Calcium is crucial to bone health, and lately, more and more studies are connecting it to cardiovascular health, cognitive health, and other aspects of wellbeing, too. Yet only approximately 30% of Americans are receiving as much calcium as they should be2. Postmenopausal women, vegetarians, top athletic women, and individuals with lactose intolerance are particularly at risk of calcium deficiency, and levels are also extremely low among adolescents, particularly young women1. Something else to keep in mind: to ensure your body gets an adequate amount of calcium, it must also get an adequate amount of vitamin D, because vitamin D plays a crucial role in the body's absorption of calcium.
The two primary types of calcium found in supplements are calcium carbonate and calcium citrate. Calcium carbonate must be taken with food, because the body requires stomach acids to absorb it. Calcium citrate is more easily absorbed; this is the type of calcium found in the Omega Cookie.
In two cross-sectional studies of healthy men and women, scientists from Harvard School of Public Health found that those who took in more calcium and vitamin D had improved insulin levels, and therefore stronger protection against diabetes. These results agreed with a previous meta-analysis and review that "found that the data from observational studies showed a'relatively consistent association' between low intakes of calcium, vitamin D, or dairy intake and type-2 diabetes." According to the authors of that review, in non-blacks, the highest levels of intake resulted in a 64% reduction in prevalence of diabetes and 29% reduction in prevalence of metabolic syndrome, a common precursor to diabetes7.
Another review, this one from Tufts-New England Medical Center, offers hope to those who already have diabetes. The researchers concluded that sufficient levels of vitamin D and calcium, which for some people may be attainable only through supplementation, "may be beneficial in optimizing glucose metabolism8."
From the website of the Office of Dietary Supplements at the National Institutes of Health:
Several clinical trials have demonstrated a relationship between increased calcium intakes and both lower blood pressure and risk of hypertension, although the reductions are inconsistent. The authors of a systematic review of the effects of calcium supplements for hypertension found any link to be weak at best, largely due to the poor quality of most studies and differences in methodologies. Other observational and experimental studies suggest that individuals who eat a vegetarian diet high in minerals (such as calcium, magnesium, and potassium) and fiber and low in fat tend to have lower blood pressure.
The Dietary Approaches to Stop Hypertension (DASH) study was conducted to test the effects of three different eating patterns on blood pressure: a control "typical" American diet; a diet high in fruits and vegetables; and a third diet high in fruits, vegetables, and low-fat dairy products. The diet containing dairy products resulted in the greatest decrease in blood pressure, although the contribution of calcium to this effect was not evaluated. Additional information and sample DASH menu plans are available on the National Heart, Lung, and Blood Institute Web site1.
An article from Kobe University in Japan considered the interaction of calcium and the nervous system, and how this might affect the risk and progression of Alzheimer's disease. Calcium deficiency due to insufficient nutritional intake, poor intestinal absorption or excessive urinary loss leads to secondary hyperparathyroidism. This in turn may lead to poor communication between nerve cells as seen with chronic renal failure and Alzheimer's disease. As people age, they need to increase their vitamin D and calcium intake11.
When 3,000 women were studied over the course of ten years, it became apparent that the 20% of the women with the highest vitamin D intake were 41% less likely to suffer from premenstrual syndrome than the 20% of the women with the lowest vitamin D intake. The study's authors, from the University of Massachusetts, declared, "A high intake of calcium and vitamin D may reduce the risk of PMS9."
A Columbia University review of previous research had similar results. It noted that calcium and vitamin D seems to have a major influence on the menstrual cycle and PMS. The review's authors also commented that "The similarity between the symptoms of PMS and hypocalcemia is remarkable." Furthermore, in studies of women with PMS, calcium supplementation removed most of the mood-related and somatic symptoms10.
It's common knowledge that calcium aids bone health, but here is a quick review of the basic science: Ninety-nine percent of the calcium you take in is stored in your bones, which is mostly why calcium is so critical to bone health. People reach peak bone mass at age 30, and the higher it is at that point, the longer problems like osteoporosis can be delayed. This is why calcium is so important for young people. Even after 30, however, sufficient calcium intake can slow the loss of bone mass and reduce the likelihood of osteoporosis and fracture1.
A sample of some of the research behind that conclusion: the University Hospital Zurich and Dartmouth Medical School conducted a randomized placebo-controlled trial in which half of the 930 participants (average age: 61) received regular calcium and vitamin D supplementation for four years. The researchers found that "Daily supplements of calcium may reduce the risk of fractures in a healthy population by 72 per cent5." And at the European Symposium on Calcified Tissue (which sounds like a great time), "researchers suggested that daily consumption of both calcium and vitamin D was linked to a 20 per cent fall in the rates of hip damage in older people6."
1. Office of Dietary Supplements, National Institutes of Health: "Dietary Supplement Fact Sheet: Calcium." 9 July 2009.
2. Moshfegh, Alanna; Goldman, Joseph; and Cleveland, Linda. 2005. What We Eat in America, NHANES 2001-2002: Usual Nutrient
3. Intakes from Food Compared to Dietary Reference Intakes. U.S. Department of Agriculture, Agricultural Research Service.
4. NaturalNews.com: "The Link between Calcium and Vitamin D: Know How Your Cells Operate." 12 August 2009.
5. The Sarasota Herald-Tribune: "The types of calcium." 17 August 2009.
6. Nutra-IngredientsUSA.com: "Calcium pills beat fractures in new clinical trial." 9 June 2008.
7. Nutra-IngredientsUSA.com: "Symposium details Calcium-Vitamin D fracture potential." 29 May 2009.
8. Nutra-IngredientsUSA.com: "Calcium and vitamin D may protect against diabetes: Study." 12 March 2009.
9. The Journal of Clinical Endocrinology and Metabolism: "The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis." June 2007.
10. Archives of Internal Medicine: "Calcium and vitamin D intake and risk of incident premenstrual syndrome." 13 June 2005.
11. The Journal of the American College of Nutrition: "Micronutrients and the premenstrual syndrome: the case for calcium." April 2000.
12. Clinical Calcium: "Alzheimer disease and calcium." January 2004.