Black beans are an excellent dietary source of magnesium.Getty Images/iStockphoto
It’s an essential mineral many people might not think about. But here’s why you should.
Magnesium – plentiful in pumpkin seeds, spinach and black beans – plays an essential role in many bodily processes including muscle and nerve function, strengthening bones, producing protein and energy, controlling blood sugar and regulating blood pressure.
Yet, many Canadians don’t get enough magnesium. According to Health Canada, more than one-third of adults don’t meet daily requirements.
We’re not alone. U.S. data suggests that 48 per cent of Americans of all ages have lower magnesium intakes than recommended.
Here’s what to know about this under-consumed mineral – its potential health benefits, best food sources and types of supplements.
Magnesium’s health benefits
Numerous studies have tied a higher magnesium intake from foods to a lower risk of type 2 diabetes, high blood pressure, stroke, heart failure and colorectal cancer.
Recent research also suggests that consuming more magnesium-rich foods in middle age may help slow brain aging in later years.
And getting more magnesium from diet, as well as supplements, has been associated with higher bone densities and a slower rate of bone loss in post-menopausal women.
There’s solid evidence that magnesium supplementation, over the short term, is effective for treating constipation.
Magnesium is also thought to play a role in sleep since it influences the activity of certain brain chemicals that calm the central nervous system and relax muscles. Yet there’s no good evidence that supplementing with magnesium improves sleep quality.
Top food sources
Daily magnesium requirements for adults are 310 to 320 mg (for females) and 400 to 420 mg (for males). Kids ages 4 to 8 need 130 mg per day, and ages 9 to 13 require 240 mg. Teens from 14 to 18 should consume 360 mg (females) and 410 mg (males) each day.
The best food sources of magnesium are leafy green vegetables, beans and lentils, nuts, seeds and whole grains.
Spinach and Swiss chard each deliver 160 mg of magnesium per one cup cooked. Beet greens and kale are also good sources.
Pumpkin seeds provide 190 mg of magnesium per one-quarter cup. Hemp and chia seeds serve up 100 and 90 mg of magnesium per two tablespoons, respectively.
You’ll find 100 mg of magnesium in one-quarter cup of both sunflower seeds and almonds. The same serving size of cashews supplies 74 mg.
Black beans, navy beans, edamame and tempeh are also rich in magnesium.
When it comes to whole grains, teff, amaranth, quinoa, spelt and brown rice are very good sources. So are 100 per cent bran cereals, including oat bran.
Who’s at risk for getting too little?
It’s uncommon to have symptomatic magnesium deficiency because of low dietary intake in healthy people. That’s because our kidneys limit magnesium excretion in the urine when intake is low.
Even so, a habitual low-magnesium diet or losing too much of the mineral because of certain health conditions or medications can lead to magnesium deficiency.
Chronic diarrhea, Crohn’s disease and celiac disease, for example, can lead to magnesium depletion.
People with type 2 diabetes or insulin resistance may also be at risk of magnesium deficiency from increased urinary loss of magnesium.
Older adults who consume too little magnesium are also at increased risk. With age, magnesium absorption decreases and urinary magnesium excretion increases.
Proton pump inhibitors (such as omeprazole, esomeprazole and lansoprazole), used to treat acid reflux and stomach ulcers, can cause low magnesium levels when taken long-term (for more than a year).
Certain diuretics (such as furosemide and hydrochlorothiazide) increase the loss of magnesium in the urine and can lead to depletion.
Do you need a magnesium supplement?
Meeting daily magnesium requirements from foods should be your first strategy. Along with magnesium, whole foods deliver plenty of other nutritional benefits.
If you can’t get enough magnesium from your diet, consider a supplement to bridge the gap. Magnesium supplements typically come in doses of 100 to 250 mg.
Magnesium citrate and magnesium glycinate are common types of magnesium supplements. Both are well absorbed in the intestinal tract.
Magnesium citrate is also used to treat constipation since it pulls water into the intestines, making stool softer and easier to pass.
Magnesium oxide is poorly absorbed by the digestive tract. As such, it’s not the most effective type to increase magnesium levels in the body. It has a strong laxative effect and is used to treat constipation. It’s also used for heartburn.
The tolerable upper intake level of supplemental magnesium is 350 mg (this doesn’t include magnesium in foods). Consuming more than 350 mg may cause intestinal cramping, loose stools and nausea.
Consult your health care provider to determine if a magnesium supplement will benefit you.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on X @LeslieBeckRD