Health benefits of strawberries
Strawberries are a fruit we all know and most of us love. They are extremely versatile; great as an accompaniment to many meals, and a favourite at many occasions, be it a garden party, a dessert after a family meal, or whilst watching a Summertime sporting event. Despite its popularity however, not many people may be aware of the health benefits of this delicious fruit.
The strawberry is packed full of nutrients. In 100g of strawberries (about ten), there are just 32 calories, zero fat, zero cholesterol, 2g dietary fibre, 5g sugars, and 1g protein. Because strawberries are low in saturated fat, sodium and cholesterol, it means you can eat loads of them without running a high risk of weight gain. They also contain vitamin C, calcium, manganese and folate.
Vitamin C is found in most fruits and vegetables, and is brilliant for improving a whole host of bodily functions, including maintaining healthy cells, boosting collagen levels (to keep your skin looking plump and youthful), improving wound-healing, and assisting in the absorption of iron from leafy sources such as kale and sprouts.
Calcium, as many of us will know, is a mineral which is really important for maintaining strong and healthy bones. Strawberries are a source not many people think of when looking for a calcium boost, but they make slightly more interesting eating than Greek yoghurt!
Another added benefit is that, according to a literature review by Thys-Jacobs (2000), calcium can reduce pre-menstrual stress symptoms including irritability, headache, social withdrawal, menstrual cramps, anxiety and depression, all of which are common before menstruation.
Manganese is a mineral that is a little less well known than some of the others, but it also has many benefits. 100g of strawberries contain approximately 19% of your ideal daily intake of manganese, a mineral which improves bone structure and metabolism.
It also helps the body to absorb calcium, ensures the thyroid gland is working correctly (responsible for controlling metabolism and correct functioning of vital organs), and helps the body to metabolise fats and carbohydrates.
Folate, perhaps better known as Vitamin B12, is another vitamin found in strawberries and, like Vitamin C, can help with a multitude of bodily functions, including cell repair and maintenance, metabolic processes, and in the prevention of obesity and some cancers. Folate is also vital to ensure proper foetal development of the brain and spinal cord, to aid in the production of red blood cells (which can help prevent cancer), and to maintain a healthy heart.
The Benefits of Strawberries
Alongside the high numbers of nutrients found in strawberries, they also have the potential to be beneficial in many other physical and cognitive ways:
- Fighting degenerative diseases
- Fighting cancer
- Boosting immunity against illness and disease
- Regulating blood pressure
- Reducing stress
- Losing weight and burning excess fat
- Preventing memory decline
- Maintaining eye health
- Keeping skin healthy
- Promoting bone health
- Maintaining healthy teeth
- Boosting fibre levels to help with digestion
Fighting Degenerative Diseases
Eating fruit and vegetables has long been associated with a reduced risk of developing degenerative diseases such as cardiovascular disease and rheumatoid arthritis. A recent study by Alvarez-Suarez (2014) was conducted in the Mediterranean, where participants were put on a strawberry supplement diet (of 500g strawberries daily) for 1 month.
The results showed that cholesterol levels were significantly reduced compared to the baseline period. It was also shown that platelet function was improved, and the number of active platelets reduced, after the supplement diet.
Both cholesterol and platelets are a very important factor in the development of CVD, or cardiovascular disease. Having too much cholesterol can cause a build-up of fat on the wall of your arteries. This is known as atherosclerosis, and is a form of heart disease.
The arteries can become narrowed, and so blood is not passed through them to the heart as easily. This reduced blood flow to the heart can cause a variety of problems, including heart attack. Platelets are important to help blood clot after a cut or injury, but they are also a major component in blood clots which can break off and cause heart attack, stroke, or pulmonary embolism.
The mechanism by which strawberries create this change is still unknown, but the researchers of the above study suggest that it might be because they contain anthocyanins, the pigment which gives them their red colour.
Rheumatoid arthritis is an autoimmune disease which causes an inflammation of the joints, and is a degenerative disease which affects the whole body. Women are more likely than men to contract the disease, and there is little help available to those who suffer from it.
Strawberries and other berries have been thought to be helpful at reducing inflammation, and consequently the pain that goes alongside it. Again, this is due to the anthocyanins which give strawberries their red colouring.
Inflammation is reduced because strawberries can help to lower blood levels of C-reactive protein (CRP). CRP is produced by the liver and is part of the bodies’ response to inflammation. Rheumatoid arthritis is associated with very high levels of CRP, particularly during arthritic flare-ups.
They are also common in CVD, and so another reason strawberries may be effective in reducing heart disease is that they reduce levels of CRP.
As well as aiding in the fight against autoimmune diseases, strawberries are packed with antioxidants which help to fight cancer. Antioxidants fight off free radicals, which are atoms in the body with an unpaired electron. The free radical will attempt to find a particle to pair with its lone electron, and in doing so can cause massive damage and even death to cells in the body, including DNA. This damage can lead to the formation of cancer.
