raw veggie juices: cellulose hinders digestion?

hello! i tried veggie juicing including greens. I started losing hair and also got constipated.
I read that raw veggie juices contain cellulose which is not digested well by the body. There are claims that cellulose prevents absorption of minerals and vitamins rendering raw veggie juices to be an ineffective srouce of nutrition.

Does that make sense? Is there a particular way or combination that must be taken for raw veggie juices to be effective? Are only some veggies to be used?

tks in advance!