Hypertension and Calcium

People who are deficient in calcium may be at great risk of developing high blood pressure, so increasing your intake of calcium may help prevent hypertension. Among people who already have hypertension, increased intake of calcium might slightly decrease blood pressure.

Calcium plays a number of roles in the body. For instance, calcium is involved in the contraction and dilation of blood vessels,²⁸ both of which affect blood pressure.

Read more details about Calcium.

People who are deficient in calcium may be at greater risk of developing high blood pressure.^29,30,58 Among people who already have hypertension, increased intake of calcium intake might slightly decrease blood pressure, according to some but not all studies.^31,59 In an extremely large randomized, placebo-controlled trial involving 36,282 postmenopausal women, 1,000 mg of calcium plus 400 IU of vitamin D given daily did not significantly reduce blood pressure over a 7 year period in women with or without hypertension.¹³⁹

Also, some evidence hints that the use of calcium by pregnant mothers might reduce risk of hypertension in their children.¹⁰⁷

Many foods are calcium rich and/or fortified with extra calcium. When it comes to supplements, calcium comes in different forms, some of which may be more readily absorbed than others. For more information, see the Requirements/Sources and Therapeutic Doses section of the full article on calcium.

• Nutritionist or dietitian
• Naturopathic doctor
• Chiropractor
• Physician

Safety Issues

In general, it's safe to take up to 2,500 mg of calcium daily, although this is more than you need. ¹ Greatly excessive intake of calcium can cause numerous side effects, including dangerous or painful deposits of calcium within the body.

Note:If you have cancer, hyperparathyroidism, or sarcoidosis, you should take calcium only under a physician's supervision.

Some evidence hints that use of calcium supplements might slightly increase kidney stone risk. ² However, increased intake of calcium from fooddoes not seem to have this effect and could even help prevent stones. ³ One study found that if calcium supplements are taken with food, there is no increased risk. ⁴ Calcium citrate supplements may be particularly safe regarding kidney stones because the citrate portion of this supplement is used to treatkidney stones. ⁵ There is preliminary evidence that calcium supplementation in healthy, post-menopausal women may slightly increase the risk of cardiovascular events, such as myocardial infarction. However, it remains far from clear whether this possible risk outweighs the benefits of calcium supplementation in this population. ⁶ Large observational studies have found that, in men, higher intakes of calcium are associated with an increased risk of prostate cancer. ⁷ This seems to be the case whether the calcium comes from milk or from calcium supplements.

Calcium supplements combined with high doses of vitamin D might interfere with some of the effects of drugs in the calcium channel blocker family. ⁸ It is very important that you consult your physician before trying this combination.

Concerns have been raised that the aluminum in some antacids may not be good for you. ⁹ There is some evidence that calcium citrate supplements might increase the absorption of aluminum; ^{10 11 12 13} for this reason, it might not be a good idea to take calcium citrate at the same time of day as aluminum-containing antacids. Another option is to use different forms of calcium, or to avoid antacids containing aluminum.

When taken over the long term, thiazide diuretics tend to increase levels of calcium in the body by decreasing the amount excreted by the body. ^{14 15 16} It's not likely that this will cause a problem. Nonetheless, if you are using thiazide diuretics, you should consult with your physician on the proper doses of calcium and vitamin D for you.

Finally, calcium may interfere with the absorption of antibiotics in the tetracycline and fluoroquinolone families as well as thyroid hormone. ^{17 18 19 20 21 22} If you are taking any of these drugs, you should take your calcium supplements at least 2 hours before or after your medication dose.

Interactions You Should Know About

• You may need more calcium if you are taking:
  • Corticosteroids
  • Heparin
  • Isoniazid

• If you are taking aluminum hydroxide , you should take calcium citrate at least 2 hours apart to avoid increasing aluminum absorption.

• You may need more calcium if you are taking the following anticonvulsants:
  • Phenytoin (Dilantin)
  • Carbamazepine
  • Phenobarbital
  • Primidone
  • Note:It may be advisable to take your dose of anticonvulsant and your calcium supplement at least 2 hours apart because each interferes with the other's absorption.

• If you are taking the following medications, you should take your calcium supplement at least 2 hours before or after your dose of medication because calcium interferes with the absorption (and vice versa):
  • Antibiotics in the tetracycline or fluoroquinolone (Cipro, Floxin, Noroxin) families
  • Thyroid hormone

• Do not take extra calcium except on the advice of a physician if you are taking Thiazide diuretics.

• Do not take calcium together with high-dose vitamin D except on the advice of a physician if you are taking calcium channel blockers .

• You may need extra calcium if you are taking:
  • Iron
  • Manganese
  • Zinc
  • Chromium
  • Ideally, you should take calcium at a different time of day from these other minerals because it may interfere with their absorption.

• It may be advisable to wait 2 hours after taking calcium supplements to eat soy (or vice versa). A constituent of soy called phytic acid can interfere with the absorption of calcium.

• Taking supplemental calcium may be helpful if you are taking metformin.

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