text: in sugar free products? why is phenilalnine added to most sugar free products . i've been told it's laxative but i still dont understand: why sugar free proucts?. i'm diabetic . do i need to worry about having too much phenilalnine? no, you do not have to worry about it.  nutrasweet or aspartame is made up of two amino acids (components of proteins) phenylalanine and aspartic acid.  only people who are born with a genetic disease called phenylketonuria (pku), who have a decreased ability to metabolize phenylalanine should worry about consuming these artificial sweeteners.  it has been proven safe for consumption although some people complain of certain side effects like headaches, which may be psychological or related to something else.  i don't think there is any evidence of aspartame having a laxative effect.  sugar alcohols which are used as a sugar substitute because of their low impact on blood sugars may have a laxative effect if consumed in large quantities.  foods containing sugar alcohols will generally have a warning about excessive consumption.