As you have heard from media reports and perhaps read on my website, there is conflicting advice as to how much calcium we should consume and how much we should strive to add on with supplements. The side effects of nutritional supplements are emphasized in many new studies but don’t necessarily impact the choices of consumers. We have a unique American sensibility…that more of a good thing is better! So how much calcium do we need, how can we get it in our food and when do we have to supplement? The New England Journal of Medicine very nicely summed up the data and recommendations in an article under the headline “Clinical Practice” this week. It was titled “Calcium Supplements and Fracture Prevention”. So here in a nutshell or should I say milk carton is a summary of the article….
More than 98% of calcium in the body is contained within the skeleton bone which acts as a reserve for calcium, storing it and releasing it when needed. Obviously if too much is released there is a diminution of calcium in the bone causing osteopenia and worse yet osteoporosis. We lose calcium on a daily basis in urine, sweat and stool and therefore insufficient calcium intake over a prolonged period may eventually lead to low bone calcium levels. Bone loss is accelerated with menopause, especially during the first seven years of this inevitable transition (estrogen keeps calcium in the bones) as well as with advanced aging. The Institute of Medicine (IOM) has issued guidelines regarding the recommendations for dietary intake of calcium according to sex and age.
- Females (the gender I am most interested in) need 1000 mg a day between the ages of 19 and 50; the upper intake should not be more than 2500 mg. Above the age of 50 calcium intake should increase to 1200 mg and the upper intake level should be no more than 2000 mg.
- Males (I’m including them here) also need 1000 milligrams a day between the ages of 19 and 70 and should not go above 2000 mg. Above the age of 70 they need 1200 mg with a maximum of 2000 mg
It’s estimated that in the United States dietary intake of elemental calcium varies between 750 to 850 mg in women. The lowest intake is observed in those over the age of 70. In order to estimate your dairy intake you should assume that, like most adults, you consume about 300 mg of calcium per day from nondairy sources (vegetables and grains). You should then calculate your additional daily intake of dairy products and if needed add on supplements to reach the goal of 1000 or 1200 mg of calcium.
Here’s a brief review of some of the well absorbed dietary sources of elemental calcium:
- Plain low-fat yogurt, 8 ounces – 448 mg
- Low-fat to yogurt with fruit, 8 ounces – 384 mg
- Mozzarella, part skim milk, 1.5 ounces – 333 mg
- Cheddar cheese, 1.5 ounces – 307 mg
- 2% low-fat milk, 1 cup – 293 mg
- Low-fat cottage cheese, 1 cup – 206 mg
When it comes to vegetables, those with the highest amount of calcium include that ubiquitous kale, one cup has 100 mg, bok choy which has 74 mg per cup and raw broccoli with 43 mg a cup.
And then we have fortified cereals in which one cup can have anything from a 100 to over 1300 mg of elemental calcium. (Look on the box!)
Now a quick quick review of the most common over-the-counter calcium: The major type is calcium carbonate in which 40% of the tablet contains elemental calcium but requires acid in the stomach or food in order to be absorbed. My personal favorite is calcium citrate in which 21% of the tablet is elemental calcium (so you need more pills) however, this type of calcium can be taken between meals and it is absorbed even if you’re taking anti acid medication. Always look on the bottle, it will list how many pills you need to take to get the amount of elemental calcium you have decided to take. Don’t assume that one pill does it.
So how should we get our calcium and when is too much a good thing? There’s no question that individuals who are calcium depleted (those who do not include calcium in their diet i.e. those with milk intolerance or those who abstain from all milk products and don’t eat huge amounts of calcium rich vegetables) would benefit from supplemental calcium. However individuals with a normal diet and adequate calcium in their food may not need any. In pooled analyses of intake and fracture rates it’s been found that calcium plus vitamin D has only a modest protective affect on fractures, particularly among frail and elderly persons. A meta-analysis of 16 placebo-controlled trials of calcium and vitamin D supplements recently performed for the US Preventative Services Task Force showed an overall 12% reduction in the risk of any fracture.
The potential harms of calcium intake has received a recent media blitz. One set of studies that was quoted showed that calcium supplements without vitamin D was associated with an increased risk of myocardial infarction among persons randomly assigned to calcium. Statisticians however found problems with this study stating that it had marginal statistical significance. A more recent study in 2010 did not show any adverse coronary correlation when calcium was used with vitamin D. The authors of this article in the New England Journal stated in their summary that the evidence suggesting adverse cardiovascular effects of calcium supplementation is inconsistent. They go on to state that “pending further data a reasonable approach is to preferentially encourage dietary calcium intake and discourage the routine use of calcium supplements”.
And just to add to this information and perhaps confusion, a 2013 update by the US Preventative Services found insufficient evidence to assess the benefits and harms of daily supplementation with more than 1000 mg of calcium or more than 400 units of vitamin D for the prevention of fractures in non-institutionalized post menopausal women. They also found insufficient evidence to recommend for or against the use of calcium supplements in men and premenopausal women.
I will still try to assess calcium intake in the nutrition of my patients and obviously encourage those that are low to increase it to the 1000 or 1200 mg goal . But for those that are on a dairy free and kale free diet, I will continue to encourage calcium supplements in divided doses. (And for those who are not exposed to direct sunlight, especially in the winter…I do suggest Vitamin D supplements.)
Just thought it was important to share!