> Not sure if this link will work for you, but it is the actual article
> referenced in the link posted by Gysde:http://jnci.oxfordjournals.org/content/104/10/732.full
> Since you are most focused on folic acid, here's the relevant section
> (RCT = randomized controlled trial, widely regarded as the gold standard):
> <quote>
> Folic Acid

> Folate, a water soluble B-vitamin, is required for a variety of
> methylation-related processes. Although the terms “folate” and “folic
> acid” are sometimes used synonymously, the latter refers to the
> synthetic oxidized form that is commonly used in fortification and
> supplements, whereas naturally occurring folates are reduced molecules
> that exist in nature in several different forms with various degrees of
> polyglutamation. The association of folate and folic acid with cancer
> risk has been most intensely studied with regard to colorectal
> neoplasia. Although it has been proposed that synthetic sources of
> folate might confer greater protection than natural forms, results of
> one meta-analysis of observational studies of colorectal cancer showed
> that total folate (dietary plus synthetic sources) did not provide
> greater protection than dietary folate. In contrast to observational
> data showing a protective association of folate status with risk, a
> recent meta-analysis of RCTs found no effect of folic acid
> supplementation on risk of colorectal adenomas over the 3-year treatment
> period. In view of these findings, folic acid does not seem to be a
> promising avenue for colon cancer prevention as previously hoped.

> Contrary to the hypothesized benefit, the results of one trial showed
> that long-term folic acid supplementation increases risk of advanced
> colorectal adenomas (relative risk = 1.67; 95% confidence interval =
> 1.00 to 2.80) and of developing three or more adenomas (relative risk =
> 2.32; 95% confidence interval = 1.23 to 4.35). In this RCT, increased
> risk of prostate cancer was also found. Because preclinical studies show
> the potential for a pro-neoplastic effect of folate—at least in animals
> with preexisting neoplasms—the possibility of enhanced carcinogenesis is
> a concern. Consistent with this idea, observational studies have linked
> higher dietary intake as well as higher circulating concentrations of
> folate with increased prostate cancer risk; higher risk of breast cancer
> has also been shown among individuals with higher folic acid intake.
> Whether folic acid supplementation can have adverse effects is a topic
> that needs further investigation. This is particularly important in
> countries such as the United States, where government-mandated folic
> acid fortification of the food supply, which began in 1996, has resulted
> in higher overall intake of this nutrient and use of supplements
> containing folic acid is widespread.
> <endquote>

> And the snippet below, from the conclusions, is priceless:
> <quote>
> Whether these trials will find benefits from supplementation for cancer
> prevention is unknown. In considering the current evidence, many expert
> committees and organizations have made public health recommendations,
> generally concluding that nutritional supplements have little to no
> benefit in preventing cancer (Table 1 [sniped]).

> Given this general consensus, why do so many people in the United States
> continue to use dietary supplements? A large part of the answer lies in
> messages from supplement manufacturers, who suggest that there are
> health benefits, including cancer prevention, from supplements.
> Undoubtedly, use is driven by a common belief that supplements can
> improve health and protect against disease, and that at worst, they are
> harmless. However, the assumption that any dietary supplement is safe
> under all circumstances and in all quantities is no longer empirically
> reasonable. Believers in supplements are sometimes quick to discredit
> caution over supplement use, as they suggest that the tendency of
> mainstream science to ignore nonconventional evidence is tainted or that
> mainstream science is somehow corrupted by its link to a
> medical–industrial complex that seeks to protect profits rather than
> prevent disease. Results of a recent survey showed that most US
> supplement users report that they would continue to use supplements even
> if scientific evidence found them to be ineffective or if the FDA
> specifically deemed them ineffective. Perhaps, it is generally assumed
> by supplement users that these products are as well regulated as
> over-the-counter medications. These beliefs underscore the need for
> efforts by scientists and government officials to encourage the public
> to make prudent decisions based on sound evidence with respect to use of
> dietary supplements for cancer prevention.
> <endquote>

> On 5/16/2012 3:07 PM, Trawley Trash wrote:> On Tue, 15 May 2012 23:35:50 +0200
> > "GysdeJongh"<JonghSevenHundredElevenAtPlanet.nl>  wrote:

> >> Causation is no corelation. All dokters are idiots paid by big
> >> pharma, so they will do anything to deprive us from cheap and
> >> effective solutions. Supplements and vitamins are essential for your
> >> health. The more you take the better of course.
> >> Gys

> >> <http://medicalxpress.com/news/2012-05-dietary-supplements-cancer.html>

> >> Beta-carotene, selenium and folic acid - taken up to three times
> >> their recommended daily allowance, these supplements are probably
> >> harmless...

> >    ...

