Diet issues are one of those things that are really easy to miss. You can easily get used to feeling a little worse every day until significant issues sneak up on you. With that in mind a basic multivitamin is a cheap option.

You don't need to taken them every day, one multi vitamin ever other day or even one day a week can actually help with a lot of issues over the long term. Much like exercise consistency is more important than a few years of excess.

PS: I have actually been referred to a nutritionist due to medical issues.