Taking vitamins works, but they're not always necessary and they shouldn't replace good nutrition, according to Mayo Clinic. Some people benefit from taking vitamins, like pregnant women who need prenatal supplements.
Multivitamins can replace nutrients when a person isn't eating right every day, according to WebMD. Many Americans don't get the nutrients they need with their usual diet, which makes vitamins helpful. However, Mayo Clinic explains that eating a balanced diet of lean proteins, fruits and vegetables, and whole grains means vitamins aren't necessary.
Conditions that prevent the body from absorbing nutrients, such as chronic diarrhea, food allergies and liver disease, may also make vitamins necessary. Individuals who want to take vitamins should discuss dosages and types with a doctor or dietitian, Mayo Clinic advises.