DAIRY PRODUCTS, like milk, cheese, and yogurt, are high in calcium, and are commonly promoted as foods that build strong bones. Yet, osteoporosis, which is a chronic loss of bone mineral, occurs most often in nations with the highest intake of dairy products (Lanou, 2006). Women in the U.S. typically lose about half of their bone mass in a lifetime (Brown & Jaffe, 2000), with average losses of 1% for each adult-year. What is the cause of this association between a high intake of dairy products and the prevalence of osteoporosis?

For a young calf, cow milk, consumed straight from the producer, is nature’s perfect food, providing nutrients for rapid growth of bone and muscle. But humans do not grow at the rate of young calves, and so dairy products are not properly matched to the nutrient needs of humans. For example, humans do not require the high amount of protein supplied by a large intake of dairy foods. The actual human requirement for protein is 30% lower than the RDA, or only about 5–6% of calories needed to maintain bodyweight (Campbell & Campbell, II, 2006). A 175-lb. male who burns 2700 calories needs only about 35-43 grams of protein, or approximately one gram for each four-five pounds of bodyweight. Nevertheless, the average intake of protein in the Western diet is three times higher at 15%–16% of calories! Researchers have long known that excess amounts of protein increase calcium excretion from the body (Margen et al., 1974). Doubling protein intake from 35 grams to 78 grams increases the body's calcium loss by 50% (Hegsted et al., 1981). Due to the high-protein content of dairy products, consumed in combination with other high-protein foods, like animal flesh, eggs, grains, nuts, and legumes, dairy products not only fail to prevent osteoporosis, they may contribute significantly to the cause of bone loss by increasing the acid load within the body.

Normally, biocarbonates in fruits and vegetables buffer acids as they are produced in the human body during metabolism (Lanham-New, 2008). Nevertheless, according to Arnett (2008), as excessive amounts of protein are metabolized, extracellular fluid around bone begins to become more acidic, and the concentration of positive hydrogen ions builds up in the fluid. To defend against this harmful buildup of acid, bone begins to release negative hydroxyl ions to neutralize the hydrogen ions and form water. However, in the process of releasing these buffering hydroxyl ions, bone is also forced to release calcium and phosphate, which are eliminated in the urine. It is important to note that the calcium released from bone does not directly buffer and neutralize the acid. Calcium ions have positive charges, which repel positive hydrogen ions rather than attract and buffer them. This helps explain why ingesting large amounts of calcium doesn't protect against the adverse effects of excessive protein intake. 

Bone “casts” out calcium and other substances due to the action of bone cells called osteoclasts, with a “c.” Bone “brings” in calcium and other nutrients due to the action of bone cells called osteoblasts, with a “b.” Arnett described how osteoblasts are deactivated when extracellular fluid becomes more acidic, or when the fluid’s pH drops. In other words, even though dairy products like milk supply calcium, the acidic effect of an excessively high protein intake within the human body from consuming large quantities of cow milk causes a drop in fluid pH, which turns off the action of osteoblasts to absorb the milk's calcium. At the same time, the lowered pH increases the action of osteoclasts to release calcium, phosphate, and hydroxyl ions from bone. The end result is that there is a net loss of calcium and other matter from bone. The more dairy products consumed, the higher the net loss! A National Dairy Council study confirmed this. Researchers supplemented a test group with three 8–ounce glasses of milk a day, which significantly increased bone fracture rates compared to a control group that didn't receive the supplementation. The researchers concluded the rise in fractures was most likely due to a 30% increase in protein intake from milk (Recker & Heaney, 1985).

Incidentally, osteoporosis drugs work by killing osteoclasts. You might think this is an effective way to avoid bone loss, and these drugs have been shown to increase bone mineral density (BMD). However, according to Small (2005), "...there is no precise and consistent relationship between a given increase in BMD and a specific decrease in fracture risk with osteoporosis therapy." Osteoclasts are necessary for normal, healthy bone turnover. Worn out bones in an adult human are normally cast out and gradually replaced with fresh, new, stronger bone every ten years, thanks to the balanced action of osteoclasts and osteoblasts. Upsetting this continuous bone turnover, by killing osteoclasts, interferes with the renewal of bone strength, which can lead to disastrous long-term adverse effects such as spontaneous fractures of the femur. Small concluded that, "Fracture risk depends on a number of variables that contribute to bone strength in addition to BMD, such as bone size, shape, architecture, and turnover." While Sally Field cheerfully promotes the osteoporosis drug Boniva, she may not be so cheerful ten years from now if her bone strength and bone turnover have been severely compromised.

The healthiest and easiest solution to prevent osteoporosis is to lower your overall intake of protein by consuming fewer high-protein foods, like dairy products. Ironically, at lower intake levels, dairy products no longer provide any advantages over other natural foods, such as fruit, nuts, and vegetables, in supplying calcium to the diet. Oranges, dried figs, dates, collards, kale, broccoli, romaine, almonds, and other natural foods all contain ample supplies of calcium. One soon discovers that one can be just as adequately nourished, and maintain healthy bones, on a properly balanced diet of all plant foods, without dairy products whatsoever. Measured by calorie, many plant foods are higher in calcium than dairy! And there is no risk of consuming excessive amounts of protein from fruits and vegetables as a source of calcium. 

