Which b vitamin should i take for stress?

B vitamins: Talk with your physician, but most can benefit from a good b complex containing b6, thiamine, b12, folate, (folic acid) niacin, riboflavin, etc. Alternately, you could use a high-quality multivitamin that offers these as well as antioxidants and minerals. Magnesium in the form of magnesium glycinate is very helpful, and less likely than other forms to cause diarrhea.