National Nutrition Month: Magnesium
- Mar 16, 2017
- 5 min read
What is magnesium?
Magnesium is a mineral that helps many enzyme systems in the body that regulate reactions like making proteins, function of muscles and nerves (including the heart), controlling blood sugar levels, regulating blood pressure, producing energy, making DNA and RNA, and making bone. Magnesium is abundant in our bodies with about 50-60% of it being located in bone and the rest in soft tissues like muscle. Our bones act as a magnesium reservoir for the body to draw magnesium from to regulate the concentration in our blood. As we age, this reservoir is reduced by nearly half over our lifetimes.
Recommended Dietary Allowance (RDA)
The RDA is the average daily intake of a nutrient that is enough to meet the requirements of nearly all healthy people.
Sources of magnesium
A large national survey indicated that the average magnesium intake for men is about 350 mg/day and about 260 mg/day for women, which is below the RDA listed above. In those above 50 years old, the average intakes were even lower in men and women.
Magnesium is part of chlorophyll, the pigment in plants that makes them green, so green leafy vegetables are high in magnesium. Whole grains and nuts also have a high magnesium content. Some magnesium rich foods are listed below.
For more information about the nutrient contents of different foods, check out the USDA food composition database.
Magnesium deficiency
Magnesium deficiency is relatively rare in healthy people who are eating a balanced diet because both plant and animal foods contain magnesium and our kidneys are able to hold on to magnesium when our intake is low. Increased risk of magnesium deficiency could occur in the following conditions:
GI disorders: Crohn's, Celiac disease, other malabsoprtion syndromes, surgical removal of part of the intestines.
Renal disorders: Diabetes and long-term use of diuretics may cause increased magnesium loss in urine.
Chronic alcoholism: poor dietary intake, increased urinary losses
Age: many studies show that elderly people have lower intakes of magnesium and don't absorb it as well.
Magnesium deficiency could cause low calcium levels, which causes the body to draw calcium out of the bones thereby decreasing bone mass, muscle spasms and tremors, loss of appetite, nausea, vomiting, low potassium levels, and retention of sodium which may lead to swelling. These symptoms occur with progressive magnesium deficiency. Mild deficiency would not cause the severe symptoms.
Cardiovascular disease
Many studies have shown that higher levels of magnesium are associated with lower risk for heart disease. These studies have included hundreds of thousands of people and many were conducted over an extended period of time. One study found that women with the highest magnesium intake had a significantly lower risk of heart attack than women with low intakes. Studies have also shown that magnesium supplements given at just over the RDA help reduce arterial stiffness, which is a marker for heart disease. An additional 100mg per day of magnesium may also reduce risk of stroke.
High Blood Pressure
Studies suggest that there may be a correlation between magnesium and blood pressure, but it is difficult to determine the relationship because many foods that are high in magnesium are often high in potassium and fiber. Studies have found that higher levels of magnesium in our blood may decrease risk of high blood pressure, especially in women. Supplementing with magnesium does appear to reduce blood pressure, particularly for individuals who have been using diuretics, which can cause the body to lose magnesium, and those with low dietary intakes. People who follow the DASH diet (Dietary Approaches to Stop Hypertension) to lower their blood pressure should be consuming adequate magnesium as the diet emphasizes foods rich in magnesium - fruits and vegetables, low-fat dairy, and whole grains.
Migraines
New research is giving strong support for including magnesium as part of the treatment for migraine headaches. It has been previously shown that IV magnesium is effective in treating migraines, but a recent 2016 meta-analysis showed that magnesium supplements significantly decrease the frequency and intensity of migraines. Experts suggest that up to one half of people who suffer from migraines may have increased magnesium losses in their urine and that taking 400mg magnesium supplements is reasonable and safe to help treat these migraine headaches.
Diabetes
Some studies have shown that there is a reduction of Type 2 diabetes risk by 14% for every 100 mg increase in daily magnesium intake. Other large studies have found a lower risk of Type 2 diabetes with higher magnesium intakes, as well. Other studies have looked at how magnesium affects insulin sensitivity - the hormone that allows glucose into cells and decreased blood sugar. Studies indicate that higher magnesium intakes are associated with lower fasting insulin levels, indicating that magnesium improves the body's cells' sensitivity to insulin. Researchers suggest that magnesium supplements can improve blood sugar control in people who may be slightly deficient in magnesium.
Supplements
Magnesium supplements are available in the following forms: magnesium oxide, magnesium gluconate, magnesium chloride, magnesium citrate salts, and more. Magnesium hydroxide is used in some antacids. Magnesium citrate, magnesium gluconate, and magnesium lactate are more easily absorbed into the body than other forms.
If choosing to take a magnesium supplement, it may be beneficial to take a B-complex vitamin, or a multivitamin containing the B-vitamins as the level of vitamin B6 in the body determines how much magnesium may be absorbed by the cells.
Magnesium competes with calcium for absorption in the intestines, so avoid taking these supplements together.
Safety
There have not been negative side effects linked to magnesium from food. However, adverse effects have been seen from supplemental magnesium. The primary side effect is diarrhea. More serious side effects occur much later with magnesium toxicity. The Food and Nutrition Board of the Institute of Medicine set the Tolerable Upper Intake Level (UL) for magnesium at 350 mg/day. Higher doses may be taken safely under the supervision of a physician.
There are many medications that may have interactions with magnesium. It is always a good idea to check with your doctor before taking any nutrition supplements when you are on medications.
Antibiotics (i.e. Cipro, Tetracycline, Doxycycline)
Blood pressure medications (Calcium Channel Blockers - Norvasc, Cardizem, Plendil, Calan)
Diabetes meds (Glipizide, Glucatrol, Glyburide)
Digoxin
Diuretics (Furosemide, Hydrochlorithiazide)
Hormone Replacement Therapy
Levothyroxine
Foxamax
Sources:
1) Tone C. "Magnesium Intake." Today's Dietitian. 2016;18(12):18-19.
2) "Magnesium." National Institutes of Health Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/. Updated February 11, 2016. Accessed January 19, 2017.
3) Higdon J. "Magnesium." Linus Pauling Institute's Micronutrient Information Center. http://lpi.oregonstate.edu/mic/minerals/magnesium. Published 2001. Updated October 2013. Accessed January 19, 2017.
4) Chiuve SE, Korngold EC, Januzzi Jr JL, Gantzer ML, Albert CM. Plasma and dietary magnesium and risk of sudden cardiac death in women. Am J Clin Nutr. 2011;93:253-60.
5) "Magnesium." University of Maryland Medical Center. http://umm.edu/health/medical/altmed/supplement/magnesium. Updated August 6, 2015. Accessed March 15, 2017.
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