As the summer draws to close and colder days approach it is vital that we get outside in the warm sun as much as possible as vitamin D is essential for our bones and overall mental and physical well-being. In the summer we get the majority of our vitamin D from March through until the end of September.
Vitamin D is essential as it helps the body absorb calcium and phosphate that we obtain from our diet and these minerals are important for healthy bones, teeth and muscles. A lack of vitamin D, known as vitamin D deficiency, can cause bones to become soft and weak, which can lead to bone deformities. In children, for example, a lack of vitamin D can lead to rickets. In adults, it can lead to osteomalacia, which causes bone pain and tenderness (1).
What is vitamin D and what role does it play in the body?
Vitamin D is important for good overall health and strong and healthy bones. It’s also an important factor in making sure your muscles, heart, lungs and brain work well and that your body can fight infection.
Scientific studies have identified a number of important health benefits for vitamin D.
Maintaining the health of bones and teeth.
To support the health of the immune system, brain, and nervous system.
Regulate insulin levels and aid diabetes management.
Support lung function and cardiovascular health.
Influence the expression of genes involved in cancer development.
Studies have shown a link between depression and vitamin D deficiency (2)
Being outside in the sun makes you feel good and increases the good chemicals such as serotonin.
What is the daily recommended intake of Vitamin D?
For Babies up to the age of one year, they require 8.5-10mcg of vitamin D per day.
Children from the age of one year and adults require 10mcg of vitamin D a day.
This includes pregnant and breastfeeding women, and people at risk of vitamin D deficiency.
What are the main sources of Vitamin D?
From the beginning of spring time at the most people should be able to get all the vitamin D they need from sunlight. The body creates vitamin D from direct sunlight on the skin when outdoors. From October onward when the suns heat starts to fade we do not get enough vitamin D from the sun, so through the winter supplements and diet will be required for sufficient vitamin D intake,
These sources include:
Oily fish – such as salmon, sardines, herring, mackerel and fresh tuna
Red meat and liver
Fortified foods - such as most fat spreads and some breakfast cereals
Vitamin D from dietary supplements (8)
These are common risk factors for vitamin D deficiency:
Being overweight or obese
Not eating much fish or milk, or foods that are a vitamin D source
Living far from the equator where there is little sun year-round
Staying indoors for too long
Living in colder climates with less hours of sun
How long should we spend in the sun?
For most of us being out in the warm sun whilst covered from late March to late September will be sufficient to make enough vitamin D. Unfortunately it is not known exactly how much time is needed in the sun to make enough vitamin D to meet the body's requirements. There are factors that can influence the amount of vitamin D made such as skin colour and how much skin is exposed. Cancer Research UK has tips to help you protect your skin in the sun (9).
Your body will not be able to make vitamin D if you are sitting indoors by a sunny window, this is due to ultraviolet B (UVB) rays (the ones your body needs to make vitamin D) not being able to get through the glass.
Remember that the longer you stay in the sun, especially for prolonged periods without sun protection, the greater your risk of skin cancer. If you are planning to be out in the sun for a long period, cover up with suitable clothing, wrap-around sunglasses, seeking shade and apply at least SPF15 sunscreen and cream with a higher SPF if you have fair skin.
What are the symptoms of Vitamin D deficiency?
Vitamin D is essential for supporting bones and their structure. The nutrient helps regulate calcium and phosphorus – the minerals essential for maintaining strong bones – within the body.
Weakness in muscles
A study published in the British Medical Journal states: “Poor muscle strength and weakness may be associated with vitamin D deficiency, which is common among elderly people because the capacity of the skin to synthesise the provitamin calcidiol (25-hydroxycholecalciferol) decreases with age.”
Low mood or depression
A 2008 study in Norway found that people with low levels of vitamin D were more likely to be depressed, taking vitamin D improved the symptoms. The biggest effect was observed in people with more severe symptoms. However, the study only looked at people who were overweight, so it is not possible to conclude whether the results would be similar for everyone.
Getting coughs and colds
Research has suggested that vitamin D is crucial to activating our immune defences, and that without sufficient intake of the vitamin our immune cells are unable to react appropriately. A 2010 study supports this, demonstrating that flu incidence decreased when schoolchildren were given Vitamin D supplements through the winter.
In its milder form, a vitamin D deficiency can both cause and be caused by gastrointestinal problems. The nutrient is fat soluble, which means having a gastrointestinal condition that affects your ability to absorb fat also affects your absorption of vitamin D. Recent research, conducted by the University of Sheffield, suggests a large proportion of patients suffering from irritable bowel syndrome (IBS) are vitamin D deficient.
Feeling tired all the time
A study published in the North American Journal of Medical Sciences found that vitamin D deficiency was common among patients suffering from fatigue. They found that taking vitamin D helped improve their symptoms.The authors of the journal wrote: “Prevalence of low vitamin D was 77.2% in patients who presented with fatigue. After normalisation of vitamin D levels fatigue symptom scores improved significantly in all five sub scale categories of fatigue assessment questionnaires.”
The health benefits of vitamin D seem to be proven but there will no doubt be plenty more studies on the benefits of consumption. You should make sure that you get your daily requirement of vitamin D, especially as it is summer and the sun is out for most of the day.
There is of course a risk of too much vitamin D through supplements so care should be taken There is no risk of your body making too much vitamin D from sun exposure, but take care and remember to cover up and protect your skin so you do not burn.
Sources and further reading
Paul Brown - Senior Member - ACCPH
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