How come whenever i grow my nails out they are this yellow color?

I use this stuff that helps make my nails grow faster its called Nutra Nail 5 to 7 day growth with Aloe Formula that is what is on the bottle is doesn't have an ingredient label though could that stuff make my nails yellow?How come whenever i grow my nails out they are this yellow color?
I read once that if you cut a lemon in half, and stick your fingers in, it will bring out the white in your finger nails.How come whenever i grow my nails out they are this yellow color?
i used that too! and apparently i cant get my nails to look healthy. but it's been a while that i haven't used it and my nails still look a yellowish color.





you think it could be something in the ingredients and that's why it's not on it.