Taking a multivitamin is a good way to ensure your body gets all the nutrients it needs in case your meals, snacks and drinks fall short. Multivitamins, however, do not provide you with the full amount of nutrients that your body needs daily. Depending solely on a multivitamin for nutrition can be dangerous.
The daily recommended dose of magnesium, according to the University of Maryland Medical Center, is around 300 mg for adult women and around 400 mg for adult males. Pregnant and breastfeeding women need slightly more -- around 320 to 345 mg of magnesium per day. Children need much less than adults, and their requirements vary depending on age.
Magnesium in Multivitamins
The amount of magnesium in a multivitamin might vary depending on brand and type. Some multivitamins are formulated specifically for children, teens, adults or the elderly. Because each age group might need more or less of certain vitamins, this might change the dosage of nutrients found in the multivitamin. The average adult multivitamin can contain up to 100 mg of magnesium, according to the Linus Pauling Institute.
If you're relying solely on a multivitamin to supply your body with enough magnesium — or any other nutrient — you're probably not getting enough. Multivitamins are merely meant to help your body get nutrients that you might have missed through diet; they are not an optimal source to supply your recommended daily dose of any nutrient. The average multivitamin only contains about a third or less of the average adult's magnesium needs. Relying on a multivitamin to fully supply your body with enough magnesium could result in a magnesium deficiency.
A magnesium deficiency can affect your body in a variety of ways. You can develop restless leg syndrome, anxiety, sleep disorders and irritability. You might also experience nausea and vomiting, along with abnormal heart rhythms and mental confusion. Muscle spasms, weakness, hyperventilation and seizures might also occur if you have a severe magnesium deficiency. If you believe you aren't getting enough magnesium, include more magnesium-rich foods in your diet. Whole grains, vegetables and nuts are all good food sources of magnesium.