Together, magnesium and calcium are crucial to bone health and other important bodily functions. But the way your body uses them means the minerals have to work in tandem to be fully effective.
On this page, we explain:
- the role magnesium and calcium play in keeping your body healthy
- why magnesium is key to how your body uses calcium
- how to make sure you’re getting enough of the minerals, via food and supplements
- Why magnesium and calcium are important for good health
- Why calcium needs magnesium to be effective
- How your body absorbs magnesium and calcium
- Knowing what foods to eat
- Types of supplements, how much to take and when to take them
- What causes a magnesium or calcium deficiency
- Possible side effects of magnesium and calcium supplements
- How magnesium and calcium help with sleep
Why magnesium and calcium are important for good health
Magnesium helps bones form and remain strong. It enables the small mineral crystals that comprise part of your bone structure to increase in density and gain strength. It also allows your bones to absorb calcium more readily, which has several benefits (see Calcium below).
Aside from strengthening your skeleton, magnesium contributes to:
- normal energy-yielding metabolism
- normal muscle function
- electrolyte balance
- normal functioning of the nervous system
- normal protein synthesis
Of all the essential minerals found in your body, calcium is the most abundant, and nearly all of it is stored in your bones and teeth.
Like magnesium, it’s vital to bone health. It enables bones to develop and grow, keeping them strong and dense up to the age of around 25, when they begin to lose density as part of the ageing process. Calcium helps slow this decline.
Calcium also contributes to normal:
- muscle function
- blood clotting
- neurotransmission (nerve cells passing signals to each other)
- digestive enzyme function
Why calcium needs magnesium to be effective
Your body doesn’t rely on magnesium to absorb calcium. But without it, calcium can become toxic, depositing itself in soft tissues, kidneys, arteries and cartilage rather than in bones where it has the greatest benefit.
This can lead to some quite severe health conditions. Balancing calcium with the right amount of magnesium stops these potentially harmful issues occurring.
Magnesium helps maintain a balance of hormones
Having too much calcium in your blood stimulates your body into releasing a hormone called calcitonin, while preventing it from secreting the parathyroid hormone (PTH).
- Calcitonin—causes your bones to absorb more calcium, but limits how much goes into your soft tissues
- PTH—draws calcium out of the bones and deposits it in the soft tissues
Your body needs to be able to regulate the balance of these hormones, and it can do that with the help of magnesium. Sufficient amounts of magnesium suppress PTH and stimulate calcitonin, sending calcium to the bones rather than the soft tissues and preventing certain bone diseases.
Magnesium helps regulate the heartbeat
Calcium makes muscles contract, while magnesium lets them relax. Together, they regulate the heartbeat. Electrical impulses provoke the calcium within the cells of the heart muscle, stimulating a contracting movement. Magnesium helps the cells—and, therefore, the muscles—to relax.
Magnesium helps enzymes convert vitamins to facilitate calcium absorption
Your body needs two vitamins to properly absorb calcium:
- Vitamin D—certain enzymes in your body require magnesium to be able to convert vitamin D into its active form (known as calcitriol)
- Vitamin K (K1 and K2)—these promote the calcification of bones and prevent blood vessels and kidneys from calcifying
How your body absorbs magnesium and calcium
- oral form—those you take by mouth, such as tablets
- transdermal form—those you absorb through the skin, such as lotions and sprays
With food and oral supplements, the minerals pass through parts of your body known as the gastrointestinal tract, which comprises your:
- small intestine
- large intestine
Transdermal supplements, on the other hand, absorb into your skin, bypassing primary processing by the digestive system. Read more about the transdermal method below.
How effectively your body absorbs and retains a mineral is dictated by that mineral’s “bioavailability”—that is:
- how much of it you take in overall, through food and supplements
- the health of your gastrointestinal tract
- your diet in general
Magnesium’s bioavailability varies from supplement to supplement. Those supplements that dissolve well in water or other liquid tend to be more completely absorbed than less soluble forms.
And some studies have found that magnesium chloride—which BetterYou’s supplements use as a source—is more bioavailable than magnesium oxide and magnesium sulphate, for example.[ 1 ]
Calcium absorption varies from person to person too, but on average is around 30% of overall intake. This is why the recommended advice is often to take smaller doses of calcium several times a day rather than a single large dose.
Factors that affect mineral absorption
Consuming certain foods and drinks
If you eat/drink the following, it might affect how well your body absorbs minerals:
- Too much red meat
- Too much salt
- Processed fats
- Refined sugars
- Soft drinks
- Foods high in oxalic acid (such as spinach, rhubarb and chocolate)
If you have low levels of gastric acid or suffer with digestive complaints, your body may not be able to fully absorb magnesium or calcium.
For maximum absorption, you should take calcium supplements with food.
As you get older, your body releases calcium through sweat, skin cells and waste. Because of this, calcium absorption can vary depending on how old you are.
Knowing what foods to eat
A diet rich in both magnesium and calcium can have a range of health benefits.
Food sources that contain high levels of magnesium include:
- Brown rice[ 1 ]
- Dark green vegetables (e.g. spinach)
- Legumes (e.g. lentils, split peas, tofu)
- Beans (e.g. black, kidney, edamame)
- Nuts (e.g. almonds, cashews, brazil nuts)
- Seeds (e.g. sunflower, sesame, pumpkin)
- Wholegrain cereals[ 3 ]
The following foods and drinks are rich sources of calcium:
- Milk (including soy milk)
- Nuts (e.g. pistachio, almonds, hazelnuts)
- Sesame seeds
- Spinach and kale
- Many fortified breakfast cereals[ 3 ]
Types of supplements, how much to take and when to take them
What to take
Magnesium and calcium supplements come in a wide range of forms—as pills, capsules, tablets, powders and liquids.
