The cholesterol-lowering fruit that boosts your brain, heart and gut

Humans have been eating grapes for more than 20,000 years, but it was much more recently, in the early 2000s, that scientists began probing their wide-reaching health benefits.

“The interest started with resveratrol – a compound found richly in red and black grapes – and the longevity and cardiovascular benefits,” says Dr Zhaoping Li, chief of the division of clinical nutrition at UCLA Health, who has studied the fruit herself. Since then, grapes, and the long list of nutrients they contain, have been linked to better brain, gut and even bone health.

As a result, Li always keeps her home stocked with bunches. “I’m in California; we grow lots of grapes in different colours that are always available and very affordable,” she says. “I usually have two different grapes at home, one green, one purple.”

Here are six ways grapes can benefit your health – and her tips on the best ways to enjoy them.

Lowers cholesterol

Grapes have been shown to lower cholesterol in Li’s research, published in the journal Nutrients. “We had healthy individuals eat a cup and a half of grapes every day for four weeks,” she says. Despite the extra daily snack, no one gained weight.

“But we did see an overall decrease in cholesterol,” she says. Both total cholesterol and “bad” LDL cholesterol were reduced by 6 per cent. “You would not expect giving people more calories, mostly from sugar, would improve their cholesterol profiles.”

The grapes seemed to inhibit the liver – the body’s main cholesterol creator – from making new cholesterol, while also preventing cholesterol absorption in the gut and reducing levels of especially harmful oxidised cholesterol, which is inflammatory, Li explains.

Protective compounds found in grapes, including catechins, proanthocyanidins and anthocyanins – which are collectively known as flavonoids – are thought to be responsible for the fruit’s cholesterol-lowering properties, Li says. They also contain fibre, which helps flush excess cholesterol from the body, she notes.

This is good news for heart health, as lower cholesterol levels reduce the risk of heart attacks and strokes.

‘Grapes have a real impact on our gut microbiome.’

Dr Zhaoping Li, UCLA Health

Improves blood pressure

Polyphenols, anti-inflammatory compounds found in fruit such as grapes, are also thought to bring extra benefits for heart health. They act as antioxidants in the body, meaning they deactivate harmful compounds called free radicals that circulate in our blood and damage our cells.

One large study by Harvard researchers linked eating grapes, as well as other foods rich in polyphenols such as apples and pears, to a lower risk of high blood pressure. The scientists believe this may be down to the polyphenols in grapes widening blood vessels.

Li recommends swapping a salty snack for a handful of grapes to see the biggest blood pressure benefit. “If you replace some unhealthy, particularly salty foods in your diet, with grapes, that would make the benefit even more significant,” she says.

Increases gut microbiome diversity

“It’s not an exaggeration to say that grapes benefit our gut health,” Li says. In her research, people who ate grapes daily for four weeks saw an increase in the variety of bacteria living in their gut, a change that has been repeatedly linked to a lower risk of developing chronic conditions, such as type 2 diabetes and heart disease.

In Li’s study, grape-eating also led to an increase in Akkermansia, bacteria that has been linked to better metabolic and immune health, in the gut. “So grapes have a real impact on our gut microbiome,” she says.

These changes are likely down to the variety of nutrients, including fibre and polyphenols, found in grapes that feed the beneficial bacteria in the gut, in turn increasing the variety that are found there and boosting the concentration of healthy bugs, Li explains.

Supports brain health

“There is plenty of data to demonstrate that grapes are beneficial to the brain,” says Li.

A systematic review of eight studies from the University of Aberdeen found grapes can enhance cognition, improving attention, spatial memory and executive function (the ability to manage everyday tasks). The researchers put these findings down to the high flavonoid content of grapes, particularly anthocyanins. This flavonoid, found in purple grapes rather than green ones, has long been linked to better brain health.

Separate animal studies have linked resveratrol, a polyphenol found in the skins and seeds of grapes, to better memory and a lower risk of developing plaques in the brain, which are associated with Alzheimer’s.

