Calcium


 

Calcium Clinical Report Summary

Written Exclusively for MyNutritionStore.com by Rachel Parker 

 

Calcium is an effective treatment for high blood pressure, premenstrual syndrome and bone loss, according to numerous double-blind, placebo controlled human studies (1, 2, 3, 4, 5). These types of studies are considered the highest standard in clinical research. Calcium, when combined with Vitamin D, has been shown to prevent and treat bone loss and osteoporosis, a disease that usually afflicts older women and makes their bones porous and vulnerable to fractures (1, 2). Studies show that calcium can help alleviate the symptoms of premenstrual syndrome like water retention and pain (1, 3). Calcium is also effective at lowering high blood pressure, especially in pregnant women who are not able to take certain drugs because of potential risk to the baby (1, 4, 5).

 

Calcium Overview

 

Calcium is one of the most abundant and important minerals in the human body. It is essential for bone development and cell function in the muscle, nervous and endocrine systems. Nearly all of the body's calcium, 99%, is found in bones and teeth. The best source of dietary calcium comes from dairy products like milk, yogurt and cheese. Calcium can also be found in lesser concentrations in dark green vegetables such as spinach and broccoli. Studies from the United States Department of Agriculture (USDA) show that most adults are not getting enough calcium in their diet: 55% of men and 78% of women fall short of the recommended amounts. That is why many doctors recommend supplemental calcium to fill the gap. Post menopausal women are especially in need of calcium as scientists found that when a woman's estrogen and progesterone levels drop, so does the ability to synthesize calcium. Supplements generally come in two forms: calcium citrate or calcium carbonate. Calcium is typically combined with other ingredients like magnesium and Vitamin D for maximum absorption. In fact, new research finds that Vitamin D is a crucial component for getting calcium absorbed into the bones (1).

 

Safe Use of Calcium

 

The recommended adequate intake of calcium for adults is 1,000 mg a day with an upper limit of 2,500 mg a day (1). Calcium is considered to be generally safe although it may inhibit the absorption of certain medications like digoxin and the antibiotic ciprofloxacin (1).  

 

Clinical Studies for Calcium

 

Researchers have conducted hundreds of clinical studies to determine the efficacy of calcium. The strongest evidence supports the use of calcium to treat three specific conditions: high blood pressure, premenstrual syndrome and bone loss or the more severe osteoporosis. More details on this research can be found below in study abstracts from medical journals (1, 2, 3, 4).

 

1. Bone Loss and Calcium

 

Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age or older. Dawson-Hughes B et al.

BACKGROUND: Inadequate dietary intake of calcium and vitamin D may contribute to the high prevalence of osteoporosis among older persons. METHODS: We studied the effects of three years of dietary supplementation with calcium and vitamin D on bone mineral density, biochemical measures of bone metabolism, and the incidence of nonvertebral fractures in 176 men and 213 women 65 years of age or older who were living at home. They received either 500 mg of calcium plus 700 IU of vitamin D3 (cholecalciferol) per day or placebo. Bone mineral density was measured by dual-energy x-ray absorptiometry, blood and urine were analyzed every six months, and cases of nonvertebral fracture were ascertained by means of interviews and verified with use of hospital records. RESULTS: The mean (+/-SD) changes in bone mineral density in the calcium-vitamin D and placebo groups were as follows: femoral neck, +0.50+/-4.80 and -0.70+/-5.03 percent, respectively (P=0.02); spine,+2.12+/-4.06 and +1.22+/-4.25 percent (P=0.04); and total body, +0.06+/-1.83 and -1.09+/-1.71 percent (P<0.001). The difference between the calcium-vitamin D and placebo groups was significant at all skeletal sites after one year, but it was significant only for total-body bone mineral density in the second and third years. Of 37 subjects who had nonvertebral fractures, 26 were in the placebo group and 11 were in the calcium-vitamin D group (P=0.02). CONCLUSIONS: In men and women 65 years of age or older who are living in the community, dietary supplementation with calcium and vitamin D moderately reduced bone loss measured in the femoral neck, spine, and total body over the three-year study period and reduced the incidence of nonvertebral fractures.

 

2. Premenstrual Syndrome and Calcium

 

Calcium carbonate and the premenstrual syndrome: effects on premenstrual and menstrual symptoms. Premenstrual Syndrome Study Group. Thys-Jacobs S et al.

