The Optimal Time to Take Calcium Supplements for Robust Bones, Backed by Science

Medically reviewed by Allison Herries, RDN

It is crucial to take calcium supplements at the appropriate time of day to ensure maximum absorption. Various elements affect how well you absorb these supplements, including their form and quantity, as well as the impact of medications, dietary nutrients, meal contents, age-related changes, genetic variations, and hormonal levels.

When to Take Calcium: Morning vs. Evening

• 
  The case for morning
  
  Developing a routine of including calcium in your morning meal ensures consistency. Additionally, incorporating vitamin D-rich foods such as eggs, milk, yogurt, and cereal into your breakfast can improve the body’s ability to absorb calcium.
• 
  Medication matters
  
  If the medications you take in the morning have interactions with calcium, it’s advisable to schedule them for a later time.
• 
  The case for evening
  
  Calcium aids in regulating the sleep-wake cycle by assisting the brain’s functioning.
  
  tryptophan
  
  To produce melatonin, you need this vital amino acid. Therefore, consider taking calcium supplements before going to bed to improve your sleep quality.
• 
  Stomach acid counts
  
  Certain forms of calcium supplements rely on stomach acid for improved uptake, so if you often miss your morning meal, it’s advisable to consume these supplements later in the day along with dinner.

Factors Affecting Calcium Absorption

Type of Calcium

• 
  Common types
  
  The two most prevalent types of calcium supplements are
  calcium carbonate along with calcium citrate
  .
• 
  Calcium carbonate
  
  Calcium carbonate offers 40% elemental calcium and necessitates stomach acid for proper absorption; hence, it is advisable to take it along with meals.
• 
  Calcium citrate
  
  Calcium citrate offers 21% elemental calcium and doesn’t necessitate stomach acid for absorption. It can be taken regardless of whether you eat or not.

Dose

• 
  Absorption limit
  
  Calcium is most effectively absorbed when
  
  500 mg or below
  
  is taken
  
  at one time
  
  .
• 
  Split dosage
  
  If your daily intake goes above 500 mg, consider dividing the dosage into several smaller amounts taken at different times of the day to total 500 mg.

Medication Interactions

Calcium can interact with certain medications, such as:

• 
  Synthroid (levothyroxine)
  
  Calcium supplements may hinder the uptake of Synthroid, which is prescribed for hypothyroidism treatment. It’s advisable not to take Synthroid for at least four hours after consuming calcium supplements.
• 
  Lithobid
  (lithium)
  
  : Prolonged use of lithium, a medication utilized for stabilizing moods and employed in treating
  bipolar disorder
  This could result in elevated calcium levels. Consuming additional calcium supplements might exacerbate this risk even more.
• 
  Antibiotics
  
  Calcium has the potential to decrease the uptake of certain antibiotics like Cipro (ciprofloxacin) and Vibramycin (doxycycline). To prevent this interaction, it’s advisable to consume Cipro either two hours prior to or six hours following calcium intake, and similarly, take Vibramycin an hour before or four hours after consuming calcium.
• 
  Bisphosphonates
  
  :
  Fosamax
  (alendronate) is a
  
  bisphosphonate that
  
  Fosamax helps with osteoporosis, yet calcium can decrease its effectiveness. It’s advised to take Fosamax at least half an hour prior to taking any calcium supplements.
• 
  Thiazide diuretics
  
  Microzide (hydrochlorothiazide) is a diuretic prescribed for managing hypertension and edema; however, it may elevate calcium levels. Consequently, it’s advisable to refrain from taking calcium supplements alongside Microzide to mitigate the heightened risk of excessive calcium levels.
• 
  Lanoxin (digoxin):
  
  Large amounts of calcium supplements may elevate the chances of irregular heartbeat in individuals using Lanoxin, which is prescribed for heart failure.
• 
  Acid-suppressive medications
  
  The uptake of calcium carbonate relies on acidity levels. Consequently, medicines that reduce stomach acids like Pepcid (famotidine) and Prilosec (omeprazole) might lower the absorption of calcium carbonate.
• 
  Tivicay (dolutegravir)
  
  Calcium supplements can reduce Tivicay levels. To ensure its efficacy, take Tivicay, an HIV medication, either 2 hours prior to or 6 hours following the intake of calcium.

Other Nutrients

• 
  Vitamin D
  
  : Taking
  vitamin D
  with calcium helps enhance calcium absorption. Take vitamin D with a healthy fat like fish oil or avocado to help your calcium absorb even better. Adults need
  
  a minimum of 15 micrograms (600 IU)
  
  of Vitamin D daily.
• 
  Vitamin K
  
  :
  Vitamin K
  assists in laying down calcium in the bones and stops it from building up in undesired areas, like the blood vessels, thus avoiding the stiffening of artery and vein walls.
• 
  Iron supplements
  
  Because calcium reduces the uptake of
  iron supplements
  Take iron supplements at least two hours separate from calcium supplements.
• 
  Zinc supplements
  
  Calcium supplements have decreased
  zinc
  absorption.

