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Dr. A. Clark
Dr. A. Clark, Pediatrician
Category: Pediatrics
Satisfied Customers: 4437
Experience:  33 years of experience as a general pediatrician in private practice and in pediatric urgent care.
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Why does my sons breath smell like rotten eggs He is 9 and

Customer Question

Why does my son's breath smell like rotten eggs? He is 9 and has 2 known food allergies (peanut and shellfish) but to my knowledge has had no exposures recently. About 2 months ago he complained that he would burp rotten eggs if he ate bananas. Since then he has avoided bananas, denies any burping or gas but his breath smells strongly of rotten eggs. Now he has had moments in the past when he has complained of gastric pain and gas and he was visibly uncomfortable. His oral health is good and he eats a great diet full of a variety of foods (but the allergens of course). I tried Tums to see if he was having indigestion or reflux that he wasn't recognizing but it didn't help.
Submitted: 7 years ago.
Category: Pediatrics
Expert:  Dr. A. Clark replied 7 years ago.
Allergy to foods would likely not cause this type of reaction but rather rashes, diarrhea, etc. It is more likely due to carbohydrate intolerance: lactose, fructose, and/or sorbitol (really an alcohol but used as a flavor enhancer, especially in diet foods) The problem is that when the intestinal mucosa cannot absorb a substance, enzymes are necessary to break them down, particularly with complex sugars like lactose and fructose (fruit sugar). When they cannot be broken down with the enzymes, either because of a lack of that enzyme (lactose intolerance is quite common) then bacteria begin to attack the substance and the result is fermentation (just as with beer) and gas and odor production. Lactose intolerance is very common after the first year of life, especially in populations of Asian or African heritage where they historically never had a dairy industry and thus only drink milk until weaned from the breast, as with every other mammal.

The first thing I would do is eliminate lactose since avoiding dairy products is pretty simple. This includes not just milk but cheese, yogurt, ice cream, pudding, etc. but not foods cooked with a little milk. Do this for a couple of weeks to test the effect and then move on to fructose and finally sorbitol, which you will be surprised to see in many foods for their sweetener effects as so many foods eliminate sugar.

I'm sure eventually you will figure out the offending substance and be able to get him through this.

Edited by Dr. A. Clark on 1/29/2010 at 12:31 AM EST
Customer: replied 7 years ago.

Dr. Clark,


Thank you for your answer. I'd like to give you a little more background information so you understand my response. We are caucasion. I am a registered dietitian and have 2 children with food allergy. However, I am not an expert in all areas of nutrition as it is a vast field. My youngest is allergic to wheat. So, elimination diets are a way of life for us. My clinical and food expertise helps me understand your response. The parent (who is a little tired of food eliminations) in me is resistant to eliminating another food without just cause. I understand that trial and error may be necessary to get an answer to my problem. However, this is a relatively new problem in my 9 year old (maybe a month or so). Do you really think this could be lactose intolerance? I'm more accepting of the fructose intolerance theory because he has reported the rotten egg burps after eating bananas. However, ugh....eliminating fruit from his diet seems like a formidable task. I know...this is coming from someone who has already eliminated foods from her children's diets already. If we take that next step, how long would be realistic to expect to see an improvement? Also, would fructose intolerance take this long to develop? The only major problem he has had recently was influenza A in late September. Otherwise, he is a very healthy kid. Neither my husband nor I have any food allergies or intolerances. Any additional help would be appreciated.

Expert:  Dr. A. Clark replied 7 years ago.
It can occur at any time but a recent illness could also cause a temporary intolerance. I would expect improvement within 2 weeks on each elimination. If that does not pan out then then next step is the gastroenterologist I would think.
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Customer: replied 7 years ago.
Thank you Dr. Clark. While I was waiting for your response I started going through the cupboards. My son received some "gummy snacks" at Christmas time and he has been eating a few of them nearly every day. This is about when the problem started. The snacks contain sorbitol. I should have thought of this. I work with adults who have diabetes and warn them regularly about the GI side effects of sugar alcohols. I will eliminate sorbitol and other sugar alcohols first and then will try either milk or fruit next if I don't see any improvement. Thank you for you help.
Expert:  Dr. A. Clark replied 7 years ago.
As you probably know, sorbitol is used to induce diarrhea in poisoning cases since it is a cathartic substance. It is an alcohol but unabsorbable due to its chemical structure so it is used for adding sweetness without calories to "diet" foods and snacks but unfortunately many people are very sensitive to it and it is EVERYWHERE!

I hope this is the offending agent and all will be well.