Antioxidants fight cancer in a number of ways. Vitamin C found in strawberries does so by boosting the immune system. Strawberries also contain ellagic acid, an antioxidant which supresses cancer cell growth. Lutein and zeathancins, also found in strawberries, fight free radicals by minimising the negative effects they can have on our cells.
A study by Chen et al (2011) has also shown that freeze-dried strawberry powder mixed into water can help to prevent oesophageal cancer. Patients at high risk of oesophageal cancer were prescribed either 30 or 60g of freeze-dried strawberry powder per day for six months.
The researchers found that taking 60g had significantly reduced the histolic grade of oesophageal lesions in over 80% of the patients. The histolic grade refers to the amount that a tumour or lesion looks like the rest of the surrounding tissue. The lower the grade, the more normal the tumour appears.
As well as lowering the grade of the throat lesions, those taking 60g per day also showed reductions in the number of a variety of free radicals. Unfortunately, the mechanisms by which strawberries can have this effect on cancer are unknown.
Boosting Immunity Against Illness And Disease
Strawberries can boost immunity against illness and disease due to the high volume of vitamins and minerals found in them. Immunity is mainly boosted by vitamin C, a common vitamin which fights off bacteria, improving the connectivity of tissues (which in turn means tissues are more resistant to attack), and through combating free radicals.
Regulating Blood Pressure
High salt diets mean that there are very high levels of sodium in the body. Some negative effects of sodium include encouraging the body to hold on to excess fluid which burdens the heart, increasing the risk of heart failure, osteoporosis, stomach cancer and kidney disease, and severely increasing blood pressure.
Strawberries are a ‘medium source’ of potassium (153mg per 100g), which can help to regulate blood pressure by mediating against the negative effects of sodium.
Somewhat surprisingly, strawberries can be really good for relieving stress and irritability. This is particularly important nowadays when 59% adults say their lives are more stressful than they were 5 years ago, and nearly 250,000 people in the UK were diagnosed with work-related stress (Labour Force Survey, 2014).
Stress is negative not only because of its own symptoms, but also because it can lead to other physical and mental health problems including heart disease and depression.
Not only do they satisfy the sugar craving you might get when you’re stressed (chocolate always makes stress go away!), they also contain magnesium. Magnesium is a mineral which people know little about, but it turns out it plays quite a complex role in stress, something we all know too much about!
When you are stressed, magnesium will be released into the bloodstream, and from there into your urine where you expel it from the body. The more stressed you become, the more magnesium you lose. The clincher is that lower magnesium levels make you more prone to stress, so this can leave you in a vicious negative cycle.
Breaking this cycle is simple enough by eating foods high in magnesium, in order to replace that which you lose during stress. This in turn will buffer you against the risk of stress in the future. One of those foods is strawberries.
Losing Weight And Burning Excess Fat
Strawberries are great for weight loss for three different reasons:
Firstly, they can increase the body’s production of a hormone (adiponectin) which leads to an increased metabolism and appetite suppression. They do this because, yet again, they are packed full of anthocyanins.
Secondly, they reduce the rate of digestion for starchy foods, meaning the rise in blood sugar after the meal is controlled. You will then find that you have a reduced craving for sugar. This process occurs because strawberries contain polyphenols, micronutrients which block the digestive enzyme activity of certain starches.
Thirdly, they can improve the functioning of hormones which help you to lose weight. This works because strawberries have anti-inflammatory properties. Inflammation, as well as causing the problems mentioned above, can also disrupt hormone functioning.
Eating strawberries will reduce this inflammation, which means the hormones will start functioning correctly again.
Preventing Memory Decline
As well as helping with physical problems, strawberries are also good for maintaining strong cognitive abilities. Devore et al (2012) studied the effects of berries on memory by asking participants (16000 women) to recall all the details they could about a paragraph they had just heard, or to remember a list of words or numbers.
They did this in a longitudinal cohort study (where diet was also being measured) over a period of six years (one test every two years). The results were quite remarkable.
Those who ate the most strawberries and blueberries had significantly slower rates of memory decline. The result was equal to approximately two and a half years’ worth of ageing. In other words, eating strawberries and blueberries can make your memory two and a half years younger than your counterparts.
The researchers believe that this is due to the intake of flavonoids (plant pigment with antioxidant components) and anthocyanides. One of the best parts about this study is that on average, those who ate the most berries were only having approximately 200g strawberries a week.
Not only can strawberries reduce memory decline, but they can also reduce the risk of developing Alzheimer’s’ disease, which currently affects 1 in 14 people over the age of 65 (Alzheimer’s Society, 2014). A study by Currais et al (2014) assessed the effect of fisetin-infused water on the development of Alzheimer’s in mice that both had and did not have an Alzheimer’s gene.
Fisetin is a flavanol which is prolific in strawberries, and has been shown to protect neurons from degeneration due to ageing. The researchers found that within nine months, mice without the water began to lose their cognitive abilities, including getting lost in a water maze they were previously proficient at.
