Veganism is one of my eccentric habits; not using sunscreen is the other one. Again, I have been reading a huge amount on the topic after I have been diagnosed with extremely low levels of vitamin D (and this was when I was living in the South of the UK, not in Scotland). It turns out that a large majority of people are vitamin D deficient - it is in fact big public health issue. Because we mainly live indoors and use sunscreen as soon as there is a ray of sunshine, we have no chance of producing vitamin D naturally.
Just to mention a few facts I did not know (and I realized, most of the people around me don't know either...):
- Vitamin D is extremely important; it is not a "detail"; low vitamin D levels have been associated with many diseases, particularly depression or auto-immune diseases like MS.
- The main source of vitamin D intake is the sun. Some foods contain vitamin D (like fish), but it is practically infeasible to get the amounts you need from food.
- Sunscreen blocks vitamin D - so you should expose yourself without sunscreen. It may seem weird and you may think I am heading straight for skin cancer, but it seems somewhat reasonable to believe that our skin has evolved to allow us to deal with small and reasonable amounts of sun. You will not get a sunburn in 20 minutes if you expose yourself consistently over the year (i.e. not by exposing yourself for the first time in July in Greece) and if you stay in the shadow the rest of the time. Like our ancestors would have probably done as well. I have tested this strategy myself and have not worn sunscreen for years now, nor have had sunburns...
- There is no evidence that sunscreen protects you from skin cancer. Sunscreen prevents you from burning, but if anything, it may well be that sunscreen leads to people to stay much more in the sun than they would otherwise and that may actually lead to an increase in skin cancer... Here is a link to a good lecture on the topic if by a researcher from UCSD, who presents quite a convincing case again sunscreen.
- You cannot produce vitamin D if the sun is lower than 45 degrees, that is, you have no chances of making vitamin D between November and March if you live north of Madrid. Importantly, you need to expose yourself for at least 20 minutes a day (and this is if you expose most of your body, which most of us can't do for practical reasons) between 10 am and 3 pm (when the sun is high enough). This is exactly when we have been told to avoid the sun and use sunscreen...
- California and Australia have also very high rates of vitamin D deficiency. This is probably because everyone is using sunscreen.
The major success of public health campaigns promoting the use of sunscreen may very well be one of the biggest failures in the history of public health campaigns. Because of that, people are putting on massive amounts of sunscreen, vitamin D levels are at record lows and are probably the cause of all sorts of other major issues.
- The current recommended daily allowance is 600 IU (International Units) in the EU. Scientists overwhelmingly agree that this is low, way too low. To put this in perspective, when you go in the sun for 20 minutes, you would produce (depending on the time of the day and your skin) around 3 to 5,000 IU of vitamin D. My understanding is that an intake of between 2,000 and 4,000 IU a day throughout the year is the minimum I need. In case you worry about intoxication, there have been no cases diagnosed of intoxication unless you take millions of IU... There is certainly nothing to worry about with doses less than 5,000 IU. One thing I would mention though is that there seems to be an important interaction between vitamin D and another vitamin, called K2, for which there is much less research done to this day but, in my opinion, deserves attention. K2 used to be part of our diet when we were eating grass fed cows (it would then be present in their milk and in cheese) but now few of us eat milk or meat from grass fed cows. K2 apparently could play an important role in bringing calcium to our bones. So many people who take vitamin D also take vitamin K2. I take plant based vitamin K2 derived from a product called natto. This is real food by the way, so not a synthetic supplement. It is just that natto itself is not that tasty...
Recommended reading: A recent article published in the British Medical Journal called "Diagnosis and Management of Vitamin D Deficiency" is a great summary of the past and ongoing research on the topic. I have followed their recommendations and took 10,000 IU per day for 3 months. Now I am taking 5,000 IU per day.
There is fascinating ongoing research on the role of vitamin D in cancer prevention and again, everything seems to indicate that we require much higher levels of Vitamin D than we once thought... So do your homework and get informed!