Does taking psyllium fiber supplements effect nutrient absorbance?

They should not: For the most part, dietary fibers don't really bind to much except good at holding onto water (thus softening stool) and so does not prevent absorption of nutrients. So don't worry, take your fibers. Most of us in the good us of a don't consume enough fibers. If you can, do it for better health. If you have concerns, consult doc. Good luck.