And that’s just the kind you take by mouth—there are also many types of transdermal supplements (those you absorb through the skin). We explain transdermal magnesium below.
If you choose to take an oral supplement, try to avoid carbonates (i.e. magnesium carbonate or calcium carbonate), as these are the hardest for your body to absorb. Instead, look for magnesium chloride (the most bioavailable form of magnesium) or citrates (magnesium citrate or calcium citrate).
If you take calcium supplements, make sure you also take magnesium so your body can properly metabolise the calcium.
Rather than take magnesium supplements as tablets or capsules, for instance, you can apply them directly to your skin, in forms such as:
The idea is that the mineral absorbs quickly into the highly porous upper layer of your skin (the epidermis), through to the blood vessels and muscles beneath.
At no point does it need to travel through your gastrointestinal tract, meaning you absorb the mineral in greater amounts and avoid the risk of digestive problems.
How much to take
Because magnesium and calcium work so closely together, it’s important to take them in the correct amounts.
A rule of thumb often used is a ratio of one part calcium to one part magnesium. So, if you take 500mg of calcium you should also take 500mg of magnesium. Most calcium and magnesium supplements follow this ratio.
The recommended daily amount of magnesium is 300mg for men (aged 19–64) and 270mg for women (aged 19–64 years).[ 4 ]
With calcium, it’s at least 1,000mg per day for adults. Women aged 51 and older, and men over the age of 70, are advised to increase their daily intake to 1,200mg.[ 5 ]
As magnesium competes with calcium at doses higher than 250mg[ 6 ], if your calcium levels are already low it might cause you to develop a calcium deficiency. Generally, though, taking both minerals in their daily recommended amounts is completely fine.
When to take
Whatever supplements you choose to take, in terms of dosage always follow the directions on the packaging.
If you’re taking transdermal magnesium supplements—those you apply directly to your skin, like many of BetterYou’s products—you can take these whenever you like. Many people like to take them a short time before bed, to aid sleep. Read more about taking magnesium to aid sleep here.
It’s best to take oral magnesium supplements with a meal to reduce the risk of you suffering an upset stomach or diarrhoea. If you’re taking them to help you get to sleep at night, do so around 20 to 30 minutes before you go to bed.
Like magnesium, calcium can be taken transdermally, at any time of the day.
With oral supplements, because your body can’t fully absorb more than around 500mg of calcium at a time, the recommended advice is to divide your doses and take them at different times of the
What causes a magnesium or calcium deficiency
Your body tends to retain calcium and either store it or reuse it. With magnesium, however, it typically uses up all its stores, meaning you must replenish it every day. This is why you’re more likely to develop a deficiency in magnesium rather than calcium.
As your body gets most of its nutrients from the food you eat, the most common cause of any deficiency is diet. Consuming certain types of food and drink hinders your body’s ability to absorb minerals and affects their bioavailability.
Another factor is overfarming. The intensive nature of today’s agriculture means the soil in which fruit and vegetables are grown is less rich in nutrients.
Having low levels of magnesium is known as hypomagnesemia. To read more about what causes this condition, click here.
The following are known as possible causes of hypocalcaemia (calcium deficiency):
- Coeliac disease, inflammatory bowel disease, Crohn's disease and some other digestive diseases
- Lack of parathyroid hormone (PTH)
- Consuming too much magnesium
- Kidney failure
- Vitamin D deficiency
- Phosphate deficiency
- Prolonged use of some medicines, such as chemotherapy or corticosteroids
If you follow a vegan diet, you might become deficient in calcium if you don’t eat enough calcium-rich or calcium-fortified foods.
If you’re lactose intolerant, you must eat plenty of non-dairy foods that are rich in calcium to avoid developing a deficiency.[ 7 ]
Possible side effects of magnesium and calcium supplements
There aren’t too many side effects from taking magnesium and calcium supplements, whether by mouth or transdermally (through the skin).
With oral magnesium supplements, you might suffer a laxative effect if you take too much. Taking supplement with food helps lessen these effects.
Alternatively, you can take these minerals transdermally—for example, by applying a lotion, spray or cream to your skin. This is a fast and effective alternative to tablets and capsules.
Because the magnesium doesn’t go through your digestive system, you don’t need to take it with food or drink and you won’t suffer any adverse effects.
With calcium, you might feel bloated or constipated or suffer with wind. Again, to avoid this, take your supplements with a meal and spread them throughout the day. Calcium citrate usually has fewer or less intense side effects than calcium carbonate.
How magnesium and calcium help with sleep
If you have trouble sleeping, or wake frequently during the night, it could be the sign of a deficiency in either magnesium, calcium or both. The two minerals are natural aids that can help you fall asleep and have a restful sleep.
Magnesium regulates your neurotransmitters and ultimately calms your nervous system in readiness for sleep. It also works alongside melatonin—a hormone your body produces naturally—to control your body clock and sleep-wake cycles. Read more about how magnesium helps poor sleep here.
Research has linked disturbed sleep patterns—including the lack of a deep REM sleep phase—with low levels of calcium.[ 8 ]