9 health benefits of cranberries
Cranberries are native to North America but are grown all around Europe today. They are a very tart berry with a sharp flavour that when mixed with the right ingredients can lead to a fabulously rich and exciting creation. They are popular in the UK as an accompaniment to Christmas dinner, and they also make delicious tarts and smoothie ingredients as well as a great addition to porridge and muesli for breakfast. What many people don’t know is that cranberries are loaded with nutrition and have great health benefits alongside their great taste.
100g cranberries contain 46 calories, and they contain no cholesterol, fat, or sodium, making them a very healthy choice of snack. Even better is that they are filled with dietary fibre (18% of your RDA), vitamin C (22%) and manganese (18%). They are also a good source of vitamin K (6%) and vitamin E (6%).
Everybody knows that vitamins and minerals are really good for you, but it’s helpful to know exactly what benefits they can give to the body:
- The dietary fibre found in cranberries comes in two forms; soluble fibre and insoluble fibre. 75% of the fibre from cranberries is insoluble, meaning that the fibre doesn’t dissolve in water. This allows for the creation of bulky stool which moves through the intestinal passage with ease, to avoid constipation. Insoluble fibre can’t be digested, so it moves through your bowels and ensures they remain healthy and digestive problems are avoided.Cranberries also contain soluble fibre (25% of the total fibre content). This fibre can be dissolved in water, and forms a gel. It ensures food is digested slowly which has two benefits; firstly it ensures the body isn’t overloaded with sugar and fat from the food you have recently consumed, and it also helps you to feel fuller for longer.As a weight-loss tool, soluble fibre is particularly effective at helping you to eat less without feeling like you are starving yourself.
- Vitamin C is a crucial nutrient for good health which can only be found in our diets; the body doesn’t make vitamin C on its own. Therefore, eating foods high in vitamin C is very important. 100g cranberries contain nearly a quarter of the RDA of vitamin C, so they are an excellent choice to increase intake.Vitamin C is important for a variety of reasons, but its main functions are to support the immune system in fighting off disease, helping the body to absorb iron (which is vital for the production of haemoglobin in red blood cells to carry oxygen around the body) and the production of collagen, which gives structure to soft tissues and helps wounds to heal.In fact, an extreme lack of vitamin C can cause scurvy, a disease characterised by anaemia, exhaustion, bleeding gums, swelling and other painful symptoms. Sailors used to suffer from scurvy frequently, and so they used to carry cranberries aboard their ships to avoid this nasty disease.
- Manganese is a very important mineral which is not very well known. It has several significant functions, including bone production, blood sugar control, and collagen production to ensure skin is healthy. 100g cranberries contain 18% of the RDA of manganese, making them one of the best food sources for this vital trace mineral.
- Although cranberries do not have an extremely high concentration of vitamin K, they are still a very useful addition to the diet for ensuring that enough vitamin K is consumed. Vitamin K is not only found from foods, but the body also produces a small amount in the gastrointestinal tract.Any vitamin K that isn’t used is stored in the liver until it is needed, so it is not necessary to consume foods containing vitamin K every day. Nevertheless, it has two very important roles in the body.Firstly it allows blood to clot; without this function, even small wounds would bleed exponentially and you would suffer from significant blood loss. Secondly, there is emerging evidence suggesting that vitamin K is very important in bone production and health.
- Vitamin E is a fat-soluble vitamin which helps to keep the immune system strong, has a role in the formation of red blood cells, and facilitates the body in using vitamin K. Cranberries contain 6% of the RDA of vitamin E, which doesn’t sound like a lot but as it is important for so many functions, having a variety of sources to find vitamin E is very helpful.
Benefits of Cranberries
As well as the general health benefits provided by the nutrients in cranberries, there are also some specific health benefits that can help people with particular problems:
- Urinary Tract Infections
- Cardiovascular Disease
- Stomach Ulcers
- Tooth Decay
- Immune System Dysfunction
- Respiratory Infections
1. Urinary Tract Infections
UTIs are a very common problem, and it is estimated that more than half the women in the UK will suffer from one at least once in their lifetime. It is a problem that affects both genders however, and can be extremely uncomfortable, painful, and can lead to more serious problems such as kidney infections.
UTIs occur when bacteria travels up the urinary tract and causes an infection; this can be caused by a number of reasons, including frequent intercourse (particularly with multiple partners), wiping from back to front after urination (for women).
For years cranberry juice has been recommended to treat UTIs. There is some evidence that UTIs can be prevented by consuming cranberries on a regular basis, but unfortunately there is no clear-cut evidence showing that once a UTI has occurred, cranberry juice will be helpful.
