Make sure to read the ingrediants because off brands and other brands will put fillers in them that are not good for you or put the cheapest things in there. i would do some research on good vit companies. there are a lot of good and reputable companies out there.
I take either a women's multi or a CarbSmart vitamin daily. It's supposed to be "good insurance." But I always buy the cheapest drugstore brands.
There's a lot about our food supply that isn't optimal - soil conditions, monoagricultural practices, if you eat any packaged foods there's additives for freshness and processing thrown in. There's probably a lot about our food that can compromise the uptake of vitamins and minerals. That's the only reason I take a multi every day. It's just cheap insurance.
FWIW, I've been on a low-carb diet for almost 20 years and have had periods in there where I didn't take any vitamins, usually due to long periods of traveling, months being out of the country or whatever, and it didn't affect my health.
Do what you want. But you'd do best avoiding foods like grains and eating mostly fresh fish and meats, green veggies, the lower carb fruits, and nuts. Stay away from anything processed, including grains.