Generally regarded as safe by the U.S. Food and Drug Administration, magnesium carbonate can be used in both foods and medicines. It's a form of magnesium, which you need in small amounts for good health. Adults should consume between 310 and 420 milligrams per day of this essential mineral, depending on their age and gender, as it is important for forming proteins, regulating blood pressure and blood sugar and nerve and muscle function. Check with your doctor before using magnesium carbonate as a supplement to make sure this would be safe for you.
As a Supplement
While magnesium chloride, oxide and citrate may be the more visible forms of magnesium supplements on the store shelves, you can also purchase magnesium carbonate supplements to help increase your magnesium levels. This compound is used to increase the magnesium content of certain foods too.
As a Food Additive
Magnesium compounds like magnesium carbonate are used as food additives. They keep powdered or granulated foods from forming clumps, regulate acidity in foods and help foods maintain their colors. Foods that may contain this additive include salt, powdered sugars, powdered milk, dairy products, processed fruits and vegetables, processed meat and seafood, soups, sauces, condiments, bakery products, candies, prepared foods, alcoholic beverages, sports and energy drinks and cereals.
Side Effects and Interactions
Magnesium carbonate isn't likely to cause side effects in the small amounts used in foods, but it may cause side effects in some people when used as a supplement or medication. These include nausea, diarrhea and flatulence.
Magnesium supplements can interact with some medications, including proton pump inhibitors, diuretics, osteoporosis medications and antibiotics, so check with your doctor before taking supplemental magnesium to make sure it would be safe for you.
Potential for Toxicity
Adults should limit themselves to no more than the tolerable upper intake level of magnesium from supplements, which is 350 milligrams per day. In rare cases, very high magnesium levels can cause a condition called paralytic ileus, in which the intestinal muscles are paralyzed, causing a blockage of the intestines. High doses could also lead to magnesium toxicity, with symptoms including difficulty breathing, irregular heartbeat, very low blood pressure, facial flushing, vomiting and heart attack.