Calcium for Bones at Your Heart’s Expense?
Two recent studies have forced us to take another look at a habit that many women have taken up in recent years: taking calcium supplements for healthier and stronger bones. Before we take a look at those studies, let me give you a little background.
A calcium primer
Calcium is the most abundant mineral in the body and is found in bones and teeth. Calcium helps your body maintain balance in its natural process of building and rebuilding bone.
Only 1% of the total calcium is present in the blood to support a number of metabolic functions. The remaining 99% is stored in bones and teeth as a reservoir for supporting their structure and function.
Throughout life, old bone material is naturally removed by your body and new bone material is formed using available calcium.
Calcium and menopause
During childhood, bone formation exceeds bone breakdown. In aging adults, particularly postmenopausal women, bone formation is reduced and bone mass falls. Short-term calcium deficiency will cause symptoms like numbness, tingling of the fingers, fatigue, muscle cramps, convulsions and decreased appetite. Long-term deficiency is thought to contribute to osteoporosis (loss of bone density) and increased risk of bone fracture.
To prevent calcium deficiency, it is recommended that you get 1,000 to 1,200 milligrams of calcium a day in your diet.
Some calcium-rich foods include those in the dairy food group like cheese, yogurt, and milk; dark leafy greens like spinach and kale; and fortified foods like whole grain cereals, soymilk, and orange juice, etc.
Calcium absorption from food varies, but on average, your body can retain about 30% of the calcium you eat. And by the way, caffeine and alcohol decrease your ability to absorb calcium.
As a result, many people take supplements of calcium, along with Vitamin D, which can help with the body’s absorption of calcium.
But, is taking calcium supplements an effective strategy for bone health? Does it have implications for your heart health?
Controversy over calcium supplements
Three major studies give us something to think about when it comes to taking calcium supplements for better health.
- A Women’s Health Initiative (WHI) study supplemented healthy postmenopausal women with 1,000 mg calcium carbonate plus 400 IU of Vitamin D daily or a placebo. After seven years, the women who received calcium plus Vitamin D had an increase in bone density without a decrease in bone fractures, but with a small increase in kidney stones.
- Earlier this year, a large Swedish study suggested that women consuming high dietary calcium or calcium supplements (above 1,400 mg/daily) might be more likely to die from heart disease, but not from stroke, than those with calcium intake of 600-1,000 mg/day.
- Also reported in 2013, a re-analysis of the WHI clinical trial data combined with the data from the WHI observational study followed 93,000 women for 8 years and concluded that there was not enough evidence to demonstrate that calcium and Vitamin D increased the risk for heart attack, coronary heart disease, total heart disease, stroke or total cardiovascular disease.
Here is what we know:
- Calcium supplements do not prevent bone fractures in healthy post-menopausal women.
- Calcium supplements increase the risk of kidney stones.
- Calcium supplements may increase the risk of heart attacks.
If you are healthy, physically active, and eat a healthy, well-balanced diet, you probably do not need a calcium supplement unless you are specifically told by your doctor to take one.
The best way to determine if you are getting 1,000 to 1,200 milligrams daily is to start tracking your consumption. In addition to reading nutrition labels, there are many online tools that will give you nutrition information about foods, including the USDA National Nutrient Database.
It is important to note that decisions concerning calcium and Vitamin D supplements may depend on multiple factors like age, sex and individual risk factors. As always, consult with your doctor before adding medications or supplements. Protecting your bones and your heart together requires combining the right dietary balance with physical activity. You can do both!
Until next time!
Stephanie Coulter, MD
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Visit the Center for Women's Heart & Vascular Health at www.texasheart.org/women.