some vitamin or mineral deficiencies can cause symptoms such as fatigue pallid-looking skin brittle hair or fingernails diarrhea memory problems and a weakened immune system. but most deficiencies have to be extreme or have to continue for a long time to cause noticeable problems. if you're worried about vitamin or mineral deficiencies talk to your doctor. tests are available to measure levels of key vitamins or minerals such as vitamin d b12 or iron.
how do i know if i'm deficient in an important vitamin or mineral?