Known as the sunshine vitamin, Vitamin D is derived from sunlight on the skin and its primary function is maintaining healthy bones, teeth and muscles. Vitamin D is essential for bone development, as it helps the body to use calcium.
But given that the UK has significantly less sunlight during the winter months, between October and early March achieving the recommended dosage can be challenging for even the most dedicated long distance runner.
Why is Vitamin D so important?
It has been estimated that around 10 million people in the UK have low Vitamin D stores due to lack of sunlight in the winter months. This statistic means that approximately one in five adults isn’t getting the right amount of Vitamin D a day, which can lead to major health implications.
‘Vitamin D is made by the body when sunlight is absorbed by the skin, and is used to regulate our levels of calcium and phosphate,’ says Asina Aktar, consultant dietician at BMI.
‘These two minerals are needed by the bones and muscles to keep them healthy and strong. Vitamin D deficiency can present itself in the form of rickets in children and osteomalacia or osteoporosis in adults. These conditions cause the bones to soften and fracture or start to bend, often resulting in pain and tenderness in the bone and surrounding muscles,' she adds.
What are the symptoms of Vitamin D deficiency?
Symptoms of Vitamin D deficiency range from fatigue to general aches and pains, increased susceptibility to illness, low mood, depression, struggling to concentrate and even problems with memory.
Dr Sam Rodgers, General Practitioner and Medical Director of Medichecks champions greater understanding of the necessity of vitamin D, and urges people in the UK to have their levels checked.
‘Insufficient levels of Vitamin D are more damaging than most people are aware,’ argues Dr Rodgers. ‘People think it’s just about bone health, and while this is an essential role of the hormone, we are reliant on it for far more. For starters, you are more likely to catch respiratory infections and it can take longer to recover from injury and illnesses.'
'We see increased levels of autoimmune disease in people with vitamin D deficiency, this includes problems like hypothyroidism and multiple sclerosis,' he adds. 'There are also increased rates of heart disease such as heart attacks and heart failure. It is also important in thinking and memory.’
Where do you get Vitamin D from?
The main natural source of vitamin D is from sunlight directly on the skin. 'It’s also advisable to make sure you get natural sunlight exposure on your face, neck and upper arms every day where possible,' advises Boots pharmacist Angela Chalmers. '15-20 minutes exposure each day is adequate, taking care to avoid sunburn if it's a really sunny day.'
However, sunbathing isn't always an option in the UK during the winter months. If you are experiencing any of the symptoms of Vitamin D deficiency you should visit your doctor and ask for a blood test. If results show that you are deficient then it’s worth taking approved Vitamin D supplements, available in all good pharmacies and health food shops.
How much Vitamin D do you need?
The NHS recommends that babies up to the age of one year need 8.5-10mcg of vitamin D a day, children from the age of one year and adults need 10mcg of vitamin D a day.
'To help maintain Vitamin D levels, you can buy Vitamin D supplements from healthcare retailers including your local pharmacy and you can take up to 25mcg per day,' says Chalmers.
'Current guidelines recommend Vitamin D supplement use to prevent deficiency among at-risk groups. These include infants and children aged under 5, pregnant and breastfeeding women, people over 65, people who have low or no exposure to the sun, and people with darker skin.'
However, proceed with caution and speak to your GP first if you're not sure about the correct dosage, as it is possible to take too much Vitamin D. ‘Excess Vitamin D causes high calcium levels in the blood, and can result in nausea, confusion, constipation and an upset heart rhythm,' says Asina Aktar, consultant dietician at BMI.
'The advised limit is 100mcg and most overdoses are caused by having too many supplements rather than from the sun or certain foods.’
Can you get Vitamin D from foods?
While sunshine and supplements are the easiest ways to ensure you receive sufficient levels of Vitamin D, you can also derive it from certain foods. ‘You should increase the amount of vitamin D rich foods you eat,’ recommends Dr Sam Rodgers. ‘The richest dietary sources of vitamin D are oily fish such as salmon, sardines, mackerel and fresh tuna.'
'Mushrooms (particularly if you leave them out to bathe in the sun) are the only good natural source for vegetarians,' he adds. 'Egg yolks contain Vitamin D, however you need to eat 20 a day to meet your basic vitamin D requirements, which may prove difficult! There are also a range of fortified juices, cereals and other foods so it is always worth checking the nutrition panel to see how much of your Vitamin D requirements are provided by packaged foods.’
Do runners get enough Vitamin D?
Vitamin D is particularly important for runners and fitness fans. 'Many of us strain our bodies, by squeezing in as much exercise as we can to our busy lifestyles, in order to meet our fitness targets,' says Cassandra Barns, nutritionist for qnutrapharma.com. 'Vitamin D makes sure we absorb enough calcium from our foods, which helps to support our muscle growth, joints and immune system.‘
If you run outside regularly for 30 minutes a day or more, then technically you should be getting ample Vitamin D during the summer months, but in the winter this can become more of a challenge and even runners can struggle to get sufficient amounts.
‘In the UK from mid-October to the start of April, the sunlight doesn’t have enough UVB rays for the skin to create vitamin D,’ says Aktar.
‘This inefficiency leads to lots of people becoming deficient of vitamin D with a reported 39% of the population having a low vitamin D status in winter. It’s also typically more difficult for people with dark skin to get enough vitamin D because they have more melanin in their skin, which absorbs UVB rays.’
Vitamin D supplements
Top up your Vitamin D stores with one of the following supplements, and don't forget to run outside as much as possible!
- Once A Day Sunshine D, £5.24 qnutrapharma.com
- Boots Vitamin D Supplements, £4.99 Boots.com
- Vitamin D3 Spray, £6.99 Powerhealth.co.uk
- Holland & Barrett Vitamin D3 100 Tablets 10ug, £3.59 Hollandandbarrett.com