Magnesium is a vital mineral that our bodies need for numerous functions, from regulating blood pressure to supporting muscle and nerve function. Naturally present in various foods, added to some food products, and available as a dietary supplement, magnesium plays a crucial role in maintaining overall health. This article dives deep into “What Is Magnesium Foods,” exploring the best sources, recommended intakes, and the importance of this essential nutrient.
Understanding Magnesium’s Role in Your Body
Magnesium acts as a cofactor in over 300 enzyme systems that regulate biochemical reactions within the body [1-3]. These reactions include protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. It is crucial for energy production, oxidative phosphorylation, and glycolysis. Furthermore, magnesium contributes to bone structural development and is essential for synthesizing DNA, RNA, and the antioxidant glutathione. This mineral also facilitates the active transport of calcium and potassium ions across cell membranes, a process vital for nerve impulse conduction, muscle contraction, and maintaining a regular heart rhythm [3].
An adult body contains approximately 25 grams of magnesium, with 50% to 60% stored in the bones and the remainder in soft tissues [4]. Less than 1% of the total magnesium is found in blood serum, with levels tightly regulated between 0.75 and 0.95 millimoles (mmol)/L [1,5]. Hypomagnesemia, or magnesium deficiency, is defined as a serum magnesium level below 0.75 mmol/L [6]. The kidneys primarily control magnesium homeostasis, typically excreting around 120 mg of magnesium daily through urine [2]. This excretion decreases when magnesium levels are low [1].
Assessing magnesium levels isn’t straightforward because most of it resides inside cells or in bone [3]. The commonly used method is measuring serum magnesium concentration, though it doesn’t strongly correlate with total body magnesium or tissue concentrations [6]. Other assessment methods include measuring magnesium concentrations in erythrocytes, saliva, and urine; measuring ionized magnesium concentrations in blood, plasma, or serum; and conducting a magnesium-loading test. However, no single method is universally satisfactory [7].
Recommended Daily Intake of Magnesium
The Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies provides intake recommendations for magnesium through Dietary Reference Intakes (DRIs) [1]. DRIs are reference values used for planning and assessing nutrient intakes for healthy individuals, varying by age and sex. These values include the Recommended Dietary Allowance (RDA), Adequate Intake (AI), Estimated Average Requirement (EAR), and Tolerable Upper Intake Level (UL).
The RDAs for magnesium are listed in Table 1. For infants up to 12 months, the FNB established an AI based on the mean magnesium intake of healthy, breastfed infants and those receiving solid foods from 7–12 months.
Table 1: Recommended Dietary Allowances (RDAs) for Magnesium [1]
| Age | Male | Female | Pregnancy | Lactation |
|---|---|---|---|---|
| Birth to 6 months | 30 mg* | 30 mg* | ||
| 7–12 months | 75 mg* | 75 mg* | ||
| 1–3 years | 80 mg | 80 mg | ||
| 4–8 years | 130 mg | 130 mg | ||
| 9–13 years | 240 mg | 240 mg | ||
| 14–18 years | 410 mg | 360 mg | 400 mg | 360 mg |
| 19–30 years | 400 mg | 310 mg | 350 mg | 310 mg |
| 31–50 years | 420 mg | 320 mg | 360 mg | 320 mg |
| 51+ years | 420 mg | 320 mg |
*Adequate Intake (AI)
Top Magnesium-Rich Foods to Include in Your Diet
Magnesium is abundant in various plant and animal foods and beverages. Excellent sources include green leafy vegetables like spinach, legumes, nuts, seeds, and whole grains [1,3]. Generally, foods high in dietary fiber are also rich in magnesium. Some breakfast cereals and fortified foods also contain added magnesium. However, processing methods like refining grains can significantly reduce magnesium content [1].
Even tap, mineral, and bottled waters can contribute to magnesium intake, although the amount varies by source and brand, ranging from 1 mg/L to over 120 mg/L [8].
Typically, the body absorbs about 30% to 40% of the magnesium consumed through diet [2,9].
