Can eating your favourite summer berries guarantee good health?

Unfortunately, some of these trials can be a bit of a mixed bag when it comes to delivering results you can rely on.

We pick through the evidence to see whether these claims are really the cherry on the top.

Brain health

It would be great if warding off dementia or Parkinson’s was as easy as eating a few blueberries. While some studies into the benefit of eating berries for cognitive health showed promise, others have been inconclusive.

In a 2017 study, published in the Canadian journal Applied Physiology, Nutrition and Metabolism, a group of 26 older adults (aged 67+) were either given 30ml of blueberry concentrate or a placebo.

After 12 weeks, the group taking the concentrate – equivalent to eating 230g (two punnets) of blueberries every day – showed improvement in cognitive tests and increased brain activity.

Dr Gordon McDougall – a scientist at The James Hutton Institute (a leading agricultural and environmental research centre based in Scotland) – said other studies into how berries help brain health have had mixed results.

Verdict

While there have been promising outcomes from lab and animal tests, Dr McDougall said more human studies are needed to draw any definite conclusions.

Cancer prevention

Berries are sometimes touted as cancer-fighting foods. However, due to the lack of scientific studies in humans, the jury is still out on whether they pack any punch against the disease.

Dr McDougall said while there’s evidence from lab and animal studies that berries may slow down cancer progression, there’s limited evidence this is the case with people.

“The evidence that they influence matters in humans is less strong, mainly because such studies are difficult to do,” he said.

Verdict

More studies are needed to confirm whether berries can slow down cancer progression in people.

Gut health

Given the upcoming seasonal excess, we want our digestion to be in tip-top shape. Thankfully, there’s some evidence eating berries is good for your gut health.

A 2020 study in the Royal Society of Chemistry concluded that consuming berries may increase good bacteria in the gut and have a prebiotic effect in healthy people.

A 2018 study Evidence for Health Benefits of Berries, co-written by Dr McDougall, found that digestion has a pivotal role in unleashing the health benefits of berries. As the fruit passes through the digestive system and is fermented by bacteria in the colon, it produces phenolic metabolites, which act as antioxidants and are dispersed into the bloodstream.

Verdict

Berries are good for your gut.

Heart health

Berries aren’t just delicious, they might also be good for your heart.

A 2018 paper – also published in the Royal Society of Chemistry – evaluated 45 randomised trials to see whether berries have any effect on the risk factors of cardiovascular disease, such as high cholesterol and blood pressure.

It found evidence that eating berries could reduce bad cholesterol while increasing good cholesterol. It could also reduce blood pressure, too. However, there was a big difference in the length of the trials. One study was for two days, while other studies lasted up to six months.

There are also various berries used in the studies – such as bilberries, whortleberries, and black raspberries – that aren’t available on our supermarket shelves. Berry extracts, juice and freeze-dried powders were used in other studies.

Verdict

While research is promising, more is needed into how many berries you’d need to consume for them to have a beneficial effect on your heart health.

Antioxidants for health

Experts we spoke to agreed that no single fruit or vegetable provides all the nutrients you need to be healthy.

University of Otago Department of Human Nutrition Professor Rachel Brown recommends taking a colourful approach to your fruit and vege intake.

“Regularly include berries as part of your five-plus a day but having a variety of fruits and vegetables of all different colours is best.”

Dietitians NZ also recommend you chow down on whole grains, legumes, nuts, seeds and spices to up your antioxidant levels.

Risks with eating imported frozen berries

If you’re like me, frozen berries are a weekly staple. Chucked into smoothies or on top of cereal, they’re an easy way to help you get a quick fruit fix.

But if you’re eating imported frozen berries, you may get more than you bargained for.

In 2022, imported frozen berries were linked to an outbreak of hepatitis A in New Zealand. Fifteen cases of hepatitis A has been associated with the recent outbreak, and seven people were hospitalised. As a precaution, Pams brand frozen berries were recalled because of a possible link to the cases.

It’s not the first outbreak in New Zealand. In 2015, five people came down with the infectious liver disease after eating Fruzio Mixed Berries.

Hepatitis A is spread through contact with the faeces of an infected person or through environmental contamination, such as manure used as soil fertilisers.

In most cases, your body will clear the infection, but if you’re immune-compromised or elderly, the disease can linger for up to six months.

Symptoms may feel like the flu, and you may look jaundiced, lose your appetite and have stomach pain.

A 2019 review, published in the journal Epidemiology and Infection, examined cases of hepatitis A from frozen fruit between 2008 and 2018. It found that frozen strawberries were responsible for 41% of hepatitis A outbreaks worldwide.

In North America and Europe, cases of norovirus have also been linked to eating frozen fruit.

So should you stop buying imported frozen fruit? No, but the Ministry for Primary Industries (MPI) recommends boiling your berries for at least one minute before eating them.

Just washing the fruit won’t eliminate the risk.