Overview

Blueberries are often given the “superfood” title, encompassing many health benefits due to being packed with antioxidants. Studies show these antioxidants protect the body from cell damage; hence, any foods containing these compounds are great for preventing cancer. It has been shown that including these little berries in your diet could do wonders in cancer prevention.  

Diet has always been a key focus when it comes to cancer prevention. So, antioxidant-rich foods are continuously of keen interest when it comes to studying diet in cancer prevention.

Why not provide yourself with the best chances in life by simply including a few superfoods like blueberries in your diet?

Nutritional value of blueberries

A 100g portion of raw blueberries contains:

• 2.4 g of fibre
• 77 mg of potassium
• 6 mg of calcium
• 9.7 mg of vitamin C
• 57 kcal

Antioxidants in blueberries

Blueberries are among some of the highest antioxidant-containing common fruits.¹ The berry also contains a large number of what’s known as phytochemicals. These are plant-based bioactive compounds produced with the intention of self-protection. These compounds possess high antioxidant function and also present antiviral, antiallergic and antimicrobial effects.²

Phytochemicals and their role in cancer control

Of all the phytochemicals blueberries do contain, anthocyanins have the biggest hand in contributing to the health benefits of blueberries.³ Anthocyanins are essentially blue, red, or purple pigments found in plants, which have many anticancer properties, including:^4,5

• Reducing cell proliferation
• Reducing inflammation
• Scavenging activity
• Stimulation of phase II detoxifying enzymes

Blueberries also contain resveratrol, which is another bioactive compound known to have anticancer activity, anti-inflammatory and neuroprotective properties.^6,7

General vitamins and minerals contributing to well-being 

More generally, blueberries are super nutritious snacks, being rich in dietary fibre and vitamins B, C, E and A. Furthermore, blueberries provide you with a good amount of essential trace minerals such as selenium, iron, zinc, lutein and manganese.⁸

• Selenium has been shown to contribute to the normal functioning of the immune system as well as being needed during pregnancy for overall health⁹
• Lutein is associated with its anti-inflammatory properties, and a sufficient amount of it in the body may reduce the likelihood of acquiring chronic diseases further along in life¹⁰

Aside from the named phytochemicals earlier, vitamin C plays a substantial role in overall health and protecting the body against free radical damage.¹¹

• As humans, we are not able to make ascorbic acid (vitamin C ) due to  lacking the enzyme gluconolactone oxidase required in its production¹²
• As a result, it is crucial for us  to be supplemented with the vitamin via other means, mainly through fruits, vegetables and diet

Vitamin C intake is key for keeping your immune system strong, meaning you’ll be less likely to get those dreaded cold and flu symptoms during winter.

Mechanism of Action

Anti-inflammatory properties

One of the ways anthocyanins produce their anti-inflammatory effects is through the inhibition of TLR4 protein expression.¹³

• Toll-like receptors (TLRs) are immune receptors that recognise specific structures of pathogens and their products - pathogen-associated molecular patterns (PAMPs).
• TLR4 is a specific TLR which mainly regulates internal toxin reactions, with the TLR4/CD14 signalling pathway being a key pathway associated with the inflammatory response.
• When signalling events occur in this pathway between key components, lots of inflammatory factors are expressed  and produce inflammatory effects.
• It is shown in vivo and in vitro (studies both within the natural organism and outside in the lab), that anthocyanins can suppress these inflammatory factors being expressed. Therefore, anthocyanins prevent any negative effects from the immune system on our bodies.

Antioxidant properties

Anthocyanin compounds prevent oxidative stress in your body (the imbalance of free radicals and antioxidants in your body) which lead to negative health effects.¹⁵

• Free radicals are unstable molecules that need an extra electron to become stable.
• Anthocyanins act as reducing agents that scavenge any free radicals and provide electrons through hydrogen-atom donation or single electron transfer.
• The free radicals become stable, and oxidative stress is reduced.

Cell proliferation and apoptosis

Anthocyanins trigger the death of cancer cells (apoptosis) and prevent the spread of cancer (metastasis).¹⁶

Specifically in blueberries, anthocyanins inhibit enzyme activity related to collagen degradation.¹⁷

• In cancer, increased activity of collagen degrading enzymes allows  for the invasion of tumour cells into other healthy cells¹⁸ 
• Therefore, with anthocyanins inhibiting collagen-degrading enzyme activity, cancer metastasis is reduced significantly. This prevents surrounding healthy organs from becoming cancerous and keeps the tumour localised in the body

Research Studies

Overview of studies linking blueberries to cancer prevention

There have been many studies outlining numerous links between blueberry consumption and cancer prevention. Research shows that the fruit can prevent carcinogenesis, which is the formation of new cancer cells through cell proliferation and metastasis.

