We Asked 4 Dietitians the One Supplement They Actually Take—They All Said the Same Thing

Dietitians agree on this go-to supplement for better rest, recovery and daily nutrient support when diet alone falls short

Reviewed by Dietitian Katey Davidson, M.Sc.FN, RD, CPT

Key Points

• Dietitians recommend magnesium supplements when food alone doesn’t meet daily needs.
• Magnesium supports sleep, muscle and nerve function, making it important to prioritize.
• Individual needs vary, so work with a healthcare provider for personalized advice.

Getting your nutrition from food first is an important goal, but even nutrition experts can have occasional nutrient gaps. Registered dietitians spend their careers helping others eat well, so it may be surprising that many turn to supplements to fill in where food falls short.

Although individual needs vary, some supplements are more widely beneficial than others, since certain nutrients can be difficult to get through diet alone. We asked four dietitians which supplement they take every day, and they all gave the same answer: magnesium. Keep reading to learn why magnesium is often recommended as a go-to supplement and what you should know before considering it yourself.

Why Dietitians Take Magnesium

Magnesium is an essential mineral that plays a role in hundreds of processes throughout the body—from supporting muscle function and nerve signaling to helping regulate blood sugar levels. It’s naturally found in foods like nuts, seeds, leafy greens, legumes and whole grains. However, many people don’t consume enough of these foods on a regular basis.

As a result, nearly half of Americans fall short of the recommended daily intake, which is 400–420 milligrams (mg) per day for men and 310–320 mg for women, says Elizabeth Ward, M.S., RDN.

For Ward, this gap was the reason she began supplementing. “I started taking [magnesium] because I realized I wasn’t getting enough magnesium every day from food.”

Beyond filling nutrient gaps, dietitians shared several other reasons they take magnesium daily. One of the most common? Better sleep. Magnesium helps regulate gamma-aminobutyric acid (GABA), a brain chemical that calms the central nervous system. This can make it easier to unwind at the end of the day and improve overall sleep quality. As dietitian Lisa Moskovitz, RD, CDN explains, “When I do take it at night I will feel more rested and I have better quality sleep.”

Magnesium’s benefits extend beyond sleep. It also supports muscle and nerve function. Megan Huff, RDNsays it has made a noticeable difference: “I started taking magnesium glycinate for restless legs and leg cramps, and since taking it, I haven’t experienced either for two years!”

For Ashley Kitchens, M.P.H., RDthe draw was athletic recovery. “As a CrossFit athlete, I train hard five days a week. Because magnesium plays a key role in muscle function, I added it in to supplement my workouts and recovery.”

Who Is Most Likely to Benefit

While magnesium can be helpful for many people, dietitians say certain groups may be more likely to benefit from supplementation:

• Athletes and Very Active Individuals. People who exercise frequently or sweat heavily may have increased magnesium needs. “You lose magnesium through sweat, plus it’s critical for muscle contraction and recovery,” says Kitchens.
• Older Adults. As we age, the body becomes less efficient at absorbing magnesium from food, making supplementation potentially beneficial for this group, explains Kitchens.
• People with Sleep Difficulties. “People who wake up in the middle of the night, don’t wake up feeling well-rested are most likely to benefit from magnesium,” says Huff. However, it’s important to consider that underlying health issues may also be contributing and should be discussed with a healthcare provider.
• People with Low Magnesium Intake. Individuals who don’t regularly consume magnesium-rich foods due to dietary limitations or picky eating patterns may also fall short. Working with a registered dietitian can help improve food choices and determine whether supplementation is needed.

Who Should Use Caution

Although magnesium supplements are generally safe for most people, certain groups should speak with their healthcare provider before starting one.

People with chronic kidney disease, in particular, need to be cautious. Healthy kidneys help remove excess magnesium from the body, but when kidney function is impaired, magnesium can build up to unsafe levels, warn Kitchens and Huff.

Huff also notes that individuals with myasthenia gravis—an autoimmune condition that causes muscle weakness—should consult a healthcare professional before supplementing. Since magnesium has a muscle-relaxing effect, it may worsen symptoms in some cases.

Potential Side Effects

Magnesium supplements are generally well tolerated, but the most common side effects are digestive. “High doses of magnesium from supplements or medications such as laxatives and antacids that contain magnesium can result in diarrhea, nausea and cramping,” says Ward. She adds that magnesium oxide, in particular, is more likely to cause stomach upset.

To minimize these effects, Kitchens recommends starting with a lower dose and increasing gradually. She learned this firsthand after taking too high of a dose before bed and experiencing noticeable digestive discomfort the next morning.

At very high doses, more serious effects—such as low blood pressure or an irregular heartbeat—can occur, Kitchens notes.

Ward also cautions that magnesium supplements can interact with certain medications, including antibiotics and osteoporosis treatments, potentially reducing their effectiveness. For this reason, always let your healthcare provider and pharmacist know about any supplements you’re taking.

What to Look for When Buying Magnesium

Not all magnesium supplements are created equal. Dietitians recommend keeping a few key factors in mind when choosing one:

• Choose a Well-Absorbed Form. Forms like magnesium glycinate (or bisglycinate) and magnesium malate are typically well absorbed and gentle on the stomach. In contrast, magnesium oxide tends to be less bioavailable and more likely to cause digestive discomfort.
• Match the Form to Your Goal. “Know what your goal and objective is with taking magnesium so you can find the best form for your goals and needs,” says Moskovitz. For example, magnesium citrate is often used for its mild laxative effect, while magnesium glycinate is commonly chosen for sleep and muscle support.
• Follow Dosing Instructions. The recommended upper limit for supplemental magnesium is 350 mg per day for adults. Exceeding this amount isn’t necessary unless advised by a healthcare provider, says Ward.
• Look for Independent Testing. To ensure quality and accuracy, Huff suggests choosing supplements verified by an independent organization such as NSF International, USP or Informed Choice.
• Watch for Misleading Claims. “Common red flags when it comes to searching for a magnesium supplement is vague labeling and companies that make wild health claims without any evidence to back them up,” says Kitchens.
• Be Cautious with Added Ingredients. Huff advises against products that contain proprietary herbal blends or extra nutrients that may interact with medications or lead to excessive intake when combined with other supplements. In many cases, taking just a magnesium supplement on its own is the simplest and safest choice.

Our Expert Take

Dietitians generally recommend a food-first approach to nutrition, but in some cases, supplements can help fill nutritional gaps. With nearly half of adults falling short of the daily recommendations for magnesium from food alone, it’s easy to see why dietitians choose to supplement and often recommend magnesium.

That said, not everyone needs a magnesium supplement, and more isn’t always better. Individual needs can vary based on diet, health status and lifestyle. For that reason, it’s important to work with a healthcare provider to determine what’s right for you.