In short, yes. Coffee is acidic. But it's not acidic in the way you might think it is. Coffee, like most things we like to drink, is naturally acidic. Acids yield flavor, literally by donating protons to receptors on the tongue. That's why other common drinks such as beer, soda, fruit juice and wine are naturally acidic (and are all more acidic than coffee, in fact). 

Defining Acidity in Coffee 

Why Coffee Makes You Feel Sick

Bean Remnants

This is the level of particulate matter (leftover bean solids) in your coffee. To minimize this:

• Use a filtered brew method with a paper filter (far better than wire mesh filters).
• Avoid using a French press, since there's no filter used and you're more likely to swallow grounds.
• You can avoid dark roasts, as dark roast coffee beans have been roasted longer and as such, are more fragile and easier to break up when being ground. However, there isn't much of a difference in the pH between dark and light roast coffees.

Caffeine

Per above, the more bean material in the brew, the more caffeine will continue to be extracted in the stomach. Caffeine generally prompts the body to produce more gastric juice. Again, brew method can make a big difference: Americanos and espressos carry less caffeine than drip.

Milk

Adding milk and its proteins to coffee will absolutely soothe the overall coffee drinking experience, but only for the palate. In the stomach, dairy proteins stimulate the production of gastric juices. In the presence of other acids, this can, for many people, be a recipe for discomfort.

Low Acidity Coffees