> >> We have a window into less than half of the biology of what these
> >> nutrients are doing," Byers says. "We say generalized things about
> >> them, calling them an antioxidant or an essential mineral, but true
> >> biology turns out to be more complex than that. The effects of these
> >> supplements are certainly not limited to the label we give them. And,
> >> as we've seen, sometimes the unintended effects include increased
> >> cancer risk."

> >    ...

> >> ...Byers says. "My conclusion is that taking
> >> high doses of any particular nutrient is more likely to be a bad
> >> thing than a good thing."

> >    In plain English Byers words translate to: "We don't know, that means
> >    it's possible."

> >    Let's turn to some other sources.

> >    From wikepedia:

> >    http://en.wikipedia.org/wiki/Folic_acid

> > !   Cancer

> > ! Many cancer cells have a high requirement for folic acid and
> > ! overexpress the folic acid receptor. This finding has led to the
> > ! development of anti-cancer drugs that target the folic acid
> > ! receptor.[31]

> > ! A meta-analysis published in 2010 failed to find a statistically
> > ! significant cancer risk due to folic acid supplements.[32]

> > ! Some investigations have proposed good levels of folic acid may be
> > ! related to lower risk of esophageal, stomach, and ovarian cancers, but
> > ! the benefits of folic acid against cancer may depend on when it is
> > ! taken and on individual conditions. In addition, folic acid may not be
> > ! helpful, and could even be damaging, in people already suffering from
> > ! cancer or from a precancerous condition. Likewise, it has been
> > ! suggested excess folate may promote tumor initiation.[33] Folate has
> > ! shown to play a dual role in cancer development; low folate intake
> > ! protects against early carcinogenesis, and high folate intake promotes
> > ! advanced carcinogenesis.[34] Therefore, public health recommendations
> > ! should be careful not to encourage too much folate intake.[34]

> > ! Diets high in folate are associated with decreased risk of colorectal
> > ! cancer; some studies show the association is stronger for folate from
> > ! foods alone than for folate from foods and supplements,[35] Colorectal
> > ! cancer is the most studied type of cancer in relation to folate and
> > ! one carbon metabolism. One study concluded that there was not strong
> > ! support for an association between prostate cancer risk and
> > ! circulating concentrations of folate or vitamin B12. The researchers
> > ! noted that while elevated concentrations of vitamin B12 may be
> > ! associated with an increased risk for advanced stage prostate cancer,
> > ! that this was not true of folic acid and that the association between
> > ! B12 and cancer risk required examination in other large prospective
> > ! studies.[36]

> > ! Most epidemiologic studies suggest diets high in folate are associated
> > ! with decreased risk of breast cancer, but results are not uniformly
> > ! consistent. One broad cancer screening trial reported a potential
> > ! harmful effect of much folate intake on breast cancer risk, suggesting
> > ! routine folate supplementation should not be recommended as a breast
> > ! cancer preventive,[37] but a 2007 Swedish prospective study found much
> > ! folate intake was associated with a lower incidence of postmenopausal
> > ! breast cancer.[38] A 2008 study has shown no significant effect of
> > ! folic acid on overall risk of total invasive cancer or breast cancer
> > ! among women.[39] Folate intake may not have any effect on the risk of
> > ! breast cancer but may have an effect for women who consume at least 15
> > ! g/d of alcohol.[40] Folate intake of more than 300 µg/d may reduce the
> > ! risk of breast cancer in women who consume alcohol.[40]

> > ! Most research studies associate high dietary folate intake with a
> > ! reduced risk of prostate cancer.[36] Recently, a clinical trial showed
> > ! daily supplementation of 1 mg of folic acid increased the risk of
> > ! prostate cancer, while dietary and plasma folate levels among vitamin
> > ! nonusers actually decreased the risk of prostate cancer.[41] A Finnish
> > ! study consisting of 29,133 older male smokers observed prostate cancer
> > ! risk had no relationship with serum folate levels.[7] [edit]

> >    And there is no mention of cancer risk here on a government website
> >    for users:

> >    http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000723/

> >    There are many known cancer hazards
> >    in foods, for example nitrates used as preservatives.  People who
> >    are serious about reducing cancer risk have a lot of reading to do,
> >    and excess vitamins is among the least of their worries.

> >    You have a long way to go before you have half the evidence of the
> >    link between lung cancer and cigarettes that we had in 1960.  There
> >    is much anecdotal evidence even before this.  Particularly notable
> >    was the death of King George VI from lung cancer in 1952.  The
> >    strong anecdotal evidence connecting smoking and lung cancer was the
> >    reason that those statistical studies were funded.

> >    It is wrong to claim that statistical studies alone prove cause and
> >    effect.  The frequent use of the comparison with tobacco is
> >    disingenuous.  In this case it is even wrong to claim that statistical
> >    studies show the claimed linkage.

> --
> deT notsuH                    bass-ackwards          ude.hcimu@pcird
> After a certain age, if you don't wake up aching in every joint, you
> are probably dead.