Caffeine gets a hard rap sometimes; and coffee isn’t supposed to be a health food! However, facts is facts (don’t write to me about my grammar, thank you).
There is a large bunch of studies, which keeps growing, showing coffee to have benefits or protect from a wide variety of illnesses, from Alzheimer’s to cancer.
Or more exactly, coffee-drinkers benefit and seem to suffer less than tea or juice only drinkers. So it isn’t necessarily cause and effect—it might mean coffee drinkers have some other health benefit, that leads them to drink more coffee than average.
So coffee drinkers do well, but not because they drink coffee. That’s an important caveat.
That said, here we go:
A recent study published in the New England Journal of Medicine found that coffee consumption lowered all-cause mortality by over 10% at 13-year follow-up.
Despite the fact that caffeine consumption can cause a short-lived increase in blood pressure, coffee might actually be good for your cardiovascular system.
It’s probable that drinking coffee gives you something else than just the caffeine, which protects you.
Certainly, coffee beans contain antioxidant compounds that reduce oxidation of low-density lipoprotein (LDL) cholesterol. Coffee consumption has also been linked with reduced concentrations of inflammatory markers.[2-7]
Moderate coffee intake was associated with a lower risk for coronary heart disease as far out as 10 years and new data suggest that an average of 2 cups a day protects against heart failure.
It’s not just heart. There are vascular (blood vessel) benefits to the brain. According to a 2011 meta-analysis, consuming between 1 and 6 cups a day reportedly cut stroke risk by 17%. And a Swedish study of women showed an equally remarkable 22% to 25% stroke reduction. And a meta-analysis presented at the European Meeting on Hypertension 2012 found that 1 to 3 cups a day may protect against ischemic stroke in the general population.
Diabetes and Weight Loss
You’ve probably heard of so-called “metabolic syndrome,” the dangerous cluster of hypertension, hyperglycemia, abnormal lipid levels, and increased body fat. It leads to diabetes.
Numerous studies have linked regular coffee drinking with improved glucose metabolism, insulin secretion, and a significantly reduced risk for type 2 diabetes.[12-14]
Preliminary data from an ongoing study also suggest that coffee consumption can actually promote weight loss. Overweight patients treated with green coffee beans in supplement form lost an average of 17 pounds over 22 weeks.
Evidence suggests that moderate to heavy coffee consumption (more than 4-6 cups a day) can reduce the risk for numerous cancers, including endometrial16] prostate, head and neck,[18,19] basal cell carcinoma (skin), and certain breast cancers. The benefits are thought to be at least partially due to coffee’s antioxidant and antimutagenic properties, meaning it blocks the rapid dividing process.[16,18]
Senility and Dementia
It’s clear that coffee temporarily affects cognition – it perks you up! But that’s only temporary. More interesting is the fact that coffee has lasting effect on cognitive well-being. A study published in the Journal of Alzheimer’s Disease showed that patients with mild cognitive impairment who drank 3 – 5 cups a day, did not progress to dementia over the following 2 to 4 years. 
Animal studies suggest that caffeine may suppresses formation of amyloid-beta plaques. Again, good anti-inflammatory properties also help.
Caffeinated coffee has long been thought to be neuroprotective in Parkinson disease.[23, 24]
On the negative side, coffee has an unfortunate accelerating effect on Huntington’s chorea.
A 2011 study suggested that coffee consumption might also benefit mood : Women who drank 2 to 3 cups of coffee per day had a 15% decreased risk for depression compared with those who drank less than 1 cup per week. A 20% decreased risk was seen in those who drank 4 cups or more per day.
The short-term effect of coffee on mood may be due to altered serotonin and dopamine activity, whereas the mechanisms behind its potential long-term effects on mood may relate to its antioxidant and anti-inflammatory properties, factors that are thought to play a role in depressive illnesses.[26-29]
The liver might help break down coffee, but coffee might protect the liver (in some cases). Evidence suggests that coffee consumption slows disease progression in patients with alcoholic cirrhosis and hepatitis C and reduces the risk of developing hepatocellular carcinoma.[30-33]
A 2012 study reported that coffee intake is associated with a lower risk for nonalcoholic fatty liver disease (NAFLD), while other recent work found that coffee protects against liver fibrosis in those with already established NAFLD.