Skip to content

Signs you may have a Magnesium deficiency (and what you can do about it)

Find out if you need to supplement or if your diet can be enough.

Most people won’t need to take a magnesium supplement, though it can be immensely beneficial for the few segments of the population who do. 

The trick is: how do you know if you should be taking it? If you did have a magnesium deficiency, how would it show? 

What does magnesium do? 

Magnesium is important because it plays several roles in the body.  

It is a mineral that helps more than 300 enzymes carry out a number of chemical reactions in the body. These include building proteins and strong bones, and regulating blood sugar, blood pressure, and muscle and nerve functions. It also acts as an electrical conductor, contracting muscles and making the heart beat steadily.  

Low magnesium levels don’t usually cause any symptoms. Chronically low levels, however, can increase the risk of heart disease, high blood pressure, osteoporosis and Type 2 diabetes. 

Signs of magnesium deficiency 

According to the T.H. School of Public Health at Harvard, the most common signs of magnesium deficiency include: 

  • Fatigue, weakness 

  • Poor appetite 

  • Nausea, vomiting 

  • Numbness or tingling in skin 

  • Muscle cramps 

  •  Seizures 
  • Abnormal heart rate 

Who is at risk of magnesium deficiency 


The most common risk factors include alcohol abuse, advanced age, conditions that interfere with digestion, and Type 2 diabetes mellitus.  

Long-term, excessive intake of alcohol is often associated with a poor diet that is low in magnesium, digestive upset that leads to malabsorption, and issues with various organs. These organs can remove too much magnesium from the body through the urine, leaving you depleted. 

Older adults tend to have lower magnesium intakes. Natural aging also seems to cause decreased absorption of magnesium in the gut, as well as increased excretion via urine. An additional contributing factor is that the elderly are more likely to be on medications for chronic diseases that can lower one’s magnesium stores. 

Another segment that is at risk are those with conditions that include malabsorption. Several diseases can interfere with digestion and lower the amount of magnesium that gets absorbed. The largest segment of the small intestine (the ileum) absorbs most magnesium, but this is compromised in those who have conditions like celiac and Crohn’s disease. Anyone who has had surgery to remove the ileum—which can occur with colon cancer, ulcerative colitis or Crohn’s disease—is at increased risk of deficiency. 

Lastly, insulin resistance or uncontrolled diabetes can cause the kidneys to make extra urine, as it tries to get rid of the high levels of blood sugar in the body. This increased amount of urine can also flush out magnesium, so a deficiency can occur in those with Type 2 diabetes mellitus.  

Diagnosing a deficiency 

It is possible to have a magnesium deficiency yet have normal blood level results. More than half of the mineral is stored in our bones, with the remaining found in tissues throughout the body. 

It is thought that low to moderate magnesium deficiency isn’t likely to produce any noticeable symptoms. That said, over a third of Canadian adults aren’t getting an adequate intake via their diets. The mineral is one of four nutrients that have the highest inadequate intakes among the population, according to numbers from Statistics Canada

Severe deficiency tends to occur with the conditions mentioned above: a long-term low magnesium diet, malabsorption issues, alcohol abuse or use of medications that deplete the mineral (these can include certain diuretics, antibiotics and proton pump inhibitors). 

A diet high in fat can also cause less magnesium to be absorbed. 

Good food sources of magnesium 


Magnesium can be found in several different foods, so it’s easy to incorporate more into your diet. Foods like dark green leafy vegetables and legumes contain magnesium, as do nuts, seeds, whole grains and fortified cereals. You can also find magnesium in poultry, beef and fish. 

Some other great sources include almonds, peanuts and cashews; pumpkin seeds; peanut butter; black and kidney beans; soybeans and soymilk; tofu and edamame; quinoa; cooked spinach and Swiss chard; white potato with the skin on; brown rice; oatmeal; salmon; bananas; raisins; dark chocolate (made with at least 70% cacao); milk and yogurt.  

Fortunately, just a few servings of magnesium-rich foods a day are enough to meet your needs. 

Required Daily Allowances 

Men between 19 and 30 years old need 400 mg of magnesium per day, while women of the same age group need 310 mg. Men over 31 need 420 mg per day, while women in the same age range need 320 mg, according to the folks at Eat Right Ontario.  

When to supplement 


If anyone has problems absorbing the nutrient, they may be prescribed a magnesium supplement. Over-the-counter varieties are available in different forms. The liquid type, such as magnesium citrate or chloride, may be better absorbed than the kind that comes in solid tablet form, such as magnesium oxide and sulfate. 

It is important to know that at high doses, magnesium can have a laxative effect. In fact, it’s a common ingredient in antacids and laxatives. Too much can cause nausea, abdominal cramping and diarrhea. 

No one of any age should have more than 350 mg of magnesium per day from supplements. 

Magnesium supplements can also interact with certain types of antibiotics and other medicines. As always, it’s best to check with your doctor before considering taking them.