Is it possible to overdose on vitamins by taking a vitamin supplement while eating foods that contain vitamins naturally?
Like if I were to take Omega fish oils supplements at the same time as eating plenty of fish.

i don't think it is possible to overdose while taking a supplement and eating a good diet. but you should not take more than the recommended dose stated on the bottle.

The RDA is only enough for a completely healthy person to just get by.
You can only overdose on fat-soluble vitamins (like A,) but it would take an enormous amount to do so, more than a doctor could prescribe, which is more than you could probably take in. Don't worry.

This answers my question, thanks for the replies.