I'm just a little confused about it all!
I believe we are meant to be in the sun since we don't have fur
But how much is too much sun????
Depending on where you live in the world, our skin manufactures vitamin D at differing optimum exposures.
Light-skinned people need to expose 85% of skin to the midday sun for 10-20 minutes a day
Dark-skinned people need to expose 85% of skin to the midday sun for 90-120 minutes a day
(Note: if you are in the UK like I am, the above amounts may stand you in good stead from April to September. But during the other six months of the year you’ll need to look to supplementation to top up your vitamin D levels, unless you can relocate somewhere sunnier or consider UVB lamps. The body has only limited ability to store vitamin D so no amount of summer sun will carry you through a UK winter).
A raw vegan diet really helps protect your skin and I think if you're long term LFRV you can extend the above to 30 minutes and 130 minutes respectively.
As you get away from northern latitudes the number of hours in a day that the sun's rays are hitting the earth at the right angle for Vit D production increase. In the UK, it's only between 11am and 3pm during the summer - April to September (and not at all during the winter). Nearer to the equator these hours obviously expand in both directions and the number of months that they are around increases too.
Well if we look again at our origins, tropical rain forests, the best place to get sun is under tree coverage. We would be out in the sun all day long, just under trees shaded from most of the harsh rays. Yes sunlight/UV light does penetrate down through the canopy because there are plants that grow on the forest floor. If they are there, they are getting light because they are green and photosynthesizing. I had someone argue that with me before. "But it is shaded there!" Anyway.
So with that said, if we move out from under the shade then it is the 10-15 mins of sun for the day. After that, you body starts to store. Your body can store vitamina D for the winter months. That is good for us northern folk.
If possible, avoid the sun from 10-4. If you are out at that time, wear hats and linen clothing or long sleeve cotton. Essentially that mimics the tree canopy. The light fabrics do not stop the UV completely, but they shade it out so that it does not overwhelm your skin. I am moderately fair-skinned. This has helped. I cannot quantify how much vit D I make, but I do still get a slight tan so the sun is getting through.