Yesterday I answered the question of whether butter has lactose. Answer: not very much.
Today I'm going to look into the logical consequence, sparked by a question emailed to me.
Over the years I have not been able to get a good answer as to why I must avoid butter or subject myself to having to tolerate abdominal bloating, etc.
That's a good question. If somebody is bothered by butter and it's not the lactose, then what it is?
Assuming there is a direct connection, then the only other component to butter is the milk fat. Butter is probably 80% milk fat and 1% lactose. That would make the fat a logical culprit.
Is there such a thing as milk fat intolerance?
I don't know. The research on the subject is practically non-existent. And contradictory.
My searches have come up with a grand total of two studies in the medical literature.
The first was "Do Lipids Play a Role in Milk Intolerance?" J. P. Costet, et al., pp. 156-61 in Milk Intolerances and Rejections, J. Delmont, ed. Basel: Karger, 1983. In this limited study the authors did find that 9% of their test subjects could not tolerate milk fats. From this they concluded that the "role of lipids in milk rejection this appears moderate and of little importance."
The second study is from the European Journal of Clinical Nutrition. 1997 Sep;51(9):633-6, "Milk fat does not affect the symptoms of lactose intolerance," Vesa TH, Lember M, Korpela R.
OBJECTIVE: This study investigated the role of the fat content of milk on symptoms of lactose intolerance. DESIGN: Subjects recorded intolerance symptoms using a visual analogue scale (VAS) following ingestion of three test milks for varying fat content for a two-day period. SUBJECTS/SETTING: The subjects were thirty adult volunteers, patients of two Estonian out-patient clinics with diagnosed lactose intolerance. The study milks were drunk at home or at work. All thirty subjects completed the study protocol. INTERVENTION: Each subject drank, in random order, fat-free milk (4.9% lactose), high-fat milk (8% fat, 4.9% lactose), and a lactose-free and fat-free control milk. They drank 200 ml of the milk twice a day for two days, one milk type per session, with five days between sessions. The subjects noted their gastrointestinal symptoms during the test periods and during a 5 d milk-free period at the beginning of the study. The occurrence and severity of symptoms were compared. A global measure of the severity of symptoms was defined by computing the sum of the symptoms scores. RESULTS: The sum of symptoms was higher during all milk periods than during the milk-free period (P < 0.01). There were no statistically significant differences in the occurrence or severity of symptoms during the fat-free milk period compared with the high-fat milk period. CONCLUSIONS: Even a marked difference in the fat content of milk did not affect the symptoms of lactose intolerance. Consequently, there seems to be no case for recommending full-fat milk products in the treatment of lactose intolerance.
This is again an extremely limited study, both in number and duration. Nor is it obvious that a fatty milk would produce the same results as butter.
Fats in general don't tend to produce gas in the intestines. Carbohydrates - sugars, starches, fibers - are the main gas producers. That makes it hard to blame the fat in butter just as fat.
If we're back to using logic - a slippery course whenever food is concerned - we're not left with many answers. Here are the possibilities.
1. My questioner is wrong about butter being the problem.
2. Milk fat intolerance is real but not properly identified as a problem.
It would be convenient to jump to the conclusion that the medical community has fallen down on this. On the other hand, I also just heard from somebody who wrote me that her LI symptoms went away when she changed toothpaste. That's why I never trust anecdotal information. Anecdotes make my head hurt.
Hey, Bill Gates. Have I got a study for you to fund.