How to Choose a Calcium Supplement?

You are likely aware that calcium is crucial for bone health; however, did you know that it is the most abundant mineral in the body? About 99% of the body’s calcium is present in bone and teeth! Even though calcium is found in abundance, your body still needs a constant supply of calcium from food. It is because there is a continuous exchange of calcium from the bone to the bloodstream and vice versa to perform normal bodily functions. Some calcium is also lost as part of the body’s metabolism as sweat, urine, and feces.

Though food is the best way to get this nutrient, calcium supplements have also found their way as a convenient choice. Supplements do an excellent job of filling in the dietary gap should your diet fall short of calcium-rich foods. Also, supplements are very effective and the best way to meet the increased demand for calcium in specific age groups and people with certain health conditions.

If you have been advised to take calcium supplements, making a choice can be challenging given the variety of options- chews, tablets, pills. The following information may help you choose the best form and combination of calcium supplements to meet your dietary requirements. Before we go further, here are some basics on calcium, which may be helpful to choose a calcium supplement that is suitable for you.

What are the benefits of calcium, and how much do you need?

Although calcium is a mineral well known for its bone and teeth forming properties, it has more uses to your body than you know. Calcium is an essential nutrient that needs to be consumed every day. We lose calcium through skin, nails, sweat, urine, and feces every day. Since your body cannot make its own calcium, it is important to ensure daily intake. While your body can manage with low calcium levels for a short time, chronic deficiency leads to health problems; hence maintaining adequate intake is crucial.

Here are some of the benefits of calcium,

  • Supports healthy blood pressure by facilitating the dilation of blood vessels.
  • Aids nerve transmission and cell signaling.
  • Promotes hormone secretion.
  • Regulates muscle contraction, including the heartbeat.
  • Necessary for forming blood clots to prevent blood loss in an injury.

The daily recommended intake for calcium is 1,000 milligrams (mg) daily, which rises to 1,200 mg per day for women over age 50 and men over age 70. Approximately 30% of calcium from food or supplements is absorbed by the body[1]. The absorption rate can vary widely due to multiple factors. For example, in pregnancy, when more calcium is required for the growing fetus, the calcium absorption rate increases. Studies show that calcium absorption in the intestine more than doubles in a pregnant woman. This helps the expectant mother to meet the calcium demands of the growing fetus[2].

Besides the increased demand, calcium absorption in the body is dependent on dietary factors and co-nutrients. Dietary factors that influence absorption include fat (a high-fat diet reduces absorption) and the presence of phosphorus (increases absorption)[3]. The presence of optimal levels of vitamin D is a significant influence on calcium absorption in the body. Without enough vitamin D, your body cannot make the hormone calcitriol (the “active vitamin D”). Low levels of calcitriol lead to insufficient or inadequate calcium absorption from the diet[4]. Hence, maintaining optimal vitamin D levels promotes better calcium absorption from the diet and supplements. For this reason, most calcium supplements also include vitamin D3 to improve absorption and boost bone mineral density. If you are looking for a calcium vitamin d supplement, choose products with terms “calcium and vitamin d,” or “calcium vitamin d3” on their labels.

Who should consider calcium supplements?

Even if you consume a healthy, nutritious diet, you may fall short of your daily calcium needs if you are,

  • a postmenopausal woman
  • women who are pregnant or lactating
  • a woman with irregular periods or no periods
  • a female athlete
  • an individual with milk allergy or lactose intolerance
  • consume large amounts of protein or sodium, which can cause your body to lose calcium
  • receive treatment with corticosteroids.
  • elderly over the age of 75 years or with malabsorption issues.
  • have undergone a weight loss surgery
  • people undergoing treatment for chemotherapy
  • patients with ulcerative colitis, kidney failure, or take chronic diuretic medications
  • suffer from celiac or inflammatory bowel disease, which could interfere with your calcium absorption.
  • having low levels of vitamin D and or magnesium can also lead to improper calcium absorption.

If you deal with any of the above conditions that deplete body calcium, taking extra calcium as a supplement is highly beneficial.

How to choose your calcium supplement?

With so many calcium supplements in the market, choosing the right supplement can be challenging. Here are a few pointers that can help you choose the best calcium supplement to meet your calcium needs.

