What Happens to Your Body When You Take Magnesium and Iron Together?

If you have anemia, mineral deficiencies, or other health conditions, your healthcare provider may recommend taking both magnesium and iron supplements. They can be taken together if you follow certain precautions.

1. May Improve Metabolism

Iron is an essential mineral that is responsible for many bodily processes. Iron is found in hemoglobin, which helps to carry oxygen throughout the body. Other benefits of iron include that it:

• Supports growth and development
• Supports muscle metabolism and healthy tissue
• Supports the immune system 
• Produces hormones

2. May Regulate Blood Pressure

Magnesium is another essential mineral involved in over 300 biochemical reactions in the body. Magnesium helps to regulate blood pressure and blood sugar, helps to keep bones strong, helps muscles contract, and helps to keep a steady heartbeat. Research has shown that magnesium may be helpful in treating migraines, anxiety and depression, and insomnia.

Eating a healthy, well-balanced diet can help ensure you get enough magnesium. Individuals with diabetes and celiac disease are more at risk of not getting enough magnesium.

3. May Decrease Risk of Anemia

Like many nutrients, magnesium and iron work synergistically in the body and may both affect anemia. Research has shown that those who consumed higher amounts of dietary magnesium have a lower risk of developing anemia. Those who are deficient in magnesium are more likely to have anemia. Taking both iron and magnesium may help improve and prevent anemia.

4. May Lead to Upset Stomach

Iron supplements are known to cause gastrointestinal side effects such as nausea, constipation, and diarrhea. Magnesium can also cause an upset stomach. Some forms of magnesium are used to treat constipation, which can lead to diarrhea. Taking iron and magnesium together can increase these side effects.

More iron is absorbed by the body when it is taken on an empty stomach. It is best to take it one hour before or two hours after meals. If stomach upset occurs, it can be taken with food, but not dairy products. The calcium in dairy products will decrease the absorption of iron.

Chelated forms of magnesium are more gentle on the stomach and have improved absorption. Magnesium should be taken with a meal. Taking magnesium on an empty stomach increases the risk of nausea and diarrhea.

5. May Reduce Effectiveness

Certain types of magnesium may reduce how much iron is absorbed by the body. Spacing apart the times when you take iron and magnesium may counteract this. If you cannot separate them, you need to be cautious about which type of magnesium you take.

In one case report, a woman developed iron deficiency anemia despite taking iron supplements. She was also taking excessive magnesium laxatives. Upon discontinuation of the magnesium laxatives, her anemia improved. It is thought that magnesium oxide inhibited the absorption of the iron supplements.

How to Take Them Together

If your healthcare provider recommends both iron and magnesium supplements, it is best to take them at separate times.

Iron is best absorbed on an empty stomach, one hour before or two hours after a meal. Taking iron with orange juice, citrus fruits, strawberries, or a vitamin C supplement can improve absorption.

If you get an upset stomach from taking iron, try taking it with a small amount of food, but avoid coffee, tea, dairy products, and high-fiber foods. These will decrease the amount of iron that your body absorbs. Try to separate other medications from iron by at least two hours. 

Magnesium is best taken with food. Taking magnesium on an empty stomach may cause nausea or diarrhea. It is best to separate magnesium from your medications by about two hours. Also, be sure to choose a magnesium supplement that will absorb well.

Magnesium has been shown to have calming effects and may help with sleep.

How Much Iron and Magnesium Should You Take per Day?

Recommended daily allowances for iron vary depending on age, sex, and health conditions:

• Adults, age 51 and over: 8 milligrams (mg) per day (mg/day)
• Adult females, ages 19 to 50: 18 mg/day
• Adult males, ages 19 to 50: 8 mg/day

Women who are menstruating or pregnant need more iron. During pregnancy, the iron requirement increases to 27 mg/day. While breastfeeding, the iron requirement decreases to 9–10 mg/day. Vegans and vegetarians (people on plant-based diets) also need more iron, as iron from plants is not absorbed as well.

Recommended daily allowances for magnesium also vary depending on age and gender:

• Adult females, age 31 and over: 320 mg/day
• Adult male, ages 31 and over: 420 mg/day
• Adult females, ages 19 to 30: 310 mg/day
• Adult males, ages 19 to 30: 400 mg/day

When to Avoid Taking Them At the Same Time

Separate the two supplements in these cases:

• If you have a sensitive stomach, it is best to separate your doses of iron and magnesium. Both can contribute to an upset stomach, and you are more likely to continue taking medications that do not cause debilitating side effects.
• If treating a deficiency with high doses of iron or magnesium, taking iron and magnesium together can cause them to compete for absorption, resulting in decreased effects. It is best to separate the doses by at least two hours.
• If taking magnesium for its laxative or antacid effects, separating doses will ensure that both medications get absorbed and will work as intended.

Consult a Healthcare Provider

Iron and magnesium supplements can interfere with the absorption of other medications. Most interactions can be managed by separating doses by at least two hours. Speak with your healthcare provider for more specific instructions.