Jepson and Craig (2008) performed a meta-analysis (a comparison of all the research that has been completed up to the date of the report), and found that cranberry juice can decrease the number of symptomatic UTIs experienced over a 12 month period, and it is particularly effective for women who suffer recurrent UTIs regularly.
More recent research suggests similar, and states that it may work because the anthocyanins in cranberries stop bacteria from adhering to the walls of the urinary tract, which will reduce the length of time that the bacteria is present for (Shmuely et al, 2012).
Further studies (Stapleton et al, 2012; Takahashi et al 2013) have confirmed that cranberry juice appears to be good at preventing UTIs, although how much cranberry juice should be consumed is still unclear.
2. Cardiovascular Disease
Cardiovascular disease (CVD) is a general term which describes diseases of the heart and blood vessels, which can occur as a result of a number of factors, including blood clots and atherosclerosis (a build-up of fatty deposits on the walls of the arteries). Illnesses which come under the umbrella of CVD include coronary heart disease, stroke, peripheral arterial disease and aortic disease.
Cranberries contain a variety of antioxidant compounds called oligomeric proanthocyanids (OPCs), anthocyanidin flavonoids, cyanidin, peonidin and quercetin. They may prevent cardiovascular disease because they can protect against cholesterol plaque formulation in the heart and blood vessels. This is the process by which atherosclerosis occurs.
Fatty deposits form on the walls of arteries, which restricts blood flow to and from the heart. This can cause a variety of heart problems, such as heart attack and stroke.
The antioxidants found in cranberries also lower LDL cholesterol levels which help to prevent plaque build-up. Furthermore, they increase HDL cholesterol levels (good cholesterol) which is important for preventing heart disease.
Cancer is one of the most deadly and common diseases in the UK.
Recent statistics from Cancer Research UK show that in 2011 there were over 330,000 cancer diagnoses, the most common being breast, lung and prostate cancer. In 2012, over 160,000 people died from cancer, and lung, breast, bowel and prostate cancer accounted for almost half of these deaths.
It is thought that half of all people born after 1960 will be diagnosed with some form of cancer in their lifetime (Ahmad et al, 2015), so it is extremely important to do whatever is possible to prevent this from happening.
Cranberries contain quercetin, a flavonoid (plant pigment) which is thought to inhibit the development of both breast and colon cancers, as well as encourage apoptosis, a type of cell death which doesn’t usually happen in cancer cells.
Research by Ferguson et al (2004) has found that cranberries contain a variety of flavonoids which have an ‘antitumor effect’, meaning that they can help to eliminate tumours. Diets high in flavonoids in general (not specific to quercetin) are thought to be beneficial to those suffering with cancer, and may help to reduce risk of breast, lung and pancreatic cancer.
Clinical trials in patients with a high likelihood of developing colorectal cancer showed a decrease in the size and number of precancerous rectal tumours following the ingestion of quercetin and curcumin supplements.
Colorectal cancer has also been shown to be reduced following high fibre diets, and cranberries (along with other fruits and vegetables) are an excellent source of both soluble and insoluble fibre.
Cranberries are one of the leading fruit sources of quercetin, with approximately 20-30 mg of quercetin per 100g cranberries.
This makes them an ideal addition to the diet of anyone wishing to prevent cancer, particularly breast and colon cancers.
Another benefit of cranberries for cancer is that they contain high amounts of salicylic acid, which can help to reduce cancer symptoms including swelling and blood clots, and it can also help to eliminate tumours.
Further anti-cancer benefits of cranberries include inhibiting the expression of a variety of enzymes which exacerbate cancer cell growth and reduce apoptosis, whilst increasing the expression of enzymes which encourage free-radical destruction (compounds which can cause cancer by altering DNA and other cells).
4. Stomach Ulcers
Stomach ulcers, or gastric ulcers, are open sores which develop on the lining of the stomach. There are two main causes of stomach ulcers; helicobacter pylori (H-pylori) bacteria, and non-steroidal anti-inflammatory drugs (NSAIDs).
H-pylori bacteria are common bacteria which can irritate the stomach and upper intestinal lining, causing an ulcer to form. The reason H-pylori infects people is unknown, but it is a relatively common bacteria which can be treated fairly effectively. Non-steroidal anti-inflammatory drugs include ibuprofen and aspirin, and these can cause stomach ulcers because they inhibit the production of prostaglandins, natural chemicals which promote inflammation.
Although many prostaglandins can cause painful and uncomfortable symptoms, some protect the stomach lining from the corrosive effects of stomach acid. Because NSAIDs reduce the production of these chemicals, the stomach lining is at greater risk of damage by stomach acid, in the form of ulceration.
