Shea butter and SPF?

Okay thanks! I read it in a forum and wasn’t sure exactly what it meant.
http://theglamlaboratory.blogspot.com/2011/06/cracking-code-shea-butter-and-spf.html?m=1
http://sheabutter.infinitepossibilitiesllc.com/
http://blog.bulkapothecary.com/natural-spf-shea-butter/
http://almostexactlyblog.wordpress.com/2013/05/15/natural-sunscreens-why-you-need-to-switch/
I don’t recall where I saw the exact forum with that discussion… but there was one mom who was like ” well my baby’s a redhead and that spf isn’t going to be enough. “
Lol

Which leads me to my next question: Since things like shea butter coconut oil olive oil vitamin e vitamin c vitamin a green tea and/ or reversatrol have some uv protection would it be possibld to make an effective sunscreen with these sole ingredients?These all have some photo protection.

Two other things
1. I know that PABA is an irritant yet it is also a good sunscreen . So for companies and consumers that want natural products why do they not ask for PABA and why do they make it seem horrid when it is mentioned? From what I can tell it never caused any serious kinds of illness. Is is just an irritant on the skin.

2. In regards to wearing sunscreen but not getting vitamin D; Is there any way a sunscreen can be formulated with vitamin D and would it ease peoples minds? Furthermore there are two types of vitamin vitamin d2 and d3. Do both of these vitamins get metabolized by cholesterol in the skin in presence of sunlight? And which one are more people deficient in?
Thanks for answering all my questions Randy S and great website!!