SINGAPORE – Hong Kong actor Andy Lau recently revealed on a programme by video-sharing app Douyin that he drinks more than 20 cups of coffee a day when he works.

While the 61-year-old Heavenly King is an extreme example of a heavy coffee drinker, coffee lovers and health experts have been bugged by this perennial question: Is coffee good or bad for you?

A study published in the Journal of Agricultural and Food Chemistry in January found that coffee with milk may have an anti-inflammatory effect in people. This is thanks to the combination of proteins and antioxidants, which doubles the anti-inflammatory properties in immune cells. 

According to another study in Japan, published in the Journal of the American Heart Association in December 2022, drinking two or more cups of coffee daily may double death rates among people with high blood pressure.

The amount of research that has gone into studying the pros and cons of caffeine has been overwhelming.

Do the benefits outweigh the risks? Should people with certain medical conditions avoid caffeine? And just how much coffee is okay in a day?

Dr Naras Lapsys, a consultant dietitian at The Integrative Medical Centre, notes that coffee contains a wide range of antioxidants, such as polyphenols, compounds which are also found in fruit, vegetables and whole grains.

“Polyphenols can help manage blood pressure levels, reduce chronic inflammation and help lower blood sugar levels, which is helpful for those with Type 2 diabetes,” he says.

A meta-analysis, published in the journal Diabetes Care in 2014, studied 45,335 people with Type 2 diabetes for up to 20 years. It found that those who drank more cups of coffee a day had a lower risk of developing diabetes.

The decreased risk of developing diabetes ranged from 8 per cent with one cup a day to 33 per cent for six cups a day.

Apart from polyphenols, coffee is rich in nutrients such as vitamin B, folate, potassium and magnesium that are found naturally in coffee beans.

“They are found in small amounts in coffee. But if you drink more than one cup a day, which many do, it can provide your body with a significant amount of nutrients,” says Dr Lapsys.

Mr Derrick Ong, founder and accredited dietitian at Eat Right Nutrition Consultancy & Clinic, says overall evidence derived from studies shows that coffee is more healthful than harmful.

A wide range of other research has also uncovered numerous other health benefits of coffee.

Some studies have indicated that drinking three to five cups of joe a day is associated with lowered risk of death due to cardiovascular disease, says Ms Natalie Yeo, a dietitian at Singapore Heart Foundation.

For instance, according to a study of 83,076 women published in a journal titled Circulation in 2009, drinking four or more cups of coffee each day was associated with a 20 per cent lower risk of stroke, compared with not drinking at all.

A meta-analysis of 36 studies recorded in the same journal in 2014 looked at the relationship between coffee consumption and risk of cardiovascular diseases, such as heart disease, stroke and heart failure, among men and women.

It found that a moderate coffee intake of three to five cups a day was linked with a 15 per cent lower risk of cardiovascular disease when compared with zero coffee consumption.

A Finnish study, published in the European Journal of Clinical Nutrition in 2007, tracked coffee consumption and the development of Parkinson’s disease in 6,710 men and women over 22 years. It discovered that those who drank at least 10 cups of coffee a day had a significantly lower risk of developing the disease than non-drinkers.

The Finns are among the world’s top coffee drinkers.

Commenting on the findings, Mr Ong says caffeine may produce a stimulating effect on the brain cells, which may be why heavy coffee drinkers had a lower risk of developing Parkinson’s disease.

However, too much caffeine can be harmful, warn health experts.

As caffeine is a strong source of stimulant and psychoactive substance, it can impact how the brain works in terms of one’s thoughts, feelings and behaviour, says Dr Lapsys.

“Consuming too much coffee can overstimulate the mind. It can lead to nervousness, irritability, headaches, dehydration and heart palpitations,” he adds.

According to Ms Yeo, some people may be more sensitive to caffeine than others, as effects vary across people depending on how quickly one metabolises it.  

“Hence, if you experience side effects such as anxiety, irritability, stomach discomfort or insomnia, consider cutting down your intake and speak to your healthcare provider for a recommended intake,” she says.

So how much coffee should one drink in a day?

Dietitians say up to 400mg of caffeine – roughly four cups of brewed coffee – is safe for most healthy adults.

However, Dr Lapsys points outs that different types of coffee contain varying amounts of caffeine.

For instance, a single- or double-shot espresso contains 60 to 70mg of caffeine, whereas a pack of instant coffee has about 60mg, he says.

But, as the saying goes, everything in moderation. Ms Yeo says coffee, when consumed in balanced amounts, can influence one’s energy levels, cognition, memory and mood, which, in turn, increase mental alertness and concentration.

Dr Lapsys adds: “The impact of coffee can be felt immediately and can last for about six hours. It helps when a person has to do decision-making tasks or something that requires focus.”

Those who can metabolise caffeine quickly can reap the benefits of caffeine better than those who do it slowly, says Mr Ong. 

Besides genetic testing, one way to test if your body is able to metabolise caffeine quickly is through trial and error. 

“For example, if you experience heart palpitations after just one cup of coffee or if you cannot sleep after drinking one cup five hours before bedtime, you are more sensitive to the effects of caffeine,” he adds.

Though coffee may impart a number of health benefits, certain groups of people should be wary of their intake.

For instance, pregnant women and those breastfeeding should not consume above 200mg of caffeine a day, say dietitians. 

Ms Yeo notes that it is also not ideal for those with stomach issues, such as heartburn or acid reflux to consume coffee, as caffeine is acidic and could irritate the gastrointestinal tract. 

Children, adolescents, those with chronic diseases such as heart conditions and/or high blood pressure, as well as people with sleeping disorders should also watch their coffee intake, she adds.

Children should limit their caffeine intake to a minimum of 2.5mg per kilogram of body weight, while adolescents can consume about 100mg of caffeine, which is around one cup of coffee a day.

Ultimately, moderation is key, say experts. 

Ms Yeo adds: “Although coffee may appear to have some health benefits and does not seem to have detrimental effects for most healthy individuals, it is not recommended to start drinking coffee or increase consumption for any health benefit.”

The Bottom Line is a new series which aims to answer burning questions on health and well-being.

Extracted from The Straits Times publication

https://www.straitstimes.com/life/the-bottom-line-is-coffee-good-or-bad-for-health

by Amrita Kaur

A version of this article appeared in the print edition of The Straits Times on March 29, 2023, with the headline 'The Bottom Line: Is coffee good or bad for health?'.