however, and undigested lactose will reach your large intestine. That will do two things. The lactose will pull water into the intestines, the reverse of normal, and that can create diarrhea. And the bacteria that naturally lives in everyones’ colons can be of the type that ferments lactose and this will create the gas that causes cramps, bloating, and flatulence.
There are other types of bacteria that digest lactose, and these are the types found in yogurt and also are available in probiotic pills. Yogurt is naturally auto-digesting, that is, the bacteria it contains should be sufficient to digest all the lactose it contains. Many yogurt products in the U.S. have additional milk solids added to them so that this is no longer true. You need to experiment to find out which yogurt would work for you. Frozen yogurts are even chancier, because the freezing process tends to kill off the cultures unless they are added back in later.
Lactase pills are readily available. They all should work, but some people find that some brands work better than others for them for unknown reasons.
The aging process of cheese literally squeezes out the remaining whey liquid that contains lactose. Aged cheese should be low in or even free of lactose, but studies have given various percentages even for the same cheese type.
Most of this info taken from the largest web site on LI I’m familiar with, Planet Lactose.
*A few mammals don’t have lactose in their milks for various reasons.