Latte, cappuccino or short black, a morning coffee is an essential for many people looking to kick start their day.
But while the humble coffee may be a vital feature of the daily grind, how much is too much?
First, the bad news about caffeine (and coffee)
Remember: Caffeine is a drug, says Steven Meredith, a researcher in behavioral pharmacology at the Johns Hopkins School of Medicine.
While low to moderate doses are generally safe, caffeine is addictive and users can become dependent on it and find it difficult to quit or even cut back, he says. (Caffeine dependence was even named as a new mental disorder this year.)
Anyone who’s ever quit cold turkey knows it can trigger pounding headaches, mental fuzziness and fatigue for a couple of days until the body adjusts.
Other effects of too much caffeine:
- It increases anxiety and disrupts sleep patterns, leading to a vicious cycle of restless sleep, relying on caffeine to help with daytime fatigue, followed by more insomnia.
- Caffeine interacts with some medications, including thyroid medication, psychiatric and depression drugs, the antibiotic Cipro and the heartburn drug Tagamet.
- It increases blood sugar levels, making it harder for those with type 2 diabetes to manage their insulin, according to a number of studies; it also can slightly raise blood pressure. If you have difficulty controlling either your blood pressure or diabetes, switching to decaf may help, says Rob van Dam with Harvard’s School of Public Health.
- Caffeine potentially leads to some spinal bone loss in postmenopausal women if they typically drink more than three cups, or 300 mg of caffeine, a day, but don’t get enough calcium in their diet, says Linda Massey, emeritus professor of nutrition at Washington State University. An older woman should make sure she gets at least 800 mg of calcium daily — through food or supplements — to offset caffeine’s effect on calcium, adds Bess Dawson-Hughes, M.D., director of the Bone Metabolism Laboratory at Tufts University in Boston.
Coffee itself can also mess with your stomach.
If you have problems with acid reflux or heartburn, then coffee and even tea might not be right for you.
And if you have high cholesterol and you don’t want your coffee adding to the problem, you need to use a paper filter to trap the cafestol, a compound in coffee that raises LDL cholesterol levels, says van Dam.
- offee’s not your friend if you’re prone to heartburn. Coffee is highly acidic and is irritating to the gastrointestinal tract. Switching to decaf won’t help: In fact some research has found that decaf increases stomach acid even more than caffeinated coffee. Neither will switching methods of brewing or roasting. Avoiding coffee is the only solution.
- Caffeine’s not your friend if you have acid reflux. Caffeine seems to be the main culprit by relaxing the sphincter muscle that normally keeps stomach acid from bubbling up the esophagus. Decaf coffee has significantly less of a reflux effect, studies have found.
Now, the good news about caffeine (and, of course, coffee)
Caffeine has been shown to protect against a host of problems.
Some studies have found that those who drink lots of coffee (but not decaf) seem to be four to eight times less likely to develop Parkinson’s disease, according to the NIH’s National Institute of Neurological Disorders and Stroke, and “that is more likely to be due to caffeine” than to any nutrients in coffee, says van Dam.
Some other benefits of coffee:
- It may reduce the risk of Alzheimer’s and dementia. A caffeine habit in your 40s and 50s – three to five cups daily of the high-octane stuff, not decaf – seems to reduce by up to 70 percent the risk of Alzheimer’s and dementia in your 70s, a 2009 University of Florida study found. Other studies have found that regular caffeine consumption may help slow the rate of cognitive decline in older adults.
- Coffee cuts suicide risk. A 2013 study by Harvard’s School of Public Health found that those who drank two to three cups of caffeinated coffee a day cut their suicide risk by 45 percent — possibly because caffeine’s stimulant effect helps boost people’s moods.
- It lowers the risk of oral cancers. Older adults who drank four or more 8-ounce cups of regular coffee daily were half as likely to die of mouth and upper throat cancer. Decaf had a weaker effect, while no protection was found with tea.
- Coffee lowers the risk of stroke for older women. A 2009 U.S. study and a 2011 Swedish study both found that older women who drink more than a cup of caffeinated coffee daily have a 20 to 25 percent lower risk of stroke. A 2008 Swedish study found a similar result in older men.
While the pros and cons of drinking coffee have been debated for decades, new research from the University of South Australia reveals that drinking six or more coffees a day can be detrimental to your health, increasing your risk of heart disease by up to 22 per cent.
In Australia, one in six people are affected by cardiovascular disease.
It is a major cause of death with one person dying from the disease every 12 minutes.
According to the World Health Organization, cardiovascular disease is the leading cause of death, yet one of the most preventable.
Investigating the association of long-term coffee consumption and cardiovascular disease, UniSA researchers Dr. Ang Zhou and Professor Elina Hyppönen of the Australian Centre for Precision Health say their research confirms the point at which excess caffeine can cause high blood pressure, a precursor to heart disease.
This is the first time an upper limit has been placed on safe coffee consumption and cardiovascular health.
“Coffee is the most commonly consumed stimulant in the world – it wakes us up, boosts our energy and helps us focus – but people are always asking ‘How much caffeine is too much?’,” Prof Hyppönen says.
“Most people would agree that if you drink a lot of coffee, you might feel jittery, irritable or perhaps even nauseas – that’s because caffeine helps your body work faster and harder, but it is also likely to suggest that you may have reached your limit for the time being.
“We also know that risk of cardiovascular disease increases with high blood pressure, a known consequence of excess caffeine consumption.
“In order to maintain a healthy heart and a healthy blood pressure, people must limit their coffees to fewer than six cups a day – based on our data six was the tipping point where caffeine started to negatively affect cardiovascular risk.”
Using UK Biobank data of 347,077 participants aged 37-73 years, the study explored the ability of the caffeine-metabolizing gene (CYP1A2) to better process caffeine, identifying increased risks of cardiovascular disease in line with coffee consumption and genetic variations.
Prof Hyppönen says that despite carriers of the fast-processing gene variation being four times quicker at metabolising caffeine, the research does not support the belief that these people could safely consume more caffeine, more frequently, without detrimental health effects.
“An estimated three billion cups of coffee are enjoyed every day around the world,” Prof Hyppönen says.
“Knowing the limits of what’s good for you and what’s not is imperative.
“As with many things, it’s all about moderation; overindulge and your health will pay for it.”
More information: Ang Zhou et al, Long-term coffee consumption, caffeine metabolism genetics, and risk of cardiovascular disease: a prospective analysis of up to 347,077 individuals and 8368 cases, The American Journal of Clinical Nutrition (2018). DOI: 10.1093/ajcn/nqy297
Journal information: American Journal of Clinical Nutrition
Provided by University of South Australia