Calcium is the most abundant mineral found in the body. Most of the calcium in your body (99%) is locked up in your bones and teeth, but some of the calcium (1%) is circulating around the body and is necessary for the body systems to function normally, including vascular function, muscle contraction, nerve transmission, and hormone secretion (to name a few). Our bodies tightly regulate how much calcium is circulating by using the stores found in our bones - our bones are continuously being remodeled - calcium gets stored in the bones, and also gets taken out and used by the body. It is strange to think of our bones as being metabolically active, but they are.
Adequate calcium intake is necessary to maintain strong bones and prevent osteoporosis. Osteoporosis is a state in which bones have a low density and therefore are brittle and at risk of fracturing. Approximately 10 million people in the U.S. have osteoporosis (80% of them are women), and another 30 million have osteopenia, which is a precursor to osteoporosis.
Throughout childhood, adolescence, and early adulthood our bones are not only growing in length, but they are also getting stronger. We reach peak bone density by around age 25-30 years. After that, our bones slowly lose density over time. Adequate calcium and vitamin D (which we will talk about in the next blog entry) intake is necessary throughout our life. In childhood, healthy intake of calcium and vitamin D will ensure our bones to their highest peak density. After age 25-30, continuing with healthy calcium and vitamin D intake will slow and prevent bone loss that naturally occurs over time. The bottom line: get your bones as strong as you can, and keep them strong for as long as you can!
How much calcium do you need? It depends on your age, as well as a couple other factors such as pregnancy and breastfeeding, as well as some medical issues (such as malabsorption disorders like Celiac, or certain medications like steroids). Each person is a little bit different, but this is a great guide to most women.
Current recommended daily allowances for calcium:
Age 4-8yrs: 1,000mg
Age 9-18yrs: 1,300mg
Age 19-50yrs: 1,000mg
Age 50 and older: 1,200mg
Pregnancy and lactation: 1,300mg
The BEST source for getting calcium is through your foods. You should only take a calcium supplement if you cannot eat enough calcium in your diet. Calcium is best absorbed and utilized by the body when eaten, not as a supplement. Recent studies have shown an increased risk of cardiovascular disease (including heart attacks or strokes) in people who take excessive calcium through supplementation.
Different foods have different calcium amounts. As you can see, there are many food sources of calcium, and not just dairy. Try to space your calcium intake throughout the day (at each meal or as a snack), as your body can only absorb around 500mg at a time.
Maintaining healthy amounts of calcium in your diet, in conjunction with adequate vitamin D intake (see our next blog entry) is the best way to prevent osteoporosis in women. The last piece of the puzzle is weight-bearing exercise! You have to put small amounts of stress on your bones in order to keep them healthy and strong. Some examples of weight-bearing exercises are brisk walking, running, hiking, yoga, weight lifting, Tai Chi, soccer, basketball, dancing, and others - anything that uses gravity and puts weight on your bones. Your goal is to do at least 30 minutes, 5 days per week.
Some good resources include the NIH Office of Dietary Supplements, the NIH Osteoporosis and Bone Health Resource Center, the National Osteoporosis Foundation, and the American Cancer Society. Or call us and schedule an appointment to discuss your specific nutrition needs.
