For the first time I had Jarrow's Methyl Folate 5-MTHF 400 mcg after breakfast followed by a quarter of Jarrow's 5mg B12 after 1 hour. This gave me a severe headache the whole day and by evening I could feel pain in right chest extending down to my right arm. I am continuing to take the b12 (started with small dose) but am very afraid to take quatrefolic again. I bought this folate thinking its the best in the market (4th gen) but my first day experience was not a good sign. How do I decide which folate is best for me? I am now even afraid to try metafolin.