Tuesday, January 15, 2013

Feature Article: New Research On Diet Soda

Consumption of artificial sweetener and sugar containing soda and risk of lymphoma and leukemia in men and women. 
American Journal of Clinical Nutrition 2012; 96:1419-28.

Last month, a very interesting article was published examining diet soda consumption and risk of certain cancers.  The results were a bit surprising and a bit disturbing.  I thought I’d use this post to explain the ramifications of this investigation. 

Summary Of Findings
The objective of this study was to examine the association between diet soda consumption and risk of 3 cancers: non-Hodgkin’s lymphoma, multiple myeloma, and leukemia.  The study included 47,810 men from the Health Professional Follow-up Study and 77,218 women from the Nurses’ Health Study.  Participants were followed for 22 years.  Here are the main findings:

-When the 2 cohorts were combined, there was no significant association between diet soda consumption and risk of these cancers.

-Men consuming the most diet soda had a 31% increased risk of non-Hodgkin’s lymphoma and a 102% increased risk of multiple myeloma.

-This association was not seen in women.

-Men consuming the most regular soda (not diet) had a 66% increased risk of non-Hodgkin’s lymphoma.

Why You Should Be Concerned
1) This is a very well designed study.  Harvard’s Nurses’ Health Study and Health Professional Follow-up Study are two of the best cohort studies in the whole world. 

2) A recent very large study in rats saw increases in risk of these cancers with a high consumption of aspartame, which is the sweetener used in diet soda.

3) This association is biologically plausible.  Aspartame in liquid breaks down to its 3 ingredients; methanol, aspartic acid, and phenylalanine.  Formaldehyde is metabolized from methanol and is a documented carcinogen.

Why You Should Not Freak Out Entirely
1) There is a lot of previous research on the health effects of aspartame, I mean a lot.  It is arguably the most tested food substance in the history of the world.  The results of this research in both humans and animals is that it is safe.

2) When the cohorts were combined, there was no association between diet soda and these cancers.  Also when women were analyzed separately, there was no association between diet soda and these cancers.

3) The men showing an increased risk of cancer were drinking a lot of diet soda, an average of 11 servings per week.  A serving is considered 12 ounces.  Men with lower consumption, even up to 6 servings per week, saw no increased risk of these cancers.

4) It may not even have been the aspartame that caused the problem.  Because there was an increased risk in non-Hodgkin’s lymphoma in men drinking a lot of regular soda, the researchers theorized that it may be something else in soda in general, perhaps another ingredient common to both diet and regular soda (such as the caramel coloring) or a substance used in the packaging.

5) There is really no reason that there should be a sex difference in risk of cancer with this exposure.  The sex difference in risk combined with the fact that risk was elevated in regular soda drinkers as well means the results could have been due to chance.  In fact, the researchers mention as much in their own conclusions.

As the first study to show harm with high levels of diet soda consumption, this will no doubt spur new research in this field.  We should all keep our eye on it. 

My clients and readers of my books know that I advocate 100% sugar avoidance and, instead, occasional non-nutritive sweetener use twice a week on splurge meals.   It is my opinion that this level of consumption is safe, even after reading this study.  Two or three diet cokes a week have never been shown to cause any problem, including in this investigation.  If you are drinking tons of diet soda every day, is this study enough to make you stop?  It probably would be for me. 

However, my clients and readers of my books already know that daily consumption of diet soda is a bad idea for a number of reasons.  But that is a whole other story and this post is long enough already!

Although this study is the first to suggest a potential negative health effect of diet soda, keep in mind that lots of research has found an association between regular soda and risk of obesity, diabetes, and even heart disease.  Artificial sweeteners, although far from perfect, when consumed in moderation, are still the lesser of two evils.

Before I read this study, I had aspartame in the “occasional use” category.  In other words, I looked at it as I did red meat.  Now and again consumption is not likely to cause a problem, but daily consumption may.  After reading this article and considering all previous literature, I still look at it this way.

One last note: both this study, and the study in rats focused on aspartame, also known as Equal.  Sucralose, also known as Splenda, has not been shown to have any negative health effects.  Therefore, when you do occasionally use an artificial sweetener, it may be a good idea to go for products made with Splenda instead of Equal just to be on the safe side.