Q. I keep hearing about how bad coffee is for you. I also hear about how good coffee is for you. What gives?

The average American drinks over 400 cups of coffee a year, so how this popular beverage affects our health is an important issue.

Let's start with the bad part.

For the general population, the evidence suggests that coffee drinking doesn't have any serious detrimental health effects.

This is a summation from Dr. Rob van Dam, assistant professor in the Department of Nutrition, Harvard School of Public Health.

Dr. van Dam says that drinking up to six cups of coffee a day is not associated with an increased risk of death from any cause. He warns that some people may want to avoid coffee or switch to decaf. These include pregnant women and those who find it difficult to control their blood pressure or blood sugar.

"If you're drinking so much coffee that you get tremors, have sleeping problems, or feel stressed and uncomfortable, than obviously you're drinking too much coffee," Dr. van Dam said. "But in terms of effects on mortality or other health factors, we don't see any negative effects of consuming up to six cups of coffee a day."

The cup he's talking about is an eight-ouncer with 100 mg of caffeine, not one of those grandes you get at Starbucks, which can keep you awake until Jimmy Fallon goes off the air.

Now for the good part.

Some research has suggested that drinking coffee may protect against cardiovascular disease, type 2 diabetes, Parkinson's disease, several cancers, liver cirrhosis, depression and Alzheimer's disease.

Again, a nice summary from Dr. van Dam:

Coffee may have potential health benefits, but more research needs to be done.

When studying the effects of coffee, the focus is not just on the caffeine in the brew. Coffee contains more than 1,000 compounds that can impact your health.

There is another health issue that doesn't receive much publicity. How you brew your coffee has an effect upon LDL cholesterol, also known as the bad cholesterol.

Coffee contains substances that raise LDL levels in your body. Brewing it with a paper filter removes these substances. Other methods of coffee preparation, such as the French press, espresso or simple boiling, put the substances in your cup. Single-serving coffee pods, such as those used in a Keurig coffee maker, contain filters.

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