Three or four cups of coffee a day does you more good than harm

by Robin Poole / 29 November, 2017

Who can resist a decent flat white? Now, what about if it's also good for you? Photo / Getty Images

Drinking moderate amounts of coffee – about three or four cups a day – is more likely to benefit our health than harm it, our latest research shows. This is important to know because around the world over two billion cups of coffee are consumed every day.

Earlier studies have suggested beneficial links between coffee drinking and liver disease. Our research group has an interest in liver conditions. As such, we had previously conducted two meta-analyses, one looking for links between coffee drinking and cirrhosis and another at coffee drinking and cancer of the liver. We found that there was a lower risk of both conditions in people who drank more coffee.

Most of the evidence, however, is from observational studies, which can only find probable associations but can’t prove cause and effect. To overcome these limitations, we plan to conduct a randomised controlled trial in patients with non-alcoholic fatty liver disease to see if coffee works as a treatment to reduce the risk of the disease progressing.

But before we can start giving coffee to patients, we needed to know whether coffee drinking had any recognised harms, so we decided to conduct an umbrella review to capture as much important information about coffee drinking and health as we could. Umbrella reviews combine previous meta-analyses and give a high-level summary of research findings.

Many benefits

Overall, our umbrella analysis showed that drinking coffee is more often linked with benefits than harms. For some conditions, the largest benefit appeared to be associated with drinking three to four cups of coffee each day. This included lower risk of death from any causes, or getting heart disease. Drinking coffee beyond these amounts was not associated with harm, but the benefits were less pronounced.

Drinking coffee was also associated with a lower risk of developing type 2 diabetes, metabolic syndrome, gallstones, renal stones and gout. We also found that it was associated with a lower risk of getting some types of cancer, Parkinson’s disease, depression and Alzheimer’s disease. But liver diseases stood out as having the greatest benefit compared with other conditions.

Reassuringly, harms were not apparent apart from during pregnancy when coffee drinking was linked to low birth weight, premature birth (in the first six months of pregnancy) and miscarriage. This is not new knowledge, and there are guidelines for limiting caffeine intake in pregnancy. We also found a small increase in risk of fracture in women, but there is some discrepancy in the evidence and further investigation is needed.

Coffee drinking during pregnancy is linked with low birth weight. OndroM/Shutterstock

Careful how you consume it

Findings of our umbrella review should be interpreted with caution. Evidence in the review came mainly from observational research, so we can’t extrapolate our findings to suggest people start drinking coffee or increasing their intake in attempts to become healthier. What we can say is that people who already enjoy moderate amounts of coffee as part of their diet are most probably getting health benefits from it, rather than harm.

Our research is about coffee. It’s not about sugar, syrups, biscuits, cakes and pastries. Standard health messages still apply to those types of food. In other words, if you already drink coffee, enjoy it, but try to make it as healthy as possible.

Robin Poole, Specialist Registrar in Public Health, University of Southampton

The Conversation

This article was originally published on The Conversation. Read the original article.

MostReadArticlesCollectionWidget - Most Read - Used in articles
AdvertModule - Advert - M-Rec / Halfpage

Latest

Richard Prebble: Jacinda Ardern will face the tyranny of events
86009 2018-01-19 00:00:00Z Politics

Richard Prebble: Jacinda Ardern will face the tyra…

by Richard Prebble

I predicted Bill English would lose the election and the winner would be Winston Peters. But no forecaster, including the PM, predicted her pregnancy.

Read more
Aokigahara: More than just the ‘suicide forest’
85966 2018-01-19 00:00:00Z World

Aokigahara: More than just the ‘suicide forest’

by Justin Bennett

It's known as a 'suicide forest', but Justin Bennett found Aokigahara's quiet beauty outweighed its infamous reputation.

Read more
Truth and Lye: New perspectives on the brilliance of Len Lye
85816 2018-01-19 00:00:00Z Arts

Truth and Lye: New perspectives on the brilliance …

by Sally Blundell

New essays on New Zealand-born US artist Len Lye elevate him to the status of Australasia’s most notable 20th-century artist.

Read more
Brain activity may hold the secret to helping infertile couples
86046 2018-01-19 00:00:00Z Health

Brain activity may hold the secret to helping infe…

by Nicky Pellegrino

For about a third of infertility cases in New Zealand, there is no obvious reason why seemingly fertile couples struggle to conceive.

Read more
Farewells on the Auckland wharves, captured by photographer John Rykenberg
85964 2018-01-19 00:00:00Z Life in NZ

Farewells on the Auckland wharves, captured by pho…

by Frances Walsh

More than one million images from Rykenberg Photography, taken around Auckland, are now in the Auckland Libraries Collection. But who are the people?

Read more
'Termite hell' for Golden Bay man after he woke covered in insects
86027 2018-01-18 11:59:55Z Environment

'Termite hell' for Golden Bay man after he woke co…

by Hamish Cardwell

A Golden Bay man spending his first night in his new house says he woke to find his bed, walls and floor covered in hundreds of creepy crawlies.

Read more
Ten ‘stealth microplastics’ to avoid if you want to save the oceans
86015 2018-01-18 11:18:49Z Environment

Ten ‘stealth microplastics’ to avoid if you want t…

by Sharon George and Deirdre McKay

There's a growing movement to stop the amount of wasteful plastic that goes into our oceans, but what about the tiny bits we can hardly see?

Read more
It's time to chlorinate New Zealand's drinking water
86001 2018-01-18 09:41:15Z Social issues

It's time to chlorinate New Zealand's drinking wat…

by The Listener

The inconvenience to chlorine refuseniks is tiny compared with the risk of more suffering and tragedy from another Havelock North-style contamination.

Read more