Caffeine Intake and Coffee and Breast Cancer Risk
I debated whether or not to write about this, but decided that it is too good an example of the deluge of confusing and conflicting news to ignore. If you are a regular reader of this blog, you will remember that not long ago, I wrote about a study that suggested that moderate coffee drinkers had a lower risk of breast cancer than those who drank less or no coffee.
Now comes this meta-analysis (meaning that the authors reviewed many studies) suggesting that caffeine intake and coffee may increase breast cancer risk. Please note that I am surely not suggesting that you make any changes, or even consider any changes, to whatever your coffee habits may be. Indeed, I have a dear friend who is a liver specialist, a doctor, and he strongly believes that five (!) or more cups of coffee each day do all sorts of good things for our health. Personally, I drink one big mug in the morning (with half and half which is my daily indulgence. Each time I try to switch it out to even whole milk, it just does not do it for me.), and that's it. I have many friends who drink a lot more coffee each day than that (including the liver specialist!), and they are just fine.
So, in the spirit of "if you don't like the recommendation, just wait a bit and it will be changed", here is the summary from Gynecologic Oncology:
Coffee and caffeine intake and breast cancer risk:
An updated dose-response meta-analysis of 37
Gynecologic Oncology, 05/13/2013
Jiang W et al. – The authors conducted an updated meta–analysis to summarize the
evidence from published studies regarding the association of coffee and caffeine intake
with breast cancer risk. Findings from this meta–analysis suggested that coffee/caffeine
might be weakly associated with breast cancer risk for postmenopausal women, and the
association for BRCA1 mutation carriers deserves further investigation.
Pertinent studies were identified by a search of PubMed and by reviewing the
reference lists of retrieved articles.
The fixed or random effect model was used based on heterogeneity test.
The dose–response relationship was assessed by restricted cubic spline model
and multivariate random–effect meta–regression.
37 published articles, involving 59,018 breast cancer cases and 966,263
participants, were included in the meta–analysis.
No significant association was found between breast cancer risk and coffee (RR =
0.97, P = 0.09), decaffeinated coffee (RR = 0.98, P = 0.55) and caffeine (RR =
0.99, P = 0.73), respectively.
And the association was still not significant when combining coffee and caffeine
(coffee/caffeine) (RR = 0.97, P = 0.09).
However, an inverse association of coffee/caffeine with breast cancer risk was
found for postmenopausal women (RR = 0.94, P = 0.02), and a strong and
significant association of coffee with breast cancer risk was found for BRCA1
mutation carriers (RR = 0.69, P < 0.01).
A linear dose–response relationship was found for breast cancer risk with coffee
and caffeine, and the risk of breast cancer decreased by 2% (P = 0.05) for every 2
cups/day increment in coffee intake, and 1% (P = 0.52) for every 200 mg/day
increment in caffeine intake, respectively.