On the other hand, those who had consumed fisetin-infused water kept a similar cognitive profile to those of the mice without the gene for Alzheimers.
Although this study is clearly using animal models instead of humans, the results may very well be transferable. Very often in science, animal models are used first to assess the possibility that the same effect will occur in humans. This prevents unnecessary harm to humans.
Following successful animal trials, human trials can then take place. Mice models for Alzheimer’s disease prove to be particularly effective for representing disease progression in humans, and often provide transferable results.
Maintaining Eye Health
As previously mentioned, vitamin C is found in many fruits and vegetables including strawberries. Not only is it good for promoting good immune system functioning, but it also can keep eyes healthy, and cataracts at bay. Cataracts are a clouding of the lens of the eye, caused by proteins in the lens clumping together as a result of both ageing and too much UV light exposure.
They are the world’s leading cause of blindness and vision impairment, and so preventing them is extremely important. There are enzymes in the eye which breakdown the damaged proteins to prevent them clumping together. Vitamin C is a powerful antioxidant which can protect these important enzymes from being destroyed by free radicals.
Alongside preventing cataracts, vitamin C can also support the health of ocular blood vessels, meaning the eye is more likely to receive a healthy blood supply. Furthermore, consuming vitamin C can prevent the development of Age-Related Mascular Degeneration (AMD), which is known as a ‘nutrition-responsive disorder’.
Vitamin C can slow the progression of AMD by as much as 25%, and so it is important to consume the recommended amount. 100g strawberries contain 98% of the recommended daily allowance for vitamin C, and so they are a great way to boost your vitamin C intake.
Alongside vitamin C, strawberries also contain potassium which can regulate eye pressure. This is what the optician is measuring when they administer a puff of air to each eyeball during an eye test. Eye pressure is important for eye health as untreated high ocular pressure can cause severe eye problems including blindness.
Keeping Skin Healthy
There are a number of reasons why strawberries are good for your skin. Firstly, they contain vitamin C, salicylic acid, antioxidants and exfoliants, which can all contribute to a healthy skin cleanse. This is why strawberry extract is often used in skin-care products. Secondly, strawberry juice has skin-lightening and toning properties and so can improve the complexion of your skin.
Thirdly, the antioxidants contained in strawberries which have previously been mentioned not only fight off free radicals which can prematurely age the skin, but also increase the collagen content of skin. This can help it to appear more plump and youthful. Fourthly, ellagic acid found in strawberries can help to reduce the appearance of fine lines and wrinkles as it can prevent damage from UV light.
Promoting Bone Health
Although many people only think of getting calcium from dairy products, fruit are another excellent source of calcium to ensure good bone health. Strawberries not only contain calcium, but they also contain manganese, potassium and folate, all of which contribute to the formation of bone mass. Manganese also aids in the absorption of calcium, which ensures that all the calcium you consume is used efficiently.
Maintaining Healthy Teeth
Strawberries contain malic acid, which is a natural enamel whitener. They also contain polyphenols, compounds which inhibit the breakdown of starches in the mouth. This helps to reduce plaque build-up, which can cause tooth decay and gum disease.
It is worth noting, however, that due to the acidic and sugary nature of strawberries, using them as an enamel whitener daily will probably make them worse rather than better. It is best kept as a solution for special occasions, when you can thoroughly rinse your mouth afterwards to remove excess acids.
Boosting Fibre Levels To Help With Digestion
Finally, strawberries are packed full of both soluble (40%) and insoluble (60%) dietary fibre. The solubility of fibre is important as it determines how they interact with food in the gut. Soluble dietary fibre attracts fluid and creates a gel, which slows down digestion. This can prevent the absorption of cholesterol, promote a feeling of fullness, and also help to maintain healthy insulin function.
Insoluble fibre is important for gut health, and can add bulk to help prevent constipation. The fibre passes through the digestive tract in tact as is does not dissolve in water, and in doing so can speed up the passage of food and waste through the digestive system.
As strawberries contain both types of fibre (a rather rare phenomenon), they are very useful to eat regularly to maintain a healthy digestive system.
Things to Be Aware Of
Despite the high number of health benefits strawberries can have, there are a few things to be aware of.
First of all, like many fruits, they do have a high sugar content which can be unhealthy if consumed in excess. As long as you maintain a healthy, balanced diet and ensure you practise good oral care, however, you should be perfectly fine to eat as many strawberries as you like.
They are also a favourite of pests, and so are often covered in pesticides. Where possible, buy organic, and failing that, ensure that you wash them thoroughly before eating in order to avoid ingestion of unhealthy chemicals.
Strawberry allergies do exist, so you should be aware of this before you try eating them. The symptoms can range from swelling and hives to anaphylactic shock, and so if you are prone to food allergies you should make sure you are tested for allergies at your GP before you eat strawberries.
We hope you enjoyed reading this article and feel encouraged to include more strawberries into your diet. Happy eating!