Because of spam, I personally moderate all comments left on my blog. However, because of health issues, I will not be able to do so in the future.

If you have a personal question about LI or any related topic you can send me an email at I will try to respond.

Otherwise, this blog is now a legacy site, meaning that I am not updating it any longer. The basic information about LI is still sound. However, product information and weblinks may be out of date.

In addition, my old website, Planet Lactose, has been taken down because of the age of the information. Unfortunately, that means links to the site on this blog will no longer work.

For quick offline reference, you can purchase Planet Lactose: The Best of the Blog as an ebook on or Almost 100,000 words on LI, allergies, milk products, milk-free products, and the genetics of intolerance, along with large helpings of the weirdness that is the Net.

Friday, June 01, 2007

One to Three Pints of Gas a Day - And Not in Your Car

Everybody knows that one of the symptoms of lactose intolerance is gas. Lots of gas. Foul, smelly gas. Noisome gas, for those who know the proper meaning of the term.

The gas is produced when undigested lactose is fermented in the intestines by the bacteria that naturally live there.

An article from by their chief medical adviser Dr. Martin M. Lipman tells us more:

The average person produces one to three pints of gas per day and eliminates it in 14 to 23 passes, some while asleep. More than 99 percent of this gas mixture is odorless, and consists of carbon dioxide, nitrogen, and oxygen, which we inadvertently swallow when we eat, drink carbonated beverages, chew gum, or smoke. Some carbon dioxide is made in the stomach.

In addition, the normal bacterial population of our colon (large bowel) produces a tiny amount of hydrogen gas and methane by fermenting the carbohydrates left over from the small intestinal digestive process and forming hydrogen sulfide (like the smell of rotten eggs), methanethiol (like the smell of decomposing vegetables), and dimethyl sulfide (a heavy sweetish odor). In fact, less than 1 percent of the gas we produce accounts for all of the odor.

Passing that gas mixture causes the anal sphincter to vibrate, producing a veritable symphony of sounds depending on the force with which the gas is expelled and the resistance of the sphincter. Who can forget that rousing campfire scene from Mel Brooks' 1974 masterpiece, "Blazing Saddles"?

When excess gas occurs alongside nausea, vomiting, diarrhea, constipation, or involuntary weight loss, the need to see a physician is obvious. But by and large, gas as an isolated complaint is rarely due to a serious disorder. When a patient comes to me complaining about excess gas, a careful history, a physical exam, and a few well-chosen laboratory tests can rule out those few, more notable, causes: irritable bowel syndrome, lactose intolerance, celiac disease, or gastroesophageal reflux disorder. In the vast majority of cases, flatulence indicates nothing more than that the patient is alive and eating a healthy diet.

Unfortunately, there's nothing you can do to eliminate gas once it's already begun. Far better to remember to take lactase pills at the first bite of dairy and not feel sorry later.

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Anonymous said...

I have this problem very badly. The smell is so bad that it offends me, so I can imagine how others feel. It is like sulfur. Does this mean I am lactose intolerant? What products will help this?

Steve Carper said...

Not only is it like sulfur, it actually is sulfur. Hydrogen sulfide is the chemical that gives farts their awful smell.

And yes, this can certainly be a symptom of lactose intolerance. Bacteria in the colon make hydrogen sulfide from undigested lactose that reaches them.

Therefore, there are two ways to attack the problem.

One, you can take lactase pills with dairy to digest the lactose before it can reach the colon.

Two, you can change the composition of the bacteria to types that digest rather than ferment lactose. Yogurt with live and active cultures can do this. Or you can take a probiotic specially formulated for those with lactose intolerance, like Digestive Advantage or Lactagen.

Check my April archives. I covered Digestive Advantage and Lactagen on April 4 and 5.