“The other likely mechanism is actually through the gut microbiome,” Li adds. By eating grapes and benefiting your gut health, this in turn could mean benefits for the brain, she explains. “The gut microbiome is directly linked to brain function.”

Boosts bone and muscle health

“Grapes, like a lot of other fruit, decrease inflammation, which plays a major role in ageing and chronic diseases,” Li notes.

Lab-based research has linked eating two portions of grapes a day with improved muscle mass. “Animal studies, meanwhile, have demonstrated that grapes can help bones retain calcium, which could be beneficial to slow[ing] down bone loss or bone ageing,” says Li.

“These findings may be because grapes have properties like antioxidants and anti-inflammatory functions.”

‘If you have 100 calories worth of grapes, that is much better than the equivalent amount of cereal or snacks like cookies.’

Dr Zhaoping Li, UCLA Health

Slows ageing

Back in 2003, Dr David Sinclair, now a Harvard professor, found that resveratrol could increase cell survival in yeast, and later in mice. A subsequent 2014 study of 800 people living in Italy whose diets were naturally high in resveratrol didn’t identify any health improvements – throwing the life-extending ability of grapes into doubt.

However, new research from the University of Navarra found that people who eat lots of food rich in polyphenols, including grapes as well as berries and other dark fruits, seem to be ageing more slowly.

While it’s hard to distinguish whether the benefits are down to simply eating more fruit, polyphenols are known to reduce inflammation, which is thought to play a role in ageing.

The healthiest way to eat grapes

The recommended portion size is 80 grams, which is 10 to 12 grapes, or about a handful. This serving contains about 54 calories, 0.6 grams of fibre and 12 grams of sugar. As grapes are 80 per cent water, it’s also a hydrating snack.

When it comes to picking a colour, dark varieties of grapes, such as red, purple and black, are thought to be more nutritious than green grapes. They contain anthocyanins and more resveratrol than green grapes, which are the powerful compounds linked to better heart and brain health.

However, Li recommends enjoying a variety of different grape colours. “They have variable amounts of nutrients and the biggest health benefits are likely to come from enjoying a wider range,” she says.

Whether you enjoy them fresh or freeze them to snack on when it’s hot or you’re ill is down to personal preference. Freezing grapes at home won’t change their nutritional value, Li says.

However, if you buy them frozen, they may be even more nutritious. “The grapes would have been frozen right after being harvested, when they are usually more ripe and nutrient-dense than the ones that have been shipped to grocery stores,” she says.

Grapes typically take longer to eat when frozen, which can help with portion control.

However, enjoying grapes in the form of red wine isn’t recommended, Li says. “Research shows you would need to drink 1000 litres of red wine per day to get the required dose of resveratrol [to achieve the heart health benefits]” – though there may be some other health upsides from drinking wine, she notes. “I think the benefit mostly comes from relaxing and decreasing your stress levels.”

The potential pitfalls

“Grapes have quite a lot of sugar,” Li says. This could affect blood sugar levels, especially for people with type 2 diabetes. However, grapes can be a healthy swap, especially for less nutritious foods in your diet. “If you have 100 calories’ worth of grapes, that is much better than the equivalent amount of cereal or snacks like cookies,” she says.

The verdict: Are grapes good for you?

“Regularly eating grapes, despite it being quite a high-sugar fruit, can really benefit your health,” Li says. “They are natural, contain a variety of nutrients, and give you carbohydrates, minerals, vitamins. They also provide soluble fibre and phytonutrients, such as resveratrol.”

FAQs

Can you eat grapes daily?

“There’s no particular harm to having grapes every day,” Li says. However, this shouldn’t be at the expense of removing other fruit from your diet. “I would recommend variety over having the same thing every day,” she adds.

Why is eating grapes associated with good luck?

It is a Spanish tradition to eat 12 grapes in the first minute of a new year, with each grape representing one month of luck for the year ahead. It is thought to have originated in the early 1900s when there was a bumper harvest, leading farmers to invent the custom as a marketing tactic.

The Telegraph, London