On Your Health

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Magnesium: What It Is and Why We Need It

Magnesium is one of those nutrients we don’t hear quite as a much about. It’s never really been a media darling like protein, say, or calcium. Or even zinc. Maybe it’s because we don’t need as much magnesium as we do other nutrients. Protein, for example. A 140-pound sedentary woman in her 50s needs about 53 grams of protein a day. That same woman’s magnesium requirement? 310-320 milligrams. Most Americans don’t get the recommended amount of magnesium. The National Institutes of Health (NIH) tells us that teenage girls and 70+ year-old men are the most likely to be deficient.

Despite the fact that many of us don’t get as much magnesium as we need and may not know very much about this essential mineral, it’s needed for more than 300 biochemical reactions in the body. The magnesium needed for these reactions and processes is ionized magnesium. There are three types of magnesium found in blood serum: ionized (55-70 percent); protein-bound (20-30 percent) and complexed with anions (5-15 percent).

Magnesium helps keep our heartbeat steady and our bones strong. It supports a healthy immune system and aids the function in our nerves and muscles. It helps us make protein and regulate blood sugar. It’s absorbed in the gut and excreted through the kidneys.

Measuring magnesium levels in the body isn’t as simple as a blood test, because most of our bodies’ magnesium stores are housed in our bones (50-60 percent) and the majority of the rest in soft tissues. Not even 1 percent of our total magnesium is present in blood serum. According to the NIH, the most common and readily available metric is the measurement of serum magnesium, even though serum levels don’t always correlate to total-body magnesium levels. Other assessment tools include measuring magnesium levels in urine, saliva and red blood cells, conducting magnesium loading/tolerance testing or measuring only the ionized magnesium concentrations in plasma, serum or blood. 

You’re at increased risk of magnesium deficiency if you have celiac disease, regional enteritis or chronic diarrhea, have parathyroid disorders and hyperaldosteronism, or if you are taking antibiotics. Long-term use of diuretics, medicines used to combat ulcers or reflux, kidney problems and poor diet/not eating enough can also lower your magnesium level. Some genetic disorders can cause a loss of magnesium through excessive sweating or urinating. Drinking too much alcohol can also increase your risk of magnesium deficiency. 

No magnesium measurement method is terrifically accurate; fortunately getting plenty of magnesium in your daily diet is pretty easy to do.   

The amount of magnesium needed daily depends on age and sometimes gender:

  • Babies, up to 6 months 30 mg
  • Babies, 7 months to 1 year 75 mg
  • Children, ages 1 to 3  80 mg
  • Children, ages 4 to 8  130 mg
  • Children, ages 9 to 13 240 mg
  • Girls, ages 14 – 18         360 mg
  • Boys, ages 14 – 18         410 mg
  • Women             310-320 mg
  • Men                 400-420 mg
  • Pregnant women         350 – 360 mg
  • Pregnant teens         400 mg
  • Breastfeeding women 310-320 mg
  • Breastfeeding teens         360 mg

Symptoms that you may be low on magnesium are also common indicators of a wide array of other illnesses and ailments, but if you’ve ruled out other causes and/or have most or all of them, a visit to your doctor to talk about magnesium may be in order.

Fatigue is one of the first signs of magnesium deficiency. Other early-stage symptoms are weak or stiff muscles, loss of appetite, nausea, vomiting or muscle spasms. Without treatment, a magnesium deficiency can lead to more serious symptoms like abnormal heart rhythms, seizures, changes in personality and tingling or numbness. But there can also be hyperexcitability and/or shaking. Long term, a magnesium deficiency can affect brain function, bone density and nerve and muscle function.

Good dietary sources of magnesium include:

  • Pumpkin seeds
  • Chia seeds
  • Potatoes
  • Avocadoes
  • Fortified cereal
  • Nuts, especially peanuts, almonds and cashews
  • Spinach
  • Rice
  • Black beans
  • Whole wheat bread
  • Peanut butter, almond butter
  • Edamame
  • Yogurt

Other foods containing lower levels of magnesium are:

  • Broccoli
  • Carrots
  • Oatmeal
  • Beef
  • Kidney beans
  • Chicken breast
  • Bananas
  • Raisins
  • Apples
  • Fish, like salmon or halibut
  • Milk

Another way to improve your magnesium level is to make your body a little better at absorbing magnesium. Some ways to optimize your absorption are quitting smoking, treating any vitamin D deficiencies, eating vegetables raw rather than cooked, eschewing supplements containing high doses of zinc and avoiding calcium-rich foods two hours before or after eating foods rich in magnesium.

About magnesium supplements:

A variety of supplemental magnesium formulations is available, and including magnesium oxide, magnesium citrate and magnesium chloride.  Magnesium oxide is commonly found in pharmacies, but its absorption rate may be lower than other choices. Magnesium chloride contains a lower percentage of elemental magnesium, yet it absorbs at an impressive rate and chloride may have a positive effect on kidney function and metabolism. Magnesium citrate is inexpensive, easily absorbed and because it contains citric acid, it magnesium citrate has a mild laxative effect, making it a good choice for people with constipation challenges, but not so terrific for people with chronic diarrhea or loose stools.

Your doctor may recommend a magnesium supplement for you in addition to encouraging you to eat a diet rich in magnesium. Because too much magnesium can be as dangerous as too little, it’s best not to self-diagnose or self-prescribe magnesium deficiencies or supplements. Be sure to discuss any and all other medications you take with your doctor as well, to make sure they interact well together.


For more lifestyle and wellness content, visit the INTEGRIS Health For You blog.


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