Saturday, October 18, 2014

Do you believe that drinking carbonated beverages containing sugar will cause your telomeres to shorten and hasten your death?

It's very difficult to teach students to be skeptical of the scientific literature and how it's reported. I read this press release from the University of California, San Francisco (San Francisco, USA) and dismissed it as ridiculous but I can't really tell you why. It's from one of the top research universities in the world.

What do you think? Do you believe this study? If not, why not? How do you explain why you are skeptical about this research but not about other research?

Kim Krisberg, who describes herself as "freelance public health writer" writes at The Pump Handle [New research finds that drinking soda may lead to cell aging and disease, regardless of obesity]. She doesn't appear to be skeptical.
UCSF scientists find shorter telomeres in immune cells of soda drinkers

Sugar-sweetened soda consumption might promote disease independently from its role in obesity, according to UC San Francisco researchers who found in a new study that drinking sugary drinks was associated with cell aging.

The study revealed that telomeres — the protective units of DNA that cap the ends of chromosomes in cells — were shorter in the white blood cells of survey participants who reported drinking more soda. The findings were reported online October 16, 2014 in the American Journal of Public Health.

The length of telomeres within white blood cells — where it can most easily be measured — has previously been associated with human lifespan. Short telomeres also have been associated with the development of chronic diseases of aging, including heart disease, diabetes, and some types of cancer.

"Regular consumption of sugar-sweetened sodas might influence disease development, not only by straining the body's metabolic control of sugars, but also through accelerated cellular aging of tissues," said Elissa Epel, PhD, professor of psychiatry at UCSF and senior author of the study.

"This is the first demonstration that soda is associated with telomere shortness," Epel said. "This finding held regardless of age, race, income and education level. Telomere shortening starts long before disease onset. Further, although we only studied adults here, it is possible that soda consumption is associated with telomere shortening in children, as well."

The authors cautioned that they only compared telomere length and sugar-sweetened soda consumption for each participant at a single time point, and that an association does not demonstrate causation. Epel is co-leading a new study in which participants will be tracked for weeks in real time to look for effects of sugar-sweetened soda consumption on aspects of cellular aging. Telomere shortening has previously been associated with oxidative damage to tissue, to inflammation, and to insulin resistance.

Based on the way telomere length shortens on average with chronological age, the UCSF researchers calculated that daily consumption of a 20-ounce soda was associated with 4.6 years of additional biological aging. This effect on telomere length is comparable to the effect of smoking, or to the effect of regular exercise in the opposite, anti-aging direction, according to UCSF postdoctoral fellow Cindy Leung, ScD, from the UCSF Center for Health and Community and the lead author of the newly published study.

The average sugar-sweetened soda consumption for all survey participants was 12 ounces. About 21 percent in this nationally representative sample reported drinking at least 20 ounces of sugar-sweetened soda a day.

"It is critical to understand both dietary factors that may shorten telomeres, as well as dietary factors that may lengthen telomeres," Leung said. "Here it appeared that the only beverage consumption that had a measurable negative association with telomere length was consumption of sugared soda."

The finding adds a new consideration to the list of links that has tied sugary beverages to obesity, metabolic syndrome, type 2 diabetes, and cardiovascular disease, and that has driven legislators and activists in several U.S. jurisdictions to champion ballet initiatives that would tax sugar-sweetened beverage purchases with the goal of discouraging consumption and improving public health.

The UCSF researchers measured telomeres after obtaining stored DNA from 5,309 participants, ages 20 to 65, with no history of diabetes or cardiovascular disease, who had participated in the nation's largest ongoing health survey, called the National Health and Nutrition Examination Survey, during the years 1999 through 2002. They found that the amount of sugar-sweetened soda a person consumed was associated with telomere length, as measured in the laboratory of Elizabeth Blackburn, PhD, professor of biochemistry at UCSF and a winner of the 2009 Nobel Prize in Physiology or Medicine for her telomere-related discoveries.

###

Additional study authors include, from UCSF, Nancy E. Adler, PhD, professor of psychiatry and director of the Center for Health and Community, and Jue Lin, PhD, an associate researcher with Blackburn's lab; from UC Berkeley, Barbara A. Laraia, PhD, director of public health nutrition; from the University of Michigan, Belinda Needham, PhD, assistant professor of epidemiology; and from Stanford University, David H. Rehkopf, ScD, assistant professor of medicine.

14 comments :

  1. OK, layman taking a stab at it here:
    Professor of psychiatry? o-0
    Why only soda and not other sources of sugar? Or is soda such a major dietary sugar source in North America, that we can use it as a good proxy for total intake?
    Also, what do "ballet initiatives" have to do with this? ;-) (I mean, it's good exercise and all....)

    ReplyDelete
    Replies
    1. Tbh it's a step up from seeing a grown man in a diaper.

