A few years ago, I wrote about the dark and light side of coffee (pun-intended). Since then, coffee has been making a bigger comeback as a superfood and even more research on its benefits continues to be released. This makes many who enjoy the performance enhancing effect of habitual caffeine consumption pleased. (1)
In this blog, I review some of the most recent studies on coffee and health outcomes. On my homepage, I get into the exciting world of the epigenetics of coffee. Specifically, I discuss how one’s individual variations in detoxifying enzymes of caffeine and neurotransmitter responses to coffee both have an impact on how it affects one’s particular body. In fact, these individual differences may be what accounts for some conflicting evidence on coffee’s role in wellness.
Updates in Coffee
Coffee and Mortality:
A 1971-2002 large cohort study of 43,727 participants analyzed data from questionnaires, chemistry panels, exercise tests, and blood pressure, electrocardiography, and anthropometry measurements. The relationship to mortality was reported below (bold emphasis mine):
During the 17-year median follow-up, 2512 deaths occurred (804 [32%] due to cardiovascular disease). In multivariate analyses, coffee intake was positively associated with all-cause mortality in men. Men who drank more than 28 cups of coffee per week had higher all-cause mortality (hazard ratio [HR], 1.21; 95% CI, 1.04-1.40). However, after stratification based on age, younger (<55 years old) men and women showed a significant association between high coffee consumption (>28 cups per week) and all-cause mortality after adjusting for potential confounders and fitness level (HR, 1.56; 95% CI, 1.30-1.87 for men; and HR, 2.13; 95% CI, 1.26-3.59 for women).
CONCLUSION: In this large cohort, a positive association between coffee consumption and all-cause mortality was observed in men and in men and women younger than 55 years. On the basis of
these findings, it seems appropriate to suggest that younger people avoid heavy coffee consumption (ie, averaging >4 cups per day). However, this finding should be assessed in future studies of other populations. (2)
A more recent meta-analysis determined that this effect was related to a dose-response and showed a risk reduction in coffee drinkers averaging 4 cups a day:
Several studies have analyzed the relationship between coffee consumption and mortality, but the shape of the association remains unclear. We conducted a dose-response meta-analysis of prospective studies to examine the dose-response associations between coffee consumption and mortality from all causes, cardiovascular disease (CVD), and all cancers. Pertinent studies, published between 1966 and 2013, were identified by searching PubMed and by reviewing the reference lists of the selected articles. Prospective studies in which investigators reported relative risks of mortality from all causes, CVD, and all cancers for 3 or more categories of coffee consumption were eligible. Results from individual studies were pooled using a random-effects model. Twenty-one prospective studies, with 121,915 deaths and 997,464 participants, met the inclusion criteria. There was strong evidence of nonlinear associations between coffee consumption and mortality for all causes and CVD (P for nonlinearity < 0.001). The largest risk reductions were observed for 4 cups/day for all-cause mortality (16%, 95% confidence interval: 13, 18) and 3 cups/day for CVD mortality (21%, 95% confidence interval: 16, 26). Coffee consumption was not associated with cancer mortality. Findings from this meta-analysis indicate that coffee consumption is inversely associated with all-cause and CVD mortality. (3)
One could therefore conclude that 4 cups of coffee a day could be the “goldilocks” of daily coffee consumption.
A 2013 article in The Journal of American College of Cardiology compiled 72 cited reference and even went so far as to recommend coffee for those with an increased risk of cardiovascular disease. They also gave some tips on how to brew it (bold emphasis mine):
The currently available evidence on CV effects related to habitual coffee consumption is largely reassuring. Coffee can be included as part of a healthy diet for the general public and also for those with increased CV risk or CV disease. Those with dyslipidemia may consider brewed and filtered coffee as opposed to preparations made from boiling beans without filtering. While many of coffee’s benefits probably derive from its caffeine content, decaffeinated coffee seems to offer some health benefits too and may be a reasonable option for those who experience uncomfortable effects from caffeine stimulation. Drinkers of caffeinated coffee in particular might be advised to ensure adequate calcium consumption from dietary sources to guard against potential adverse outcomes related to bone health. Finally, it is possible that individuals who consume coffee differ in other important dietary and sociological aspects from the nonconsumers. Therefore, the possibility that coffee consumption may be acting as a surrogate marker of some other dietary or lifestyle risk factor cannot be fully excluded. (4)
There has been some evidence of caffeine impairing blood sugar (5), therefore, it may not be a good idea for those with blood sugar handling issues to partake in isolated caffeine supplements. However, caffeine wrapped in the aroma-enticing coffee bundle may be a different story, as there’s more aromatic polyphenols to modulate the caffeine effect. In fact this cohort study of 3,497 diabetic men without heart disease at baseline found:
CONCLUSIONS These data indicate that regular coffee consumption is not associated with increased risk for CVDs or mortality in diabetic men. (6)
Several studies have shown that fracture risk is not increased in women who drink coffee. (7-8) However, bone density could be impacted in those with heavy coffee consumption. (8)
Caffeine and Weight
Some people drink coffee for caffeine’s thermogenic effect (8-9), and indeed, some studies show that this may be helpful. However, too high isolated caffeine intake can also impose some risks as discussed above. (4)
After pouring through over twenty abstracts and reading a dozen or so articles, the general conclusion I have is that if you’ve got the genetic prowess to handle coffee, go for it. However, buy quality coffee and go for the sweet spot of less is more, especially no more than 4 cups a day (which in my opinion is still quite high). Otherwise, best stay clear and get your polyphenols from other sources, like veggies or essential oils. 😀 (Click here to read more.)
(1) Smith A, Sutherland D, Christopher G. Effects of repeated doses of caffeine on mood and performance of alert and fatigued volunteers. J Psychopharmacol. 2005; 19:620.
(2) Liu J, Sui X, Lavie CJ, et al. Association of coffee consumption with all-cause and cardiovascular disease mortality. Mayo Clin Proc. 2013; 88:1066.
(3) Coffee consumption and mortality from all causes, cardiovascular disease, and cancer: a dose-response meta-analysis. Am J Epidemiol. 2014 Oct 15;180(8):763-75. doi: 10.1093/aje/kwu194. Epub 2014 Aug 24.
(4) Effects of Habitual Coffee Consumption on Cardiometabolic Disease, Cardiovascular Health, and
All-Cause Mortality. Journal of the American College of Cardiology. September 2013; 62(12):1043-1051. doi:10.1016/j.jacc.2013.06.035
(5) Caffeine ingestion impairs insulin sensitivity in a dose-dependent manner in both men and women. Appl Physiol Nutr Metab. 2013 Feb;38(2):140-7. doi: 10.1139/apnm-2012-0201. Epub 2012 Nov 9.
(6) Coffee Consumption and Risk of Cardiovascular Diseases and All-Cause Mortality Among Men With Type 2 Diabetes. Diabetes Care. June 2009. 32(6): 1043-1045. doi: 10.2337/dc08-2251
(7) Coffee drinking: a minor risk factor for bone loss and fractures. Age Ageing. 1992;21(1):20-6. http://www.ncbi.nlm.nih.gov/pubmed/1553855
(8) Long-term Coffee Consumption in Relation to Fracture Risk and Bone Mineral Density in Women. Am J Epidemiol. 2013;178(6):898-909. http://www.medscape.com/viewarticle/811500
(9) Changes in caffeine intake and long-term weight change in men and women. Am J Clin Nutr. March 2006. vol. 83 no. 3 674-680.
(10) Body weight loss and weight maintenance in relation to habitual caffeine intake and green tea supplementation. Obes Res. 2005 Jul;13(7):1195-204.