Barista Sean McManus of Barefoot Coffee Traders in Manly.
Barista Sean McManus of Barefoot Coffee Traders in Manly. Photo: James Brickwood

Hipsters, rejoice! Your beards might be going out of fashion, and the skinny jeans may be far more uncomfortable than you would ever admit, but the coffee? Well, it just might be doing you good.

And for those already thinking ahead to a post-Christmas health kick, it is not necessary to strike your single-origin beans off the menu, unless you have a particular health condition that makes it advisable to do so.

In fact, says Professor Clare Collins of the Dieticians Association of Australia, "One of the first things that people give up when they go on a health kick is coffee, and that's a crazy thing to do, because there's evidence of health benefits."

There is no evidence that up to 200 milligrams - the equivalent of one strong, barista-made coffee - poses any risk to pregnancy.
There is no evidence that up to 200 milligrams - the equivalent of one strong, barista-made coffee - poses any risk to pregnancy. Photo: James Brickwood

Collins has undertaken a systematic review of all the studies related to coffee and its health effects, and says there is good news for coffee drinkers: they have a lower risk of dying unexpectedly and developing type 2 diabetes than those who do not drink coffee, and are less likely to develop liver cancer.

So why does it always feel like coffee is something of a dietary no-no; that it's bad for us? One of the reasons may be that there's so much conflicting information about caffeine in general and coffee in particular, and as in all things, some studies are better than others.

For example, in recent months there have been media reports that drinking black coffee makes you more likely to be a sociopath (truly), that it might cure baldness, and that it can help fight liver disease. The latter study, conducted by Monash University, fits in with other quality research showing that coffee is protective against liver cancer, the organ that metabolises caffeine.

In moderation, coffee has a rightful place in a healthy diet.
In moderation, coffee has a rightful place in a healthy diet. Photo: Peter Schofield

But with so much conflicting information around, what is the truth about what we know for sure about coffee and its health effects? Fairfax Media spoke to a number of specialists in a range of medical fields, and the consensus was that moderate coffee intake was at worst neutral to most people's health, and likely to be beneficial in some ways.

Which is not to say that it can be guzzled freely without it having an impact on your health. Caffeine is a stimulant; it promotes wakefulness, quickens the heart rate and elevates blood pressure.

According to Professor Garry Jennings, director of the Baker IDI Heart and Diabetes Institute, for most people caffeine is unlikely to cause a problem, but it is not recommended for people with specific conditions in which a short-term increase in heart rate and blood pressure might stress the heart.

"My own suspicion is that there is little in it either way," Jennings says. "That is, if regular caffeine intake through tea or coffee has positive or negative health effects, these are minimal. That doesn't stop researchers banging on about it though!"

It is important to note, says Collins, that whatever protective properties coffee has are not driven by caffeine, but by other bioactive properties in the drink, such as flavanols, which have antioxidant properties.

"When you look at the biochemical role of coffee, it seems to have a task at a cellular level that I would explain is a bit like a contract cleaner: it's able to come in and speed up some important biochemical processes related to fixing damage in cells or clearing away debris so that some of the molecules related to insulin and glucose can work more efficiently," she says.

One of the areas of health in which coffee has caused most concern is its effect on pregnancy. But here too, says Professor Michael Permezel​, chair of the Australian and New Zealand College of Obstetricians and Gynaecologists, there is little strong evidence that it is harmful.

While many women avoid coffee altogether during pregnancy (and, it should be said, many find themselves suddenly repulsed by the taste thanks to the hormones at play), there is no evidence that up to 200 milligrams – the equivalent of one strong, barista-made coffee, or one instant coffee and a cup of tea – poses any risk to pregnancy.

At higher levels of caffeine consumption, the evidence is mixed: some studies say more than 200 milligrams a day is harmful; others say it is not.

"If there is any problem with more than 200 milligrams, it's probably miscarriage," Permezel says, and again, is it not known why, but it may be linked to elevated blood pressure and its effect on circulation.

So the wisest course of action is for pregnant women to limit their coffee intake to one a day. There is also potentially a connection between coffee and risk of pre-term birth and placental insufficiency, but the evidence is weak.

Given that caffeine makes the heart beat faster, some people will find that it makes them feel more anxious, says Dr Robyn Brown, an addiction specialist at the Florey Institute of Neuroscience and Mental Health. But overall, it's pretty harmless, and its role in helping fight fatigue helps many people be more productive.

Caffeine blocks the adenosine receptors in the brain, whose job it is to promote sleep. So when the effects of the caffeine wear off, some people can experience a slight "crash", as the adenosine has accumulated while the caffeine was active.

This is one of the reasons scientists are optimistic about caffeine's potential effect on the neurodegenerative condition Parkinson's disease. Caffeine's impact on the adenosine receptor means that it increases dopamine in the brain, which helps people with Parkinson's disease as they have a lack of dopamine.

That is not to say, Brown stresses, that caffeine will stop you from getting Parkinson's – its effect is not that strong – but just that it appears to have neuroprotective benefits.

"Put it this way, if I had Parkinson's disease in my family, I'd probably be drinking coffee every day," she says.

Finally, what about caffeine and children? They are best kept apart, says Collins, at least until the teenage years, as children's immature bodies mean they take even longer to metabolise caffeine, and its effect on wakefulness is probably something most parents would prefer to avoid.

But despite all the brew-haha (sorry), coffee is a good news story. While we brace for the endless round of stories about how to counteract festive season overeating and the importance of laying off the alcohol over the summer, rest assured that, in moderation, coffee has a rightful place in a healthy diet, holding its own alongside the chia porridge infused with ironic fruit.

You're welcome.