First, a response to a response.
 
Robert Cohen wrote to you:
> the Average American consumes the same cholesterol contained in 53 slices
of bacon every single day in their milk and dairy.  A 52-year-old  will
have consumed the equivalent of 1 million slices of bacon worth of
cholesterol.<
 
Let's examine this.  A slice of bacon has 5 mg of cholestrol.  (Bacon, as
it happens, is actually a fairly low cholesteol meat.)  So 53 slices of
bacon would provide 265 mg of cholesterol, or about the same as 1 egg.
 
Whole milk contains 33-35, say 34, mg of cholesterol in 1 cup, or 8 oz.
So you would need to drink between 7 and 8 cups, just about a half-gallon,
of whole milk per day to get 265 mg of cholesterol.  Does the Average
American consume this much (and remember, it has to be whole milk -- skim
and lowfat milks have much lower cholesterold counts)?  I doubt it.  The
National Dairy Council estimates that dairy products (excluding butter)
contribute 10% of the Calories to the national diet.  The average person
consumes 2000-2500 Calories per day.  1 cup of whole milk has 150 Calories.
 So the average american has the equivalent of fewer than 2 cups of milk a
day.  Total.   That's a lot less than 7 to 8 cups.  And that's from all
milk products in all foods combined, some of which, of course, are likely
to be from lowfat milks.   Beware of impressive sounding statistcs.
 
Now for some of your questions.
 
>1. I have heard that there are basically 3 things people may be reacting
to in dairies: lactose, casein, whey. Some people
may be sensitive to some, but not others. E.g. sensitive to casein, but not
whey. Is this true?<
 
Yes.  Casein and whey are two entirely different families of proteins, and
so they may cause different reactions in people.  This is compounded by the
fact that human milk and cow's milk have very percentages of each type of
protein.  Human milk is predominantly beta-casein and lacks alpha-casein
entirely.  Cow's milk has half again as much alpha-casein than beta-casein.
 These differences may account for some sensitivities.  Lactose reactions
are intolerances, not allergies: people who are lactose intolerant cannot
digest the lactose properly, causing gastroinestinal problems.
 
 
>2. If the reaction is to proteins - casein, whey - can one take protein
digesting enzymes to break them up? I am already taking bromelain, there
are plenty others out there as well. Or is the reaction to specific chains
of aminos that are found in milk
proteins and would not be broken down by these enzymes.<
 
I doubt that a protein digesting enzyme would be of use, but I am not an
expert on this.
 
 
>3. If the reaction is to casein (or even whey) why is there reaction to
other dairies, such as yogurt. I thought that bacteria in yogurt use the
milk proteins to make the proteins they need, therefore the only milk
proteins found in yogurt would be 'residual' proteins, not yet digested by
the bacteria. Is this residual amount of milk proteins responsible for the
reactions?<
 
For the most part, the bacteria in yogurt feed on the lactose, so that
natural (i.e., non-commercially processed)  yogurt is lower in lactose than
the milk it comes from.  I don't think the bacteria do anything to the milk
proteins at all.  Again according to the National Dairy Council, whole milk
has 3.29 g of protein per 100 g of whole milk; whole milk yogurt has 3.47 g
of protein per 100 g of yogurt.  Protein is hardly "residual" in yogurt.
 
 
>4.a. Is it possible that reaction to milk proteins really happens due to
other reasons. For example, gluten, yeast overgrowth,
or other problems causing 'leaky gut syndrome' or similar problems. So your
body now starts absorbing incompletely digested milk proteins and then
starts developing antibodies to them. Has anybody had these kinds of
problems? And if yes, has milk intolerance improved when those problems
were taken care of?
 
4.b. The reason I am thinking of this is that if the body is developing
antibodies to milk proteins they must be getting into
blood steam. The body does not normally develop antibodies to things still
in the gut, as that will be broken down and there
is no reason to 'waste' immune system efforts on it. If milk particles
(proteins, lactose, whatever) are getting into bloodstream then the problem
is with the 'leaky gut'. Does this make sense?<
 
You may be confusing issues here.  Some people with gluten sensitivities,
as well as people with a variety of intestinal ailments, may lose their
ability to produce the lactase enzyme that digests lactose.  In many cases
healing the ailment brings back the ability to produce the lactase, and so
the lactose intolerance ends.  Whole proteins do sometimes get into the
bloodstream, and that is the source of some allergic reactions.  As for the
rest, biopsies of patients with milk-protein allergies show that their
intestines have serious lesions.  Does this constitute a "leaky gut"?  I
don't know.  But it may very well cause lactose intolerance.
 
 
>5. Could the problems with milk (and eggs, etc. for that matter) be due to
hormones, antibiotics, pesticides, etc that go into
cows and end up in milk? Anybody switched to organic dairies (or eggs,
etc.) and found their symptoms improve?<
 
Some people think this is true.  I don't have enough evidence to say
anything definite.
 
 
>6. I have seen a lot of references to paleolythic diets, eating only what
could be picked in nature/killed with a stick. Dairies
are usually excluded from that list on the basis that neanderthals did not
raise cows. But they were still breast fed as infants.
Does anyone know why these diets exclude milk if it's a natural part of
one's life early on? How is human milk different from
cows, goats, etc.?<
 
Human milk differs from the milk of other animals because each one is
optimized for the needs of their own specific young.  Sea lions, for
example, have milk that is 35% fat but with no lactose.  Each kind of milk
also has variations in the percentages and exact makeup of vitamins,
minerals, proteins, etc.    For most of human history and human evolution
adults did not drink milk at all.  According to some theories, they lived
instead on a diet of very lean meats and lots of greens, fruits, roots,
nuts, berries, and so forth.  This is the diet that was publicized in the
book, The Paleolithic Perscription.  Their point, very loosely, was that
the human body has been naturally selected for this diet for much longer
than it has for the modern diet that includes large amounts of grains,
dairy products, and fatty foods, so that the optimum diet is the older one.
 
 
Hope this helps,
 
Steve Carper
author of Milk Is Not for Every Body: Living with Lactose Intolerance.
http://ourworld.compuserve.com/homepages/stevecarper