Calcium form: Calcium supplements come in many forms, usually in combination with another substance. Each combination contains varying amounts of calcium – referred to as elemental calcium. Calcium carbonate contains 40%, calcium citrate 21%, calcium gluconate 9%, and calcium lactate 13% of elemental calcium.

Combination of nutrients:  Calcium supplements formulated with other nutrients make a good choice. Most common include calcium vitamin d supplement,  calcium, vitamin d3, and magnesium combination. Calcium and vitamin D work in tandem in the bone-building process. Vitamin D helps explicitly in calcium absorption and supports body muscles[5]. Although calcium and vitamin D are often the focus in bone loss and osteoporosis, several other nutrients have also been identified to be crucial in bone-building. If you need a calcium supplement to improve your bone strength, ensure your supplement also provides the following nutrients. Minerals like copper, zinc, selenium, magnesium are known to be important[6]. In particular, a significant link has been found between bone density and magnesium intake in some studies[7].

Calcium as Microcrystalline Hydroxyapatite (MCHA): MCHA comes from bovine bone and contains calcium and phosphate, two essential bone-building nutrients in the form of hydroxyapatite. This form of calcium is easily absorbed by the body. It is important to note that most of the calcium found in the skeleton and teeth are in the hydroxyapatite form, made of calcium and phosphorus, which gives rigidity[8]. Other nutrients present in MCHA form include magnesium, zinc, and chromium. The benefit of choosing this type of calcium is that it is the organic form of calcium and provides other minerals.

Amount of calcium: Calcium is best absorbed when supplied in small amounts throughout the day with meals. Calcium is best absorbed in the range of 500- 600 mg. If the supplement dosage is 2 or 3 tablets per day, it is suggested to split it as one tablet per meal to meet the dosage instead of taking it all at once.

Choose quality: Choose supplements that come from manufacturers who pursue stringent quality measures. Avoid calcium supplements from unrefined oyster shells, dolomite, or coral, as they may contain lead or other toxic metals.

Here are some suggestions for high-quality calcium supplements, 

Calcium (MCHA) by Pure Encapsulations: Pure Encapsulations Calcium Microcrystalline Hydroxyapatite (MCHA) supports bone mineral composition. The Calcium microcrystalline hydroxyapatite comes from an animal source. Microcrystalline hydroxyapatite (MCHA) is a calcium compound containing a mixture of minerals in their natural ratios and residues of matrix, proteins, and glycosaminoglycans. The formulation is gluten-free and non-GMO. One tablet provides 250 mg of calcium from microcrystalline hydroxyapatite (bovine). The suggested dosage is to consume one capsule daily, with or between meals, or as directed by your healthcare physician.  

Cal-6+mg by Douglas Laboratories: This dietary supplement is a unique formulation that contains 6 types of calcium. In addition, it also provides vitamin D3, vitamin C, magnesium, boron, L-lysine, and glutamic acid. The recommended dosage is to take three tablets per day with meals. The six types of calcium come from Calcium Citrate/Gluconate/Carbonate/Lactate/Ascorbate and Microcrystalline Hydroxyapatite).

Liquid Calcium Magnesium 1:1 by Integrative Therapeutics: If you are someone that hates popping pills or struggle with swallowing pills, Integrative Therapeutics Liquid supplement is for you. It provides calcium and magnesium in the ratio of 1:1 in liquid form, along with other bone-building nutrients like vitamin D and boron. Integrative Therapeutics Liquid Calcium Magnesium is free of soy, gluten, and dairy, suitable for people with a sensitive digestive tract. The product is also free of xylitol, a type of sugar alcohol, and has zero added sugars. It can be consumed by adults and children over 12 years of age. The suggested dosage is one tablespoon once daily with food or as recommended by your healthcare provider.

If you are already taking a calcium supplement, be sure to inform your healthcare provider about it. It is also vital to adhere to the daily dosage recommended by the supplement manufacturer. Increase your calcium dosage only when your doctor asks you to do so. Taking more calcium than required can lead to discomfort and side effects.


[1]Committee to Review Dietary Reference Intakes for Vitamin D and Calcium, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010.