Cranberries have often been called a superfood – but why? Here are seven reasons why these tart red berries really are super! By Hatty Willmoth.

Sour red cranberries have been used to dye clothes, to celebrate Christmases and Thanksgivings, and to treat and prevent a host of ailments, for hundreds of years.

But how does their impressive reputation as a health-giving ‘superfood’ stack up against the evidence?

1. Rooted in Native American tradition

The cranberries we recognise as cranberries today are called Vaccinium macrocarpon and are an American species related to blueberries.

There is a breed of cranberry native to the British Isles, but these are not generally the ones we see on supermarket shelves.

Small, sour and bright red, cranberries are grown in wetlands and harvested throughout the late summer and early autumn, ready to be made into sauces, dried like raisins, and squeezed for juice.

Native American people traditionally used cranberries for a plethora of purposes.

Many groups used cranberries as medicines for fever, stomach cramps, constipation, bladder problems and other complaints. Others used them to dye clothes and make jewellery, or dried the leaves to use like tea or tobacco.

As a food, Native Americans ate cranberries as fresh or dried fruit, as well as incorporating them into recipes with other ingredients. Most notably, they would combine squashed cranberries with ground, dried venison and tallow (animal fat). The result was called ‘pemmican’; something the National Geographic has dubbed “the original energy bar” because it kept for months and provided essential fuel for traders and travellers during long winters.

2. Great for the gut

But how healthy are cranberries? It turns out, very – and one of the reasons might be because of the way in which cranberries affect the gut.

The microbes that live in our digestive tracts – including bacteria and yeasts – play a huge role in gut health, and the foods we eat can impact the quantity and diversity of these microorganisms.

Some foods encourage the growth of bacterial strains that we know are beneficial to our health; these are called prebiotics.

A study by the University of Massachusetts in 2017 found that bifidobacteria – a type of helpful bacteria present in our guts – consume a carbohydrate found in cranberries called xyloglucan.

That means that, by eating cranberries, we may be encouraging these bacterial communities to grow in our digestive tracts.

The study only tested the bacteria outside of a gut, so it’s unclear what the actual human effects of cranberries might be in this context. However, it indicates that cranberries may be an effective prebiotic, helping to promote good gut health.

3. Cranberries and UTIs

It’s a widely held belief that women with UTIs (urinary tract infections) should drink cranberry juice, and recent research confirms that there’s some truth to this.

A review from Flinders University, Australia, published in April 2023, concluded that consuming cranberries and cranberry products could be an effective way to prevent a UTI.

Dr Jacqueline Stephens, one of the study’s co-authors, said that this was important because untreated UTIs could move to the kidneys, causing pain and even sepsis in severe cases.

Treatment commonly consists of a course of antibiotics which, while effective, can come with its own ramifications.

Prevention, then, is the best way to reduce the risks associated with UTIs, concluded Stephens.

The key distinction is that cranberries were not found to resolve active UTIs, but to help prevent them happening in cases where they kept coming back.

More specifically, the review found that cranberry juice and cranberry-containing supplements reduced the risk of recurrent symptomatic UTIs in women by more than a quarter, and in children by more than half.

Researchers came to this conclusion after analysing the results of 50 trials, cumulatively involving almost 9000 participants.

Cranberries and cranberry products were effective, they said, because they contained proanthocyanidins (PACs), a plant compound particularly abundant in cranberries that has been the subject of a great deal of research.

PACs are believed to prevent harmful bacteria Escherichia coli from attaching to the lining of the bladder and urinary tract, so it can’t cause an infection.

However, other research from 2019 (less robust and on pigs) has suggested that it is oligosaccharides (a type of complex sugar in cranberries) that does this instead.

Either way, consuming cranberries may be an effective way to prevent harmful bacteria from causing UTIs in some people.

4. Antimicrobial in general

In the case of UTIs, then, cranberries have an antimicrobial function; but can this be extended to other microbes?

It has been suggested, for instance, that PACs in cranberries may have a similar effect on the bacteria Helicobacter pylori attaching to the lining of the stomach.

Studies have shown, with varying degrees of success, that cranberry consumption may suppress H. pylori infections and consequently reduce the risk of stomach cancer.

On a completely different note, researchers at the American Chemical Society have been attempting to develop an antimicrobial lipstick using cranberry extract, hoping to protect wearers from a range of viruses, bacteria and fungi, spurred on by the Covid pandemic.

5. Powerful antioxidant and anti-inflammatory properties

But driving away microbes is not the only thing PACs are good for; they’re also great for reducing inflammation in the body.

PACs are a type of antioxidant, which means they help reduce damage caused by free radicals (a by-product of chemical reactions) and generally reduce internal wear and tear.

Antioxidants are anti-inflammatory substances by nature, and can be effective against a whole host of inflammatory conditions, from arthritis to heart disease.

Cranberries are particularly rich in these antioxidants – and not just PACs. They also contain quercetin, myricetin, peonidin, ursolic acid and anthocyanins.

To most people these are just long words with little meaning, but suffice it to say that it’s a powerful combination all contained within one small berry.

These plant compounds – aka ‘polyphenols’ – give cranberries their rich red hue and are responsible for the majority of their ‘superfood’ attributes.

Cranberries have been shown to be effective at helping to: improve brain function, from memory to dementia risk; reduce ‘bad’ cholesterol; improve the health of the heart and blood vessels; reduce the risk of cardiovascular disease; and promote good metabolic health more generally.

These are all conditions which are caused or exacerbated by inflammation in the body, so anti-inflammatory foods such as cranberries can have a positive effect.

6. Rich in essential nutrients

Cranberries also contain plenty of vitamins and minerals that contribute towards their health-giving properties.

They contain vitamin C, which helps: protect cells from damage; maintain healthy skin, blood vessels and bones; and support wound healing and the immune system. Vitamin C, also known as ascorbic acid, is also another antioxidant.

Other vitamins in cranberries include vitamin E – good for the skin, eyes, and immune system – and vitamin K1, which helps with wound healing and bone health.

Cranberries are a good source of minerals such as manganese and copper too. Manganese helps make and activate some of the enzymes in the body, enabling processes such as digestion.

Meanwhile, copper is a trace element, often low in a Western diet, that is implicated in blood health, infant growth, brain development, immunity and strong bones.

7. Versatile, but best when least processed

Cranberries are not just super healthy; they’re also delicious in many forms.

Perhaps most popular is cranberry juice, but fruit juices are generally high in sugars and low in fibre, so they may cause spikes in blood sugar levels.

Plus, a 2012 study found that many of the helpful antioxidant compounds in cranberries were most abundant in their skins, so would be mostly lost in the juicing process.

However, if cranberry juice is what you like, you may want to keep in mind that the same study found that not-from-concentrate juice retained far more antioxidants than juice from-concentrate.

Alternatively, dried and freeze-dried cranberries might be your cranberry of choice. Dried cranberries retained a moderate amount of their beneficial compounds, while researchers detected no loss of antioxidants at all when cranberries were freeze-dried.

Do you prefer cranberries in a sauce? Researchers found that this tart festive treat was best when homemade.

In fact, their general conclusion was: “Commercially processed products contained significantly lower levels of polyphenols [antioxidants] as compared to fresh and home-processed preparations.”

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