Magic Mineral

Magnesium has many benefits for older adults — if they’re consuming the right amounts.

Ubiquitous in the human body, magnesium is the fourth most abundant mineral primarily located within the cells, as well as in bones and teeth. Yet, aging can complicate the body’s relationship with magnesium.

Nearly every cell in the body uses magnesium for the hundreds of biochemical reactions that occur in the body every day. It helps maintain normal muscle contractions, heart rhythm, energy production, bone growth, blood pressure, and blood sugar levels.

“Inadequate intake of magnesium can cause metabolic changes that may contribute to heart attacks, strokes, osteoporosis, elevated blood pressure, and elevated blood sugar,” says Melissa Sujak, registered dietitian and diabetes care and education specialist at Northwestern Medicine.

The body more easily absorbs some types of magnesium than others. Some studies show that the body absorbs magnesium in the aspartate, lactate, and chloride forms more completely than magnesium oxide and sulfate.

But other minerals, such a calcium and zinc, may cut the absorption rate of magnesium in half. For example, depending on what other foods are on the menu, you might absorb only about half of the magnesium that you ate at that meal, Sujak says.

The Dietary Guidelines for Americans recommend a daily intake of 420 mg of magnesium for men and 320 mg for women, but estimates indicate that more than 60% of Americans fall below that amount.

“Magnesium is considered a shortfall nutrient in older adults,” says Bethany Doerfler, senior clinical research dietitian at Northwestern’s Digestive Health Center. Part of the blame lands on the standard American diet — full of highly processed, low-magnesium foods. “The best sources [of magnesium] are dark greens and other plant foods, such as nuts, seeds, legumes, and whole grains,” Doerfler says.

If your diet skips a lot of plant-based, fiber-filled foods, you may not be getting enough magnesium.

“Food[s] containing dietary fiber provide magnesium, as well as leafy green vegetables because the center of the chlorophyll molecule contains magnesium,” Sujak says. The risk of overconsuming magnesium from food is low. However, older adults who use magnesium-containing laxatives and antiacids risk magnesium toxicity.

“People with kidney disease may not excrete magnesium as well, and supplementation, especially higher doses, needs to be monitored by a doctor,” Doerfler says.

Keep in mind, too, that magnesium acts as a natural laxative; oral magnesium supplementation can cause diarrhea, Doerfler says.

The highest level more people can tolerate without diarrhea risk: 350 mg a day. “Signs of excess magnesium are changes in mental status, diarrhea, nausea, appetite loss, muscle weakness, difficulty breathing, low blood pressure, and irregular heartbeat,” Sujak says.

Yet, when consuming magnesium through food, “there’s no upper limit” Doerfler says. Properly functioning kidneys will excrete excess magnesium from food in the urine.

There’s one more way to up your intake of magnesium: You can apply magnesium oil directly to your skin, and your sweat glands will absorb it. This delivery system alleviates the potential gastrointestinal side effects of oral magnesium.

The body easily masks a magnesium deficiency, because it compensates for low blood levels by pulling magnesium out from the cells to maintain blood magnesium levels within a normal range.

How can you tell if there’s a true magnesium deficiency? The best way to determine adequate magnesium levels is to test the magnesium levels in the urine or red blood cells, which isn’t part of routine bloodwork. You or your physician would need to request it.

Consult with a healthcare provider and a registered dietitian to learn how to add more dietary sources of magnesium into your diet and before starting any supplements.

10 Magnesium-Rich Foods

  • Nuts (almonds, peanuts, cashews)
  • Pumpkin seeds
  • Peanut butter
  • Beans (specifically black beans and kidney beans)
  • Soybeans, soy milk
  • Leafy greens (cooked spinach, cooked Swiss chard)
  • White potato with skin
  • Brown rice
  • Oatmeal
  • Salmon


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