Calcium: An Essential Mineral

May 20th, 2009

Calcium is best known as the mineral that builds and maintains strong teeth and bones. In addition, calcium is essential for the body’s basic functions, including nerve transmission, blood pressure and clotting, heartbeat and hormone regulation.

Strong Bones

About 99% of the calcium in our bodies is found in our bones. To ensure a lifetime of strong bones, it’s especially important to optimize your calcium intake  through the age of 30, when bone is deposited most rapidly. Get regular weight-bearing exercise, such as walking, dancing, weightlifting, or racquet sports, at all ages.

After 30, bone tissue begins to break down more rapidly than new bone tissue is created. As a result, you start to lose bone mass and bone density.  If too much bone tissue is lost (and/or not enough bone mass is deposited early in life), the bones can become porous and brittle. This condition is known as osteoporosis, and it affects an estimated 44 million Americans, 80% of them women.

Men and women are both at risk of osteoporosis, but the disease usually affects women at a younger age because women begin to lose bone tissue rapidly following menopause. Estrogen-replacement hormones can slow post-menopausal bone loss, but there are some risks associated with ERT.  For women with or at risk of osteoporosis, medications like Fosamax can help slow bone loss and strengthen bones. Maintaining adequate calcium intake throughout life can also reduce the risk of osteoporosis.

Calcium from Dairy

Dairy products like milk, cheese and yogurt are excellent sources of calcium. The new Food Pyramid released in early 2006 recommends that adults consume up to 3 servings of low-fat dairy products a day, mainly to ensure sufficient calcium intake.

Although dairy products are high in calcium, they can also be high in saturated fat, which raises LDL cholesterol and contributes to the risk for heart disease. When eating dairy, stick to low-fat or fat-free products.

Conventionally-produced (non-organic) dairy products usually contain bovine-growth hormone and antibiotics, which are fed to cows and are present in their milk.   Pick dairy products labeled “organic” to avoid those chemicals.

Finally, dairy products contain lactose, a simple sugar that many people have trouble digesting.   About 25% of Americans suffer from lactose intolerance. It is much more common in ethnic minorities than in people of European descent.  It’s estimated that 50% of Hispanics, 80% of African-Americans and almost 100% of Asians lack the enzyme needed to digest lactose.  Symptoms of lactose intolerance range from mild to severe.

Recent studies suggest a possible link between lactose intake and an increased risk for ovarian and prostate cancer. Prostate cancer is the most common cancer among American men, affecting one in six males.

Non-Dairy Calcium Sources

Some non-dairy foods, such as green leafy vegetables and dried beans and legumes are high in calcium. However it isn’t always as absorbable as the calcium in dairy products due to compounds known as oxylates and phytates. On the other hand, the calcium in vegetables from the cabbage family, such as cabbage, kale, bok choy, and broccoli is as well-absorbed as dairy-based calcium. Other sources of calcium include calcium-enriched soy-milk, rice-milk, and soy cheeses.

Calcium Absorption

More than three out of four American adults currently meet the FDA’s calcium recommendations. However, Optimal calcium absorption depends on several other nutrients, the most important of which is Vitamin D.

Our skin produces Vitamin D when it is exposed to sunlight (without sunscreen) but most Americans do not get enough sunlight to meet their vitamin D needs, particularly in the winter.  Dark-skinned and elderly people are at particular risk for vitamin D deficiency.  Dietary sources of Vitamin D include fortified milk or milk alternatives and egg yolks. We can also get Vitamin D from taking dietary supplements.

Finally, smoking and drinking alcohol can weaken your bones. Consuming too much caffeine and/or protein can also increase your calcium requirements. In sum, a healthy diet and lifestyle work together to ensure strong healthy bones throughout life.