      Delete
  2. The main reason I feel skeptical towards it is that I feel skeptical towards all dietary research. A great deal of it is correlational crap, often with statistics that do not adequately take into account multiple-hypothesis testing in their experiments. This paper might not fit that trend, I haven't read it, but so much of this kind of research is poor that it's a useful prejudice. Also, a lot of dietary research seems driven by a latent Puritanism. It might turn out to be correct, but there is a reaching element there: death needs a scapegoat that's you're personal fault and/or a target for regulators.

    Like Steve, I wonder why soda and not sugar in general? Or calories in general? And of course, what reason do they have to think that the direction of causality goes from more soda consumption to telomere length and not from telomere length to increased soda consumption? And how strong is this correlation anyway?

    For all that it could be true, but for the most part I dismiss dietary research out of hand unless something tips me off that the authors have done a better job than most examples of the type.

    ReplyDelete
    Replies
    1. your. No idea why "you're" came out. Brain offloading too much to my fingers I guess.

      Delete
  3. This paper explains why one should be skeptical: http://www.stat.columbia.edu/~gelman/research/unpublished/p_hacking.pdf

    ReplyDelete
  4. No doubt you are aware of comments like the following:

    "Better choice of diet and activities has great potential to reduce the rate of telomere shortening or at least prevent excessive telomere attrition ..."
    From:
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370421/

    "... measurements in peripheral blood leukocytes from individual mice showed that CR [caloric restriction] resulted in maintenance and/or elongation telomeres ..."
    From:
    http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0053760

    1. I take "carbonated beverages containing sugar" as a surrogate for eating lots of Jellied Donuts.
    2. No doubt the analysis could be flawed, but I'm sure there are scientists (from the DI) funded by Pepsi rechecking the sources and math as I write.
    3. If the results are accurate no doubt there are multiple steps from sugar intake to telomere shortening.

    Such things aside I see no reason to doubt the results.

    On the other hand, experience has taught me that folks who eat a lot of Jelly Donuts are certain to see many many problems with this work.

    ReplyDelete
  5. I think it is important for scientists to explain to students and the public that a genuine scientific explanation requires a mechanism -- it is not clear what possible mechanism there would be for soda causing telomeres to shorten.

    Otherwise it is like the old joke about ice cream causing street crime on the basis of the correlation between ice cream sales and street crime (both high in summer and low in winter).

    ReplyDelete
  6. Larry is a biochemist, so I'm going to have him the privilege to dismiss the following claims:

    "HFCS (High Fructose Corn Syrup)and cane sugar are NOT biochemically identical or processed the same way by the body. High fructose corn syrup is an industrial food product and far from “natural” or a naturally occurring substance. It is extracted from corn stalks through a process so secret that Archer Daniels Midland and Carghill would not allow the investigative journalist Michael Pollan to observe it for his book The Omnivore’s Dilemma. The sugars are extracted through a chemical enzymatic process resulting in a chemically and biologically novel compound called HFCS. Some basic biochemistry will help you understand this. Regular cane sugar (sucrose) is made of two-sugar molecules bound tightly together– glucose and fructose in equal amounts.The enzymes in your digestive tract must break down the sucrose into glucose and fructose, which are then absorbed into the body. HFCS also consists of glucose and fructose, not in a 50-50 ratio, but a 55-45 fructose to glucose ratio in an unbound form. Fructose is sweeter than glucose. And HFCS is cheaper than sugar because of the government farm bill corn subsidies. Products with HFCS are sweeter and cheaper than products made with cane sugar. This allowed for the average soda size to balloon from 8 ounces to 20 ounces with little financial costs to manufacturers but great human costs of increased obesity, diabetes, and chronic disease.Now back to biochemistry. Since there is there is no chemical bond between them, no digestion is required so they are more rapidly absorbed into your blood stream. Fructose goes right to the liver and triggers lipogenesis (the production of fats like triglycerides and cholesterol) this is why it is the major cause of liver damage in this country and causes a condition called “fatty liver” which affects 70 million people.
    The rapidly absorbed glucose triggers big spikes in insulin–our body’s major fat storage hormone. Both these features of HFCS lead to increased metabolic disturbances that drive increases in appetite, weight gain, diabetes, heart disease, cancer, dementia, and more.

    But there was one more thing I learned during lunch with Dr. Bruce Ames. Research done by his group at the Children’s Hospital Oakland Research Institute found that free fructose from HFCS requires more energy to be absorbed by the gut and soaks up two phosphorous molecules from ATP (our body’s energy source).

    This depletes the energy fuel source, or ATP, in our gut required to maintain the integrity of our intestinal lining. Little “tight junctions” cement each intestinal cell together preventing food and bacteria from “leaking” across the intestinal membrane and triggering an immune reaction and body wide inflammation.

    High doses of free fructose have been proven to literally punch holes in the intestinal lining allowing nasty byproducts of toxic gut bacteria and partially digested food proteins to enter your blood stream and trigger the inflammation that we know is at the root of obesity, diabetes, cancer, heart disease, dementia, and accelerated aging. Naturally occurring fructose in fruit is part of a complex of nutrients and fiber that doesn’t exhibit the same biological effects as the free high fructose doses found in “corn sugar”.

