How Healthy Is Coffee? The Latest Evidence

Introduction

The body of evidence suggesting that moderate coffee consumption is both safe and beneficial in healthy individuals continues to mount. Drinking up to five cups per day may play an important role in mental and physiologic health, as well as longevity.[1] Let’s take a look at the latest research.

New Data

Two large studies [2,3] published on July 10, 2017, in Annals of Internal Medicine report that coffee intake is linked to significantly lower risk for death from all causes. For the first time, researchers explored the relationship between coffee consumption, health, and mortality around the globe while controlling for preparation differences. Benefits were observed across diverse European populations and different racial and ethnic groups. This supports previous research showing an association between coffee consumption and a reduction in all-cause mortality. [4,5]

Coffee, Caffeine, Cardiovascular Disease

It may seem counterintuitive that a substance known to increase blood pressure could reduce the risks for coronary disease, [6] heart failure[7] and atrial fibrillation[8] Yet another study found no association between caffeine and premature atrial or ventricular contractions[9]

It could be that the beneficial properties of coffee counteract its negative effects. Coffee beans appear to reduce oxidation of low-density lipoprotein cholesterol as well as inflammatory markers. [10-14]

Cerebrovacsular Disease and Stroke

The vascular benefits of coffee are not lost on the brain. A meta-analysis [15] found that consuming one to six cups per day cut stroke risk by 17%, and a study of Swedish women showed a 22%-25% risk reduction[16] Another meta-analysis, of patients without cerebrovascular disease, concluded that one to three cups per day may protect against ischemic stroke in the general population, [17] and a Japanese study discovered that drinking coffee for an average of 13 years reduced stroke risk by 20%. [18]

Diabetes

Coffee appears to play an important role in warding off hyperglycemia, abnormal lipid levels, and increased body fat. Numerous studies have linked regular coffee drinking with improved glucose metabolism, insulin secretion, and a significantly reduced risk for diabetes[19-23] Experts have suggested that coffee’s inverse correlation with diabetes might be associated with its anti-inflammatory properties [23] and the antioxidant mechanism of chlorogenic acid, thought to reduce glucose absorption. [24]

Cancer

Studies have linked coffee consumption with reduced risk for numerous cancers, including endometrial (more than four cups daily), [25]  prostate (six cups daily), [26] head and neck (four cups daily), [27,28] and breast cancer (more than five cups daily) [29,30]basal cell carcinoma (more than three cups daily) [31]; and melanoma. [32] The benefits are thought to be at least partially due to coffee’s antioxidant and antimutagenic properties. [33,34] More recently, research discovered a significant reduction in colorectal cancer incidence in those consuming more than 2.5 cups daily. [35]

Neurodegeneration

In addition to providing a quick mental boost, coffee appears to benefit longer-term cognition. One study reported that patients with mild cognitive impairment avoided progression by drinking three to five cups per day. [33] Other research [34] has found a correlation between caffeine and memory consolidation, and between coffee and prevention of Lewy body formation[36] Research on mice suggests that caffeine suppresses amyloid-beta production, whereas coffee boosts granulocyte colony-stimulating factor, interleukin-10, and interleukin-6 levels. Caffeinated coffee has long been thought to be neuroprotective in Parkinson disease as well.

Depression

Research suggests that coffee consumption can boost mental health and protect against depression.
[37,38] In one study, women who drank two to three cups of coffee per day had a 15% decreased risk for depression compared with those who drank less than one cup per week. A 20% decreased risk was seen in those who drank four cups or more per day. Short-term effects on mood may come from altered serotonin and dopamine activity. Long-term effects may be related to coffee’s antioxidant and anti-inflammatory properties. [39-42]

Liver Disease

Coffee consumption can protect the liver, slowing the progression of alcoholic cirrhosis and hepatitis C and reducing the risk for hepatocellular carcinoma. [43-46] Other research has found that it lowers the risk for nonalcoholic fatty liver disease (NAFLD) [47] and can protect against liver fibrosis in patients who already have NAFLD. [48] Among people with a genetic predisposition for alcoholic hepatitis, those who did not drink coffee on a regular basis were more likely to have developed the disease. [49]

And That’s Not All…

An assortment of other research suggests that coffee intake might also relieve dry-eye syndrome[50] decrease the risk for gout, [51] and fight infection even potentially protecting against methicillin-resistant Staphylococcus aureus (MRSA)[52] Although the mechanism of action remains unclear, coffee (and tea) drinkers in the study were approximately one half as likely to have MRSA in their nasal passages.

The Risks

It may seem counterintuitive that a substance known to increase blood pressure could reduce the risks for coronary disease, [6] heart failure[7] and atrial fibrillation[8] Yet another study found no association between caffeine and premature atrial or ventricular contractions[9]

It could be that the beneficial properties of coffee counteract its negative effects. Coffee beans appear to reduce oxidation of low-density lipoprotein cholesterol as well as inflammatory markers. [10-14]

Observational but Ample

As Dr Mandrola told Medscape, “[T]he literature [on coffee] is replete with studies showing the same thing.” He suggested that it may be time to “[s]top studying coffee and move our attention to more pressing issues.”

It is important to remember that most of this voluminous evidence is associational and doesn’t prove causality. The sheer volume of the observational data does suggest, though, that going back for a second cup of coffee might not be a bad decision.