Calcium

Here is your science lesson for the day.

Calcium builds bone until the age of 35 and then helps to prevent bone loss after that. To ensure that calcium is absorbed from the intestines there needs to be the right amount of calcium in diet and the right amount of vitamin D in body.

Vitamin D is actually a hormone produced by the skin when it is exposed to sunlight (15 minutes a day is enough). It must be activated by PTH (parathyroid hormone) turning it into calcitriol (Active D). Calcitriol increases the rate at which calcium is absorbed from food in the intestine.

Falling calcium levels in the blood cause an increase in PTH secretion which converts more vitamin D into calcitriol and increases the amount of calcium that is absorbed from food. If blood calcium levels go up PTH stops being secreted and the body stops making calcitriol so less calcium is absorbed. The key is to consume only moderate amounts of calcium rather than megadose. 600 mg of calcium a day is enough (7.5 oz can of salmon with bones). Megadosing calcium supplements will actually cause the body to absorb LESS calcium.

Calcium-rich foods:
salmon (with bones)
collards, bok choy, mustard greens, dandelion greens, kale
broccoli, brussels sprouts
figs, oranges
navy beans, pinto beans, kidney beans


Co-factor nutrients ensure the calcium-PTH-calcitriol regulatory mechanism is working properly.

Magnesium - essential for release of PTH - moves calcium from blood into bones
Copper - moves calcium from blood into bones
Manganese - moves calcium from blood into bones
Phosphorus - essential for laying down bone - EXCESS blocks secretion of PTH and blocks absorption of calcium and magnesium from intestines - keeps soft drinks bubbly (nothing worse for the bones of a teenage girl than Coke or Pepsi)
Vitamin A - enables calcitriol
EFAs - enable calcitriol

These co-factor nutrients are found in seafood (fish), beans (tofu), vegetables (spinach), whole grains (brown rice, oatmeal), nuts (almonds, brazil, walnuts), and seeds (sesame).