As drug delivery systems go, you’d be hard-pressed to find a tastier one than coffee. In fact for many of us, caffeine is the only thing that makes mornings tolerable.

A full two-thirds of Canadians had a coffee today, according to the Coffee Association of Canada. So we like our cup of java, which is great, because it seems that with more research showing its benefits, doctors and dietitians like coffee too. Or at least, they’re beginning to agree it’s probably not as harmful as once thought.

Earlier this month, a panel of experts advising the U.S. government on dietary guidelines went so far as to say there is currently “strong evidence” that a moderate amount of coffee a day is not likely to cause any long-term health problems. For them, a moderate amount means as much as 5 cups a day.

“In fact, consistent evidence indicates that coffee consumption is associated with reduced risk of type 2 diabetes and cardiovascular disease in healthy adults,” they said.

So what is that ”consistent evidence”? Here’s a look at some recent studies that have been turning coffee from a once-guilty pleasure to just a pleasure.

Keep in mind, though, that most of these studies are what scientists call “observational.” That means researchers have observed that coffee drinkers seem to have a lower risk of certain diseases, but they can’t be sure it’s the coffee itself that’s responsible. Only a large, controlled trial could help eliminate other factors that could be at play.

So take these studies with cream, sugar and a pinch of salt.

In the plus column...

Coffee linked to lower heart risks

It’s long been thought that the problem with coffee is that it raises our blood pressure, which is hard on the heart and sets us up for heart disease. But several recent, larger studies have found the opposite, that coffee may be linked to lower heart risks.

One study out this month in the journal Heart looked at the coffee-drinking habits of more than 25,000 South Koreans and found that those who drank moderate amounts of coffee a day tended to be less likely than non-coffee drinkers to have calcium clogging their heart arteries.

While they couldn’t prove that coffee actually reduced artery calcium, they said their study did at least show that coffee drinking was not linked to an increased heart risk.

A meta-review in 2012 of five large studies on coffee drinking, meanwhile, found that a moderate amount of coffee was linked to a lower risk of heart failure. That study concluded that “the current heart failure prevention guidelines suggesting coffee poses harmful effects may warrant revision to reflect the research showing that coffee may in fact provide moderate protection against heart failure incidence.”

Linked to reduced diabetes risk

Several studies in the last few years have also linked moderate coffee drinking to a reduced risk of type 2 diabetes. Most recently, a meta-analysis looked at 28 of these studies and found what scientists call a dose-response relationship: the more coffee that people drank, the lower their risk of developing diabetes -- even if they drank decaf. /

What makes coffee so special? Doctors aren’t really sure. The researchers speculate coffee has micronutrients called polyphenols that may help improve insulin sensitivity and reduce blood sugar absorption, but they also say that the only way to be sure is to conduct longer-term, randomized controlled trials.

Linked to lower MS risk

Coffee drinking has also been linked to a lower risk of developing multiple sclerosis. The research is so new that it hasn’t yet been published, and won’t be presented to the American Academy of Neurology until the spring. But researchers reviewed data on two studies in the United States and Sweden and found that those who drank at least four cups of coffee a day were one-third less likely to develop MS than those who didn’t drink coffee at all.

The researchers speculate that caffeine might suppress the production of cytokines, which promote inflammation throughout the body and which could play a role in the development of MS. But the research in this area is still new so more studies are needed.

Linked to lower risk of Parkinson’s disease

Several studies have noticed a strong link between drinking one to two cups of coffee a day and having a lower risk of developing Parkinson’s disease. Indeed, a large study conducted in 2000 found that men who did not drink coffee were five times more likely to develop Parkinson's than those who drank four to five cups a day.

Some researchers speculate caffeine may block a neurotransmitter called adenosine, and thus increase dopamine in the brain, which helps regulate movement. Others suggest the link may simply have to do with the fact that people who have caffeine addictions already naturally have higher levels of dopamine.

But there’s also been Canadian research suggesting caffeine might actually help treat Parkinson’s, by improving movement symptoms somewhat. So far, that’s only been shown in small, short-term studies, but it’s an intriguing area of research.

On the minus side...

It might raise cholesterol

One review of 12 randomized controlled trials in 2012 found that daily coffee drinking was linked to increased cholesterol and LDL cholesterol in particular. Those who already had high cholesterol were particularly sensitive to the cholesterol-raising effect of coffee.

The researchers noted that coffee contains an oily substance called cafestol, which is a known cholesterol-elevating agent. The good news, they found, is that cafestol can be mostly filtered out by making coffee with a paper filter, instead of using a French press or a percolator.

It may not be safe in pregnancy

The jury is still out on how much caffeine -- if any at all -- is safe during pregnancy. Caffeine can cross the placenta and reach the fetus, and some research has linked the drug to an increased risk of miscarriage.

One large study in 2008 found that women who consumed 200 mg or more of caffeine per day -- about the amount in two cups of coffee -- had twice the miscarriage risk as women who consumed no caffeine. Those researchers concluded that women should consider stopping caffeine consumption during pregnancy because of the risk.

Health Canada currently says that pregnant women can safely consume up to 300 mg of caffeine a day while pregnant, but other groups say it’s best to simply avoid all caffeine until after delivery.