Magnesium
by Karen Schroeder Kassel, MS, RD, MEd
Magnesium is an essential mineral that has a hand in many vital body functions, for example releasing energy, building protein, and stabilizing bone. It is also one of several nutrients that helps keep blood pressure within a healthy range. And since magnesium is plentiful in vegetables, legumes, and whole grains, it is easy to consume enough if you are eating healthy food.
Functions TOP
Magnesium's functions include:
- Activating more than 300 enzymes (Enzymes are chemicals that regulate a variety of body functions, including making body proteins and causing muscle contractions.)
- Aiding in the metabolism of fat and carbohydrate to produce energy
- Ensuring proper nerve and muscle function and keeping heart rhythm steady
- Helping synthesize nucleic acids (DNA and RNA) and proteins, which are the building blocks of body tissue
- Giving structure to cell membranes
- Helping keep bones and teeth healthy
Recommended Intake TOP
| Age Group |
Recommended Dietary Allowance
(mg/d) | |
|---|---|---|
| Male | Female | |
| 0-6 months |
Adequate intake
(AI) = 30 | AI = 30 |
| 7-12 months | AI = 75 | AI = 75 |
| 1-3 years | 80 | 80 |
| 4-8 years | 130 | 130 |
| 9-13 years | 240 | 240 |
| 14-18 years | 410 | 360 |
| 19-30 years | 400 | 310 |
| 31-50 years | 420 | 320 |
| >51 years | 420 | 320 |
| Pregnancy (18 years or younger) | n/a | 400 |
| Pregnancy 19-30 years | n/a | 350 |
| Pregnancy 31-50 years | n/a | 360 |
| Lactation (18 years or younger) | n/a | 360 |
| Lactation 19-30 years | n/a | 310 |
| Lactation 31-50 years | n/a | 320 |
Magnesium Deficiency TOP
Magnesium deficiency is rare because most people have large stores of this mineral in their body. However, it can be caused by diseases or medications that interfere with the body's ability to absorb magnesium. Symptoms of a magnesium deficiency include: irregular heartbeat, nausea, confusion, depression, tingling, weakness, loss of appetite, and muscle contractions and cramps.
Conditions and medications that may lead to a magnesium deficiency include:
-
Gastrointestinal disorders, such as:
- Severe diarrhea
- Chronic or severe vomiting
- Surgical removal of part of the intestine
- Intestinal inflammation
- Malabsorption disorders, including:
- Crohn’s disease
- Cystic fibrosis
- Celiac disease
- Diseases of the pancreas, liver, or gallbladder
- Thiazide diuretics (can increase loss of magnesium in the urine)
- Certain antibiotics
- Poorly controlled diabetes (can increase the loss of magnesium through urine)
- Alcohol use disorder—Alcohol increases urinary excretion of magnesium. People who drink heavily typically have poor diets that are lacking in many essential nutrients, including magnesium.
- Kidney disease—The kidneys are important for reabsorption and excretion of magnesium.
Tolerable Upper Intake TOP
It's also possible to get too much magnesium. The Office of Dietary Supplements publishes tolerable upper intake levels for magnesium.
| Age Group |
Tolerable Upper Intake Levels
(mg/d) | |
|---|---|---|
| Male | Female | |
| 1-3 years | 65 | 65 |
| 4-8 years | 110 | 110 |
| 9-18 years | 350 | 350 |
| 19+ years | 350 | 350 |
| Pregnancy (18 years or younger) | n/a | 350 |
| Pregnancy 19+ | n/a | 350 |
Magnesium Toxicity TOP
Magnesium toxicity through food intake is not a concern for most healthy people. However, people with kidney disease may develop toxicity because the kidneys are responsible for regulating the level of magnesium in the blood. Also it is possible to take too much magnesium in supplements. Symptoms of magnesium toxicity include:
- Diarrhea
- Abdominal cramping
- Nausea and diarrhea
- Muscle weakness
- Irregular heartbeat
Major Food Sources TOP
Magnesium is found in a variety of foods. The best sources are legumes, nuts, whole grains, and certain vegetables. "Hard" water (which is high in dissolved minerals, specifically calcium and magnesium) is also a source of magnesium.
Foods that provide high levels of magnesium include:
- Wheat bran
- Almonds
- Spinach
- Cashews, dry roasted
- Soybeans
- Soymilk
- Black beans
- Edamame
- Whole wheat bread
- Shredded wheat cereal
- Oatmeal
Health Implications TOP
Blood Pressure
Greater magnesium intake is associated with a lower incidence of high blood pressure. This is the finding of a few large clinical studies. One of these, the DASH (Dietary Approaches to Stop Hypertension) study found that a diet high in magnesium, potassium, and calcium and low in sodium and fat can significantly lower blood pressure. You can get these nutrients by eating a diet rich in fresh fruits and vegetables, legumes, whole grains, and low-fat dairy foods.
Based on the growing number of studies showing a positive role for magnesium in managing blood pressure, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends maintaining an adequate magnesium intake to prevent and manage high blood pressure.
Heart Disease
Several studies have found links between magnesium status and heart health. Many of these suggest that an adequate intake of magnesium is protective of the heart. However, further study needs to be done to clarify magnesium's role.
Osteoporosis TOP
Since a significant amount of magnesium is stored in the bones and one of magnesium's roles is to help keep bones healthy, it would make sense that magnesium would help protect bones from the thinning of osteoporosis. Several studies have suggested just that—magnesium supplementation may improve bone mineral density. However it is still not clear, and more study needs to be done.
Tips For Increasing Your Magnesium Intake TOP
It is easy to meet your magnesium needs through foods. To increase your intake, try some of the following:
- Sprinkle wheat germ over your morning bowl of cereal or oatmeal and on top of casseroles or in baked goods.
- Throw a handful of nuts into a spinach salad to add a little crunch and some extra nutrition.
- Wrap beans, rice, sauteed vegetables, and a little bit of cheese in a warm tortilla for lunch.
- Add beans to dishes like chili, soup, salad, pasta, or rice.
- Have a bowl of whole grain cereal for breakfast or to snack on; if you are not used to the taste, mix it with your usual cereal.
- Bake a potato and top it with sauteed spinach, black beans, and salsa.
- Spread peanut butter on your toast or bagel instead of butter, margarine, or cream cheese.
RESOURCES:
Eat Right—Academy of Nutrition and Dietetics
http://www.eatright.org
International Food Information Council Foundation
http://www.foodinsight.org
CANADIAN RESOURCES:
Dietitians of Canada
http://www.dietitians.ca
Health Canada
http://www.hc-sc.gc.ca
REFERENCES:
Appel L, Moore T, Obarzanek E, et al. A clinical trial of the effects of dietary patterns on blood pressure. N Engl J Med. 1997;336(16):1117-1124.
Magnesium. Office of Dietary Supplements website. Available at: https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional. Updated February 11, 2016. Accessed April 29, 2016.
Osteoporosis. EBSCO DynaMed website. Available at:
...(Click grey area to select URL)
Updated April 29, 2016. Accessed April 29, 2016.
The seventh report of the Joint National Committee on Prevention, Detection, and Treatment of High Blood Pressure. Hypertension. 2003;42(6):1206-1252.
Last reviewed April 2016 by Michael Woods, MD
Last Updated: 4/29/2016