From Pure Matters

By Dr. Shyam Parikh, PharmD

Most adults, especially women, are often recommended by their healthcare providers to take a calcium supplement to help their bones. Questions often arise regarding which calcium product has better absorption and the best time and way to take these supplements. I would like to point out some key points to consider to maximize the effectiveness of your calcium supplement.

1. The two most common forms of calcium are calcium carbonate and calcium citrate. Both of these forms are similarly absorbed if taken properly. Calcium carbonate is the most common calcium and is best absorbed when taken with food, while calcium citrate can be taken with or without food. If you have reduced levels of stomach acid it will be easier for your body to absorb the calcium citrate.

2. Calcium absorption peaks when the body gets no more than 500 mg at a time. So if your healthcare provider has suggested taking 1,000 mg/day it would be better to take two servings off 500 mg each, rather than taking one serving of 1,000 mg.

3. Vitamin D improves calcium absorption and it’s very important to also get an adequate intake of vitamin D (400 IU) along with calcium.

4. Magnesium is also required for absorption and utilization of calcium. It prevents magnesium from building up in your soft tissues and gets calcium to your bones.

5. Calcium absorption decrease with age, so if you are over the age of 50, it’s recommended that your daily intake is 1,200 mg/d.

6. Dietary factors can influence calcium excretion and absorption:
- High intake of sodium, protein, caffeine, and alcohol tend to increase calcium excretion
- Oxalic acid (found in some vegetables and beans) and phytic acid (found in whole grains) tend to reduce calcium absorption. For most people, though, this will be of little consequence.

7. Calcium supplements can interfere with medications you take. You may need to take these medications and your calcium at separate times to prevent some of these interactions. Calcium tends to decrease the absorption of the following drugs when taken together:
- Bisphosphonates
- Antibiotics: fluoroquinolones and tetracyclines
- Levothyroxine
- Phenytoin
- Tiludronate disodium
- Aluminum and magnesium supplements increase the urinary calcium excretion
- Mineral oil and laxatives decrease calcium absorption
- Glucocortocoids can cause calcium depletion with long term use
- Thiazide-type diuretics can cause as increase in calcium levels in the blood as well as urine