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Factors That Lower or Increase Calcium Levels

Written by Biljana Novkovic, PhD | Last updated:
Medically reviewed by
Ognjen Milicevic, MD, PhD, Puya Yazdi, MD | Written by Biljana Novkovic, PhD | Last updated:

Both hypo- and hypercalcemia are often caused by serious diseases or disorders that require medical attention. Work with your doctor to discover what’s causing abnormal calcium levels and to treat any underlying conditions. In this article, we summarize additional strategies that can help improve your calcium levels. Read on to find out more.

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 [3].

PTH raises blood calcium levels by increasing the absorption of calcium from the gut and kidneys. This hormone can also mobilize calcium and phosphate from the bones: that is, it can break down and free the mineral content of bones to compensate for low calcium levels. This process is known as bone resorption [3].

PTH also increases the amount of vitamin D that is converted to its active form, calcitriol. Active vitamin D increases calcium absorption in the gut. If PTH levels drop too low, so does calcium [3].

Read more to learn about calcium here:

Does Calcium Intake Reflect Blood Calcium Levels?

In a nutshell, no. Blood calcium levels are tightly controlled by PTH [4]. That’s why your calcium blood levels usually won’t rise with increased calcium intake and absorption and won’t fall with reduced calcium intake.

There are, however, a couple of things you can do to improve your health in hypocalcemia or hypercalcemia.

Do not attempt to self-diagnose these conditions. Work with your doctor to get an accurate diagnosis!

Increasing Blood Calcium Levels

1) Address Underlying Health Issues

Hypocalcemia, or low blood calcium, is often caused by underlying health conditions, such as an underactive parathyroid gland (hypoparathyroidism) or vitamin D deficiency.

That’s why the most important thing is to work with your doctor to find out what’s causing your low calcium and to treat any underlying conditions.

Discuss the additional lifestyle changes listed below with your doctor. None of these strategies should ever be done in place of what your doctor recommends or prescribes!

2) Vitamin D

If your body is deprived of vitamin D – from lack of sun exposure and insufficient dietary intake – your calcium levels can drop. 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 are getting enough! [5, 6, 7].

If you can’t get enough vitamin D from the sun, discuss vitamin D supplements with your doctor.

3) Eat Foods High in Calcium

Your calcium levels might be low because you are not getting enough of this nutrient in your diet. Your doctor will tell you if that’s the case based on other tests, such as PTH and bone mineral density.

In the meantime, make sure your diet is healthy and well balanced and that it contains enough of all essential nutrients, including calcium.

The best food sources of calcium are dairy products: milk, yogurt, and cheese [8, 9, 10].

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.

Plant-Based Diets

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 include [11, 12, 13, 14]:

  • Tofu (calcium-set is best)
  • Kale, broccoli, sprouts, cauliflower, bok choy, collard greens
  • Nuts (hazelnuts, walnuts, almonds)
  • Kidney beans

Dairy-free Diets

If you follow a paleo-style or carnivore diet, you are probably avoiding dairy, soy, and nuts. Good calcium sources for people on meat-heavy diets include [11, 15]:

  • 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.

4) Avoid Foods that Bind Calcium

If you’re not getting enough calcium, make sure you’re not overdoing foods that decrease calcium absorption, such as spinach, potatoes, rhubarb, and beets [16].

5) Reduce Phosphorus Intake (Processed Foods)

Phosphorus binds calcium, leaving less available for your body to use. You can increase your calcium 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) [17, 18, 19, 20, 21, 22, 23, 24].

Also refrain from refined sugars/carbohydrates and drinks containing phosphoric acid. These may increase the loss of calcium through urine [25].

6) 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 [26, 27].

7) 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) [28, 29].

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 [30, 31, 32, 33, 34]:

9) Calcium Supplements

If you can’t meet your dietary calcium needs, discuss supplementing with your doctor.

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.

10) Magnesium

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!) [5, 35, 36, 37].

Most people eat less magnesium than recommended. If your magnesium is on the low side, discuss magnesium supplements with your doctor.

11) Pay Attention to Calcium-Lowering Drugs

Certain medications can reduce your calcium levels. Talk to your doctor if you have low calcium levels and take any of the following medications [38, 5]:

  • Bisphosphonates (osteoporosis treatment)
  • Cisplatin (chemotherapy)
  • Antibiotics (rifampin, plicamycin, aminoglycosides)
  • Anti-seizure drugs
  • Calcitonin
  • Chloroquine (malaria)
  • Proton-pump inhibitors (acid reflux)
  • Corticosteroids (anti-inflammatory)

How To Decrease Blood Calcium Levels

High blood calcium levels are usually due to a serious underlying disease. Do not attempt to diagnose and/or treat them yourself.

1) Address Underlying Health Issues

The two most common causes of elevated calcium levels are high parathyroid gland activity (hyperparathyroidism) and cancer [39].

If your hypercalcemia is mild and you are already working with a healthcare professional to address the causes, some of the strategies below may help. Discuss them with your doctor. None of these strategies should ever be done in place of what your doctor recommends or prescribes!

When you have hypercalcemia, your doctor may prescribe the following:

  • Intravenous fluids
  • Calcitonin, corticosteroids, loop diuretics, or bisphosphonates
  • Dialysis (if other treatments are not working or kidneys are damages).

You shouldn’t make any drastic changes to your diet, lifestyle, or supplement regimen without medical guidance.

2) Reduce Foods High in Calcium

Depending on what your doctor says, you may need to 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.

3) Avoid Supplements and Drugs Containing Calcium

It perhaps goes without saying that you shouldn’t take calcium supplements if you have high calcium blood 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).

4) 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 [40].

5) Limit 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. You may need to stop supplementing vitamin D or to decrease your dosage [5, 6, 7].

Importantly, sun exposure doesn’t cause dangerously high vitamin D (or calcium) levels. Even if you get too much sun, sunlight will degrade any excess vitamin D [41].

6) Watch Out for Calcium-Raising Drugs

Certain medications may raise your calcium blood levels. Talk to your doctor if you have high calcium levels and are taking any of these medications [42, 43, 44, 39, 45, 46]:

  • Lithium
  • Theophylline
  • 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

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 [15].

Food Serving size Calcium (mg)
Yogurt 6 oz 300
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


If you have hypo- or hypercalcemia, you should always work with your doctor to understand what’s causing it and to treat any underlying conditions.

If your doctor tells you you need to up your calcium, you can do so by eating more calcium-rich foods, getting enough vitamin D (preferably from the sun), magnesium, and healthy fats.

If your calcium levels are high, you may need to decrease foods rich in calcium in favor of low-calcium foods and avoid all vitamin D- and calcium-containing supplements.

Review the drugs and supplements you are taking with your doctor. Make sure they are not adversely affecting your calcium levels.

About the Author

Biljana Novkovic

Biljana received her PhD from Hokkaido University.
Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science and health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.


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