Magnesium in diet

Magnesium is needed for more than 300 biochemical reactions in the body. It helps to maintain normal nerve and muscle function, supports a healthy immune system, keeps the heartbeat steady, and helps bones remain strong. It also helps adjust blood glucose levels. It aids in the production of energy and protein.

There is ongoing research into the role of magnesium in preventing and managing disorders such as high blood pressure, heart disease, and diabetes. However, taking magnesium supplements is not currently advised. Diets high in protein, calcium, or vitamin D will increase the need for magnesium.

Most dietary magnesium comes from dark green, leafy vegetables. Other foods that are good sources of magnesium are:

• Fruits (such as bananas, dried apricots, and avocados)
• Nuts (such as almonds and cashews)
• Peas and beans (legumes), seeds
• Soy products (such as soy flour and tofu)
• Whole grains (such as brown rice and millet)
• Milk

Side effects from high magnesium intake are not common. The body generally removes extra amounts. Magnesium excess most often occurs when a person is:

• Taking in too much of the mineral in supplement form
• Taking certain laxatives

Although you may not get enough magnesium from your diet, it is rare to be truly lacking in magnesium. The symptoms of such a shortage include:

• Hyperexcitability
• Muscle weakness
• Sleepiness

Lack of magnesium can occur in people who abuse alcohol or in those who absorb less magnesium including:

• People with gastrointestinal disease or surgery causing malabsorption
• Older adults
• People with type 2 diabetes

Symptoms due to a lack of magnesium have three categories.

Early symptoms:

• Loss of appetite
• Nausea
• Vomiting
• Fatigue
• Weakness

Moderate deficiency symptoms:

• Numbness
• Tingling
• Muscle contractions and cramps
• Seizures
• Personality changes
• Abnormal heart rhythms

Severe deficiency:

• Low blood calcium level (hypocalcemia)
• Low blood potassium level (hypokalemia)

These are the recommended daily requirements of magnesium:

Infants

• Birth to 6 months: 30 mg/day*
• 6 months to 1 year: 75 mg/day*

*AI or Adequate Intake

Children

• 1 to 3 years old: 80 milligrams
• 4 to 8 years old: 130 milligrams
• 9 to 13 years old: 240 milligrams
• 14 to 18 years old (boys): 410 milligrams
• 14 to 18 years old (girls): 360 milligrams

Adults

• Adult males: 400 to 420 milligrams
• Adult females: 310 to 320 milligrams
• Pregnancy: 350 to 400 milligrams
• Breastfeeding women: 310 to 360 milligrams

Diet - magnesium

National Institutes of Health website. Magnesium: fact sheet for health professionals. ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/#h5. Updated September 26, 2018. Accessed May 20, 2019.

Yu ASL. Disorders of magnesium and phosphorus. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 119.

Updated by: Emily Wax, RD, CNSC, University of Virginia Health System, Charlottesville, VA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.