Calcium and Supplements: What You Need To Know

BY CHRISTINE TWINING, MD, FAC E

Most of us learned as children that calcium was important for strong teeth and bones. Our parents made sure we drank enough milk and ate our spinach, two of the more popular natural sources of calcium. And if you were one of those kids that hated spinach with a passion, you could get still get plenty of calcium by eating yogurt or drinking orange juice with added calcium.

These days, many adults no longer drink three glasses of milk per day. In fact, the U.S. Department of Agriculture (USDA) reports that consumption of milk has been declining since the 1970s. Furthermore, most people don’t keep track of their daily calcium intake, nor do they know how much calcium they should be taking on a daily basis, which foods contain calcium, or even which supplements or multivitamins are the best source of calcium.

The situation has become even more confusing in the past few years due to reports that link calcium supplements to an increased risk of cardiovascular disease, heart attacks and other health problems. Yet other studies have found no adverse effect from calcium supplements.

The resulting conundrum has left many people asking, “Should I or should I not take calcium supplements?”

First things first: calcium intake remains crucial for building and maintaining bone health, during skeleton development in childhood and adolescence, and particularly after menopause to prevent osteoporosis and fractures. Your body also needs calcium for proper muscle and nerve function, for the electrical circuits in your heart, for hormone release, blood clotting and many other tasks. These functions are so important that your body will actually take calcium from your bones if you don’t take in enough through food and/or supplements. This weakens your skeleton over time, leaving you at risk for a fracture.

In general, adults should take between 1,000 milligrams and 1,200 milligrams of calcium each day, and menopausal women should take 1,200 milligrams daily. Certain medical conditions such as hypoparathyroidism, gastric bypass surgery and other digestive disorders increase these requirements, while other conditions decrease them. Talk to your endocrinologist about what is right for you.

Also keep in mind that daily calcium recommendations are the total amount of calcium you need from dietary and supplemental sources. Experts agree that it is best to get as much of your daily calcium needs from food as possible.

So which foods are the best ones to choose? Dairy products such as milk, yogurt and cheese are some of the best known sources of calcium, particularly lowfat yogurt, as this typically has more calcium added than regular yogurt.

Unfortunately, not everyone is able to eat these foods due to lactose intolerance (an inability to break down lactose, a sugar found in milk products), milk allergies, taste preferences, or other concerns. The good news is that there are many other quality food sources of calcium such as almond, rice and soy milks, which are usually fortified with calcium, as are some orange juices and other drinks. Dark green leafy vegetables such as broccoli, spinach and kale are also high in calcium, as well as salmon and almonds, although the quantities needed might be a bit daunting (see “A Guide to Calcium-Rich Foods” on page 10 for details).

If you’re unable to get enough calcium from food, there are many over-the-counter supplements available. As with most things, not all supplements are equal.

Below are a few tips to help you select a preparation that is right for you.

  • Most supplements contain calcium carbonate. This is not absorbed as well when taken on an empty stomach, so it is best to take this with food. Alternatively, it could be taken at bedtime when the stomach acid level helps to dissolve the calcium. Calcium citrate supplements are absorbed a bit more readily by the gut and can be taken on an empty stomach. Chewable supplements are easier for some people to take than large pills.
  • You should choose a supplement with no more than 500 to 600 milligrams of elemental (readily absorbed) calcium because your body can’t assimilate more than this at one time. Therefore, if you are getting all of your calcium from a supplement, you will need to take it twice a day, every three to four hours. Make sure you talk with your doctor about your dosing schedule and type of calcium that is best for you.
  • Calcium supplements can interfere with the absorption of other medications such as thyroid hormone. Calcium can also result in constipation for some, limiting the amount that a person can take comfortably.
  • There can be too much of a good thing when it comes to calcium – and more than 1,200 milligrams per day is not better. Taking calcium in excess of your daily requirement puts you at an increased risk for kidney stones and possibly heart or prostate problems.

Research from Australia suggests that women in particular increased their risk of heart attacks with increased calcium intake. The study also suggested that daily supplements may increase calcification of the arteries and veins, which then could raise the risk of heart attack. However, subsequent research from a Boston study of more than 74,000 women found that these supplements are safe in terms of heart health. This newer study found no raised risk of heart attack or stroke among women taking calcium supplements during 24 years of follow-up.

In fact, calcium supplementation was actually associated with lower risk of heart disease. Yet there needs to be caution in interpreting these findings, as the researchers noted that the women in this study who took calcium supplements exercised more, smoked less and ate less trans fat (artificial trans fat – or transfatty acids – are created in an industrial process that adds hydrogen to liquid vegetable oils to make them more solid) than women who did not take supplements, calling into question whether the supplements prevented heart attacks or stroke, or other positive behaviors affected the women’s health.

It’s important to remember that some risks come from taking too much calcium, not from getting your recommended daily allowance. Unfortunately, some patients have been confused about this and have tried to avoid calcium altogether. While no one wants to run the risk of developing a medical condition from taking too much calcium, avoiding the nutrient altogether simply is not healthy for your skeleton. You still need 1,000 to 1,200 milligrams every day to prevent bone loss.

Dr. Christine Twining is an endocrinologist and Medical Director at the Maine Medical Partners Center for Endocrinology and Diabetes, a group of eight endocrinologists in Scarborough, Maine. She practices general endocrinology with a focus on thyroid disease, metabolic bone disease and transitional care. She is on the clinical faculty at Tufts School of Medicine and also serves as an advisor to Maine Medical’s Med-Peds residents.

After graduating from Duke School of Medicine, Dr. Twining completed a combined Internal Medicine-Pediatrics residency at Yale followed by Endocrinology fellowship at the University of South Carolina. Dr. Twining has been an active AACE member since 2006. She served as the Fellow-in-Training Representative to the Board of Directors in 2007-2008 and has served as AACE’s representative to the Young Physicians Section of the AMA since 2010. She is the Immediate Past President of the New England Chapter of AACE and has served on the NE AACE Board since its reinstatement in 2008. She has served on many AACE committees, including Endocrine Training Support, Socioeconomics, Chapters, Membership, Pediatric Endocrinology, and Endocrine University and the Task Force on Women in Endocrinology.