Vitamin B-12 is also added to some foods, such as fortified breakfast. Food sources of vitamin B-12 include poultry, meat, fish and dairy products. If you have difficulty achieving this amount, some experts recommend adding a fish oil supplement to your daily regimen. Vitamin B-12 (cobalamin) plays an essential role in red blood cell formation, cell metabolism, nerve function and the production of DNA, the molecules inside cells that carry genetic information. Dont obtain two to three servings of fish a week. Are a vegan or a vegetarian who eats a limited variety of foods. In addition, stools may appear darker in color in patients taking products containing iron. These effects are generally dose-related. Rochester, Minn.: Mayo Foundation for Medical Education and Research 2017. Supplements may be appropriate for people who: Dont eat well or consume less than 1,600 calories a day. Gastrointestinal side effects associated with oral iron therapy have included nausea, constipation, anorexia, heartburn, vomiting, and diarrhea. Reversal of skin aging with topical retinoids.

New York, N.Y.: Houghton Mifflin Harcourt 2017. In: Academy of Nutrition and Dietetics Complete Food and Nutrition Guide. Office of Dietary Supplements, National Institutes of Health. Vitamin A deficiency causes anemia and dry eyes. This kind of deficiency isn't common in the United States. People who have low levels of vitamin A appear to benefit most from vitamin A supplements. Research suggests that supplementation might reduce death due to measles. Vitamin A supplements are recommended for children with measles who are at an increased risk of vitamin A deficiency. The association between use of vitamin A supplements and reduced risk of lung, prostate and other types of cancer is unclear. It's not entirely clear what role beta-carotene played. You may report side effects to FDA at 1-80. Call your doctor for medical advice about side effects. This is not a complete list of side effects and others may occur. A large clinical trial showed that people at high risk of advanced age-related macular degeneration reduced their risk of developing the condition by 25 percent by taking a specific combination of vitamins that included beta-carotene. upset stomach headache or unusual or unpleasant taste in your mouth.

Large doses of oral vitamin A supplements don't appear to affect acne. Research on oral vitamin A for specific conditions shows:

Multivitamin side effects