There's so much fun stuff to read about it for a medically untrained layperson like me. Let's see, things I remember reading from off the top of my head, but don't know how true or accurate or likely they are:

- Cholesterol is converted into Vitamin D by the sunlight, so our dietary cholesterol shunning, cholesterol lowering drug culture lowers the amount of Vit D which can be created by the sun.

- UVB is needed to make Vit D from sunlight, so our sunscreen culture makes that less likely.

- UVA counters the making of Vit D in the skin, so our office culture where people sit inside behind windows which block UVB and allow through UVA is bad for Vit D levels.

- Our margarine and other odd fats promoting culture leads to trans fat and other i-don't-remember-what abnormal fats being used in body part construction and repair, and they are more likely to oxidise and distort and weaken cells and lead to an increased risk of skin cancer from sunlight.

- Our recommended blood/cell/something levels of Vit D are less than that seen naturally in people who live in Equatorial regions.

- Not all Vit D supplements are equal, eating in a powdered tablet form will cause some to be absorbed, eating in a gel tablet form will lead to more getting through the stomach to the gut and cause more to be absorbed, eating with fatty/oily food will cause more to be absorbed and used than eating it dry, using a spray under the tongue will cause absorbtion directly into the blood stream so you can more accurately predict how much will become available for bodily use, but when created by sunlight it's self regulating. So if you don't get it via sunlight, have levels checked regularly so you don't overdose. And since you can't accurately predict how much of a tablet will be absorbed, you might need to take more than you otherwise thought to get the change in level you were planning for.

So if there is truth to these, it's not just a case of sunlight causes skin cancer, but sunlight on odd-fat-weakened skin increases chances of skin cancer which office working sunscreen wearing sun avoiders have less ability to fight off.

Sounds so simple and believable it can't be true, but also so simple and believable that even if it isn't true in the slightest I'll still remember it easily. Hrm.