Multivitamin supplements are a convenient way to prevent vitamin deficiency when your diet does not provide adequate nutrition. While multivitamin supplements don't mean you can eat unhealthy foods all the time and get away with it, they do provide backup nutrition when your diet falls short of optimal.

Most multivitamin supplements also include minerals. Some very important minerals that people can be easily deficient in are magnesium, iron, calcium and zinc. Multivitamin supplements also usually contain many different vitamins, including the ones listed below.

Vitamin A is one of the vitamins multivitamins supplements usually contain. It's relatively rare to be deficient in vitamin A, unless you are older. You need vitamin A to have your immune system function at its best, and it's also important to prevent certain types of birth defects and bone loss. However, it can be toxic in large doses, so avoid overuse.

Beta-carotene is an antioxidant that is present in many multivitamin supplements; it can help increase white blood cells, and improve your immune system function. Vitamin A and beta-carotene both work to keep your eyes healthy.

Folic acid is an especially important supplement to take during pregnancy, and is included in most prenatal multivitamin supplements. If you are deficient in folic acid while you're pregnant, your baby could be born with low birth weight or neural tube defects such as spina bifida.

The B vitamin family has quite a few members, with most included in multivitamin supplements. Folic acid is one of these, and pyridoxine is another. Vitamin B12 and pyridoxine help control the levels of homocysteine in the blood. Homocysteine, when high, can contribute to strokes, heart disease, and Alzheimer's disease. Vitamin B12 can help fight anemia, heart disease and memory loss. Vitamin B1, or thiamine, is important for proper brain function. Niacin, also called vitamin B3, is a preventative for a disease called pellagra. Although pellagra is relatively rare, it can occur in someone who is deficient in niacin; people suffering from pellagra have inflamed mucous membranes, mental confusion, diarrhea, and scaly sores on the skin.

Vitamin C strengthens your immune system and is an antioxidant. It helps keep your skin healthy, and aids in wound healing and in the prevention of scars.

Adequate amounts of vitamin D are essential to making sure you absorb enough of the mineral calcium. If you don't get enough vitamin D, you can have fractures, bone loss, and can experience a disease called rickets. This can cause severe bone pain to occur. Vitamin D can be manufactured in the body if you get enough exposure to sunlight, but it's often necessary in multivitamin supplements because today, many people don't get enough sunlight. In addition, the deficiency is very painful and detrimental. However, it can be toxic in large amounts, so don't overdo.

Vitamin K, too, is another important vitamin, and its deficiency can cause osteoporosis (brittle bones), easy bruising, and bleeding.

Calcium is among the mega minerals that are important to good health, and is found in many multivitamin supplements. Along with vitamin D and vitamin K, it's necessary to your diet in order to maintain adequate bone mass. You need enough calcium in your diet or through multivitamin supplements for good health, and it also reduces the risk of fracture in bones for older people.

Multivitamin supplements can provide more than 100% of the recommended daily allowance of some vitamins, but in most cases, it's not safe to consume very large amounts of any vitamin or mineral by itself. The levels included in multivitamins are usually safe, but if you take too many supplements in individual form and too much of them, extremely large doses could be unsafe.

Although in theory it's possible to get everything you need from your diet, it's rare to get enough vitamins and minerals every day from your diet, in adequate amounts. There are lots of multivitamin supplements available, and it's important that you do some research to determine the best one for you. Monitor yourself carefully if you do decide to start taking multivitamin supplements, since any side effects may be detrimental; stop taking them if you do experience side effects and see if the side effects go away. If you do experience side effects, ask your doctor to recommend a multivitamin supplement for you.

There are about a dozen recognized vitamins that humans are recommended to consume in certain quantities. A long term shortage in any of them can cause symptoms of vitamin deficiency. While multivitamin supplements can do a great job of preventing vitamin deficiencies, they're not a substitute for a healthy lifestyle, including a healthy diet and regular exercise.