Vitamins beneficial? Yes, everyone needs vitamins. Did you mean vitamin pills?
I don’t me to be glib, but it depends. If you eat a balanced diet with a variety of foods in adequate amounts (including a variety of vegetables and fruits and some non-vegan foods), or if you already eat fortified foods (that have vitamins added), then no, or probably no, you don’t need a vitamin pill (unless you have a medical problem).
Sometimes women don’t get enough iron in their diet, but iron is a mineral, not a vitamin. Good sources of Vitamin B12 include meat, fish, eggs, poultry, dairy products, and fortified breakfast cereals. With packaged foods you can check the nutrition label.
If you “lack energy” then you may need more rest, or maybe you are stressed-out, or maybe you are anemic (low red blood cell count).
Sometimes serious athletes are exhausted from over-training, but that doesn’t happen to most people. Some people feel weak from obesity and not getting enough exercise (low fitness level.)
Maybe your body isn’t acclimated to the hot summertime temperatures.Sometimes the heat of summertime makes people feel weak, and sometimes (if they perspire a lot) they may need more electrolytes.
You can look up the sources of electrolytes. Many women could use more calcium, which is found in dark green vegetables and dairy products or bones (chew carefully).
With vitamin pills, it’s possible to take too many. Don’t take more than the label indicates.
If your condition persists for two weeks or more or if it worsens, then see a doctor.