OBJECTIVE: Previous reports have suggested that disturbances in calcium regulation may underlie the pathophysiologic characteristics of premenstrual syndrome and that calcium supplementation may be an effective therapeutic approach. To evaluate the effect of calcium carbonate on the luteal and menstrual phases of the menstrual cycle in premenstrual syndrome, a prospective, randomized, double-blind, placebo-controlled, parallel-group, multicenter clinical trial was conducted. STUDY DESIGN: Healthy, premenopausal women between the ages of 18 and 45 years were recruited nationally across the United States at 12 outpatient centers and screened for moderate-to-severe, cyclically recurring premenstrual symptoms. Symptoms were prospectively documented over 2 menstrual cycles with a daily rating scale that had 17 core symptoms and 4 symptom factors (negative affect, water retention, food cravings, and pain). Participants were randomly assigned to receive 1200 mg of elemental calcium per day in the form of calcium carbonate or placebo for 3 menstrual cycles. Routine chemistry, complete blood cell count, and urinalysis were obtained on all participants. Daily documentation of symptoms, adverse effects, and compliance with medications were monitored. The primary outcome measure was the 17-parameter symptom complex score. RESULTS: Seven hundred twenty women were screened for this trial; 497 women were enrolled; 466 were valid for the efficacy analysis. There was no difference in age, weight, height, use of oral contraceptives, or menstrual cycle length between treatment groups. There were no differences between groups in the mean screening symptom complex score of the luteal (P = .659), menstrual (P = .818), or intermenstrual phase (P = .726) of the menstrual cycle. During the luteal phase of the treatment cycle, a significantly lower mean symptom complex score was observed in the calcium-treated group for both the second (P = .007) and third (P < .001) treatment cycles. By the third treatment cycle calcium effectively resulted in an overall 48% reduction in total symptom scores from baseline compared with a 30% reduction in placebo. All 4 symptom factors were significantly reduced by the third treatment cycle. CONCLUSIONS: Calcium supplementation is a simple and effective treatment in premenstrual syndrome, resulting in a major reduction in overall luteal phase symptoms.

 

3. High Blood Pressure and Calcium

 

Calcium supplementation and prevention of pregnancy induced hypertension. Purwar M et al.

In a randomized controlled trial 201 healthy nulliparous women were randomly allocated by means of a computer generated randomization list. From 20 weeks of gestation until delivery they received either 2 g of oral elemental calcium (n = 103) per day or an identical placebo (n = 98). Eleven women (5.47%) were lost to follow-up after randomization. The study groups were very similar at the time of randomization; with respect to several clinical and demographic variables. Treatment compliance was very similar in both groups as was determined by pill count. The rate of pregnancy induced hypertension was lower in the calcium group than in the placebo group 8.24%; vs 29.03%; (RR = 0.28; 95% CI 0.14-0.59). The incidence of gestational hypertension was 6.18% in the calcium group and 17.20% in the placebo group (RR = 0.28; 95% CI 0.08-0.80), and the incidence of preeclampsia was 2.06% in the calcium group and 11.82% in the placebo group (RR = 0.13; 95% CI 0.01-0.64). In conclusion calcium supplementation given in pregnancy to nulliparous women reduces the incidence of pregnancy induced hypertension.

 

Calcium References

 

  1. Dietary supplement fact sheet: Calcium. National Institutes of Health Office of Dietary Supplements. Sept 2005; http://ods.od.nih.gov/factsheets/calcium.asp.
  2. Dawson-Hughes B et al. Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age or older. N Engl J Med. 1997; 337(10):670-6.
  3. Thys-Jacobs S et al. Calcium carbonate and the premenstrual syndrome: effects on premenstrual and menstrual symptoms. Premenstrual Syndrome Study Group. Am J Obstet Gynecol. 1998;179(2):444-52.
  4. Purwar M et al. Calcium supplementation and prevention of pregnancy induced hypertension. J Obstet Gynaecol Res. 1996;22(5):425-30.
  5. McCarron D, Reusser M. Finding consensus in the dietary calcium-blood pressure debate. Am J Clin Nutr. 1999; 18(5): 398S-405S.
image
image