Is an apple a day really good for your health?

BBC News

7 hours ago

We're told an apple a day keeps the doctor away, but does this humble fruit really have an outsized positive effect on our health?
The world loves apples. Every year, almost 100 million tonnes of apples are produced globally. These fruits, which comes in a wide range of colours and flavours, have long had a reputation for helping us stay healthy.
The popular phrase "an apple a day keeps the doctor away" originates from a slightly wordier Welsh proverb written in 1866: "Eat an apple on going to bed and you'll keep the doctor from earning his bread."
But is there any truth at the core of this longstanding maxim? And are apples especially healthy compared to other fruit?
First, let's think about the nutrients that apples contain. For one thing, they are a rich source of phytochemicals, including flavanols. These compounds have been linked to numerous health benefits, such as maintaining a healthy weight and lowering your heart disease risk.
Why apples are so healthy
Apples also contain various polyphenols, including anthocyanins, which help give some apple peel its red colour and are associated with improved heart health. Another polyphenol you'll find in apples is phloridzin. It has been found to help control blood glucose.
There's also lots of fibre in apples, largely pectin, which reduces the amount of low-density lipoproteins (LDLs) – the unhealthy form of cholesterol – in our blood. Pectin also lowers the amount of sugar and fat we absorb from food, helping to stabilise our blood sugar levels.
These nutrients in apples do seem to offer health benefits. A 2017 review of five studies reported that eating apples is associated with an 18% reduction in the risk of developing type 2 diabetes. Another review from 2022, which analysed 18 studies, found that eating more apples, or apple-derived foods such as apple juice, can reduce cholesterol, if you sustain the habit for more than one week.
Having a healthy diet in general can lower your risk of cancer by up to 40%, largely thanks to bioactive compounds, phytochemicals, that are common in apples. Some studies have even linked apple consumption to having a lower risk of developing certain cancers.
Regularly eating apples appears to be associated with various health benefits – and we know they're packed with healthy compounds. But are apples, specifically, any more effective than other plant-based foods at keeping the doctor away?
"Apples don't have much vitamin C, and they have no iron or calcium, but they have so many other ingredients that promote health and do wonderful things for the body," says Janet Colson, professor of nutrition and food science at Middle Tennessee State University in the US.
Apples contain compounds that are common to many fruits and vegetables, including those helpful polyphenols, says Flavia Guzzo, associate professor of plant biology at the University of Verona in Italy.
Polyphenols are strong antioxidant molecules. They help to balance the ratio of antioxidants to free radicals in our bodies – free radicals are highly reactive, potentially cell-damaging oxygen molecules. By keeping free radicals in check, we reduce our risk of developing diseases including cancer and heart disease through long-term inflammation.
Some researchers say apples have the "second highest level of antioxidant power among all fruits".
Apples also contain the polyphenol phloridzin, which is much less common within the other fruits in your fruit bowl. Like pectin, phloridzin appears to lessen the amount of sugar we absorb into our blood from food.
Apples are also a good source of phenolic compounds, which are another form of phytochemical. We get one study found that people living in the US get around one fifth of their total phenolic intake from apples. Research suggests that apple phenolic compounds are associated with a lower risk of heart disease, cancer, asthma, diabetes and obesity.
But it isn't just the powerful polyphenols and antioxidant punch that has led some scientists to recommend apples over other fruit. In several papers, scientists recommend regular apple-eating because the fruits are simply so widely available. That means that eating them regularly is something that is relatively achievable for many people.
It's clear that apples have the potential to improve our health. But it's quite a big claim to say that eating one every day will prevent us from having to go to the GP.
Thankfully, one 2015 study took on this exact question. Researchers analysed a survey of nearly 9,000 people, which the participants stated what they ate during one 24-hour period, which they said was indicative of their typical daily diet.
They found that apple-eaters were more likely than apple-avoiders to keep the doctor away, however, this result wasn't statistically significant when taking into account that apple-eaters are more likely to be more educated and were less likely to smoke.
"The main finding, that there isn't much of an association between people who regularly consume an apple a day and the likelihood of visiting a physician, is because it's complex," says lead researcher Matthew Davis, adjunct associate professor of epidemiology at Dartmouth Geisel School of Medicine in New Hampshire, US.
"People who consume apples, based on our analyses, are healthier in general."
But they also found that daily apple-eaters were less likely to be reliant on prescription medication – and this was still a significant finding when adjusting for socioeconomic differences between participants who ate one apple per day and those who didn't.
Therefore, the paper concludes, a more pertinent saying might be: "An apple a day keeps the pharmacist away."
But Davis has issues with the apple-a-day phrase, and says there may be another reason why he and colleagues didn't find a connection between daily apple consumption and going to the doctor.
"The underlying assumption is that you only visit the doctor when you're sick, but people visit the doctor for annual check-ups and other prevention-type things," he says. This is why Davis also analysed the data around the likelihood of using prescription medication, too.
"This implies that apples reduce the likelihood of having a chronic illness," he says.
But ultimately, he says, apples alone aren't enough to stop you having to visit the GP, and that the most impactful thing is having a healthy diet overall. "Which, really, is what the saying is getting at," he says.
Colson agrees that the apple-a-day phrase alludes to regularly eating plant-based foods. Apples are a good example because they're so readily available, affordable, have a long shelf-life.
"Before fridges, you could put apples in the cellar and they would last a long time, and they don't attract mould," she says.
Other studies have found health benefits relating to daily apple-eating – but only when people consume more than one per day.
In one study published in 2020, researchers split 40 participants (who all had mildly elevated cholesterol levels) into two groups. One of those groups ate two apples per day while the other had an apple drink with similar calories. The experiment lasted eight weeks and, apart from the apple products, the participants didn't make any other changes to their diets. The researchers found that the apple-eaters had a clinically significant lower level of cholesterol, at the end of the study. However, one weakness of this study it its small size; 40 participants is a relatively low sample size from which to draw any big conclusions.
Another study found that eating three apples daily stimulated statistically significant weight loss and improved blood glucose levels (which wasn't statistically significant when followed up) in 40 overweight women.
As for how best to eat apples to get the greatest benefit from them, Guzzo advises against removing the skin first.
"We should eat the peel of apples, as this is where most of the apple's polyphenols can be found," she says.
More like this:• Can chicken soup really fight off a cold?• Do spices really benefit our health?• Are fermented foods actually good for us?
And ancient varieties are preferable to new varieties of apple, says Guzzo.
In 2021, she and colleagues published a paper looking at the nutritional value of the Pom Prussian apple, an ancient apple from northern Italy, which she found was richer in polyphenols than more modern apple varieties.
"When breeders select new varieties, they look to other traits, including size and taste and robustness of the trees," she says.
"And when they select these traits, rather than polyphenol content, the variety becomes poorer [from a health point of view]."
She says some polyphenols can produce a bitter taste, and that sweeter varieties probably contain a lower proportion of these compounds.
As for colour, Guzzo says this doesn't matter so much. Both the polyphenols that cause apple skin to be red or green are both good for us.
Ultimately, while eating an apple a day may not mean you visit the doctor less often, it could impact your overall health or your reliance on long-term medication. But, as is always the case, the bigger picture is complicated.
Eating an apple a day is great, says Guzzo – but only if that is part of a diet rich in various other plant-based foods, since that is a key driver of good health.
--