Stomach ulcers are extremely painful, and can sometimes cause pain in the neck, back and navel as well as the stomach itself. The pain occurs when stomach acid comes into contact with the stomach ulcer, and it can last from a few minutes to a few hours. Other symptoms of stomach ulcers include indigestion, heartburn, loss of appetite and nausea.
Cranberries are known to have anti-bacterial properties through the anthocyanins found within the fruit. The same mechanism which helps to reduce the risk of UTIs may also protect against the effects of H-Pylori bacteria by preventing it from adhering to the stomach lining.
Two fairly large-scale studies have shown that consuming cranberry juice can significantly reduce the amount of H-Pylori bacteria found in the stomach, and this effect was found with both adolescents (Gotteland et al, 2008) and adults (Zhang et al, 2005).
What these study show is that, like UTIs, cranberries will be good for reducing the amount of bacteria in the stomach, and so can prevent stomach ulcers, but once the ulcer exists the cranberries may have no further effect.
5. Tooth Decay
Tooth decay, known in the business as dental caries, is a very common problem in the UK. One in every three adults in England is estimated to have tooth decay, and a survey from 2012 found that one in four children also suffered from decay. Symptoms include tooth ache, sensitivity to hot, cold or sweet products, bad breath, and an unpleasant taste in the mouth.
Tooth decay is caused when food particles in the mouth combines with bacteria and saliva to create plaque. Bacteria found in the plaque interact with the carbohydrates in food to produce energy to feed the bacteria. At the same time acid is produced, and this acid can break down the surface of the tooth, and excessive erosion can cause damage to the soft, inner layer of the tooth.
As well as preventing tooth decay through good brushing practices and reducing the amount of sugary and acidic foods you consume, other elements of your diet can help to prevent tooth decay. Cranberries contain polyphenols, a type of flavonoid. A review by Bonfait and Grenier (2010) has found that polyphenols found in cranberries inhibit the production of acids, and the formation by biofilms by cariogenic bacteria, including plaque.
The article also suggested that the polyphenols may be protective against gum disease (periodontitis). Gum disease is defined by swollen, sore and infected gums, and is caused by an excessive build-up of plaque. The review found that consuming cranberries can help to reduce the inflammatory response which leads to swollen gums in periodontitis, and interferes with the processes of Porphyromonas gingivalis (including plaque formation), the main bacteria which causes periodontitis.
6. Immune System Dysfunction
The immune system is not found in one single area of the body, but is a whole-body system which protects the body against disease, infection and foreign bodies. We live in a world where we are surrounded by disease-causing agents known as pathogens. Skin and stomach acid are some of the non-specialised bodily systems which can protect against pathogens, but there are also specialised defence mechanisms called lymphocytes (a special type of white blood cell).
The immune system can be damaged in a variety of ways, including the contraction of the HIV virus, and the development of AIDS. Certain cancers affect the immune system also, including lymphoma, myeloma and leukaemia, and cancer treatments (particularly chemotherapy) can also lead to immune system dysfunction.
Although the immune system can be damaged, it can also be bolstered in a variety of ways; one of which is through the diet. Cranberries contain unique properties which can contribute to bodily health. Studies of humans have found that immune cell enhancement was evident after just eight weeks of consuming cranberry juice.
Specifically, T-cells and Natural Killer (NK) cells which identify and kill invading cells were found to proliferate in significantly greater proportions following cranberry juice consumption. Laboratory tests of cell cultures have found that compounds in cranberries can prime the immune system for activity, which means it is prepared to fight pathogens which enter the body (Percival, 2012).
Compounds found in cranberries can also help to fight against free radicals; according to the United States Department of Agriculture, cranberries have more naturally occurring polyphenolic antioxidants per gram than any other common fruit. Free radicals are molecules in the body which are missing an electron, and they wreak havoc to the body’s cells in its search for another electron. Cranberries encourage the creation of the body’s natural antioxidant enzymes which prevent the formation of free radicals.
7. Respiratory Infections
Respiratory infections are infections of the airway, lungs, sinuses or throat. They are usually caused by viruses, and are extremely common; in fact, the common cold is one of the most widespread and well known respiratory infections.
Antibiotics do nothing to treat viruses, but there are some ways to combat them. One of these solutions is to include infection-fighting foods into your diet, such as cranberries. As well as being effective at treating bacteria which cause UTIs and stomach ulcers, the fruit has been shown to be extremely protective against infection by the influenza virus (Shmuley et al, 2012).
