Calcium does a lot more than just keeping our bones strong

Q: How much calcium should I take to prevent osteoporosis (thin bones)? 

Several years ago, after stepping out of her front door, my 75-year-old neighbor Barbara turned around and, after losing her balance, fell down a flight of stairs, shattering her left ankle and breaking her right arm in 3 places. Barbara then endured 2 surgeries, one to reinforce her arm with a steel rod and pins and a second, grueling 5-hour marathon during which the surgeon collected and fit the multiple pieces of her ankle back together.

She had been taking prednisone daily to control her lupus, a painful inflammatory condition. After her emergency surgery, her doctor informed her she had osteoporosis, or "thin bones," and prescribed a bone-building medicine, plus a daily calcium and vitamin D supplement. 

Calcium does a lot more for us than just keeping our bones strong. Our muscles, nerves, and blood vessels depend on calcium to work properly. For example, every time your heart beats or you breathe, your heart and chest muscles work for you, keeping you alive and well thanks to adequate amounts of calcium in your blood.

If you run low on calcium in your blood, your body will take the calcium it needs out of your bones. It’s like an ATM (automated teller machine) but extracting calcium instead of $20 bills.

If you sometimes run low on calcium, your body occasionally must grab some calcium from your bone cells. That’s not considered a problem. But consider this: if your body needs to find additional calcium regularly, these withdrawals will eventually weaken your bones, increasing your risk of a hip fracture or worse.

How much calcium do you need?

The Institute of Medicine recommends 1000mg daily of calcium for men and women up to age 50 and 1200mg for adults older than 50. Most postmenopausal women get only 600-900mg of calcium daily through their food. This falls short of the 1000-1200mg daily calcium goal by 100-600mg daily. Some women make up that difference by taking a calcium supplement.

Supplemental calcium as tablets, capsules, and chewable caramels are easy ways to ensure women and men at risk for osteoporosis get their recommended daily dose of calcium.

Unfortunately, recent studies have shown that taking a calcium supplement may provide too much calcium. This can result in increased risks of heart attack or stroke. It’s theorized that there’s a spike in blood levels of calcium when taking a concentrated calcium supplement, which may damage your blood vessels.

Taking calcium supplements has another dark side: they encourage the formation of painful kidney stones. For these reasons, bone and kidney specialists discourage their patients from relying on getting all of their recommended daily calcium by taking a calcium supplement.

Most forms of calcium sold as supplements are calcium carbonate or calcium citrate. Calcium carbonate is the most concentrated form of supplemental calcium. It is available as flavored chewable tablets (Tums) and large pills. Calcium carbonate causes constipation in some people.

You won't absorb calcium carbonate well when taking acid-blocking medicine like omeprazole (Prilosec®) or lansoprazole (Prevacid®). Instead, you should choose calcium citrate. Have trouble swallowing large tablets? Calcium supplements are also available as gummies.

Here are 5 Tips on Getting Enough Calcium:

1. Eat calcium-rich foods.

Most people get 300mg of calcium daily from non-dairy sources. You also get 300mg of calcium per serving of dairy products like milk, yogurt, and cheese. Green vegetables, oranges, and figs also contain calcium.

2. Check out the Calcium Calculator app.

This app lets you keep track of your calcium intake. You can also check the lists of calcium-rich foods on the International Osteoporosis Foundation website, www.iofbonehealth.org.

3. You need adequate calcium and vitamin D when taking bone-building medicine.

Medicines like alendronate (Fosamax®), risedronate (Actonel®), ibandronate (Boniva®), and teriparatide (Forteo®) strengthen your bones by adding calcium back into them. If you don’t have enough calcium in your diet, they won’t work.

4. Limit supplements of calcium to 500mg at a time.

Your body absorbs calcium better at lower doses. This avoids a potential “spike” in your calcium level that can increase your risk of heart attack or stroke.

5. Get at least 400 IU of Vitamin D every day.

Vitamin D is necessary to help your body absorb calcium. Although you can get vitamin D from sun exposure, salmon (800 IU per 3 ounces), canned tuna (150 IU per 3 ounces), fortified milk (about 120 IU per 4 ounces), and fortified orange juice (80 IU per 4 ounces) are also good sources.

Dr. Louise Achey, Doctor of Pharmacy, is a 43-year veteran of pharmacology and author of Why Dogs Can’t Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Get clear answers to your medication questions at her website and blog, TheMedicationInsider.com. Ó2023 Louise Achey