What is Calcium?
Calcium is the most abundant mineral in the human body and accounts for 1-2% of the human body weight. Every cell in your body needs it to function. Calcium supports your bones, heart, muscles, and nervous system. But only around 1% of your total body calcium is found in the blood. The remaining 99% is stored in your bones and teeth [1, 2].
Calcium blood levels are mostly controlled by parathyroid hormone (PTH). Cells in your parathyroid gland – located in the neck just behind the thyroid – release PTH when they sense a drop in calcium blood levels .
PTH raises blood calcium levels by increasing the absorption of calcium from the gut and kidneys. This hormone also mobilizes calcium and phosphate from the bones: that is, it breaks down and frees the mineral content of bones to compensate for low calcium levels. This process is also known as bone resorption .
Calcium Blood Test
- Calcium bound to proteins, mainly albumin (about 40%)
- Calcium complexed with phosphate and citrate (about 10%)
- Ionized calcium, also known as free or active calcium (about 50%)
You don’t need to prepare for this test or fast beforehand. A healthcare professional will simply collect a blood sample from your vein that will be analyzed.
The calcium blood test is often done as part of a routine metabolic panel. The basic metabolic panel (BMP) checks blood sugar, calcium, and electrolytes, as well as kidney function. The comprehensive metabolic panel (CMP) also includes cholesterol, protein levels, and markers of liver function .
Your doctor may also order an ionized (free) calcium test.
Ionized calcium is the body’s active form of calcium. It is assumed to be around 50% of the total blood calcium, although the exact percentage may vary. Ionized calcium levels are often just estimated based on total blood calcium and albumin levels. Testing ionized calcium is far more precise, but it requires special equipment and is expensive .
Normal Calcium Levels
The normal ranges for calcium levels in adults are 8.5 to 10.5 mg/dL. These values can vary slightly from lab to lab .
A Word of Caution
The natural strategies listed below target increasing or decreasing calcium levels and/or activity in the body in a healthy way.
However, your calcium blood levels may not necessarily rise with increased calcium intake and absorption. For example, your blood levels will remain unchanged if your body needs to use this newly-available calcium to build bones.
On the other hand, your calcium blood levels won’t inevitably fall with reduced calcium intake.
You may have a serious medical condition, such as cancer, that’s causing bone breakdown and increasing your calcium blood levels.
In a nutshell, blood calcium levels do not accurately reflect calcium balance and activity in the body .
You can read more about the cause of high or low levels in our other posts dedicated to this topic:
- Causes of hypocalcemia (low blood calcium)
- Causes of hypercalcemia (high blood calcium)
Do not attempt to self-diagnose these conditions. Your healthcare provider should help you understand how your calcium blood levels relate to your dietary status, bone health, and overall symptoms.
How To Increase Blood Calcium Levels
1) Eat Foods High in Calcium
Your calcium levels might be low because you are not getting enough of this nutrient in your diet.
Getting enough calcium from foods can be tricky, especially if you follow a plant-based or dairy-free diet. It gets even more difficult if you’re avoiding calcium-fortified products, such as fruit juices, soy, or nut milk.
Still, the benefits of eliminating dairy outweigh its benefits for some people. Take a look at the list of calcium-rich foods you can add to your diet in these scenarios.
If you follow a vegan diet, you are at risk of getting insufficient amounts of certain nutrients, including calcium and vitamin D. Choose vegetables high in calcium but low in oxalic acid (it inhibits calcium absorption). Good sources of calcium for vegans include [12, 13, 14, 15]:
- Tofu (calcium-set is best)
- Kale, broccoli, sprouts, cauliflower, bok choy, collard greens
- Nuts (hazelnuts, walnuts, almonds)
- Kidney beans
If you follow a paleo-style or carnivore diet, you are probably avoiding dairy, soy, and nuts. This leaves you with fewer options than vegans. Good calcium sources for people on meat-heavy diets include [12, 16]:
- Canned or fresh fish with bones (sardines, sardelles, or even salmon)
- Beef tripe
Those on a more liberal paleo diet have additional sources to choose from, including kale, broccoli, bok choy, and other leafy greens.
