Who is most likely to have low magnesium?

Deficiency with symptoms is uncommon in healthy people, because the kidneys pass less magnesium into urine when intake is low.^[1] Low intake is common, though: in a 2013 to 2016 US survey, 48% of people got less than the average requirement from food and drinks.^[1] These groups are more likely to run low:

• people with Crohn's disease or celiac disease, or after surgery that removed part of the small intestine^[1]
• people with type 2 diabetes, who lose more magnesium in urine^[1]
• people with alcohol dependence^[1]
• older adults, who eat less magnesium, absorb less and lose more in urine^[1]
• people who take loop or thiazide diuretics, or a proton pump inhibitor for more than about a year^[1]

Early signs of deficiency are loss of appetite, nausea, vomiting, tiredness and weakness. Later come numbness, tingling, muscle cramps, seizures and abnormal heart rhythms.^[1] Severe deficiency can also lower blood calcium and potassium.^[1] A blood test is the usual check, but the blood level says little about the magnesium in cells and bone.^[1]