Calcium and magnesium are partner minerals, and taking both can help if your diet falls short of either one. Calcium is the main mineral in bones and teeth and triggers muscle contraction, while magnesium supports bone structure, nerve and muscle function, and more than 300 enzyme reactions. More is not better, though. The NIH sets the upper limit for supplemental magnesium at 350 mg a day, and calcium is absorbed best in doses of 500 mg or less.
Key Takeaways
- Calcium builds and maintains bones and teeth, and magnesium supports bone structure plus nerve and muscle function.
- Severe magnesium deficiency can lower blood calcium, which is one reason the two minerals are linked.
- Most adults need 1,000 to 1,200 mg of calcium and 310 to 420 mg of magnesium per day, from food and supplements combined.
- Calcium absorbs best in doses of 500 mg or less, and supplemental magnesium should stay at or below 350 mg a day unless a doctor advises otherwise.
- Food comes first. Supplements make sense mainly for people who cannot meet their needs through diet.
What Do Calcium and Magnesium Do in the Body?
Calcium is the most abundant mineral in the body, and almost all of it is stored in bones and teeth. Magnesium is a mineral that acts as a helper in more than 300 enzyme systems and also contributes to bone structure, nerve signaling, muscle contraction and normal heart rhythm, according to the NIH Office of Dietary Supplements.
Together, the two minerals cover a wide range of daily jobs, from keeping your skeleton strong to letting your muscles contract and relax properly. The diagram below shows where their roles overlap.
Why Do Calcium and Magnesium Work Together?
Calcium and magnesium work together because the body uses magnesium to move and regulate calcium. Magnesium takes part in the active transport of calcium across cell membranes, a process that supports nerve impulses and muscle contraction, and it influences hormones and vitamin D activity that control bone health.
The link also runs the other way. NIH notes that severe magnesium deficiency can cause low blood calcium because the body’s mineral balance is disrupted. In other words, a person can eat enough calcium and still have a calcium problem if magnesium is very low.
Vitamin D is the third piece of the puzzle, since it helps your body absorb calcium. If you want the full picture, read our guides on vitamin D3 and K2 benefits and the warning signs of vitamin D deficiency.
What Are the Benefits of Taking Calcium and Magnesium Together?
The main benefit of getting enough calcium and magnesium is support for bone, muscle and nerve health. The benefit comes from meeting your daily needs for both minerals, not from taking extra, and research does not show that a combined pill works better than getting each mineral separately.
Bone Health
Bones need both minerals. Calcium is the main building material, and a large share of the body’s magnesium is also stored in bone, where it contributes to bone structure. Adequate intake of both, along with vitamin D, supports bone strength throughout life.
Keep expectations realistic. The NIH notes that more research is needed to know whether extra calcium from food or supplements improves bone health in older adults, so a supplement is not a guaranteed way to prevent bone loss. Weight-bearing activity matters too, and even a daily habit like the one described in what happens when you walk 30 minutes every day puts useful load on your bones.
Muscle and Nerve Function
Calcium helps trigger muscle contraction, and magnesium helps regulate the movement of calcium and other minerals that carry nerve signals. When either mineral runs low over time, muscle and nerve function can be affected. Because symptoms like cramps or tingling have many possible causes, a blood test is a better guide than guessing.
Filling Real Nutrient Gaps
The clearest benefit of a calcium and magnesium combination is convenience for people who fall short on both. This can include people who avoid dairy, older adults who eat less, and people with digestive conditions that reduce absorption. Certain medicines, such as acid-reducing proton pump inhibitors (PPIs), can lower magnesium levels, according to NIH.
How Much Calcium and Magnesium Do You Need?
Adults need about 1,000 to 1,200 mg of calcium and 310 to 420 mg of magnesium per day, depending on age and sex. These Recommended Dietary Allowances (RDAs) include everything you get from food, drinks and supplements, except for the magnesium upper limit, which applies to supplements and medicines only.
| Mineral | Adult daily RDA (NIH) | Upper limit | Good to know |
|---|---|---|---|
| Calcium | 1,000 mg (ages 19 to 50); 1,200 mg for women over 50 and for everyone over 70 | 2,500 mg (ages 19 to 50); 2,000 mg (over 50), from all sources | Absorbed best in doses of 500 mg or less |
| Magnesium | Men: 400 mg (19 to 30), 420 mg (31+). Women: 310 mg (19 to 30), 320 mg (31+) | 350 mg from supplements and medicines only | Too much from supplements can cause diarrhea and nausea |
The magnesium upper limit does not apply to magnesium in food. According to the NIH Office of Dietary Supplements, the limit exists because high supplement doses, not foods, tend to cause side effects.
Can You Take Calcium and Magnesium at the Same Time?
