Brief Answer:
normally there is no need for supplements

Detailed Answer:
Hello,

for a normal young individual like you, the need for supplements does not exist! There are certain disorders though, which may lead to vitamin insufficiency but they mostly involve vitamin B12 and vitamin D. Both can be measured in the blood (it's a simple blood test). If they're both normal then no supplementation would be needed.

The rest of the vitamins and minerals are supposed to be sufficient in your body, as long as you have a healthy diet (no restrictions for certain types of food) and no chronic diseases or drug use.

For a woman of your age, the iron stores can get depleted if you have protracted bleeding during your menstrual cycle. Iron and ferritin can both be measured in the blood as well. Ferritin reflects the body stores of iron and is more useful than iron alone. Iron supplementation might be needed from time to time in women of your age but not without a blood test. Too much iron may cause damage.

Taking vitamins is generally not harmful but some of them may accumulate in the body and even cause toxicity. A, D, E etc are some examples. So unless you have been diagnosed with vitamin insufficiency you should only take what your doctor prescribed to you.

I hope you find my comments helpful!
You can contact me again, if you'd like any clarification or further information.

Kind Regards!

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