Updated November 06, 2014.

October 2014

Have you seen the study in the news this past week, that drinking soda can cause premature aging? Although I think the headlines are overblown, I also think the results of this research are intriguing, so I'm going to use it as a jumping-off point to begin to talk about cell aging, and how we can do things and eat things that might have positive effects in our cells, and therefore in our whole body.

What was this soda study about? The soda study appeared online in the American Journal of Public Health this month, led by Dr. Cindy Leung. The research looked at what people were eating in a sample of a nation-wide ongoing study in the United States called the National Health and Nutrition Examination Surveys (NHANES). They looked at a random sample of these people and found out what they were drinking in the way of sugar-sweetened beverages, fruit juice, and diet soda on one day 14 years ago. Since blood samples where also taken at that time, the researchers were able to check the genetic material in their white blood cells. Specifically, they measured the length of the telomeres, which are like end-caps to the chromosomes that seem to be protective of the DNA.

Why are telomeres important? The length of the telomeres is connected to the aging of the cell, and also the aging of the whole body. The older we get, the shorter our telomeres, and once they get too short, the DNA begins to become damaged and deteriorates.

The cells also stop dividing.

Recently, scientists have been finding out that we can do things to speed up or slow down this process, so there is beginning to be a rush of research along these lines. Most of the data coming out now can be thought of as the first baby steps, which are fascinating, but we should remember that they very far from being "proved". This study is a great example: information from a single 24-hour period, and even if there was an effect from the soda, we can't tell how this happened. Still, it can give us some clues.

What did this study show? There were some interesting results. First of all, it was consistent with other work that has shown an association between being overweight or obese and shorter telomeres, as well as other factors such as smoking, exercise, race, and socioeconomic conditions.

With regard to the beverages, the most striking result was that people who drank sugar-sweetened soda had, on average, shorter telomeres, and it really didn't take a lot of soda for this connection to emerge. On average, people drank about 12 oz of soda per day, and this was enough for a significant difference in telomere length, the equivalent of about 2.9 years of aging.  The more the soda consumed, the shorter the telomeres.

People who drank diet soda or sugar-sweetened beverages that weren't carbonated did not show a difference in telomere length, but the participants were not drinking nearly as much per day - just a third to a half a cup on average. There has been a huge increase in non-carbonated sugar-sweetened beverages over the last 15 years or so, but at the the time they weren't as popular, so there is less data about them.  Fruit juice consumption initially looked as it if it might be good for telomere length, but once the researchers factored in other data that could explain the difference, the correlation went away.

What does all this mean? Frankly, it's hard to know exactly what it means. On the one hand, drinking sugar-sweetened soda is associated with obesity, metabolic syndrome, cardiovascular disease, and wanting to eat more (thereby consuming excess calories). Shortened telomeres are also associated with some of those things, so it could just be part of the package, and we really don't know yet what causes what.

On the other hand, a key question is: How is sugar-sweetened soda linked to these things? Is it because it causes blood sugar to go up rapidly? If that is so, than other high-glycemic foods should also be implicated - sugar isn't even as glycemic as starch, such as in potatoes, cereal, etc., although it's much easier to quickly get a big hit of sugar when it's in liquid form. Could it the fructose (which doesn't raise blood sugar, but has problems of its own)? Is it something else in the soda? I just don't think we know, but it's important that we understand what's happening in the cells to cause this effect, and I expect that someday we will.

Another obvious possibility is that people who drink soda make other poor food choices. I corresponded with the lead researcher, Dr. Cindy Leung, about this. She told me that they took results from the Healthy Eating Index into account, which is derived from various components of the diets of the participants - fruits, vegetables, etc. Because of this, she felt that they associations they found for the beverages were separate from other possible effects of diet.

What else can influence the length of our telomeres? Although it's probably too early to say "influence", there are other aspects of diet which are associated with changes in telomere length. Basically, eating a nutrient-rich diet, containing lots of vitamins, minerals, and phytonutrients seems to be the way to go. Vegetables and fruits in particular are associated with less DNA damage. One study showed that more omega-6 fats in the diet was associated with shorter telomeres, whereas more omega-3 fats were associated with longer telomeres. This is consistent with the fact that inflammation is associated with shorter telomeres, and it shouldn't be surprising that preliminary studies have shown that foods that have high levels of anti-inflammatory agents such as the omega-3 fats in fatty cold-water fish, the curcumin in turmeric and the polyphenols in olive oil are associated with less DNA damage in general, and longer telomeres in particular.

Other lifestyle factors which may be associated with telemere length include exercise (longer), stress (shorter), smoking (shorter) and meditation (longer). Should we be surprised? No -- we absolutely know that a healthy lifestyle has these components. We just have to get out there and DO them!!

_Sources:

• _{Leung, C. et al Soda and Cell Aging: Associations Between Sugar-Sweetened Beverage Consumption and Leukocyte Telomere Length in Healthy Adults From the National Health and Nutrition Examination Surveys. American Journal of Public Health. Published online ahead of print Oct 16, 2014.}
• _{Ligi, P. Diet, nutrition and telomere length. Journal of Nutritional Biochemistry 22:10 895–901. October 2011.}