Are we getting enough calcium?

Dr. Verghese explains that while 99% of the body's approximately one kilogram of calcium resides in bones for structural support, the remaining 1% plays vital roles in every cell. This small percentage is essential for muscle contraction, nerve signaling, hormone release, and blood clotting. She illustrates calcium's importance through the example of hyperventilation, where rapid breathing alters blood chemistry and affects calcium levels, causing the familiar tingling sensation in fingers.

• The body contains about 1 kilogram of calcium, with 99% in bones and 1% distributed throughout all cells
• The 1% of calcium outside bones is critical for muscles, nerves, enzymes, hormones, and blood clotting
• Hyperventilation causes pins and needles because it changes blood alkalinity, binding more calcium to proteins and increasing neuron excitability
• Calcium levels are tightly regulated and fiercely defended by hormones
• Bones serve as a calcium reservoir to maintain exact blood and cellular calcium levels

Vitamin D functions as a steroid hormone rather than a true vitamin, and it's essential for calcium absorption. The body produces vitamin D when sunlight interacts with cholesterol in the skin, which then gets activated in the liver and kidneys. Without adequate vitamin D, dietary calcium cannot be efficiently absorbed from the gut into the bloodstream and bones, making both nutrients interdependent for bone health.

• Vitamin D is actually a steroid hormone, not a true vitamin, produced when sunshine irradiates dehydrated cholesterol in the skin
• Vitamin D helps absorb calcium and phosphate through the gut and mineralize bone
• Without sufficient vitamin D, dietary calcium cannot be adequately absorbed regardless of intake
• People with osteoporosis need about 1,000mg calcium and 1,000 IU vitamin D daily; those without need 700mg calcium and 400 IU vitamin D