Milk, bone health, and calcium absorption

Question
Dear Dr. Zilberter,

Is it true that milk and other dairy products are acid forming foods, and therefore take calcium FROM the bones rather than add to them.  I read that countries with the highest rates of osteoperosis and bone-breaking are countries with high-dairy diets.

A Harverd Nurses' Health Study found that women who consumed the most calcium from milk and dairy foods broke more bones than those who rarely drank milk. (Source: Feskanich et al. "Milk, dietary calcium and bone fractures in women: a 12-year prospective study."  American Journal of Public Health, 1997.)

Answer
Dear Wendy,

I would rather say that milk's pH at 25?C is normally 6.4 to 6.8, making it slightly acidic, however, milk can hardly be considered acid-forming. The human body maintains a pH around 7.3 -- a slightly alkaline state but to be able to do so, the body needs alkaline foods. On the other hand, not only pH of foods but also gastrointestinal tract's pH influence calcium absorption. Normal stomach acidity is generated by the digesting juices. If the stomach acidity is  reduced (e.g., due to acid-reducing medicines) calcium isn't absorbed good enough to actively participate in the bone health maintenance.

Harvard抯 Nurses?Health Study you've mentioned indeed found that women who got the most dairy calcium actually suffered more fractures than women who got little or none. However, the researchers concluded that it can be not due to calcium intake only:  "Characteristics of bone other than mass, such as microscopic fatigue damage and the loss of connectivity in supporting trabeculae [elements of internal structure of the bone: http://en.wikipedia.org/wiki/Cancellous_bone], contribute to fracture risk. Furthermore, foods high in calcium may contain other factors that influence fracture risk."


Read more:

Acidity-alkalinity of foods:
http://atkinszone-faq.blogspot.com/2008/10/which-foods-are-acid-and-which-alkali...

Foods to probably avoid to help the body to maintain the needed slightly alkaline pH:
http://atkinszone-recipes.blogspot.com/2009/07/ph-of-common-acid-foods.html

Tanya Zilberter

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