Magnesium for Women Over 40: Sleep, Muscles and What the Evidence Says

Magnesium has become one of the most talked-about supplements, recommended online for everything from sleep and anxiety to muscle cramps and migraines. Some of these uses have research behind them; many are overstated.

What is clear is that magnesium is an essential mineral, and many Americans do not get enough from food. This guide explains what magnesium does, how to get it and what to know before reaching for a supplement.

What magnesium does

Magnesium is involved in hundreds of chemical reactions in the body. According to the NIH Office of Dietary Supplements, it helps:

• Regulate muscle and nerve function
• Control blood sugar levels
• Regulate blood pressure
• Make protein, bone and DNA

About half of the body's magnesium is stored in bones, which is one reason it matters for bone health.

How much do you need?

The Office of Dietary Supplements recommends:

Many people in the U.S. get less magnesium from food than recommended, according to the ODS, although outright deficiency with symptoms is uncommon in healthy people.

Who is at risk of low magnesium?

The ODS identifies groups more likely to have low magnesium:

• People with digestive diseases, such as Crohn's disease or celiac disease
• People with type 2 diabetes, because of increased magnesium losses in urine
• People with long-term alcohol use
• Older adults, who may absorb less and lose more
• People taking certain medications, such as some diuretics and long-term proton pump inhibitors

Symptoms of deficiency can include loss of appetite, nausea, fatigue and weakness, and more severe deficiency can cause numbness, muscle cramps, seizures and abnormal heart rhythms.

Food sources of magnesium

The best way to get magnesium is from food. Many magnesium-rich foods are also high in fiber, which makes them doubly valuable. The Dietary Guidelines and the Harvard Healthy Eating Plate both emphasize these foods.

Values are approximate and drawn from typical nutrient data; amounts vary by product.

Magnesium and sleep: what does the research say?

Magnesium is often promoted as a natural sleep aid. The idea is plausible, because magnesium plays a role in nerve function and relaxation. However, high-quality evidence is limited. Studies of magnesium supplements for sleep have been small, often in older adults or people with low magnesium levels, and results have been mixed.

In other words, if you are low in magnesium, correcting that may help overall health and possibly sleep. If your levels are already adequate, a supplement is unlikely to be a powerful sleep aid. Habits like a consistent schedule, a cool dark bedroom and limiting caffeine and alcohol have stronger support. See why sleep gets harder after 40.

Magnesium for muscle cramps

Magnesium is commonly used for nighttime leg cramps. Research in older adults has generally found that magnesium supplements are unlikely to reduce cramps for most people. If you have frequent or severe cramps, talk to a clinician, because they can be related to medications, dehydration, nerve problems or circulation problems.

Other uses

Magnesium has been studied for migraine prevention, blood pressure and blood sugar control, with some promising results in specific groups. These are areas where your clinician can advise whether it is appropriate for you, rather than self-treating.

Supplement safety

Magnesium from food is not a concern, because healthy kidneys remove excess. Supplements are different. According to the Office of Dietary Supplements:

• The upper limit for magnesium from supplements and medications is 350 mg a day for adults. This does not include magnesium from food.
• Too much can cause diarrhea, nausea and abdominal cramping. Very high doses, especially in people with kidney problems, can cause dangerous symptoms including low blood pressure, irregular heartbeat and, rarely, cardiac arrest.
• Magnesium is in some laxatives and antacids, so check those labels if you also take a supplement.

Types of magnesium

Supplements come in many forms, including magnesium oxide, citrate, glycinate, chloride and others. Forms that dissolve well in liquid, such as citrate and chloride, are generally absorbed better than magnesium oxide. Magnesium citrate and oxide are more likely to have a laxative effect.

Interactions

Magnesium can interact with several medications, according to the ODS, including:

• Bisphosphonates for osteoporosis, which should be taken at least two hours apart from magnesium
• Certain antibiotics (tetracyclines and quinolones)
• Diuretics, which can raise or lower magnesium
• Proton pump inhibitors, which can lower magnesium with long-term use

Always tell your clinician and pharmacist about supplements you take. NCCIH's guide to using dietary supplements wisely and MedlinePlus offer helpful general advice.

The bottom line

Magnesium is an essential mineral that many women do not get enough of from food. Women over 30 need 320 mg a day, and nuts, seeds, beans, whole grains and leafy greens are excellent sources. Evidence that supplements improve sleep or cramps in people who are not deficient is limited. If you consider a supplement, stay under the 350 mg upper limit for supplemental magnesium and check with your clinician, especially if you have kidney problems or take medications.

Frequently asked questions

How much magnesium should a woman over 40 take?

Women 31 and older need 320 mg of magnesium a day from all sources. The upper limit for supplemental magnesium is 350 mg a day.

Does magnesium help you sleep?

Evidence is limited and mixed. Correcting a deficiency may help, but magnesium supplements are not proven sleep aids for people with adequate levels.

What are the best foods for magnesium?

Pumpkin seeds, chia seeds, almonds, cashews, spinach, black beans, edamame, whole grains and dark chocolate are good sources.

Can magnesium supplements cause side effects?

Yes. High doses can cause diarrhea, nausea and cramping, and very high doses can be dangerous, especially for people with kidney problems.