Much as I respect the Readers Digest as an excellent publication it is not an authoritative medical text.
In fact there is some evidence to suggest that folic acid may have a role in preventing bowel cancer - although this link has not been proven.
"Dietary factors are the subject of intense and ongoing investigations. Epidemiological studies have linked increased risk of colorectal cancer with a diet high in red meat and animal fat, low-fiber diet, and low overall intake of fruits and vegetables. Factors associated with lower risk include folate intake, calcium intake, and estrogen replacement therapy. However, most of these studies were retrospective epidemiological studies and have yet to be validated in prospective, placebo-controlled, interventional trials."
There is certainly no evidence , whatsoever , that changing your intake of folic acid would increase your risk of bowel cancer.
Thank you for your answer - I will continue to take my 800 mcg of Folic Acid - in addition to that I receive in food.
I also asked about the B vitamins, Vit. C,E and beta-carotene What are the "safe" upper limits of taking these vit. I do not take Mega doses of any.
To be honest I am unsure of the exact upper limits of dosing for these vitamins.
However - if you do not exceed the dosage stated on the packaging you should be fine.
I should point out that I would only advise vitamin supplementation if you had a proven deficiency.