The Best Time to Take Magnesium for Maximum Absorption, According to Dietitians
For better digestion, more restful sleep and improved focus, the timing of your magnesium supplement matters.
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Reviewed by Dietitian Emily Lachtrupp, M.S., RD
Magnesium is one of the hardest-working minerals in the human body. From energy production to muscle function, nerve health to bone formation, blood pressure regulation to blood glucose control—magnesium is involved in over 300 biochemical reactions.
To carry out these vital functions, it’s recommended that adult females get 310 to 230 milligrams, adult males 400 to 420 mg and pregnant individuals 350 to 400 mg of magnesium per day. Despite its pivotal role in various bodily processes, many fall short when it comes to the mineral. In fact, research suggests that nearly half of the U.S. population fails to consume adequate amounts of magnesium from food.
Related: 10 Signs You're Not Getting Enough Magnesium—and What to Do About It
While it’s crucial to prioritize eating more magnesium-rich foods, supplementation can also come in handy. But there’s more to taking a supplement than just popping it at any time. In fact, factors like the type of magnesium or other medications you’ve been prescribed affect when you should take a magnesium supplement. Here’s what you need to know.
Factors to Consider
Type of Magnesium
As you peruse the supplement aisle, you’ll find a myriad of magnesium supplements, each with its own set of health benefits. Choosing the optimal time to take your supplement greatly depends on the type of magnesium you select from the shelves. Below are seven of the most common magnesium supplement types and the best time to take them to maximize their benefits.
Magnesium glycinate: This well-absorbed form of magnesium is bound to an amino acid called glycine. Often touted for its relaxing and calming effects, magnesium glycinate is best taken at night before bed, says Shyla Cadogan, RD.
Magnesium citrate: Commonly used to support digestive health and relieve constipation, magnesium citrate is one of the most highly absorbable forms of magnesium. It can be taken in the morning or evening to ease and soften the passage of stool, says Erin Kenney, M.S., RD, CEO of Nutrition Rewired.
Magnesium malate: Made from a combination of magnesium and malic acid, this dynamic duo is known for supporting energy production. To reap this benefit, magnesium malate can be taken in the morning to get your day going or in the afternoon to beat the midday slump, says Cadogan.
Magnesium L-threonate: As one of the newer forms of magnesium on the market, magnesium L-threonate is often used to improve brain health and cognitive function. While it can be taken at any time, Kenney says that taking it in the morning may support mental clarity and focus throughout the day.
Magnesium chloride: When magnesium is paired with chloride ions, it forms magnesium chloride, a compound easily absorbed in the digestive tract. Although this form of magnesium is typically found in topical oils, sprays and lotions or sleep-promoting bath products, it’s also available as capsules. “When taken orally, it is usually well-absorbed and can be taken at any time of day,” says Kenney.
Magnesium taurate: A combination of magnesium and the amino acid taurine, magnesium taurate is often used for its potential cardiovascular and neurological benefits, though more research is needed to confirm these benefits, explains Kenney. This magnesium supplement can be taken at any time of day.
Magnesium oxide: Compared to other forms of magnesium, magnesium oxide is the least absorbable form and more likely to cause gastrointestinal side effects. Due to its laxative effect, it is often used to alleviate constipation. As such, it can be taken at any time of the day to support bowel movements, says Cadogan.
Other Supplements You’re Taking
Not all supplements go together, and this is especially important when it comes to minerals like magnesium and zinc. Although typically bundled together in a multivitamin, high doses of zinc may interfere with magnesium absorption. Research has shown that taking zinc above safe levels (exceeding 40 mg/day) decreases magnesium absorption into the bloodstream and disrupts the regulation of magnesium levels. This can set the stage for magnesium deficiency. If you’re also taking zinc, make sure you’re taking the recommended dosage and do so at least two hours apart from a magnesium supplement, Kenney advises.
Potential Medication Interactions
Several medications share the same absorption, metabolism and elimination pathways in the body as magnesium. That’s why when taken together, there is a risk of an interaction that can either stymie magnesium absorption or impair a medication’s effectiveness.
One example is a proton pump inhibitor, or PPI. “Proton-pump inhibitors, such as omeprazole, used to treat acid reflux and peptic ulcers, may reduce magnesium absorption by decreasing stomach acid production,” Kenney says. Similarly, she adds that diuretics can increase the loss of magnesium in urine, leading to magnesium deficiency over time.
Additionally, certain antibiotics, such as tetracyclines and quinolones, can bind to magnesium, forming compounds that are not easily absorbed by the body. The end result? Magnesium supplements may interfere with absorption and effectiveness of these antibiotics, says Cadogan. Aim to take antibiotics at least two hours before or four hours after a magnesium supplement.
Timing with Food
Determining whether to pop your supplement with or without food depends on two factors: the type of magnesium supplement and whether or not you tend to get GI upset. Certain forms of magnesium (such as magnesium oxide, chloride and citrate) are more likely to cause digestive side effects like diarrhea, nausea and stomach cramps. One way to decrease the likelihood of digestive distress? Pair those magnesium supplements with a meal. Some forms may be OK on an empty stomach, like magnesium threonate and glycinate, but pay attention to how you personally respond. If your stomach feels icky, take them with food next time.
Expert Recommendations for Magnesium Supplements
The best time to take magnesium supplements depends on the specific type of magnesium, potential drug or nutrient interactions and whether or not you experience GI side effects, says Kenney.
However, to truly benefit from your magnesium supplement and maximize its effectiveness, both dietitians agree that consistency is key. For best results, whether you take it in the morning, evening or alongside a meal, the most important factor is to remember to integrate it into your daily routine. Remember, when you’re buying any supplement, there are certain criteria you can use to evaluate if it is safe and effective, such as looking for a third-party certification seal on the product label.
Related: The Best Magnesium Supplements, According to Dietitians
The Bottom Line
Magnesium supplements can be a helpful tool to address potential deficiencies and support overall health and well-being. However, the effectiveness of magnesium supplements may also depend on the time you take them.
The ideal time to consume your magnesium supplement varies depending on the form of magnesium (check the label) and the chance you’ll experience potential digestive side effects. In addition, it’s crucial to take your supplement separately from high doses of zinc supplements, proton-pump inhibitors, diuretics and antibiotics. Most importantly, choose a time you can stick with consistently to reap the many benefits associated with magnesium intake.
Related: 5 Supplements You Shouldn't Be Taking, According to a Dietitian
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