Another Reason to Stay Up During the Night

The Study:  

 This study looked at coffee consumption and cancer risk in 67,470 females in the Nurses’ Health Study over 26 years.  Originally surveyed in 1980, these women were between the ages of 34 and 59 at the first timepoint.  Coffee consumption was measured in 1980, 1984, 1986, 1990, 1994, 1998, and 2002 through a Food Frequency Questionanire (FFQ) and converted to Cumulative average coffee intake.  Excluded patients include any participants who died, or reported any type of cancer (exceptfor nonmelanoma skin cancer) before 1980, had a history of hysterectomy, and did not complete the 1980 food frequency questionnaire.  Over the study course, participants with missing BMI information, dietary intake information, or had a new diagnosis of cancer or hysterectomy were also excluded.

672 cases of endometrial cancer occurred in the study population.  Fewer than 4 cups of coffee per day were not associated with a change in endometrial cancer risk.  Women consuming 4 or more cups of caffeinated coffee per day had a 30% lower risk of endometrial cancer compared with those who drank less than 1 cup per day.  For decaffeinated coffee, a non-significant inverse association was found among women who had 2 or more cups a day (22% less risk).  Tea consumption was not associated with endometrial cancer risk.

Limitations: 

 FFQs are notoriously at estimating a person’s dietary intake, though this study claims that it is accurate for tea and coffee intake.  The amount of cream, milk, creamer, or sugar was not measured in this study.  Variations in coffee drinks may alter the amount of caffeine and other biologically active compounds in each drink, leading to an incorrect measurement.  While confounders like alcohol intake and smoking were investigated, there may be more confounders such as employment, considering all of the participants were nurses.  Nurses in inpatient settings or overnight shifts may ingest more coffee than other nurses, and increased stress during these shifts may affect the incidence of endometrial cancer; making employment a confounder.  The study did not look at what biologically active substance may cause this decrease in endometrial cancer.

What this Means:   

 High caffeinated coffee intake may lead to a decreased incidence of endometrial cancer.   This association may not be true for decaffeinated coffee or for tea.  More research is needed to determine what substance may cause this decrease in endometrial cancer incidence. 

My Take: 

Good news for female coffee drinkers!  You may have an excuse to drink even more.  You may have trouble sleeping though.

However, this study underlined one point for me – watch what you put in your drinks!  While 4+ cups of coffee a day may be helpful,  4+ servings of cream, sugar, etc. is definitely harmful.  I am known for putting only hot chocolate mix in my coffee, and that would add 420 calories (for 4 envelopes)!  That’s almost 25% of daily recommended caloric intake.   So sip away, just watch what you put in that cup.