Whitens and Soften Your Nails

Grrrr. my nails is blackish. I ate grapes. I like grapes without skin.i used to peel off the skin with my nails. then i cook saluyot. (spinach) . i cut the stem with my nails . The following day i found my nails became blackish in color and looks untidy. It was stained by the grapes and spinach. I read from the newspaper that scrub with baking soda or whitening toothpaste is very effective to whitens your nails and to soften the cuticles with olive oil. Do you think it's true? I'll still try to see if effective because i used to prepare vegetables which stains my nails.