A study on cell cultures showed that a substance called a nondialyzable material (NDM) found in cranberries can reduce the adhesion of the influenza virus to the body, and the infectivity of the virus (Weiss et al, 2005).
Furthermore, Rones et al (2012) found that mice injected with a lethal dose of the influenza virus did not die when supplemented with NDM. These studies together suggest that the compounds within cranberries have an extremely useful function as an anti-viral treatment.
Cranberries contain a large variety of nutrients which help to prevent and treat skin problems. Acne, one of the most common skin problems in the UK, is caused by the blockage of hair follicles (tiny holes in the skin). Hair follicles contain sebaceous glands which excrete an oily substance called sebum, in order to keep the hair and skin lubricated to stop it from drying out.
When excess sebum is produced, it can mix with dead skin cells and cause a blockage in the hair follicle. This blockage becomes a spot, blackhead or whitehead, and bacteria from unclean skin can make acne more severe and can lead to infected spots.
Cranberries can help to treat acne because they have antiseptic properties to reduce the effect of bacteria on spot formation and infection. They also contain an antioxidant called resveratrol, which helps to reduce the size of spots to improve their appearance. Eating cranberries regularly, therefore, will help to prevent spots from appearing, and minimise their size when they do occur.
Many skin problems such as wrinkles are due to free radicals causing damage to the cells of the body. Cranberries are packed full of antioxidants which can protect the skin against free radical damage, and in some cases even reverse damage. Vitamins B3, B5 and C are all found in cranberries and have antioxidant properties which protect skin cells against free radical damage.
Vitamin C is most effective against free radicals created through pollution and cigarette smoke. Cigarette smoke is very damaging to the skin because it destroys collagen, a protein which maintains youthful, plump and elastic skin, which leads to wrinkles.
Vitamin C and vitamin B5 stop this damage by donating one of their own electrons to the free radical which stops the free radical on its destructive path, and as such, prevents skin cells from being damaged. Vitamin B3 is an antioxidant which prevents the formation of free radicals in the first place.
As well as being helpful to minimise the aesthetic effects of aging on the skin, research by Dong et al (2012) performed on nematode worms suggests that cranberries may have greater benefits for aging. In this study, the researchers provided the worms with one of three food extracts; cranberry, royal jelly and noni fruit.
Nematode worms have a lifespan of approximately two to three weeks, meaning it is very useful for studying the effects of ageing. The study found that the worms who consumed the royal jelly survived 25% longer than their lifespan, but that those who consumed cranberries survived 40% longer than expected.
Although it isn’t appropriate to extrapolate these results to humans directly, this study provides good evidence to suggest that cranberries do have some anti-ageing or life-lengthening effects, and that research in humans may provide positive results. The mechanisms by which these effects occur is unknown, but it is suspected that the high antioxidant content of cranberries is responsible.
Another anti-ageing benefit of cranberries may be motor function. As we age, motor function (movement) becomes more difficult and problematic. Coordination and strength deteriorates, and there are some diseases which severely affect motor function, such as multiple sclerosis and Parkinson’s disease.
Research by Shukitt-Hale et al (2005) investigated the effects of fruit supplements on various motor function measures in rats, and found that cranberry supplements elicited greater dopamine release (a neurotransmitter important in motor function), and let to significantly better muscle tone, strength and balance.
It was also found that cranberries enhanced neural functioning and increased the brain’s ability to generate a neuroprotective response to stress. In other words, rats who consumed cranberries showed much greater motor and neural functioning compared to those who didn’t consume cranberries.
Some Things to Be Aware Of
Although cranberries do have some excellent health benefits, there are a few things to be aware of when including them into your diet
- Many of the studies which have found health benefits for cranberries have used cranberry juice. In the studies, the juice will be sugar-free and natural; however there are many cranberry juice drinks available in supermarkets which have lots of added sugar. This can make them very unhealthy and calorific, so it is important to be aware of this when buying cranberry juice
- Cranberries contain large amounts of salicylic acid, which is similar to aspirin. There is some evidence that cranberries should be consumed cautiously by those with an aspirin allergy, or those who take blood thinning drugs. This is because aspirin also has blood thinning effects, and so salicylic acid may cause this to occur, and lead to an excessive blood thinning process when paired with these drugs.
- Cranberries contain a large amount of the chemical called oxalate, which is the main ingredient in kidney stones (alongside calcium). Kidney stones are a hard mass found in the kidneys created by the crystallisation of waste products from the blood. Kidney stones can cause blockages in the urinary tract when they are being passed out of the body, which can lead to urinary tract infections. Because they contain a lot of oxalate, consuming extra oxalate from cranberries may enhance the risk of developing kidney stones.