It is based on younger women who used high dose folic acid
to prevent spina bifida during pregnancy.

I have seen some young women given folic acid in amounts
up to 5mg a day! (esp if they have had a miscarriage or a
baby previously with spina bifida.)

The concern involves not CAUSING cancer but allowing it
to grow faster. Normally our immune system is removing cancerous cells all the time. If this fails or if certain nutrients are in good supply, then a cancer may take root, faster.
I think this is what we are seeing.

Also, this is only one study so far. I have seen reports that early breast cancer can be due to LOW vitamin D.
If pregnant women are low in D also (and I think that is very common), this factor has to be evaluated in any study looking at cancer.

So at this time until more information is available...moderation is the key.

There is a new DNA test coming out right now, that you can have to measure you risk for folate errors. It is being marketed by Solgar, for their new vitamin line which will target only what YOU need...called Nutrigenomx line.

I talk about it here:
http://neurotalk.psychcentral.com/thread17913.html

There is only one store in my state so far offering this service.
I was told by Solgar that within 3 months, after training other employees, it will be more common.

For people here using drugs for bipolar...antiseizure meds...Vit D is typically lost. So is folate. I've lost track of what you are using Bizi, but you may just be keeping up, and not that high.

I would get a vit D level done. This is turning out to be a huge epidemic across the health boards. About 50% of people are very low..dangerously so. Low D is very linked to cancer.