Tuesday, February 7, 2017

Coffee Lengthens, While Caffeine Shortens Your Telomeres: An Essential Paradox? The Latest Evidence Reviewed

If life "begins with coffee", will it also help you end later with coffee?
If you follow the SuppVersity on Facebook, you will be aware that the majority of studies indicates that the chronic consumption of coffee (even in amounts of 5+cups/day) has potent health benefits - at least in normal, healthy individuals. Accordingly, you may not consider the observation Larry Tucker (2017) made when he evaluated the relationship between caffeine intake and coffee consumption and leukocyte telomere length, in his latest study surprising. After all, a drink with overall beneficial effects on one's health, shouldn't have negative effects on our telomere length, a biomarker of the senescence of cells.
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What is surprising about Tucker's cross-sectional study, however, is that his analysis of data of 5826 adults from the National Health and Nutrition Examination Survey (NHANES) shows that the consumption of coffee's main active ingredient was inversely related to telomere length (F = 15.1, P = 0.0005) - or, to be more precise that the subject's telomeres were 35.4 base pairs for each 100 mg of caffeine they consumed on a daily basis; and that after adjusting for the covariates.

Caffeine shortens and coffee lengthens your telomeres - How's that possible? 

Well, the most probable answer is that other substances in coffee, such as chlorogenic acid, ameliorate the negative effects caffeine will have on the length of your telomeres.
Figure 1: The caffeine intake is negatively associated with the length of the telomeres according to the data from 5826 adults from NHANES (1999–2002) in both coffee drinkers and abstainers (Tucker. 2017).
And indeed, the data from the study seems to confirm just that. After all, a re-analysis of the link between caffeine consumption and telomere length revealed that...
  • each 100 mg of caffeine consumed by coffee drinkers was associated with telomeres that were 36.7 base pairs shorter than the cohort average (F = 9.0, P = 0.0054), while 
  • each 100 mg of caffeine consumed by non-coffee drinkers was associated with telomeres that were 40.0 base pairs shorter (F = 8.5, P = 0.0067).
This observation alone can't explain that coffee intake, in general, was positively related to telomere length (F = 12.6, P = 0.0013), independent of the covariates. If we take into consideration that coffee is not the only source of caffeine in the average American's diet, however, another factor that may interfere with the telomere length emerges: sodas, energy drinks & co.
A short telomere length correlates with an increased risk of mortality and with the (subjectively) rated health status of older subjects in Njajou (2009).
What does telomere length have to do with (healthy) aging: Over the course of your life-cycle, your telomeres naturally shorten. Part of the telomeric DNA does not replicate each time a cell divides. This is commonly referred to as the "end replication problem," and short telomeres generally lead to negative health consequences. Accordingly, the ever-shortening length of your telomere caps limits the number of cell divisions which is why it's only logical that a study in nearly 20,000 participants found that one's telomere length correlates with a 25% greater risk of early death (Weischer. 2012).

Telomeres don't just count in the years before you die, though, Njajou et al. (2009) showed that telomere length is also predictive of years of healthy life, too. Eventually, the research on the predictive accuracy of telomere length on life expectancy and/or health is yet in its infancy.
With sodas, energy drinks & co. being staples and ever-more popular contributors to the American diet, respectively, one could thus assume that the correlation is driven by the ill effects of other ingredients of this beverages - first and foremost sugar - on one's average health and thus telomere length. Whether that's a valid hypothesis, however, appears questionable in view of the fact that Frary, et al. (2005) report, based on USDA data from 1994 to 1996 and 1998, that the "[m]ajor sources of caffeine [in the US population are] coffee (71%), soft drinks (16%), and tea (12%)".
Figure 2: Caffeine intake (mg/d) from beverages and foods by age group, NHANES 2011–2012 (Drewnowski. 2016) 
Similar results have been reported more recently based on NHANES data from 2011-12 by Dewenoski, et al. (2016 | see Figure 2). It would thus be too easy to do what everybody appears to do today and to blame blame the ill effects of caffeine on the consumption of soda & co and thus eventually the obesogenic "sugar boogeyman".
While caffeine is the #1 ingredient in energy drinks, taurine has recently emerged as more important contributor to their effects than everybody may have thought | learn more
So what do you have to remember: The first thing to remember certainly is that the study at hand is only one out of at least three epidemiological studies showing a positive association between coffee consumption and (increased) telomere length (I've reported many of them in the SuppVersity Facebook News | e.g. Lee. 2015; Liu. 2016).

Accordingly, the most important thing to remember is that the study at hand adds to the evidence that your coffee addiction (if kept within reasonable limits <10 cups/day) will positively affect your telomere length and could thus even have life-extending effects.

The fact that pertinent epidemiological studies, like the one at hand, consistently show beneficial effects of caffeinated coffee and taking into account that Takahashi, et al. (2017) showed only recently that, in a rodent model, caffeine adds to the anti-aging effects of coffee, is the second thing you should remember.

The one thing you should not do, however, is to blame sugar for the surprising difference between the telomere-lengthening effect of caffeine intake and coffee that was observed in the study at hand. After all, Figure 2 should remind you that the vast majority of caffeine comes from coffee and tea, and only small quantities from sugary soda & co | Comment on Facebook!
  • Drewnowski, Adam, and Colin D. Rehm. "Sources of caffeine in diets of US children and adults: Trends by beverage type and purchase location." Nutrients 8.3 (2016): 154.
  • Frary, Carol D., Rachel K. Johnson, and Min Qi Wang. "Food sources and intakes of caffeine in the diets of persons in the United States." Journal of the American Dietetic Association 105.1 (2005): 110-113.
  • Lee, J. Y., et al. "Association between dietary patterns in the remote past and telomere length." European journal of clinical nutrition 69.9 (2015): 1048-1052.
  • Liu, Jason J., et al. "Coffee Consumption Is Positively Associated with Longer Leukocyte Telomere Length in the Nurses’ Health Study." The Journal of nutrition 146.7 (2016): 1373-1378.
  • Njajou, Omer T., et al. "Association between telomere length, specific causes of death, and years of healthy life in health, aging, and body composition, a population-based cohort study." The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 64.8 (2009): 860-864.
  • Tucker, Larry A. "Caffeine consumption and telomere length in men and women of the National Health and Nutrition Examination Survey (NHANES)." Nutrition & Metabolism 14.1 (2017): 10.
  • Weischer, Maren, et al. "Short telomere length, myocardial infarction, ischemic heart disease, and early death." Arteriosclerosis, thrombosis, and vascular biology 32.3 (2012): 822-829.