Should you take calcium, magnesium and zinc together?
Usually not, if you eat a varied diet. But if you take one, the mix matters. In one small study, a calcium tablet with a meal halved the zinc people took in from it.
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Do I need a calcium, magnesium and zinc supplement?
Most people don’t. The NHS says a varied, balanced diet should give you all the calcium, magnesium and zinc you need.
If you do take them, each one has a daily amount from supplements that is unlikely to harm you. Stay under all three.
| Mineral | Adults need a day | From supplements |
|---|---|---|
| Calcium | 700mg. | 1,500mg or less a day is unlikely to cause any harm. |
| Magnesium | 300mg for men, 270mg for women (19 to 64). | 400mg or less a day is unlikely to cause any harm. |
| Zinc | About 9.5mg for men (19 to 64), 7mg for women. | No more than 25mg a day, unless a doctor advises it. |
Sources: NHS: calcium; NHS: other minerals
More isn’t better. The Royal Osteoporosis Society (ROS) says more calcium than you need is unlikely to improve your bone strength.
Check your plate first. Calcium comes from dairy, curly kale, soya drinks with added calcium and bread made with fortified flour.
Magnesium comes from spinach, nuts and wholemeal bread. Zinc comes from meat, shellfish, cheese and bread.
Can you take calcium, magnesium and zinc together?
Check that one tablet, plus anything else you take, stays under all three limits. The catch is how calcium and zinc mix.
In a small US study, people ate a test meal with a 600mg calcium tablet. They took in half as much zinc from that meal.
| Test meal | Zinc taken in from the meal |
|---|---|
| With a 600mg calcium tablet | About half as much. |
| With 600mg calcium plus 7.8mg extra zinc | The loss was made up. |
Source: Wood and Zheng 1997
In 18 older women, about 468mg of extra calcium a day cut the zinc they took in by about 2mg a day. The authors say high-calcium diets may raise how much zinc you need.
Zinc has its own catch. High doses cut the copper your body takes in.
The NHS says this can lead to anaemia and weakening of the bones. Anaemia means too few healthy red blood cells.
Taking zinc for a reason? Read how much zinc a day before you add a combined tablet.
Who might need a calcium and magnesium supplement?
Two groups stand out in the sources, and both are about calcium. The NHS says most people get all the magnesium they need from a varied, balanced diet.
Vegans. The NHS lists calcium as one of the nutrients that are more difficult to get through a vegan diet. It says have fortified foods or consider supplements.
Good vegan sources include fortified unsweetened soya, pea and oat drinks, calcium-set tofu, sesame seeds and tahini, pulses, and white or brown bread.
People with weak bones. Are you at risk of osteoporosis (bones that get weak and break easily), or on a bone medicine? Your doctor may advise around 1,000mg of calcium a day.
Vitamin D matters here too: see calcium and vitamin D tablets.
Taking magnesium for leg cramps? See what trials found for magnesium and cramps first.
How do I read a cal mag zinc label?
Read the back of the pack, and count every product you take. The ROS warns that other supplements may also contain calcium. Most calcium supplements give 300mg to 1,000mg.
Before you buy a calcium, magnesium and zinc tablet
- Find the mg of each mineral per daily dose, not per tablet.
- Add any other supplement with calcium, magnesium or zinc, such as a multivitamin.
- Keep calcium from supplements to 1,500mg a day or less.
- Keep magnesium from supplements to 400mg a day or less.
- Keep zinc from supplements to 25mg a day or less, unless a doctor advises more.
- On a prescribed medicine? Check it with a pharmacist first.
Sources: NHS: calcium; NHS: other minerals; ROS
Say your cal mag gives 1,000mg of calcium and your multivitamin adds 200mg. That’s 1,200mg, still under 1,500mg.
Taking more than 400mg of magnesium for a short time can cause diarrhoea. Not sure which type to buy? See which magnesium to take and can you take too much magnesium.
Can I take calcium, magnesium and zinc with my medicines?
Some common medicines don’t mix well with these minerals. Tell your doctor or pharmacist before you add a tablet.
| Medicine | What the NHS says |
|---|---|
| Levothyroxine, for an underactive thyroid | Calcium supplements and indigestion remedies may not mix well with it. |
| Doxycycline, an antibiotic | Supplements that contain zinc, and indigestion remedies, may not mix well with it. |
| Ciprofloxacin, an antibiotic | Leave at least 2 hours between it and dairy or drinks with added calcium, such as plant milk. The calcium can stop your body taking in all the medicine. |
| Alendronic acid, a bone medicine | Tell your doctor about supplements with calcium, magnesium or zinc. Wait at least 30 minutes after it before another medicine by mouth. |
Sources: NHS: levothyroxine; NHS: doxycycline; NHS: ciprofloxacin; NHS: alendronic acid
On a bone medicine called a bisphosphonate? You may be prescribed calcium to take at a different time to it.
Never stop or change a prescribed medicine without your prescriber.
When to speak to a GP
Get advice if:
- You take levothyroxine, doxycycline, ciprofloxacin or alendronic acid and want to add a mineral tablet.
- You’re at risk of osteoporosis or take a bone medicine. Your doctor may advise around 1,000mg of calcium a day.
- You want to take more than 25mg of zinc a day. Only do this if a doctor advises it.
- You’re not sure how much calcium you should have. The ROS says talk to your doctor.
Curious about your own levels? See magnesium blood test and zinc blood test results explained.