BSc Sports and Exercise Science 

Personal Trainer and

Nutrition Coach 

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Should You Be Taking Vitamin D?

April 17, 2019


Vitamin D has got a lot of publicity recently, is it all for good reason or are you just wasting your money on supplements that you don’t need?


Why is vitamin D so important?


We need vitamin D to absorb calcium from our diet. Nearly all tissues and cells in our body need vitamin D and the absorption of calcium is essential for the signalling between our brain and cells, bone development and tooth formation. 


Low levels of vitamin D in the body have been associated with: Increased loss of muscle strength and mass, bone or back pain, tiredness, hair loss, muscle pain, lower immune system levels, higher blood pressure, neurological disorders and development of diabetes. 


Some of these may seem fairly dramatic when all we may require is a little more sun? However, you may notice little changes such as tiredness, hair loss or lower immune system during the winter months in the UK if you are low or deficient in vitamin D. So how do you find out? 


Are you vitamin D deficient? 


As you can see from above vitamin D is very important for the normal function of the body, however, 1 in 5 of the UK population have low vitamin D levels.


Vitamin D can also be affected by your body fat levels as vitamin D can get trapped in body fat stores leading to a lower level of vitamin D in your blood if you are overweight. As we age our ability to make vitamin D is reduced by 75% so deficiency is certainly something we need to give some thought to. 


To get enough vitamin D you should be getting about 15-30 minutes of sun each day (without sunscreen)  or 1000 IU equivalent in supplements.

If you think you may be very deficient in vitamin D, I would recommend having a quick blood test done at the doctors.


Different forms of Vitamin D?


Vitamin D is a fat-soluble vitamin, and it comes in various forms. The animal form is D3 and the Plant form is D2, these must both be modified by the body to have any effect. 


Vitamin D from Sun: 


Natural sunlight allows our body to create Vitamin D, UVB radiation from natural sunlight is made active in the liver and kidneys for use in the body. 


Unfortunately glass blocks almost all UVB radiation preventing your body from being able to make vitamin D - so sitting in a car or by a window won't make the cut. Sunscreen above SFP 15 also has a similar effect, decreasing the amount of vitamin D that is made by about 99%. 


The body is very clever in that your skin is limited to producing a certain amount of vitamin D per day and any excess is inactivated. According to guidelines 20 minutes outside in the summer sun each day can produce 100 times more than you need. So you don’t need to be out in it for hours. 


However this can change thought out the year depending on where you live, and sometimes you will make nearly no vitamin D from sunlight between November and March. Our body can store vitamin D, however only for a few weeks so you would need to go on a few holidays to get a sufficient amount. 


Vitamin D from food:


Vitamin D is rare in foods, it is found in fish, cod liver oil, mushrooms, liver and eggs, but this is in very very small amounts (except cod-liver oil) and not substantial enough. 


Some foods, like cereals and milk, are fortified with vitamin D, which means they have it added to the food. 


Getting enough vitamin D from whole foods is almost impossible, therefore your best bet is the natural sunlight. 


If you are having any serious symptoms check first at the doctors to see if you are deficient in vitamin D, it involves a simple blood test.


An overall intake of 1000 IU may be needed for most of the population and if you live in the UK from March to October you may need to ensure you are getting 15-30 minutes of midday sun (15 for those with lighter skin and 30 for those with darker skin) to get adequate vitamin D and if you are not getting in that amount of natural sunlight then you are likely to need to take 1000-2000 IU of vitamin D supplement per day. Studies have been shown that you would need to supplement with 10 times that amount to have adverse effects so it is unlikely you will have too much. 


Overall, If you think you are not getting in the sun for 15-30 minutes a day and think you may just have low levels it may be worth trying a supplement. However, if you really feel you may be very deficient then it is worth getting checked by your doctor. 


Hope that has answered all your Vitamin D questions, 


Kasia :) 


BSc Sports Science, Women’s Fitness Specialist and Personal Trainer 

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