What are the health benefits of magnesium?

Magnesium is one of the seven essential macro minerals (requiring greater than or equal to 100mg/day). The human body contains approximately 20-28 milligrams of magnesium. Over 50% of that magnesium is stored in the skeletal system, and the rest is found in muscle, soft tissues and bodily fluids.²
Magnesium plays an important role in over 300 enzymatic reactions within the body including the metabolism of food and synthesis of fatty acids and proteins. Magnesium is involved in neuromuscular transmission and activity and muscle relaxation. Magnesium deficiency, especially prevalent in older populations, is linked to insulin resistance, metabolic syndrome, coronary heart disease and osteoporosis.
This MNT Knowledge Center feature is part of a collection of articles on the health benefits of popular vitamins and minerals. It provides an in-depth look at recommended intake of magnesium, its possible health benefits, foods high in magnesium and any potential health risks of consuming magnesium.

Contents of this article:

1. Recommended intake
2. Possible health benefits of consuming magnesium
3. Foods high in magnesium
4. Potential health risks of consuming magnesium

Recommended intake

The Recommended Daily Allowance (RDA) for magnesium depends on age and gender. For children 1-8 years of age the RDA ranges from 80-130 milligrams.

Magnesium supplements are available from stores, but it is always best to obtain any vitamin or mineral through food.

Children ages 9-13 are recommended to consume 240 milligrams of magnesium per day.
After age 14, RDA recommendations are divided by gender, with men requiring more magnesium than women. After the age of 14, the RDA for men ranges from 400-420 milligrams. For women 14 years and older, the RDA ranges from 320-360 milligrams.
Magnesium has a medium level of bioavailability (the ability of a minerals absorption within the small intestine and retention of that mineral in the body for use). The efficiency of absorption depends on the amount of magnesium in the diet, overall magnesium status of the person and the diet as a whole. Unabsorbed magnesium is excreted in the feces.²
Magnesium supplements are available, but it is best to obtain any vitamin or mineral through food. It is not the individual vitamin or mineral alone that make certain foods such an important part of our diet, but the synergy of all of that foods nutrients working together. It has been proven time and again that isolating certain nutrients in supplement form will not provide the same health benefits as consuming the nutrient from a whole food. First focus on obtaining your daily magnesium requirement from foods then use supplements as a backup.

Possible health benefits of consuming magnesium

Bone health

Magnesium is important for bone formation. High magnesium intakes are associated with a greater bone density and have shown to be effective for decreasing the risk of osteoporosis in postmenopausal women.

Diabetes

Several studies have confirmed the inverse relationship between magnesium intake and the risk of diabetes. For every 100mg/day increase in magnesium intake, the risk of developing type 2 diabetes decreases by approximately 15%. Most magnesium intake in these studies was from dietary sources, not supplements. Clinical studies have shown improvement in insulin sensitivity with magnesium intake between 300 and 365 mg/day.¹
Researchers were also able to show that low magnesium levels resulted in impaired insulin secretion and lower insulin sensitivity. Since magnesium plays an important role in carbohydrate and glucose metabolism, it is no wonder magnesium status has an effect on diabetes.

Heart health

Adequate magnesium intake has been associated with a lower risk of atherosclerosis and hypertension. Rapid post-heart attack administration of magnesium reduces the risk of mortality. Improvement in lipid profiles has been seen with an intake of 365 mg of magnesium per day.

Foods high in magnesium

The best sources of magnesium are nuts and seeds, dark green vegetables, whole grains and legumes. Magnesium is also added to some breakfast cereals and other fortified foods.

Magnesium is found in a wide variety of foods, such as green leafy vegetables, nuts, seeds, brown rice, bread (especially wholegrain), fish, meat and dairy foods.

• Sunflower seeds, dry-roasted, ¼ cup: 128 milligrams
• Almonds, dry-roasted, ¼ cup: 105 milligrams
• Sesame seeds, roasted whole, 1 oz: 101 milligrams
• Spinach, boiled, 1 cup: 78 milligrams
• Cashews, dry-roasted, 1 oz: 74 milligrams
• Shredded wheat cereal, two large biscuits: 61 milligrams
• Soymilk, plain, 1 cup: 61 milligrams
• Black beans, cooked, ½ cup: 60 milligrams
• Oatmeal, cooked, 1 cup: 58 milligrams
• Broccoli, cooked, 1 cup: 51 milligrams
• Edamame, shelled, cooked, ½ cup: 50 milligrams
• Peanut butter, smooth, 2 tablespoons: 49 milligrams
• Shrimp, raw, 4 oz: 48 milligrams
• Black-eyed peas, cooked, ½ cup: 46 milligrams
• Brown rice, cooked, ½ cup: 42 milligrams
• Kidney beans, canned, ½ cup: 35 milligrams
• Milk, whole, 1 cup: 33 milligrams
• Banana, one medium: 33 milligrams
• Bread, whole-wheat, one slice: 23 milligrams.

Magnesium is lost during the refinement process of wheat, so look for cereals and bread products made with whole grains. Most common fruits, meat, and fish, are low in magnesium.

Potential health risks of consuming magnesium

Large doses of magnesium can cause a loss in central nervous system control and paralysis. Those with renal (kidney) insufficiency should not take magnesium supplements. It is very unlikely to reach magnesium toxicity with food intake and no cases have ever been reported.
It is the total diet or overall eating pattern that is most important in disease prevention and achieving good health. It is better to eat a diet with a variety than to concentrate on individual nutrients as the key to good health.
Written by Megan Ware, RDN, LD, registered dietitian and nutritionist