For a long time, coffee has been blamed for negative effects such as stunting growth and heart disease. However, recent research shows that coffee has a wealth of positive attributes. In fact, study after study is touting the merits of 3 or more cups of black coffee per day can reduce risk of some serious health conditions.
Let's start with clearing up some common misconceptions. Studies have found NO connection between coffee and increased risk of cancer or heart disease. Why the sudden reverse in thinking? Old studies failed to consider that known high-risk behaviours (smoking, drinking, physical inactivity) also tended to be common among heavy coffee drinkers.
So let's have a look at the pros and cons of drinking coffee.
PROS
Heart Disease
Not only did recent studies clear up the old myth of coffee leading to heart disease, but it actually found an association between drinking coffee and a decrease in all death rates, including those deaths attributed to heart disease. Also, they found the biggest effect in whose who drank more than 4 cups daily.
Mental Health
Coffee may have health benefits in protecting against Parkinson's disease. In fact, they found that higher coffee and caffeine consumption resulted in lower incidences of Parkinson's Disease by as high as 60%.
That's not all! Coffee has been shown to be effective in preventing Alzheimer's disease - the most common degenerative brain disease and leading cause of dementia worldwide. Several studies have shown coffee drinkers have up to 65% lower risk of developing Alzheimer's disease.
Coffee also appears to improve cognitive function and decreases the risk of depression. Women who drink 4 or more cups daily have a 20% lower risk of suffering with depression.
Diabetes
A massive study, consisting of over 1 million participants found that coffee lowered the risk of developing type 2 diabetes. Every additional cup of coffee consumed in a day, caffeinated or not, was associated with a 9% lower risk of developing this severe condition.
However, people with uncontrolled diabetes should always check with their doctor before adding caffeine to their diets.
Liver Disease
And here's more good news. Scientists now suggest that regular consumption of coffee reduced the risk of liver cirrhosis. Having as few as two cups of coffee per day lowers the chance of developing the disease by nearly 50%. Also, they found that higher consumption of coffee was linked to less risk of developing cirrhosis.
Aside: Cirrhosis is scarring of the liver as the result of many different conditions, three of the more common ones being from hepatitis, long-term alcohol abuse and fatty liver disease (linked to obesity and diabetes). Cirrhosis is potentially fatal (cause of death of roughly 1 million people annually) and has no cure, therefore this result is significant since it shows that coffee can nearly halve the risk of developing cirrhosis.
Cancer
Higher coffee intake, those who drank 4 or more cups/day, had a 20% lower risk of malignant melanoma. This was found for caffeinated coffee, not decaf though. This form of skin cancer is the 5th most common cancer in North America.
Coffee consumption was also found to lead to reduced risk of prostate cancer, with the more cups of coffee per day being linked to less chance of developing this form of cancer.
Athletic Performance
There is consistent evidence that supports the effect of caffeine for endurance-based exercise. It is best to consume coffee 1 hour prior to exercise to improve endurance exercise performance by over 10%.
Osteoporosis
A study performed in China found that higher frequency of coffee intake was associated with decreased occurrence of osteoporosis in post-menopausal women.
CONS
Now, like anything, there are always negative effects. Here we highlight them:
Cholesterol Levels
High consumption of certain type of coffee - unfiltered types such as espresso, French press or boiled coffee - has been associated with mild elevations in cholesterol levels due to the oily part of coffee not being removed.
Heart Disease
Now you may be asking yourself, why did I list coffee being a positive and negative on heart disease. That's because some studies found that 2 or more cups of coffee daily can increase the risk of heart disease but ONLY in those with a specific genetic mutation that slows caffeine breakdown in the body. Not only is this a lame mutation (compared to comic books and movies that show mutants with lasers that shoot out their eyes), but it's also somewhat common.
Withdrawal
Caffeine withdrawal from long-term, heavy coffee drinking can cause headaches, mood changes and poor concentration.
Bladder Cancer
The only form of cancer that caffeine intake has shown an association with is bladder cancer. A recent review found male coffee drinkers and non-smoking coffee drinkers were more likely to develop bladder cancer. Therefore, if this is a risk factor in your family history then you may want to lay off the java.
Environmentally
According to the latest studies, the world's coffee farms are now more harmful to the environment than ever. Specifically, they found coffee farms are being grown in direct sunlight, which leads to poor soil health, erosion and leaves the environment degraded. Currently, nearly 50% of the coffee farmland contained no shade trees at all (shade trees support soil health, fight erosion and confer side benefits).
However, their is a way to ensure that your coffee is good for the planet, and that is by buying beans that have been certified by Rainforest Alliance or the Smithsonian Migratory Bird Center. Organic and fair-trade beans are also good, but those don't specifically account for shade cover or biodiversity.
Conclusion
Health effects of coffee can be conflicting and made complicated by differences in age, gender, health status and serving size. However, the consensus in the medical community is that moderate coffee drinking in healthy people is essentially neutral or mildly beneficial.
Although coffee may have more benefits than risks, this only addressed black coffee. Adding cream and sugar to your coffee adds more fats, cholesterol and calories. Also, remember that coffee doesn't contain many nutrients, especially compared to those of natural fruit juices or fortified milk, dairy or otherwise.
Even the U.S. Department of Health and Human Services voiced in on the matter, saying "coffee can be incorporated into a healthy lifestyle" when staying within the 3 to 5 cups daily limit.
So in conclusion coffee lovers, keep doing what you're doing!
Reference
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Ding M, et al. (2014). Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and dose-response meta-analysis, Diabetes Care 37(2): 569-86
Freedman ND, et al. (2012), Association of coffee drinking with total and cause-specific mortality, New England Journal of Medicine 366(20): 1891-1904
Hodgson AB, et al. (2013). The metabolic and performance effects of caffeine compared to coffee during endurance exercise, PLoS One 8(4): e59561
Jha S, et al. (2014). Shade coffee: update on a disappearing refuge for biodiversity, Bioscience 64(5): 416-28
Kennedy OJ, et al. (2016). Systematic review with meta-analysis: coffee consumption and the risk of cirrhosis, Alimentary Pharmacology & Therapeutics 43(5): 562-74
Lucas M, et al. (2011). Coffee, caffeine, and risk of depression among women, JAMA 171(17)" 1571-8
Mostofsky E, et al (2012). Habitual coffee consumption and risk of heart failure: a dose-response meta-analysis, Circulation: Heart Failure 5(4): 401-5
Ross GW, et al. (2000). Association of coffee and caffeine intake with the risk of Parkinson Disease, JAMA 283(20): 2674-9
Santos C, et al. (2010). Caffeine intake and dementia: systematic review and meta-analysis, J Alzheimers Dis 20: 187-204
Wu W, et al. (2015). Coffee consumption and bladder cancer: a meta-analysis of observational studies, Scientific Reports 5: 9051
