Calcium recently made headlines when a study, funded in part by the maker of the antacid Tums (which contains calcium), indicated that calcium supplementation reduced premenstrual symptoms in women by 50% within three months. The symptoms alleviated included mood swings, tension, headaches, cramping, food cravings and water retention.

The case for maintaining a healthy calcium intake is strong on other fronts. Most notably, the mineral can help prevent osteoporosis, which affects more than 25 million women over the age of 45 in the United States and Canada alone, according to the American Dietetic Association (ADA). Experts believe the best way to prevent this disease is to build strong bones up to the age of 30, primarily through exercise and a well-balanced, calcium-rich diet. Exercise and diet are equally important for maintaining strong bones after the age of 30, when bone building naturally tapers off. A high calcium intake is also believed to reduce the severe bone loss that can occur following menopause.

According to the ADA, however, most women do not get adequate calcium. High intakes of caffeine, alcohol, sodium and protein compound the problem by increasing the amount of calcium lost in urine. Also, calcium absorption decreases with age.

How can you be sure you’re getting enough calcium in your diet? Here are some tips from nutritionist Debra A. Wein, MS, RD:

• Don’t underestimate calcium’s importance. Calcium is the mineral that makes up your bones; 99% of the calcium in your body is stored in your bones and teeth. The remaining one percent is in your blood and soft tissues. Without this one percent, your muscles wouldn’t contract properly, your blood wouldn’t clot, and your nerves wouldn’t carry messages. How do you get and keep this one percent of circulating calcium? From your diet and from your bones. If you don’t get enough calcium from food, your body automatically takes the amount it needs from your bones, gradually depleting them and eventually causing osteoporosis.
• Know how much calcium your body needs. For adults, the recommended Dietary Reference Intake (RDI) for calcium is 1000 to 1200 mg per day. Postmenopausal women may benefit from intakes as high as 1500 mg per day. Teenagers should aim to consume at least 1300 mg daily. But keep in mind that too much calcium has the same effect as too little: low absorption.
• Eat plenty of Low and Nonfat dairy products. Three servings of dairy – e.g., a glass of milk, a serving of yogurt, and two ounces of cheese – will provide about 900 mg of calcium. You can generally make up the balance of your RDI requirements through miscellaneous foods such as bread and vegetables.
• Consider eating more nondairy sources of calcium. Calcium can be obtained from green, leafy vegetables (100, 150, and 180 mg per cup from cooked kale, collards and broccoli, respectively), some cereals (250 mg in 3/4 cup of Total), tofu (150 mg in three ounces) and calcium-fortified orange juice (300 mg in one cup). These sources are especially useful if you’re a vegan or lactose intolerant.
• If you don’t get enough calcium from food, take a supplement. Calcium carbonate is effective and inexpensive. Calcium citrate malate is more easily absorbed but also more expensive. Both of these types are low in lead. To increase absorption and decrease the chances of constipation, take your supplements with meals, spaced throughout the day, in doses of 600 mg or less.
• Get enough Vitamin D. Vitamin D stimulates calcium absorption. Sources include vitamin D-fortified milk or soy milk, supplements and sunshine. Expose your hands, arms and face to sunlight for 10-15 minutes 2-3 times per week.
• Avoid drinking too much soda. If you drink three to four 12-ounce cans of soda a day, you may be consuming too much phosphorus, which prevents your body from using calcium correctly.