If you don’t supplement or eat fortified foods, the best solution for getting enough calcium on a strict paleo or carnivore diet is to consume bones.
2) Consider Calcium Supplements
If you can’t meet your dietary calcium needs, consider supplementing. Take a look at our post on the benefits of calcium supplements, or learn to tell apart the difference between various forms of calcium supplements (such as orotate salts vs. carbonate) in this post.
3) Get More Vitamin D
If your body is deprived of vitamin D – from lack of sun exposure and insufficient dietary/supplement intake – your calcium levels can drop too low. Vitamin D helps absorb calcium in the gut. According to recent estimates, up to 50% of the population is deficient in vitamin D – so make sure you get enough! [17, 18, 19].
4) Pay Attention to Calcium-Lowering Drugs
- Bisphosphonates (osteoporosis treatment)
- Cisplatin (chemotherapy)
- Antibiotics (rifampin, plicamycin, aminoglycosides)
- Anti-seizure drugs
- Chloroquine (malaria)
- Proton-pump inhibitors (acid reflux)
- Corticosteroids (anti-inflammatory)
5) Increase Magnesium Intake
Parathyroid hormone (PTH), which increases calcium, needs sufficient levels of magnesium to work. Recent research reveals that the ratio of calcium to magnesium you get from food is key: a 2: 1 calcium: magnesium ratio is best. That is, you should get twice as much calcium as magnesium (but not more!) [17, 21, 22, 23].
6) Reduce Phosphorus Intake (Processed Foods)
Phosphorus binds calcium, leaving less available for your body to use. You can increase your calcium levels by reducing your phosphorus intake.
Inorganic phosphorus from food additives is particularly problematic. If you have low calcium levels, avoid all processed foods, including hard cheeses. Instead, choose more foods low in phosphorus, such as vegetables and fruits, olive oil, rice and egg whites (not yolks) [24, 25, 26, 27, 28, 29, 30, 31].
7) Increase Vitamin K Intake
Vitamin K – especially K2 – works in synergy with vitamin D to increase the gut absorption of calcium. It also helps to reduce the amount of calcium lost with the urine. In rats, it lessens the symptoms of hypocalcemia (low calcium). It also increases bone mass, when taken with calcium and vitamin D [32, 33, 34].
8) Get More Healthy Fats
Fats increase the absorption of calcium. By making sure you get healthy fats with your meals, you can increase your absorption of calcium from foods.
The type of fat matters and unsaturated fats work best. Saturated fat still helps absorption, but it doesn’t increase bone mass as unsaturated fats do. Some healthy fats you should eat more often include [35, 36, 37, 38, 39]:
9) Quit Smoking
Smoking significantly reduces vitamin D and parathyroid hormone. As a result, you absorb less and get rid of more calcium. Smoking also increases bone loss and is a risk factor for osteoporosis [40, 41].
10) Reduce Alcohol Intake
Alcohol reduces the absorption of calcium and increases its loss through the urine. Excessive drinking also disrupts vitamin D production, weakens the bones, and reduces sex hormone levels (testosterone in men and estrogen in women) [42, 43].
How To Decrease Blood Calcium Levels
High blood calcium levels can be due to a serious underlying disease. Do not attempt to diagnose and/or treat them yourself. If you suspect you have hypercalcemia (“hyper” = high, “calcemia” = calcium in the blood), seek medical help as soon as possible.
If your hypercalcemia is mild and you are already working with a healthcare professional to address the causes, some of the natural strategies below may help. However, you should not make any drastic changes to your diet, lifestyle, or supplement regimen without medical guidance.
