People here are correct when they say that anecdotal information can't be 
applied generally to a group of people. I'd go even farther: Most of the time it 
can't properly be applied to the person with the anecdote. The reason is 
simple. Change.

Any scientific or medical study depends on changing as few variables as 
possible. The more things that change, the harder it is to separate out what 
difference any one change is making. When we take dairy out of our diets, we think 
we're making just one change, but the truth is that we making all sorts of 
changes simultaneously. We eat different foods, we substitute for dairy in 
familiar foods, we alter the amount of food and the ratio of nutrients, lots of 
changes we seldom stop to think about.

Remember, though, I've always advocated that if it works for you and doesn't 
cause any damage, fine. Go with it. I have no objection to those who want to 
remove dairy from their diets. I've spent over 20 years supplying people with 
all the possible information they might need if they make this decision for 
themselves.

At the same time I've always warned people that getting tested is always a 
good idea. You never know where your symptoms are coming from: and the symptoms 
you're likely to get from either lactose intolerance or dairy allergy can have 
a thousand causes, some of them quite serious. Just assuming that you have a 
food allergy can mask another unrelated illness. Trying to determine if a 
particular food is causing your problems can be a nightmare.

That's what makes medical studies on foods so incredibly difficult. People 
could be brought into a clinical setting where every particle of food is 
monitored - but that hardly compares with the realities of everyday life. Much more 
often, people just keep food diaries and try to make as few other changes as 
possible. Even so, food studies are expensive, hard to run, and harder to 
evaluate. Worse, you can't do a double blind study for food. You know if you're 
taking dairy out of your diet or not, and that will affect the results.

This explains why medical studies about food, nutrients, or medications so 
often come out with big announcements that seem to vanish or be contradicted by 
the next study. Most of these studies are of tiny groups for short periods of 
time, often using protocols that just don't have much relationship to the real 
world. Even so, they're real studies that get printed in real medical 
journals and reporters look at the conclusions and write articles that make 
headlines. That's why I always say that you should never get your medical news from a 
newspaper. Or the internet, these days.

Most reporters - most people - have no idea of how to read a medical or 
scientific paper. This is one of the greatest failings of our school system. You 
can't just read the conclusions section and use that as guidance. You have to go 
through the entire methodology and procedure to see if the experiment as a 
whole works to give you real and new information. This isn't all that hard, and 
doesn't usually require any advance medical training. A few basic questions 
are all that's needed. Is the group studied random and representative? Is the 
group healthy or do they have medical problems? How large is the group? How many 
dropped out before the study was over and why? Is the study something that 
corresponds to real eating patterns or is it totally artificial? Are the results 
a true difference or just a slight tendency? 

If you read closely, you'll soon notice that the studies that change the way 
medicine is practiced tend to be huge, long-term studies in which data from 
many papers are put together to make a larger and more comprehensive whole. This 
averages out or entirely deletes the exceptions, the poorly done studies, the 
natural variations in human physiology. Doing this takes medicine as far away 
from anecdotal information as it can safely get.

So if medicine tries to stay away from anecdotal information, who uses it? 
The answer is everybody else. All of alternative medicine is based on anecdotal 
information. All those people out there selling herbs and vitamins and enzymes 
and proteins and nutrients and nostrums. The ones selling raw milk or soy 
milk or rice milk or seaweed or spelt or sorghum. All the naturopaths and 
homeopaths and holistic practitioners. Every person whose religion gives them a 
special road to healing. They're all faith healers really, every last one, no 
matter whether a formal religion is mentioned or not. All of them absolutely depend 
on anecdotal information. They have to. Not one of them has ever done an 
actual study to back up their claims.

Let me repeat that. Not one of them has ever done an actual study to back up 
their claims.

Why should they? First, studies are difficult and expensive and 
time-consuming. Nor do they have the expertise to conduct a study. But most importantly, 
studies have one major obstacle to faith healing: they sometimes show that what 
you believe in is wrong. And the common element of all these alternative sites 
is that they're never wrong. They never allow people to come onto their pages 
and tell them that they cure is quackery, or that the money spent on their 
product was wasted, or that it had dangerous side effects, or that it prevented 
someone from getting medical help until it was too late. Instead, they give 
you anecdotes about how wonderful their product or their religion or their way 
of life is.

Steve Carper
Steve Carper's Lactose Intolerance Clearinghouse
http://ourworld.compuserve.com/homepages/stevecarper
Planet Lactose Bog
http://planetlactose.blogspot.com/