Food

• 
  Absorption inhibitors
  
  Certain plant-based foods include elements that hinder the absorption of calcium.
• 
  Oxalates
  
  :
  Oxalic acid or oxalate
  Found in large amounts in spinach, collard greens, sweet potatoes, rhubarb, and beans, this substance is the strongest inhibitor of calcium absorption.
• 
  Phytates
  
  :
  
  Phytic
  
  acid (
  
  phytate
  
  It is a weaker inhibitor of calcium absorption compared to oxalate. Phytate can be found in sources such as wheat bran and dried beans.
• 
  Caffeine and phosphorus
  
  : Caffeine and phosphorus intake also reduce the absorption of dietary calcium to an extent.
• 
  High-fiber meals
  
  High-fiber foods have the ability to attach themselves to calcium, which decreases how much calcium gets absorbed into your body. For this reason, it’s recommended not to take calcium supplements alongside meals that contain a lot of fiber.

Age

• 
  Age-related absorption
  
  Calcium absorption declines as we get older. The poor uptake of calcium in the intestines may result from the kidneys’ diminished capacity to transform vitamin D into its active state, which is essential for effective calcium absorption.
• 
  Supplement choice
  
  Your stomach might not generate enough digestive acids as you get older. Thus,
  
  calcium citrate
  
  It might be preferable for individuals with low stomach acid levels.

Genetics

• 
  Vitamin D receptors
  
  Vitamin D receptor genes are crucial for the process of absorbing calcium.
• 
  Genetic variants
  
  Variations in these genes can impact how efficiently your body utilizes vitamin D, thereby influencing calcium absorption.

Hormones

• 
  Estrogen
  
  The hormone estrogen preserves bone density by slowing down the process of bone degradation.
• 
  Postmenopause
  
  After menopause, estrogen levels decrease, which is linked to a higher risk of osteoporosis and bone loss.
• 
  Calcium and vitamin D
  
  Sufficient calcium and vitamin D consumption is essential for developing strong bones and reducing the risk of post-menopausal osteoporosis.

How Much Calcium Is Required?

Food Sources of Calcium

Here are some examples of calcium-rich foods along with their approximate percentage of the Daily Value (% DV), calculated against a daily requirement of 1,300 mg for adults. The DV indicates the portion of total daily calcium needs provided by one serving.

• 
  Yogurt, 1 cup
  
  : 415 milligrams (32% of the daily value)
• 
  Canned sardines, 3 ounces
  
  : 325 mg (25% DV)
• 
  Milk, 1 cup (8 oz)
  
  : 300 milligrams (23% of the daily value for adults)
• 
  Cheese, 1.5 ounces
  
  : 306 mg (23% of the Daily Value)
• 
  Canned salmon, 3 ounces
  
  : 181 milligrams (14% of your daily value)
• 
  Kale, 1 cup
  
  : 94 mg (7% of Daily Value)
• 
  Napa cabbage or pak choi, 1 cup
  
  : 74 mg (6% of Daily Value)
• 
  Broccoli, 1/2 cup
  
  : 21 mg (2% DV)

Ways to Enhance Calcium Absorption

• 
  Sunlight and diet
  
  As vitamin D assists with the absorption of calcium, ensuring sufficient vitamin D consumption—which should be at least 15 micrograms (600 IU) daily for adults—is crucial. This can be achieved through exposure to sunlight, dietary sources, or supplementation.
• 
  Pair with fat
  
  If you use vitamin D supplements, consume them alongside foods that have
  healthy fats
  for enhanced absorption.
• 
  Absorption limit
  
  Do not exceed 500 mg of calcium intake at one time to enhance calcium absorption.
• 
  Supplement type
  
  If you suffer from low stomach acid or use medications that reduce acidity, choose calcium citrate over calcium carbonate.
• 
  Food interactions
  
  Steer clear of combining calcium supplements with foods rich in oxalate, phytate, and fiber, as well as those containing large amounts of caffeine.

Explainer

In the U.S., the Food and Drug Administration (FDA) doesn’t oversee dietary supplements as strictly as it does with prescription drugs. Consequently, there isn’t an authority ensuring the accuracy of nutrient claims found on supplement packaging.
choosing a supplement
look for items that have been independently evaluated or accredited by groups like
NSF
,
U.S. Pharmacopeia
, or
ConsumerLab.com
For tailored advice, please speak with your healthcare provider.
Registered Dietitian Nutritionist (RD or RDN)
, or pharmacist.

Key Takeaways

• 
  Morning routine:
  
  Starting your day with calcium complements a regular schedule and works synergistically with Vitamin D-filled morning meals for enhanced uptake.
• 
  Evening benefit:
  
  Consuming calcium during the evening might help improve your sleep quality and is particularly beneficial if you miss breakfast or take medications in the morning that could interfere with how well your body absorbs the mineral.
• 
  Absorption tips:
  
  Enhance your body’s uptake of calcium by combining it with vitamin D, beneficial fatty acids, and strategic scheduling; meanwhile, steer clear of substances that hinder absorption such as foods rich in oxalates and excessive caffeine.

Read the initial article on
Verywell Health