A specific study provided evidence for the anti-cancer properties of blueberries in a mini-review. It explored the phytochemical composition, absorption, metabolism and antioxidant capacity of blueberries, including a summarised in vivo investigation.¹⁹

• Findings included several mechanisms blueberries use to produce anti-inflammatory effects and prevent oxidative stress in the body. 

Specific cancers targeted by blueberry consumption

Blueberries are not only a well-known source of antioxidants but also polyphenols. Polyphenols are nutrients that reduce inflammation, metastasis, oxidative stress and apoptosis in cancer-affected  cells – so basically all the great signs for cancer prevention and treatment.

A particular study outlines the methods and results of blueberries in breast cancer control, with findings supporting an “inverse association” of polyphenol intake and breast cancer. This means with an increased polyphenol diet, i.e. eating more blueberries, there was a decreased outcome of breast cancer.²⁰

Why existing research is not always clear-cut?

Despite the advancements in medicine, cancer is still a major public health burden globally. While some human studies have investigated the effects of blueberries, further clinical research is required to establish the extent to which consumption of blueberries reduces the incidence of varying cancer types.

There is a possibility, due to the nature of the human body, that blueberries work synergistically or additively. However, it is difficult to measure the proportional effect of the fruit against a specific intake.

Recommended daily intake

As a humble fruit, it’s pretty difficult to state a defined intake. According to the rough guide provided by the NHS, a reasonable portion of blueberries is 2 handfuls, or 4 heaped tablespoons for the average adult.

In terms of consumption for cancer prevention specifically, some dieticians recommend a cup a day could help prevent cell damage.

Incorporating blueberries into a balanced diet

As usual, the most effective approach to cancer prevention is an overarching focus on your diet. Blueberries are super beneficial, but not without a balanced diet. Acquiring all the vitamins and minerals from consuming every food group in a balanced and recommended way will maximise the benefits of additional superfoods.

It’s also easy to become bored with repetitive food choices, which is normal. By selecting a few different superfoods that you enjoy, blueberries being one, and incorporating them into your diet interchangeably, you will continually receive long-term health benefits.

Blueberry recipes

You can find healthy yet delicious blueberry recipes anywhere. Below are just some examples you may enjoy!

• Banana- blueberry protein muffins: Natural sweetness and natural ingredients, a quick recipe for many servings
• Lemon-blueberry cheesecake chia pudding: A healthy option with another superfood - chia seeds
• Blueberry-banana overnight oats: A filling, healthy breakfast that can be prepared in advance. What more could you need?

Blueberries are a diverse fruit. You can freeze them, blend them, sprinkle them on oats, eat them on their own or even bake with them. They’re going to be a favourite for everyone.

Keep in mind that the less heat and cooking the berry is exposed to, the more of its benefits it will naturally preserve. You may, therefore, choose to consume blueberries raw alone or in foods such as salads and smoothies where cooking is not required.

Precautions and considerations

Possible interactions with medications

This is only a minor consideration as of now since blueberries do not contain known interactive chemicals.

Due to the naturally occurring sugar content of blueberries, you may want to be cautious if taking diabetes medications. You should monitor your blood glucose closely, should you have a change in diet.

Allergies and sensitivities  

As with most fruits and foods, it is possible to be sensitive or allergic to them. At any given point, particularly if you are first introducing blueberries into your diet, you should monitor any changes. Should you suspect anything unusual, seek medical guidance.

Blueberry allergies can look very different in people, but symptoms could range from:

• Itching
• Tingling
• Swelling of the lips
• Nausea
• Diarrhoea

Balancing blueberry consumption with other preventative measures

It is important you receive the correct treatment for any existing cancers with blueberries or any other supplementary high-antioxidant source.

There are many other preventative measures. For example, a more effective preventative measure for skin cancer would be to wear sunscreen and limit exposure to UV rays.

Summary

There is currently lots of evidence in support of blueberries for cancer prevention due to their antioxidant and anti-inflammatory properties. However, more research can be carried out regarding their effect on specific cancer types which may provide new areas of interest.

Blueberries are a small, common fruit; however, their benefits shouldn’t be undermined. Including these berries in a varied, healthy diet will support your well-being, whether that be in preventing cancer or any other disease.