Calcium: the Goldilocks Rule

Philip J. Goscienski, M.D.

August 2013

In less-developed countries whose inhabitants have a calcium intake that is about half that of Americans' there are remarkably few hip fractures. They have few labor-saving devices and it is their increased physical activity that makes bones stronger. Calcium does matter during the bone-building window that spans the school years, kindergarten through college. At any age, too little calcium doesn't cause bones to break, it makes them bend. When calcium alone is added to the diet it has no effect on bone strength or fractures. Normal bone formation requires vitamin D and other nutrients.

In past years, doctors advised persons who suffered from kidney stones to lower their intake of calcium by limiting foods such as dairy products. That's not good advice, at least for individuals who have the most common type of kidney stones, those that consist of calcium oxalate. The current recommendation is to maintain a normal calcium intake — the Goldilocks zone. That means eating ordinary amounts of calcium-rich foods such as dairy products and green leafy vegetables and avoiding large doses of calcium supplements.

Calcium should come from normal foods. The best sources are green leafy vegetables. Sardines are an excellent source of calcium and also provide bone-building protein and omega-3 fats. It's virtually impossible to take in too much calcium from food but supplements are different matter. There is a complex mechanism that keeps the level of calcium in the blood within a certain range. A heavy dose of calcium in the form of a pill can override that regulatory mechanism.

A target of 1,000 milligrams of calcium a day is adequate for most adults. Persons over 50 and children between the ages of 9 and 18 years need about 1300 milligrams. These recommendations also apply to persons with a personal or family history of kidney stones. Stone formation can result from a very low intake of calcium, especially in persons who eat oxalate-rich foods such as spinach and rhubarb. Amounts greater than 1500 milligrams from supplements are not helpful and may be linked to heart disease. High doses of calcium in the form of supplements can also lead to kidney stones although that which comes from the diet does not.

In addition to calcium, healthy bones need a combination of vitamins, protein, omega-3 fats and minerals such as magnesium and boron. And a daily dose of exercise.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.