Morning coffee habit may be tied to longer life and healthier heart: Study
Drinking coffee only in the morning may help people live longer compared to drinking the beverage throughout the day, a new study suggests.
Researchers from Tulane University analyzed dietary and health data from more than 40,000 U.S. adults from the National Health and Nutrition Examination Survey between 1999 and 2018. The team identified two coffee-drinking patterns: morning-only and all-day drinkers.
The early-in-the-day drinkers -- those who drank their coffee between 4:00 a.m. and noon -- had a 16% lower chance of dying from any cause compared to those who didn't drink coffee, according to results published Tuesday in the European Heart Journal.
Coffee drinkers also had a 31% lower risk of dying from heart disease compared to non-coffee drinkers, the study found.
No matter how many cups of coffee the morning drinkers had, or whether they preferred decaffeinated coffee, the risk of death was still lower, according to the study.
However, those who kept drinking coffee into the afternoon and evening did not show a lower risk of death.
"This study is unique in that it looked at coffee-drinking patterns throughout the day instead of focusing on [the] amount of coffee that is consumed," said Dr. Jennifer Miao, a board-certified cardiologist at Yale New Haven Health and a fellow in the ABC News Medical Unit.
To explain their findings, the researchers suggested morning coffee may better align with the body's natural sleep and wake cycles. It may also reduce inflammation, which tends to be higher in the morning, and, in turn, lower heart disease risk.
The study did not find that coffee drinking was associated with a lower risk of cancer.
"The null association with cancer mortality is partly due to the smaller number of cases, and various types of cancer are analyzed together," Dr. Lu Qi, the study's senior author and interim chair of the Department of Epidemiology at Tulane University, told ABC News. "It is possible coffee drinking may differentially impact different types of cancer."
In other words, there may be too few cancer cases included in the study to evaluate. Additionally, because the researchers reviewed all types of cancer together, it could be that coffee has an influence on some cancers, but not others.
The study also had other limitations. The participants self-reported their coffee-drinking habits, meaning results may be inaccurate, and the researchers didn't consider long-term consumption patterns.
Experts say another reason for the lower risk of death may be that morning coffee drinkers have healthier lifestyles, including better diets and taking part in exercise. Factors including shift work or wake-up times could also play a role.
Dr. Perry Fisher, an interventional cardiologist at Lenox Hill Hospital in New York City, told ABC News he found the study's results interesting but said he wouldn't necessarily recommend changing coffee habits as a result.
"I think that we need further study to demonstrate a true relationship that would change management," Fisher said.
Qi, the study author, added that additional studies -- including with people from other countries -- would be needed to confirm the results, as well as clinical trials.
"While some studies have shown that drinking a moderate amount of coffee can be good for the heart, not all research agrees," Miao said. "Talk to your doctor before changing your coffee habits, especially if you have health risks."
Brent Gawey, M.D., M.S., is an internal medicine resident at Mayo Clinic and a member of the ABC News Medical Unit.
