Hello “How About Them Apples?” readers! This is guest blogger, Aly Peer. Nadine has asked me to write this special blog post. A little background before we begin: I completed my under graduate degree in nutrition and dietetics at The University of Minnesota – Twin Cities in May 2012. I began my dietetic internship at Concordia College – Moorhead, MN in June 2012. I will graduate from this internship program in May 2013, take my registered dietitian exam and become a registered dietitian! As part of my internship program, I have been shadowing Nadine at Morton Plant hospital for two weeks. Before I head back to chilly Minnesota, Nadine has asked me to take a look at the emerging research regarding calcium supplementation at heart health. This blog post aims to cut through the confusion and provide realistic, evidence based recommendation regarding dietary and supplemental calcium.
We have all heard it before; “Get plenty of calcium for strong bones and teeth”. This mantra has been followed by many health conscious individuals who aim to avoid osteoporosis, osteopenia and other bone disorders later in life. As a result calcium supplementation has become quite common, in fact, 60% of middle-aged and older women in the US now take calcium supplements3. Recently, however, the safety of calcium supplementation and its effects on heart health have come under scrutiny in the medical research community.
In order to make sense of the research we will first review calcium’s multiple roles in the body. Calcium digestion and absorption requires Vitamin D. Vitamin D can be obtained through the diet, through supplementation, or through the skin (skin exposed to sunlight can naturally produce active Vitamin D). About 99% of the calcium in your body is stored in your bones and teeth. This calcium helps maintain the delicate balance of both bone growth and bone breakdown (resorption). During childhood and adolescence bone growth outweighs bone resorption, but in our adult year the two processes are generally in balance. The remaining 1% of the body’s calcium performs multiple important metabolic tasks. These tasks include vascular contraction, vasodilation, nerve transmission, muscle contraction, intracellular signaling and hormonal secretion.
How much calcium is needed to support these important bodily functions? The answer depends on many factors including ones’ age, gender, pregnancy status and lactation status. The Food and Nutrition Boards at The Institute of Health recommends the following daily calcium intakes to meet requirements:
Calcium RDAs by Age and Gender
|0-6 months||200 mg||200 mg||–||–|
|7-12 months||260 mg||260 mg||–||–|
|1-3 years||700 mg||700 mg||–||–|
|4-8 years||1,000 mg||1,000 mg||–||–|
|9-13 years||1,300 mg||1,300 mg||–||–|
|14-18 years||1,300 mg||1,300 mg||–||–|
|19-50 years||1,000 mg||1,000 mg||1,300 mg||1,300 mg|
|51-70 years||1,000 mg||1,200 mg||1,000 mg||1,000 mg|
|71+ years||1,200 mg||1,200 mg||–||–|
In order to meet these recommendations and promote healthy bone status many have turned to calcium supplementation. However, recent studies call this practice into question. One such study found that women taking calcium or calcium + Vitamin D supplementation had a modestly increased risk of heart attack or myocardial infarction1. Several other studies found similar data, finding increased death rates from cardiovascular disease with high intakes of calcium supplements3, and increased risk of cardiovascular disease in men taking calcium supplements5. The data is not conclusive, however, one study foundno increase in coronary artery calcification as a result of calcium supplementation4.
How can this data be explained? Many researchers believe that calcium supplementation gives a large dose of calcium that spikes blood calcium levels rapidly. This can interfere with the important metabolic functions of calcium (including its’ role heart function) and perhaps calcify, or harden in the arteries leading to increased cardiovascular diseases. It is important to note that these negative cardiovascular effects seem to only be tied to supplementation, not dietary calcium.
So, how does this affect your daily routine?
Although supplementation has a role in preventing osteoporosis and calcium deficiency, its’ role in cardiovascular health has not been studied as diligently. Dietary sources of calcium seem to be the safest and best absorbed sources for preventing bone loss and maintaining heart health.
- Aim for 2-3 servings of low or non-fat dairy per day
One serving of dairy:
1 Cup Fluid Milk or Calcium-Fortified Soymilk
1 Cup Yogurt
1 Cup Frozen Yogurt
2 Cups Cottage Cheese
1/3 Cup Shredded Cheese
1.5 oz. Hard Cheese
- If you cannot reach calcium needs with food products (due to intolerance or aversion), supplementation can be used, but smaller doses are recommended (~400 mg 2-3 times per day instead of one 1,200 mg dose, for example)
References & Resources:
1. Bolland, Mark J., Andrew Grey, Alison Avenell, Greg D. Gamble, and Ian R. Reid. “Calcium Supplements With or Without Vitamin D and Risk of Cardiovascular Events: Reanalysis of The Women’s Health Initiative Limited Access Dataset and Meta-Analyasis.” BMJ 342 (2011): D2040. BMJ, 18 Feb. 2011. Web. 25 Feb. 2013. <http://www.bmj.com/content/342/bmj.d2040>.
2. Larsson Susana C. “Are Calcium Supplements Harmful to Cardiovascular Disease?” JAMA Internal Medicine (2013):1-2. JAMA, 4 Feb. 2013. Web. 25 Feb. 2013. <http://archinte.jamanetwork.com/article.aspx?articleid=1568524>.
3. Michaelsson, Karl, Hakan Melhaus, Eva Warensjo, Alicja Wolk, and Liisa Byberg. “Long Term Calcium Intake and Rates of All Cause and Cardiovascular Mortality: Community Based Prospective Longitudinal Cohort Study.” BMJ 346 (2013): F228. BMJ, 13 Feb. 2013. Web. 25 Feb. 2013. <http://www.bmj.com/content/346/bmj.f228>.
4. Samelson, Elizabeth J., Sarah L. Booth, Caroline S. Fox, Katherine L. Tucker, Thomas J. Wang, Udo Hoffmann, L. Adrienne Cupples, Christopher J. O’Donnell, and Douglas P. Kiel. “Calcium Intake Is Not Associated with Increased Coronary Artery Calcification: The Framingham Study.” The American Journal of Clinical Nutrition 96 (2012): 1274-280. The American Journal of Clinical Nutrition, Dec. 2012. Web. 25 Feb. 2013. <http://ajcn.nutrition.org/content/96/6/1274.long>.
5. Xiao, Qian, Rachel A. Murphy, Denise K. Houston, Tamara B. Harris, Wong-Ho Chow, and Yikyung Park. “Dietary and Supplemental Calcium Intake and Cardiovascular Disease Mortality: The National Institutes of Health – AARP Diet and Health Study.” JAMA Internal Medicine (2013): 1-8. National Center for Biotechnology Information. U.S. National Library of Medicine, 4 Feb. 2013. Web. 25 Feb. 2013. <http://www.ncbi.nlm.nih.gov/pubmed/23381719>.