Ask the Diet Doctor: The Bottom Line on Calcium Supplements

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Q: Is it safe to keep taking my daily calcium supplement?

A: Since osteoporosis (most notably brought on by insufficient calcium intake) is one of the biggest health concerns for women, taking a calcium supplement may seem like a magic bullet. But although calcium is an important nutrient, too much can have negative health consequences.

Many American women don't get enough calcium: Less than 38 percent take in 1,000 milligrams per day (mg/d), which the recommended dietary allowance for women 19 to 50 years old. And 30 percent of postmenopausal Caucasian women have osteoporosis, while 54 percent have osteopenia (weak bones but not to the level of osteoporosis).

Over-supplementation is not the answer. The Institute of Medicine has set an upper limit on calcium intake of 2,000 mg/d-beyond this you run the risk of health consequences. Elevated levels of calcium in your blood may promote calcification of your blood vessels (e.g. the depositing of calcium in your vessel walls), which decreases vascular elasticity and leads to slew of cardiac issues such as heart attacks and death.

However, research to date regarding calcium supplementation and increased risk of cardiac problems has been mixed and not of the highest quality. A recenty study published in Osteoporosis International found no relationship between calcium supplementation and cardiovascular disease in 74,245 women. They also compared women with very low intakes of calcium (<500mg/d) with ones who had calcium intakes above the upper limit of 2,000 mg/d and found no association between higher intakes and increased risk of the disease.

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Still, the results of this study should not give you free reign to wildly supplement with calcium. Bone health and cardiovascular disease are complicated physiological processes. I recommend you use calcium supplementation to fill needed gaps in your diet while also supporting your calcium intake with complimentary nutrients like vitamins D and K.

Vitamin D impacts many areas of the body. It's important for bone health because it can enhance calcium absorption while also playing a key role in bone building and remodeling. Deficiency in D is most classically associated with osteomalacia or soft bones. Find it in meats, fish, eggs, nuts, fortified milk, orange juice, and many cereals.

Vitamin K plays an integral role in blood coagulation and clotting, bone health, and the prevention of the calcification of blood vessels. Dark green vegetables like spinach, kale, Swiss chard, collard greens, broccoli, and Brussels sprouts are great sources of vitamin K. These vegetables are also some of the highest plant sources of calcium, so you'll automatically obtain the nutritional balance that you need.

To find out if you do need to take a calcium supplement, complete a quick assessment of how many calcium-rich foods you eat daily. Total your calcium intake from the foods below, and if your total is at or above 1,000mg (or 1,200mg if you are older than 50), then you don't need to supplement. If you are below the RDA, it would be prudent to either increase your intake of calcium-rich foods or take a supplement, just select one that will keep your total intake below 2,000mg/d.

* Milk, 1 cup: 300 mg

* Cheese, 1 ounce/slice: 200 mg

* Fortified soy or almond milk, 1 cup: 300 mg

* Fortified juice, 1 cup: 350 mg

* Yogurt, 6 ounces: 250 mg (variable)

* Spinach, 1 cup raw: 30 mg

* Spinach, 1 cup cooked: 250 mg

* Collards, 1 cup cooked: 350 mg

* Kale, 1 cup raw: 100 mg

* Kale, 1 cup cooked: 180 mg