1) Reduce Foods High in Calcium
Reduce your intake of foods high in calcium such as dairy, tofu, fortified cereals, and green leafy vegetables. Up your intake of low-calcium foods instead. Some healthy low-calcium food options include olive oil, resistant starch, meat, rice, apples, tomatoes, eggplant, strawberries, and asparagus.
2) Avoid Supplements with Calcium
It perhaps goes without saying that you shouldn’t take calcium supplements if you have high calcium levels. But you would be surprised to know how many dietary supplements calcium can sneak into. This includes multivitamins and over-the-counter drugs for acid reflux (such as Tums).
Go through the supplements in your cupboard, and make sure you are not inadvertently supplementing calcium.
3) Drink More Water
If you have high calcium levels, you need to drink more water. Staying hydrated helps to flush more calcium with the urine. In fact, hydration (saline drops) is the primary treatment for high calcium levels in hospitals .
4) Stop Taking Vitamin D Supplements
Vitamin D increases the amount of calcium you absorb. If your calcium levels are already too high, you don’t need to make it worse by further increasing calcium absorption from foods. Stop supplementing vitamin D [17, 18, 19].
The only risk of worsening your hypercalcemia comes from vitamin D supplements.
5) Watch Out for Calcium-Raising Drugs
- Thiazide diuretics, used to treat high blood pressure
- Androgens, used in breast cancer therapy
- Estrogens, such as in birth control pills
- Anti-estrogens, used to treat breast cancer and hormonal abnormalities
- Tamoxifen (Nolvadex), used against breast cancer
- Antacids for heartburn such as Tums
When you exercise, your body loses calcium for a short time. As you exercise, your lactate levels rise, and your body shifts toward a more acidic state. This increases calcium loss from the bones, via sweat, and through urine. In a trial with college basketball players, a normal playing session resulted in an average sweat loss of 250 mg calcium! [51, 52, 53, 54, 55]
More importantly, exercise is great for your bones in the long run. If you have high blood calcium, it usually means your bones are being degraded. Exercise helps bring calcium back into your bones [56, 57].
Do as much exercise as feels right for you. Anecdotally, even light breathing and movement helps if you feel too weak to get out of bed
7) Use a Sauna
As written above, sweating will increase the loss of calcium. An easy and relaxing way to get sweating is using a sauna. Even at temperatures as low as 98.6°F (37°C), you lose 20 mg of calcium per hour .
Plus, there are many other health benefits to using a sauna. Saunas are generally safe and similar whole-body heat therapies (hyperthermia) have been used in people with cancer. However, saunas are not safe for people with heart problems. Talk to your doctor to make sure sauna use is safe for you .
Foods High in Calcium
Below is a list of calcium-rich foods. These are ideas for foods to eat when you need more calcium, or to avoid if your calcium levels are too high .
|Food||Serving size||Calcium (mg)|
|Sardines||3.5 oz with bones||250|
|Salmon||3.5 oz with bones||240|
|Spinach||1 cup cooked||240|
|Chia seeds||1 oz||200|
|Kale||1 cup chopped||100|
|Orange||1 medium size||80|
|Almonds||Raw, ¼ cup (1 oz)||80|
|Broccoli||1 cup cooked||60|
|Brussels sprouts||1 cup cooked||60|
|Brazil nuts||1 oz||50|
Irregular Calcium Levels?
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If you have hypo- or hypercalcemia, you should always consult with your doctor. There may be serious underlying medical conditions you don’t want to miss. If your calcium levels are within the normal range, you can usually get them in the optimal range naturally.
To increase your calcium levels, eat more calcium-rich foods, and get enough vitamin D (preferably from the sun), vitamin K, magnesium, and healthy fats.
To lower your levels, up your intake of low-calcium foods and avoid all vitamin D- and calcium-containing supplements. Make sure to drink plenty of water and consider using a sauna.
Exercise is beneficial both for people with high and low calcium levels and helps strengthen your bones.