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Published on September 18, 2015

Don’t worry, coffee is good for you. Or maybe not

Don’t worry, coffee is good for you. Or maybe not

Like so many foods and beverages these days, coffee is either much maligned or all the rage.

Over the years, we’ve been warned to limit the amount of coffee we ingest or switch to decaffeinated coffee. Too much caffeine can bring unpleasant side effects such as insomnia, nervousness, restlessness and a fast heartbeat, the experts said.

More recently, coffee’s image improved thanks to a slew of new research studies touting its benefits. Now coffee is credited for reducing cancer, preventing type 2 diabetes, and even reducing symptoms of depression and incidents of suicide.

Coffee is researchers’ new cancer buster. Separate studies have shown that it seems to protect against several types of cancer, including colon cancer, endometrial cancer and liver cancer. It also protects against cirrhosis of the liver.

“The antioxidant and anti-inflammatory components of food and beverages like coffee have long been credited to reduce the risk of cancer,” says Courtney Driscoll, RD, dietitian and clinical nutrition manager at Cape Cod Healthcare.

But as a nutritionist, Driscoll is hesitant to tell people to increase their coffee consumption or consider drinking four or more cups a day—especially considering what they might add to their coffee.

“For many people, four cups of coffee would mean a significant amount of sugar and cream, which is high in fat, throughout the day,” Driscoll says. “High intakes of fat and sugar can lead to obesity, which has definitely been linked to increasing the risks of cancer.”

So what’s a coffee drinker to do? Let’s sort through the evidence:

• Diabetes. In April 2014, the Harvard School of Public Health announced new research that people who increased their coffee intake each day by more than one cup over a four-year period had an 11 percent lower risk for type 2 diabetes than those who did not.

Researchers also observed the opposite effect: those who reduced their coffee intake by more than one cup a day increased their risk of type 2 diabetes by 17 percent. The same results were not found with decaffeinated coffee or tea.

Researchers believe these results occur because high coffee consumption is associated with better glucose tolerance. Short term metabolic studies have shown that caffeine can lower insulin sensitivity, but the long term effects of caffeine metabolism are still unknown.

• Depression and suicide. Coffee also can lower the risk of suicide. Researchers from the Harvard School of Public Health reviewed data from three large studies totaling more than 200,000 people.

Over the study period of four years, physicians recorded 277 deaths by suicide. They found that the risk of suicide was 50 percent less for those who drank between two and four cups of coffee a day, compared to those who drank decaf or little or no coffee.

Researchers speculate that coffee helps because it stimulates the central nervous system and acts as a mild anti-depressant by boosting noradrenaline, dopamine and serotonin. Earlier studies have linked consumption of coffee with lower incidences of depression.

• Alzheimer’s and dementia. In another study of how coffee affects the brain, researchers discovered that caffeine is also a preserver of cognitive function in older adults and can delay or prevent the onset of dementia and Alzheimer’s disease.

A research study in Finland and Sweden published in the Journal of Alzheimer’s Disease in January 2009 showed evidence that drinking three to five cups a day of coffee in midlife had a significantly lower risk (65 percent decrease) of developing dementia or Alzheimer’s disease than those who abstained.

Some other reported benefits of coffee are a lessor risk of Parkinson’s disease and help for erectile dysfunction in overweight hypertensive men.

So is it too late to start drinking coffee and reap the benefits?

Be careful there, the Finnish researchers concluded. Their study in the Italian Longitudinal Study on Aging, published in August 2015 in the Journal of Alzheimer’s Disease, found that those who increased coffee drinking later in life were at greater risk for cognitive dysfunction than those who had remained consistent in their consumption over time.

In other words, if you’re already drinking coffee, keep it up. If not, there’s no reason to start.

And the news isn’t all good. Coffee can cause symptoms such as jitteriness, anxiety, heart palpitations and exasperate panic attacks. Pregnant women should limit their caffeine intake because caffeine crosses the placenta.

Perhaps the most alarming health problem with coffee is that two or more cups a day can increase the risk of heart disease in people with a genetic mutation that slows the breakdown of caffeine in their body. Depending on race, about half of us have some form of the mutation.

“The concern with coffee and other caffeinated beverages is usually from a cardiac standpoint because of the effects it has on our heart rate,” Driscoll says. “So it would be very important for patients to speak with their physicians before increasing their intake of caffeinated beverages.”