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Magnesium 101

Stephanie Ronco

Magnesium is a mineral that can be found in a variety of foods, including green leafy vegetables, nuts, seeds, whole grains, and legumes. Refining grains removes much of the fiber as well as magnesium, so magnesium is also often added to breakfast cereals and fortified foods. Water, including tap, mineral, and bottled water, also contains magnesium, although the amount varies significantly by source and brand. Even though magnesium is widely available, the National Health and Nutrition Examination Survey (NHANES) of 2013-2016 found that 48% of Americans of all ages consume less magnesium from food and beverages than the amount needed for optimum health. Adult men aged 71 years and older and adolescent males and females are the most likely to have low magnesium intakes.How Much Magnesium Do I Need?The Daily Value for magnesium is 420 mg for adults and children greater than 4 years of age, 400 mg for pregnant and lactating women, and 80 mg for children 1-3 years of age. There are no reports of magnesium producing a toxic effect when consumed as a naturally-occurring substance in food.Here are some foods that are good sources of magnesium:

  • 1 ounce roasted pumpkin seeds (156 mg)
  • 1 ounce chia seeds (111 mg)
  • 1 ounce dry roasted almonds   (80 mg)
  • ½ cup cooked spinach (78 mg)
  • 1 cup soy milk (61 mg)
  • ½ cup cooked black beans (60 mg)
  • 2 tablespoons peanut butter (49 mg)
  • 1 medium potato baked with skin (43 mg)
  • 1 cup cow’s milk (25 mg)

Breakfast cereal is commonly fortified with 10% of the Daily Value for magnesium. That's 42 mg per serving.Magnesium Supplements:The qualified health claim is for both foods and supplements. Magnesium is available in a variety of forms as a supplement, including magnesium oxide, magnesium citrate, magnesium chloride, magnesium aspartate, and magnesium glycinate, each with different rates of absorption. The Supplement Facts label on dietary supplement products states the amount of elemental magnesium in a serving of the product. Magnesium is commercially available as a single-ingredient dietary supplement, in products where it is combined with other specific nutrients (such as vitamin B6 and vitamin E), or as an ingredient in multivitamin/multimineral dietary supplements. Many of the single-ingredient magnesium dietary supplements contain between 200 mg and 400 mg of elemental magnesium, while the amount of elemental magnesium present in multivitamin/multimineral supplements is typically 100 mg or less. While consuming magnesium from foods typically does not cause adverse effects, magnesium supplements are known to cause diarrhea, nausea, or abdominal cramping. The Institute of Medicine established 350 mg as the Upper Limit for adults and adolescents greater than 8 years of age, as well as for pregnant and lactating women. This means that consumers over age 8 should not take more than 350mg of magnesium from all supplements combined to avoid the risk of side effects. The UL for children 1-3 years of age is 65 mg of supplementary magnesium, and the UL for children 4-8 years of age is 110 mg.Magnesium and You: Our Recommendations

  • Include a variety of foods high in magnesium in each of your meals and snacks:
    • Use fortified breakfast cereal with milk or soy milk and a sliced banana for breakfast (86 mg magnesium).
    • Choose whole grain bread for a lunchtime chicken sandwich and dip a sliced carrot into hummus. Enjoy an apple for dessert (84mg magnesium).
    • Build an afternoon snack around ½ cup yogurt mixed with ½ ounce sliced almonds, ½ ounce chia seeds, and ¼ cup raisins (122 mg magnesium).
    • Enjoy 3 ounces salmon, ½ cup black beans mixed with ½ cup chopped tomato and ¼ cup chopped avocado, ½ cup brown rice pilaf, and 1 cup steamed broccoli for dinner (163 mg magnesium).
  • Avoid magnesium supplements due to the increased risk of side effects unless specifically recommended by your physician.

By Lynn Grieger, RDN, CDCES, CHWC, CPTReferences:

  1. U.S. Food and Drug Administration. FDA Announces Qualified Health Claim for Magnesium and Reduced Risk of High Blood Pressure. https://www.fda.gov/food/cfsan-constituent-updates/fda-announces-qualified-health-claim-magnesium-and-reduced-risk-high-blood-pressure   accessed 2-25-22; published 1-10-22.
  2. FDA Reader. Simplifying Food Regulation. https://www.fdareader.com/blog/tag/qualified+health+claim  accessed 2-25-22; copyright 2020.
  3. American Heart Association. The Facts About High Blood Pressure. https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure  accessed 2-26-22; last reviewed 11/30/17.
  4. American Heart Association. Health Threats from High Blood Pressure. https://www.heart.org/en/health-topics/high-blood-pressure/health-threats-from-high-blood-pressure  accessed 2-26-22; last reviewed 10/31/16.
  5. U.S. Department of Health and Human Services. Your Guide to Lowering Blood Pressure. https://www.nhlbi.nih.gov/files/docs/public/heart/hbp_low.pdf  accessed 2-25-22; published 5-03
  6. U.S. Food and Drug Administration. Letter in Response to a Petition for a Qualified Health Claim for Magnesium. https://www.fda.gov/media/155304/download  accessed 2-25-22; written 1-8-22
  7. National Institutes of Health. Office of Dietary Supplements. Magnesium Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/  accessed 2-25-22; updated 8-11-21.
  8. Houston MC, Harper KJ. Potassium, magnesium, and calcium: their role in both the cause and treatment of hypertension. J Clin Hypertens (Greenwich). 2008;10(7 Suppl 2):3-11. doi:10.1111/j.1751-7176.2008.08575.x

For a guide to the new health claims for magnesium, don't miss: A New Health Claim for Magnesium.