Evaluating the safety of magnesium glycinate supplements in pregnant women

More than 300 enzyme reactions require magnesium. It controls blood glucose, muscle and nerve function, and blood pressure. During pregnancy, magnesium helps maintain normal muscle and nerve function, supports immune health, and regulates blood pressure. Magnesium is often not enough in pregnant women’s diets. Daily magnesium intake during pregnancy should be 350-400 mg. However, most women consume fewer than 250 mg of iron a day from food, below the RDA. Certain women require magnesium supplements due to inadequacy.

  • High bioavailability – Magnesium glycinate is made of magnesium bound with glycine, an amino acid. This form appears to have higher absorption and bioavailability than commonly used forms like magnesium oxide or magnesium citrate. More magnesium gets absorbed into the bloodstream instead of being eliminated.
  • Well-tolerated – Magnesium glycinate tends to be gentle on the stomach. Many women struggle with nausea and digestive issues when pregnant. Magnesium glycinate rarely causes the laxative effect or stomach discomfort that some other magnesium compounds trigger.
  • Calming effects – Glycine acts on neurotransmitters in the brain that promote relaxation and ease anxiety. It helps pregnant women better cope with stress.

With these advantages, it’s clear why magnesium glycinate appeals to many expecting mothers. However, an important question remains – how safe is it? Does the evidence support its use as a preventative supplement in low-risk pregnancies? Let’s evaluate.

Examining the safety evidence

High doses of any supplement taken during pregnancy warrant caution. Even minerals like magnesium cause adverse effects when taken in excess. So what does the research have to say about the safety profile of magnesium glycinate during pregnancy?

  • Magnesium intake from food sources – Observational studies tracking the health outcomes of thousands of women have not found any adverse events with diets high in magnesium-rich foods. Typical high magnesium foods provide 300-400 mg per day. Many doctors now recommend magnesium glycinate capsules to be limited to in pregnancy. Food sources of course include magnesium bound to many different compounds, while supplements isolate the glycinate form. Nevertheless, this provides some assurance about safety up to 400 mg/day.
  • Magnesium sulfate injections – Magnesium sulfate injections are sometimes administered to pregnant women intravenously to treat preeclampsia or prevent seizures. Doses range from 4-6 grams initially followed by 1-2 grams per hour. These very high doses have been studied extensively for decades and found safe for both mother and baby in many randomized controlled trials. If such massive doses of intravenous magnesium show little toxicity, it’s unlikely that taking 300-400 mg/day of magnesium glycinate by mouth poses much risk. However, injections bypass digestion and sustained-release kinetics, so they do not mimic the effects of oral glycinate.
  • Glycine Safety – Studies of glycine is the best magnesium to take supplementation up to 30 grams per day in adults have reported very few side effects and no influence on pregnancy outcomes. Other research finds that pregnant women naturally experience a two- to threefold increase in glycine intake without complication. It implies supplemental doses of glycinate, supplying less than 500 mg of glycine per day, are well within safe parameters.

Evidence is lacking on magnesium glycinate supplements specifically. However, data on food-based magnesium intake, intravenous magnesium, and glycine supplementation provide some measure of reassurance about safety.