Magnesium plays a vital role in more than 300 enzymatic reactions in the body. Its key benefits include supporting heart health and regulating heartbeat, controlling blood sugar levels, strengthening bones and teeth, relieving muscle tension, as well as improving sleep quality and reducing stress and anxiety.

However, excessive intake of magnesium can cause serious harm. Consuming amounts exceeding the recommended dosage may lead to diarrhea and abdominal cramps, and in severe cases, it may cause difficulty breathing, irregular heartbeat, and even death.

Acute magnesium poisoning is not very common, but taking dietary supplements - which often contain amounts of magnesium higher than what is found in food - may increase the risk.

These are signs of magnesium overdose, according to Health website:

Blurred vision

Confusion

Dizziness

Facial flushing

Headache

Nausea

Slowed reflexes

Muscle weakness

If high magnesium levels are left untreated, they may lead to excess magnesium in the blood, a condition known as hypermagnesemia, with serious and potentially fatal complications such as low blood pressure, respiratory paralysis, and cardiac arrest.

Taking magnesium supplements may also cause unwanted side effects, even if you do not exceed the maximum allowed dosage.

Diarrhea is one of the most common side effects because magnesium draws water into the stool. This is more likely with magnesium oxide or magnesium citrate, which are commonly used to treat constipation.

What is the excessive amount of magnesium?

The recommended daily amounts of magnesium (from food and supplements combined) are:

Ages 14 to 19: 410 mg for men and 360 mg for women.

Ages 19 to 30: 400 mg for men and 310 mg for women.

Ages 31 and older: 420 mg for men and 320 mg for women.

Women need slightly more magnesium during pregnancy, while infants and children need much less.

As for magnesium supplements alone, the safe upper limit is 350 mg for all adults over 9 years old.

The more you consume magnesium beyond the recommended amounts, the more likely you are to experience symptoms of magnesium poisoning, but this is very rare in people with normal kidney function. In this group, mild poisoning can usually be treated by stopping magnesium supplements.

Magnesium is abundant in the following foods:

Nuts and seeds: such as pumpkin seeds (contain ~150 mg per 30 grams), almonds, and cashews.

Leafy greens: like boiled spinach (contains ~78 mg per half cup).

Legumes: such as black beans and edamame.

Whole grains: such as cooked quinoa and brown rice.

Fruits: such as avocado and banana.

Dark chocolate: especially those with 70% cocoa content or more.