Calcium: U.S. adults still not getting enough

A new study suggests most U.S. adults continue to fail to get enough of the mineral through diet and supplementation to meet recommended levels.

University of Connecticut and Yale University researchers examined data from National Health and Nutrition Examination Survey collected from 9,475 adults between 2003 and 2006. They found that, although dietary calcium intake was reported highest in older age groups, the amounts remained insufficient to meet adequate intake standards for age groups 50 years and older.

These inadequate intakes come despite the fact that more than half of individuals ages 19 and older were taking a calcium supplement, according to the authors. For men, supplementation increased from 34 percent in the 19 – 30 age group to 54 percent in the 81 and older age group. The percentage of women taking supplements rose from 42 percent to 64 percent across the same range of age groups.

"Adequate lifelong calcium intake is essential to optimizing bone health," remind the study authors, who published their findings in the May 2011 issue of Journal of American Dietetic Association. They also recommend "new approaches to increasing the frequency and level of calcium supplement use to enhance calcium density in diets."

Calcium is the most abundant mineral in the body, primarily found in the bones and teeth. As bones develop, calcium, along with other minerals, crystallizes on the collagen matrix of the bone, making it denser and giving it strength and rigidity. The body loses calcium continuously, and if this loss is not replaced through diet, the body will remove calcium from the bones to perform necessary functions such as regulation of muscle contraction. This removal causes bones to become soft and brittle, making them prone to fractures.

Adequate calcium intake is necessary for strong and healthy bones. The current recommended intake of calcium is between 1,000 mg and 1,300 mg per day. Good sources (more than 300 mg per serving) of calcium include dairy products such as low-fat milk, cheese, and yogurt. Dark green vegetables such as broccoli, kale, and spinach can also add about 90 milligrams of this mineral to daily intake. In addition, calcium-fortified foods (orange juice and breakfast cereals) and dietary supplements can also help fill gaps.
Other important factors in optimizing bone health include engaging in weight-bearing exercise and obtaining recommended amounts of vitamins D and K2 daily.

Reference: Mangano KM, Walsh SJ, Insogna KL, Kenny AM, Kerstetter JE. Calcium Intake in the United States from Dietary and Supplemental Sources across Adult Age Groups: New Estimates from the National Health and Nutrition Examination Survey 2003-2006. J Am Diet Assoc 2011;111:687-95.

Thoughts:

Time and time again, studies have shown that calcium when combined with vitamin D are effective in increasing bone density. However, there's been a lot of back and forth in the calcium world around the topic of supplements, particularly their efficacy and safety. A critical piece lacking in the conversation is of absorption since calcium is one mineral that depends on a few factors -- vitamin D, doses that oversaturate absorption, too much absorbed at once.

The best approach for obtaining calcium is perhaps to consume it as we would have back in the time of our hunter-gatherers ancestors before the agricultural revolution and pastoralism, which is by getting a little here and a little there when we only obtained it from the leaves of plants. That's not to say that we should only get it from plant leaves, but that we should get it in smaller amounts in sustained fashion over the course of a day.