Has anyone here ever determined a negative effect of food supplements on weight loss?

I am a believer in food supplements--in fact I was raised on them. I get lazy, though, and fall into bad habits that can last years at a time. When I first started low-carbing (two years ago) I was steadily losing but not taking supplements. I got my act together and and for the past couple of months have been taking vitamins as regularly as I can remember to. I do find if I don't take them all as soon as I get up in the morning I won't think of them again the rest of the day. I expect it is much better to spread them out over the day, but I figure getting some is better than none.

What I'm beginning to wonder about, though, is I've been losing very, very slowly for the past month of so, with frequent gains of a pound or two without any changes in my eating, which I know is perfectly normal to many. I have noticed, though, that when the scale does suddenly go down it often seems to be after I've forgotten to take my vitamins. I'm beginning to wonder if there is a correlation, but hate to just stop taking them.

Has anyone else ever noticed this or experienced it?