Our Paleolithic ancestors did not consume milk from wild animals. (Imagine trying to catch a wild animal, and then trying to milk it!) The only milk humans consume in a wild, natural habitat is their mother’s milk until weaning. Yet, because of the marketing efforts of the dairy industry, you might think that hunter-gatherers had poor bone density. The opposite is the case.
The natural ratio of calcium to magnesium that shaped our physiology was roughly two-to-one. The high ratio found in dairy milk results in an undesirable ratio of about five-to-one in most Western diets. This high calcium intake relative to low magnesium intake is linked to an increased risk for cardiovascular disease, cancer, and osteoporosis.
The dairy industry repeatedly delivers the message that you must consume dairy to have strong bones, because dairy contains a lot of calcium. It is true that dairy contains a significant amount of calcium, however, having strong bones isn’t just about consuming a lot of calcium.
As already stated, milk and dairy products have a high Ca2+/Mg2+ ratio (approximately 12-to-1), which is not favorable for calcium absorption. In addition to the active form of vitamin D, magnesium is needed for calcium absorption. It is also needed to convert vitamin D into its active form. Consequently, simply increasing calcium in the diet does not mean calcium absorption will improve.
In fact, increasing calcium intake can have negative consequences. That’s because if the excess, unabsorbed calcium is not excreted, it can form kidney stones or be transported to soft tissues where it can harden (calcify). This can lead to arthritis in joints and the hardening of arteries, as well as the formation of plaques that block arteries.
Magnesium can help prevent these issues by aiding absorption. It stimulates calcitonin, a hormone which draws calcium out of the blood and soft tissues back into bone, helping to preserve bone structure. This further lowers the risk of the health concerns that arise from unabsorbed calcium.
The other issue relevant to bone density is the importance of calcium retention. A process called calciuresis, the excretion of calcium in the urine, is increased when one’s diet becomes too acidic. Following a contemporary Paleo diet not only balances the acid-base of your diet to prevent calciuresis, it also yields the healthy Ca2+/Mg2+ ratio your body requires.
