The Importance of Vitamin D

Now that it's officially winter, we investigate the importance of Vitamin D.

Vitamin D has been in the press a lot lately because it has been decided that we all need to be supplemented with it in the winter. As a dietitian, I have seen many different types of people with vitamin D deficiency: people who work in office jobs that don’t see the light of day 5 days per week; people who have darker skin but are otherwise healthy; and people with fair skin who burn easily so always cover up.

Luckily for me, the mutation that makes me have red hair also makes me better at producing vitamin D, so I don’t have to worry!

The main job of vitamin D in our bodies is to help us to absorb important minerals such as calcium, magnesium and zinc. Vitamin D deficiency gives symptoms such as tiredness, muscle weakness and joint pain.

When we don’t get enough vitamin D and we aren’t absorbing those important minerals, the biggest thing that happens is that our bones become weaker, so concerns over vitamin D deficiency are completely valid.

Due to my lack of personal investment in the subject of vitamin D deficiency, I thought I'd ask a non-ginger to sum up the evidence. So, I interviewed one of the very few male dietitians in existence, one of the best scientific minds I know and an all-round great guy.

Rob Davies shares his wisdom:

"Vitamin D, the happy sunshine vitamin, has, I feel, been largely overshadowed by its vitamin and mineral brethren, but recently, a lot of stirring and interest has brought vitamin D into the glaring sunlight.  

A report published by the Scientific Advisory Committee for Nutrition (SACN) has reviewed the currently available scientific evidence on vitamin D and proposed recommendations for the general public to ensure the vitamin D level in our bodies is sufficient.

So why is everyone so interested in vitamin D all of a sudden?

Well, vitamin D is known to be an important nutrient for bone growth and repair. What is interesting about vitamin D is its emerging effect on other things like cardiovascular disease, cancer, and autoimmune diseases like multiple sclerosis and type 1 diabetes. There are even links being made between obesity and vitamin D … maybe we really can blame the weather for our spare tyre… unlikely!

So, where do we get vitamin D from? How can I keep healthy bones and not die of a heart attack or cancer and not get diabetes MS or be obese?

Sadly, vitamin D is rather lacking in food. The most vitamin D harbouring foodstuff is…oily fish! Herring, mackerel, salmon, trout, fresh tuna, sardines are all top sources of this wondrous nutrient (which most people sadly, rarely eat), and you can also get some in egg yolk, fortified foods like breakfast cereals, margarine, some yoghurts and milks, and for those non-animal eaters out there, wild mushrooms. However, the largest, most abundant contributor to our vitamin D needs is the fiery ball in the sky, the sun, and also our skin, as without our skin we would not be able to convert the rays from the sun into the vitamin D our bodies will use.      

The reason that we are having problems with vitamin D is because we are designed for a lifestyle where we live and or work outside. The rate of our environmental evolution, from living in caves, walking everywhere and hunting/gathering to survive, to cars, offices and supermarkets has moved much more quickly that our biological evolution ever could and as a result, many of us are deficient.

What SACN have suggested in its report is that now everyone above the age of 4 (including those at risk groups mentioned above) should have 10μg/day BUT only during the winter months.

To combat this multifactorial problem of vitamin D, SACN helpfully suggest the Government come up with some strategies to help people get their 10μg/day…but unhelpfully provide no suggestions on actually how to do this.

One suggestion, which I have thought for a long time would be useful, could be to do a public health campaign educating people on the benefits of vitamin D. This could include dietary sources and information on supplements, so people can decide for themselves what to do (bringing  self-responsibility and autonomy to the people!).

Then, conversely, something like fortification of food products with vitamin D, either obligatory or voluntarily, would be something to consider as has been in the USA, Canada, Finland, Denmark, and Ireland, and we already do this in the UK for flour and margarine so extending this list and adding vitamin D to other foodstuffs would go some way to providing additional dietary vitamin D.

However, there is an ethical argument that should be considered: government intervention vs self-determination; right to choose vs best-interests…but something somehow somewhere should, nay, needs to be done if we are to ensure that vitamin D levels are to be optimum to benefit our health.    

In essence, it has been a long time coming for a daily vitamin D recommendation applicable to everyone and so I welcome the publication of this report, but it is only a step…a small step…into the enigmatic world of vitamin D and I really do hope it does not take another 25 years for there to be another re-evaluation of this important nutrient.”

If you think you might be vitamin D deficient, go to your GP and request to have your levels checked. Supplementation levels of 10μg per day in winter have been recommended by the report, but the maximum amount you should take is thought to be 25μg per day.

If you’re eating a couple of portions of oily fish per week and are getting out in the day light most days you’re probably fine. But if, like the majority of the population, you are indoors most of the time and hate oily fish AND/OR have dark skin, keep covered up or live in a care home, you should consider supplementation.