What magnesium does in your body
Magnesium is a mineral involved in more than 300 enzyme reactions in the body. It is essential for muscle contraction and relaxation, nerve signaling, and a steady heartbeat, and as a component of bone it also works with calcium and vitamin D to support bone health. It is sometimes nicknamed "nature's tranquilizer," but that is a popular label based on its role in muscle and nerve function, not evidence that magnesium supplements treat anxiety or insomnia. The function Korea's Ministry of Food and Drug Safety (MFDS) recognizes for magnesium is "needed for energy use and for maintaining nerve and muscle function."
Signs of magnesium deficiency
Early on, a lack of magnesium can cause loss of appetite, nausea, fatigue, and weakness. If the shortage continues, it can lead to numbness or tingling in the hands and feet, muscle cramps, or eyelid twitching, and in severe cases even an irregular heartbeat. These symptoms are common and have many other causes, though, so rather than assuming it is magnesium, it is more accurate to get checked by a doctor.
The risks of taking too much
Magnesium from food is regulated and excreted by the kidneys, so there is little risk of overdoing it. Supplements are a different story. The most common side effects are diarrhea and stomach cramps, and taking a very large amount at once can lower blood pressure or cause muscle weakness. People with reduced kidney function are at particular risk of hypermagnesemia because they cannot clear magnesium well, so they should take it only after talking to their care team.
How much do you need after 65?
In the Dietary Reference Intakes for Koreans (2020) from the Ministry of Health and Welfare and the Korean Nutrition Society, the recommended magnesium intake for adults 65 and older differs by sex: 370 mg a day for men and 280 mg a day for women. The 2025 revision adjusted some values for certain age groups, so check the official 2025 tables for the latest numbers.
When choosing a supplement, the more important number is the upper limit: 350 mg a day of magnesium from non-food sources such as supplements. Magnesium from food does not count toward it, but magnesium from different supplements must be added together. For comparison, the US NIH recommends 420 mg for men and 320 mg for women aged 51 and older, and its supplement upper limit for adults is also 350 mg.
The "315 mg (100%)" often printed on Korean labels is not a percentage of the recommended intake. It refers to the Daily Value the MFDS uses for nutrition labels (315 mg for magnesium).
Magnesium brands at Daiso
Several drugmakers sell at Daiso, but at the time of writing, most single-ingredient magnesium products we found on Daiso Mall were from Daewoong Pharmaceutical's "Dr. Bear" brand. Even within one brand, the formulations differ by purpose, so compare the labels and choose the one that fits your needs.
Amount per product
Below are the amounts per daily serving that we could confirm from Daiso Mall listings and news reports. Where a value could not be confirmed, we say so rather than leaving it blank.
| Product (Daewoong Dr. Bear) | Price and pack | Amount per daily serving | Source |
|---|---|---|---|
| Magnesium, 30 tablets | KRW 3,000 · 30 days | Magnesium 315 mg (magnesium oxide), vitamin D 10 µg (400 IU) · 1 tablet a day | Pharmacist review reported in the press (March 2025); Daiso Mall label for the 10-tablet pack of the same product |
| Magnesium, 10 tablets | KRW 1,000 · 10 days | Magnesium 315 mg, vitamin D 10 µg (400 IU) · 1 tablet a day | Daiso Mall listing |
| Calcium Magnesium Vitamin D, 60 tablets | KRW 5,000 · 30 days | Calcium 210 mg, magnesium 105 mg · 2 tablets a day / vitamin D amount not confirmed (sources disagree) | Daiso Mall listing, expert comparison column |
| Magnesium Shot, 25 ml × 5 bottles | KRW 5,000 · 5 days | Liquid magnesium gluconate · amount per bottle not confirmed | Daiso Mall listing |
- Single magnesium product (30 or 10 tablets): One tablet provides the full Korean Daily Value (315 mg). That is about 85% of the recommended intake for men (370 mg), more than the recommended intake for women (280 mg), and within the 350 mg supplement upper limit.
- Calcium Magnesium Vitamin D: Its 105 mg of magnesium is about a third of the single product, and its 210 mg of calcium is roughly a quarter of the recommended calcium intake after 65 (700 mg for men, 800 mg for women). Experts have noted that it is low if calcium is your main goal.
Taking both products exceeds the upper limit
- Magnesium 30 tablets (315 mg) + Calcium Magnesium Vitamin D (105 mg) = 420 mg a day, above the 350 mg supplement upper limit. Add any magnesium in your multivitamin as well.
- Both products also contain vitamin D. If you take a separate vitamin D supplement too, check your daily total against the upper limit of 100 µg (4,000 IU).
Is it true that magnesium oxide is not absorbed?
Magnesium oxide, used in the single product, packs a lot of magnesium into one tablet and is cheap, but its measured absorption is often lower than that of organic forms such as magnesium citrate. In a study comparing US commercial products (Firoz & Graber, 2001), magnesium oxide had the lowest absorption, about 4%. Absorption results vary a great deal with the method used and whether it is taken with food, and low absorption does not mean "not absorbed at all." Magnesium oxide also tends to cause loose stools, so if that happens, lower the dose or take it after a meal. For the Calcium Magnesium Vitamin D product, check the ingredient list on the pack to see which form of magnesium it uses.
What to check before buying
Daiso Mall's online listings do not always show the full ingredient panel, so for the exact amounts and daily serving, check the nutrition label on the pack in store or in the Daiso Mall app. If you already take calcium or a multivitamin, check that you are not doubling up on magnesium. If you take certain antibiotics (tetracyclines or quinolones) or osteoporosis medication, take magnesium at least 2 hours apart from them.
Please keep in mind
- This article is based on information checked as of the date shown at the top. New research or changes in official guidelines may change the details, so please use it as a reference rather than taking it as definitive.
- For an accurate diagnosis and advice about your health, please see a doctor in person.