Table 2: Magnesium Content of Selected Foods [10]
| Food | Milligrams (mg) per serving | Percent DV* |
|---|---|---|
| Pumpkin seeds, roasted, 1 ounce | 156 | 37 |
| Chia seeds, 1 ounce | 111 | 26 |
| Almonds, dry roasted, 1 ounce | 80 | 19 |
| Spinach, boiled, ½ cup | 78 | 19 |
| Cashews, dry roasted, 1 ounce | 74 | 18 |
| Peanuts, oil roasted, ¼ cup | 63 | 15 |
| Cereal, shredded wheat, 2 large biscuits | 61 | 15 |
| Soymilk, plain or vanilla, 1 cup | 61 | 15 |
| Black beans, cooked, ½ cup | 60 | 14 |
| Edamame, shelled, cooked, ½ cup | 50 | 12 |
| Peanut butter, smooth, 2 tablespoons | 49 | 12 |
| Potato, baked with skin, 3.5 ounces | 43 | 10 |
| Rice, brown, cooked, ½ cup | 42 | 10 |
| Yogurt, plain, low fat, 8 ounces | 42 | 10 |
| Breakfast cereals, fortified, 1 serving | 42 | 10 |
| Oatmeal, instant, 1 packet | 36 | 9 |
| Kidney beans, canned, ½ cup | 35 | 8 |
| Banana, 1 medium | 32 | 8 |
| Salmon, Atlantic, farmed, cooked, 3 ounces | 26 | 6 |
| Milk, 1 cup | 24–27 | 6 |
| Halibut, cooked, 3 ounces | 24 | 6 |
| Raisins, ½ cup | 23 | 5 |
| Bread, whole wheat, 1 slice | 23 | 5 |
| Avocado, cubed, ½ cup | 22 | 5 |
| Chicken breast, roasted, 3 ounces | 22 | 5 |
| Beef, ground, 90% lean, pan broiled, 3 ounces | 20 | 5 |
| Broccoli, chopped and cooked, ½ cup | 12 | 3 |
| Rice, white, cooked, ½ cup | 10 | 2 |
| Apple, 1 medium | 9 | 2 |
| Carrot, raw, 1 medium | 7 | 2 |
*DV = Daily Value. The U.S. Food and Drug Administration (FDA) developed DVs to help consumers compare the nutrient contents of foods and dietary supplements within the context of a total diet. The DV for magnesium is 420 mg for adults and children age 4 years and older [11].
Magnesium Supplements and Medications
Magnesium supplements come in various forms, including magnesium oxide, citrate, and chloride [2,3]. The Supplement Facts panel indicates the amount of elemental magnesium in the product.
The absorption rate of magnesium varies depending on the form. Magnesium forms that dissolve well in liquid are absorbed more completely than less soluble forms [2,12]. Studies show that magnesium in aspartate, citrate, lactate, and chloride forms is absorbed more efficiently and bioavailable than magnesium oxide and magnesium sulfate [12-16]. High doses of zinc supplements (142 mg/day) may interfere with magnesium absorption [17].
Magnesium is also a primary ingredient in some laxatives [18] and remedies for heartburn and upset stomach [18].
Potential Health Risks of Excessive Magnesium Intake
Consuming too much magnesium from food is not generally a health risk for healthy individuals because the kidneys eliminate excess amounts [29]. However, high doses from dietary supplements or medications can lead to diarrhea, often accompanied by nausea and abdominal cramping [1]. The most commonly reported forms of magnesium causing diarrhea include magnesium carbonate, chloride, gluconate, and oxide [12].
Very large doses of magnesium-containing laxatives and antacids have been associated with magnesium toxicity [58]. Symptoms include hypotension, nausea, vomiting, facial flushing, urine retention, ileus, depression, and lethargy, progressing to muscle weakness, breathing difficulties, extreme hypotension, irregular heartbeat, and cardiac arrest [29]. The risk of magnesium toxicity increases with impaired renal function [1,29].
The FNB has established ULs for supplemental magnesium for healthy infants, children, and adults (see Table 3) [1].
Table 3: Tolerable Upper Intake Levels (ULs) for Supplemental Magnesium [1]
| Age | Male | Female | Pregnant | Lactating |
|---|---|---|---|---|
| Birth to 12 months | None established | None established | ||
| 1–3 years | 65 mg | 65 mg | ||
| 4–8 years | 110 mg | 110 mg | ||
| 9–18 years | 350 mg | 350 mg | 350 mg | 350 mg |
| 19+ years | 350 mg | 350 mg | 350 mg | 350 mg |
Conclusion: Prioritizing Magnesium-Rich Foods for Optimal Health
Understanding “what is magnesium foods” is essential for maintaining optimal health. By incorporating a variety of magnesium-rich foods like leafy greens, nuts, seeds, and whole grains into your diet, you can ensure you’re meeting your daily requirements and reaping the numerous health benefits this essential mineral provides. While supplements can be helpful, prioritizing food sources should be the primary approach to achieving adequate magnesium intake.