    The takeaway: Cane sugar and the industrially produced, euphemistically named “corn sugar” are not biochemically or physiologically the same."

    Take it away Larry...

    ReplyDelete
    Replies
    1. Quest;

      You forgot to mention that the author is:
      Mark Hyman, (M.D.) founder of "The UltraWellness Center"

      Also, did I understand correctly that his source for all this "information" was his recollection of a lunchtime conversation?

      Delete
    2. "High doses of free fructose have been proven to literally punch holes in the intestinal lining." 1) What is defined as a "high dose." Is a 55:45 ratio -- compared to 50:50 ratio -- a "high dose"? 2) Intestinal linings of humans, or much smaller mammals? 3) Is Mark Hyman trying to argue that soda is really "punching holes" in people? What evidence is there of this. 4) Is the title of his article, "5 Reasons High Fructose Corn Syrup Will Kill You" sound reasonable, measured, or scientific? Best

      Delete
  7. BTW: Is telomere length REALLY an indicator of longevity...? What if I happen to find a way to lengthen the telomeres....? Can I live forever...?

    ReplyDelete
  8. Other points: anyone who can write “soaks up two phosphorous molecules from ATP (our body’s energy source)” clearly doesn’t know much biochemistry. You can’t say “soaks up” in a serious context. By “two phosphorous molecules” he means two phosphate ions, and not that they are derivatives of phosphoric acid, not of phosphorous acid. Finally, ATP is not “our body’s energy source” except in a very loose sense; it is the energy currency of the cell. The energy source is mainly sugar and oxygen.

    Then we have “euphemistically named ‘corn sugar’”: that’s advertiser-speak, not science. There is nothing euphemistic about it, as it is sugar and it comes from corn syrup, so it’s just a descriptive term.

    I used to know Bruce Ames when he was a newly appointed Full Professor at Berkeley and I was a post-doc. I heard him give a plenary lecture at a FASEB meeting in, if memory serves, 1977 in Chicago. In it he said (according to my memory) that within 25 years we would be seeing a huge increase in the incidence of cancer. 25 years later I remembered this, but I didn’t seem to be seeing the expected huge increase in the incidencd of cancer, so I went back to the printed record to see exactly what he had said. To my disappointment I could find none of that in his published lecture. This could of course just mean that I’d remembered it wrongly, but as I was quite impressed by the prediction at the time I find it hard to believe that I just imagined it. Anyway, this experience makes me more sceptical than I already was about reports of what people say orally (especially “during lunch”): people say all sorts of things at lunch that they might not want to commit to the printed record.

    ReplyDelete
  9. The hopps I need to go through to comment from this computer caused me to skip the beginning of the above comment. Before "Other points" it should have said

    This computer doesn’t like the “Reply” button, so I’m doing this as a new comment, but it’s a reply to the stuff about corn syrup.

    First of all I agree with what Keith and Cesar have written, so I won’t repeat it.

    ReplyDelete
  10. Oh dear, it still isn't right. Please treat the two comments above as a single one:

    This computer doesn’t like the “Reply” button, so I’m doing this as a new comment, but it’s a reply to the stuff about corn syrup.

    First of all I agree with what Keith and Cesar have written, so I won’t repeat it.

    Other points: anyone who can write “soaks up two phosphorous molecules from ATP (our body’s energy source)” clearly doesn’t know much biochemistry. You can’t say “soaks up” in a serious context. By “two phosphorous molecules” he means two phosphate ions, and they are derivatives of phosphoric acid (phosphates), not of phosphorous acid (phosphites). Finally, ATP is not “our body’s energy source” except in a very loose sense; it is the energy currency of the cell. The energy source is mainly sugar and oxygen.

    Then we have “euphemistically named ‘corn sugar’”: that’s advertiser-speak, not science. There is nothing euphemistic about it, as it is sugar and it comes from corn syrup, so it’s just a descriptive term.

    I used to know Bruce Ames when he was a newly appointed Full Professor at Berkeley and I was a post-doc. I heard him give a plenary lecture at a FASEB meeting in, if memory serves, 1977 in Chicago. In it he said (according to my memory) that within 25 years we would be seeing a huge increase in the incidence of cancer. 25 years later I remembered this, but I didn’t seem to be seeing the expected huge increase in the incidencd of cancer, so I went back to the printed record to see exactly what he had said. To my disappointment I could find none of that in his published lecture. This could of course just mean that I’d remembered it wrongly, but as I was quite impressed by the prediction at the time I find it hard to believe that I just imagined it. Anyway, this experience makes me more sceptical than I already was about reports of what people say orally (especially “during lunch”): people say all sorts of things at lunch that they might not want to commit to the printed record.

    ReplyDelete