Think of vitamins like a nice jacket. Maybe it's a really nice colorful jacket and it looks great on your friend Gina. It helps her feel more confident in that job interview she has coming up. She gets the job and she's very happy. However that doesn't mean that jacket is going to look great on you or be helpful in your job interview. It's never been proven that this jacket makes a difference, it just worked well for Gina.
Maybe you are already employed and not even looking for a job. Maybe you already have a nice jacket you've had for years that you wear for work and it fits you well. You might not need that jacket because you are different from Gina. But a lot of people end up buying that jacket because they heard from someone you need to have a jacket for an interview and since that one worked well for Gina it will probably work for them. No one really knows what the jacket is made of or where it came from but it looks great in the store window. The jacket company makes a lot of money and while some people might get jobs wearing the jacket it's probably because they convinced themselves the jacket would help and as in effect were more relaxed in the interview and presented themselves well.
In the end it was the power of the person's mind and not the jacket, but they give all the credit to the jacket anyway. The jacket company ends up releasing the jacket in a bunch of new colors for different types of interviews but without any proof that different colors make any difference for different interviews.
That is how jackets...I mean a lot of vitamin supplements work.
There is a great quote by Paul Chek who is a fitness specialist I've had the pleasure of listening to over the years at various conferences:
"Vitamins are like nails. Even if you have nails made of gold, if the wood you are building your boat out of is [rotten], it will still sink."
So if the quality of your diet is poor you're probably not going to get the most out of your vitamins in the first place! For a large portion of the population, as long as you eat a healthy balanced diet you probably don't need extra supplements. Don't let others convince you just because they were told it was good for them or it worked for them in the past that it will also work for you. Make sure there is a real evidence, make your money count and make sure it's something that will really benefit you.
But remember; vitamin supplements do have their place depending on your health, age, gender and a range of other factors. It's important to know what's right for you, so ask your doctor or dietitian if you're unsure. There is no one jacket fits all answer.
If you want to know more about where the vitamin craze came from there is a great video by Adam Conover from Adam Ruins Everything I highly recommend watching. Have a look below.