There is increasing evidence that folic acid (FA) suppresses immune surveillance of cancer cells and may stimulate cancer cell growth. Earlier in 2009 it was reported that folic acid supplements were associated with excess risk of prostate cancer. Norwegian investigators have reported the risk of dying from cancer is 38% higher in individuals taking FA supplements compared to those who were not. The risk for developing cancer was 21% higher in those taking FA. This nutrient is needed by the body. FA fortification of flour and grain foods has been mandated in the US (but not Norway) since 1998 to reduce neural tube defects in newborns. Those in the Norwegian study received a dose about five times higher than would be found in dietary sources. Enough is needed, but apparently excess may raise cancer risk.
PositiveTip: You really cannot overdose on nutrients from good food. Choose your diet from mainly whole food sources.