Med­ical research is begin­ning to sug­gest that vit­a­mins have ques­tion­able health benefits.

One study found that vit­a­min C is inef­fec­tive for cold–prevention unless you’re exposed to extreme phys­i­cal stress (read: ultra­ma­rathon run­ners and “sol­diers dur­ing sub-Arctic win­ter exercises”).

The New York Times looks at this trend, not­ing that in some cases, vit­a­mins may do more harm than good. How­ever, there are always excep­tions (B12 sup­ple­ments for the elderly and folic acid for women of child-bearing age have proven health ben­e­fits) and caveats:

Despite a lack of evi­dence that vit­a­mins actu­ally work, con­sumers appear largely unwill­ing to give them up. Many read­ers of the Well blog say the prob­lem is not the vit­a­min but poorly designed stud­ies that use the wrong type of vit­a­min, set­ting the vit­a­min up to fail. Indus­try groups such as the Coun­cil for Respon­si­ble Nutri­tion also say the research isn’t well designed to detect ben­e­fits in healthy vit­a­min users.