Most people can take calcium and magnesium at the same time, but spacing them out may help absorption. Calcium is absorbed best in doses of 500 mg or less, and some health-system guidance advises taking magnesium supplements apart from calcium and phosphorus supplements.
- Calcium carbonate is absorbed best with food, so take it with a meal.
- Calcium citrate is absorbed well with or without food, which can suit people with low stomach acid.
- Split large doses. If you need more than 500 mg of supplemental calcium, take it in two or more servings.
- Mind your medicines. Levothyroxine is not absorbed well within 4 hours of calcium carbonate, and magnesium-rich supplements should be separated from oral bisphosphonates by at least 2 hours.
If you take any prescription medicine, ask your pharmacist how to time your supplements.
Which Foods Provide Calcium and Magnesium?
Many foods supply both minerals, which is why a varied diet is the best starting point. Dairy products, fortified plant milks, canned fish with soft bones, kale and bok choy are good calcium sources, while seeds, nuts, leafy greens, beans and whole grains are rich in magnesium.
- Calcium-rich foods: milk, yogurt, cheese, fortified plant milks, calcium-set tofu, kale, bok choy and canned sardines or salmon with bones.
- Magnesium-rich foods: pumpkin seeds, chia seeds, almonds, cashews, spinach, black beans, edamame and whole grains.
A bowl of yogurt with oats, nuts and seeds covers both minerals in one meal. For more ideas, see our list of best breakfast foods for weight loss and our guide to foods that boost your immune system.
Who Might Need a Calcium and Magnesium Supplement?
A supplement may be useful for people who cannot reach their daily needs through food alone. Your intake, age, diet and medicines all matter, so the decision is best made with a doctor or dietitian rather than guessed.
- People who avoid dairy and do not eat fortified alternatives
- Older adults whose appetite or absorption has declined
- People with digestive conditions that reduce mineral absorption
- People taking medicines that lower magnesium, such as PPIs
- People with a doctor-confirmed low calcium or magnesium level
What Are the Side Effects and Risks?
Calcium and magnesium supplements are generally well tolerated at recommended amounts, but high doses can cause problems. Too much supplemental magnesium commonly causes diarrhea and nausea, while calcium supplements can cause gas, bloating or constipation in some people.
People with kidney disease should talk to a doctor before taking either mineral, because the kidneys help regulate magnesium and calcium levels. Never exceed the upper limits unless a healthcare provider has told you to, and tell your doctor about every supplement you take.
How Can You Take Calcium and Magnesium Safely?
- Count food first. Add up the calcium and magnesium in your usual meals so you only supplement the gap.
- Read the label. Look for the elemental amount of each mineral, not just the compound weight.
- Keep calcium doses at 500 mg or less per serving and take carbonate forms with food.
- Stay at or below 350 mg of supplemental magnesium per day unless your doctor says otherwise.
- Check your vitamin D. Calcium needs vitamin D for absorption, so ask about a blood test if you are unsure.
- Review medicines with a pharmacist and space supplements away from thyroid or osteoporosis drugs.
Frequently Asked Questions
Is it good to take calcium and magnesium together?
It can be, especially if your diet is low in both minerals. They support bones, muscles and nerves, and magnesium helps the body handle calcium. Taking them together is not required, though, and some guidance suggests spacing supplements apart. Meeting your daily needs matters more than the combination.
What is the best time of day to take calcium and magnesium?
No single time has been proven best. Take calcium carbonate with a meal, calcium citrate whenever is convenient, and split calcium into doses of 500 mg or less. Choose times you will remember, and separate supplements from thyroid or bone medicines as your pharmacist advises.
How much magnesium is too much from supplements?
The NIH upper limit for magnesium from supplements and medicines is 350 mg per day for adults. This limit does not include magnesium from food. Exceeding it can cause diarrhea, nausea and cramping, and people with kidney problems should check with a doctor first.
Can I get enough calcium and magnesium from food alone?
Many people can. Dairy or fortified alternatives, leafy greens, nuts, seeds, beans and whole grains can cover most needs. Tracking your intake for a few days shows whether a gap exists before you buy a supplement.
Do calcium and magnesium supplements build bone on their own?
No. Bone health also depends on vitamin D, physical activity, overall diet, hormones and age. NIH notes that more research is needed on whether extra calcium improves bone health in older adults, so supplements work best as one part of a wider plan.
Who should talk to a doctor before taking calcium and magnesium?
Anyone with kidney disease, anyone taking prescription medicines such as thyroid or osteoporosis drugs, and anyone who is pregnant or breastfeeding should speak to a healthcare provider first. A doctor can check your levels and recommend safe amounts.
Final Thoughts
Calcium and magnesium are partners that support strong bones, steady muscles and healthy nerves. Most people do best by getting both from food, adding vitamin D, staying active and using supplements only to fill a confirmed gap. If you do choose a supplement, respect the dose limits and ask your pharmacist about timing.
This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment.