Campbell (2008) estimated the daily need for calcium on a low-protein, plant-based diet at about 400–600 mg, which is significantly less than the 1,200 mg currently recommended for adults eating a high-protein, Western diet—a recommendation that continues to rise in a futile attempt to prevent osteoporosis by supplying more calcium through dairy products! Even at ultra-low dietary calcium intake levels of 150–200 mg a day, researchers have never seen calcium deficiency diseases in normal people who eat a natural-food diet (Paterson, 1978). Osteoporosis in otherwise normal people is never caused by lack of dietary calcium.

To summarize:
1. Calcium deficiency diseases are not caused by a low level of calcium in the Western diet.
2. Ingesting more calcium does not prevent the loss of bone calcium due to excess protein intake.
3. Dairy products contain protein in amounts that exceed human biological needs, which contributes to the cause of calcium deficiencies.

To prevent osteoporosis, even vegetarians and vegans who avoid dairy products must take care to include a proper balance of fresh raw fruit and green leafy vegetables in their diets, and they must avoid excessive protein intake from eating large amounts of grains, legumes, tofu, soymilk, hummus, and high-protein nuts and seeds. For example, cashews, almonds, pistachios, and sunflower seeds have 13%–14% calories from protein, while there are only 4–5% calories from protein in low-protein nuts, like pecans, coconuts, and macadamia nuts. A veggie burger has over 35% calories from protein!

Although fruits and vegetables supply the body with alkaline minerals, like calcium, acid from excess protein interferes with calcium absorption. The simplistic view that consuming more alkaline foods will directly neutralize an excess of acid-forming proteins ignores the vital intermediary role of human physiology. Regardless how much green salad of romaine, spinach, celery, cucumber, and tomatoes is consumed in an attempt to "balance" 2–4 ounces of almonds, such a meal still amounts to 14%–15% protein! Peanuts, which are legumes, provide 17% calories from protein, and other legumes, like lentils, green peas, and beans, provide 26%–30% calories from protein! Green vegetables also provide very high amounts of calories from protein, but they have a much smaller effect on increasing a diet's total calories from protein because they are so low in calories, and they should be used abundantly. 

Dr. Campbell observed that adverse health effects begin to appear in people consuming a diet that totals over 10% calories from protein, yet, he noted that a typical vegan diet, which includes grains and legumes, has 13% total calories from protein! Not surprisingly, a recent study found no significant difference in the prevalence of osteoporosis between groups of vegans and omnivores, and that the disease progressed with age equally in both groups (Ho-Pham et al., 2009).

Thus, even with abundant amounts of fruit and vegetables, and use of other so-called alkalinizing supplements, no one should ingest excessive amounts of calories from protein, whether from plant or animal sources, and expect to avoid the acidifying effects that negatively impact health. Referring to an acid condition in the human body, Dr. George W. Crile, the father of physiologic surgery, wrote in Man—An Adaptive Mechanism, "...acidosis is a factor in many diseases—acute and chronic." 

During World War I, Mikkel Hindhede (1920) placed the people of Denmark on a low-protein diet, and reduced the national death rate in one year by an astounding 40%! Similar reductions in mortality have been replicated in  laboratory animals feed a low-protein diet with restricted amounts of the amino acid methionine (McCarty et al., 2009). In the global flu pandemic of 1918, Denmark had the world's lowest mortality (Murray et al., 2006). The potential exists today for comparable reductions in mortality and healthcare costs from a plant-based, 5–6% protein diet. Unfortunately, the people in Denmark had an unappealing bland diet imposed on them, and they quickly reverted to a high-protein diet after the war. They now have the highest per capita rate of osteoporosis in the world (Nationmaster.com, 2009). Fortunately, we have much more appealing foods we can use on a low-protein diet.

Sweet fruits, avocados, and raw, unsalted, low-protein nuts, such as pecans, macadamia nuts, and coconuts, are some examples of the best foods that provide the necessary concentrated sources of energy from unrefined fat and carbohydrates in a plant-based diet to maintain bodyweight, while keeping overall protein intake at 5–6% of calories. See Sample Menus below.

For more information, also see: 
The Optimal Diet for Humans; 
Bananas, Coconuts, and Green Smoothies: Nature's Perfect Foods.
For a comparison of calories from protein in nuts, grains, legumes, fruit, and vegetables, see Maintaining Healthy Bodyweight on a Raw Food Diet.
Calculate your maintenance calorie allowance with The Body Fat Guide. 

Because teeth are bones, a low-protein, plant-based diet applies equally as well in preventing diseases of the teeth, gums, and jaw. The World Health Organization (2003) reported that when the pH of saliva rises to an alkaline value of 7, it becomes super-saturated with calcium and phosphate, and remineralizes worn tooth enamel. Victoria Boutenko (2005) described how she raised her salvia pH by consuming large quantities of dark leafy green vegetables in green smoothies made with fruit. Dr. Melvin Page reported that 25 nurses without tooth decay were found to have 2.5 times more calcium than phosphorous in their blood, which is the normal ratio in bone (Get Health Care Solutions, 2009). Unfortunately, the average intake of phosphorous in the Western diet is four times greater than the intake of calcium. Phosphorous is most often found in high-protein foods like dairy products! Salt, caffeine, alcohol, refined carbohydrates, lack of sunshine, and lack of weight-bearing exercise are some other factors that contribute to bone loss (Vegetarians in Paradise, 2009).

If possible, use a nutrient counter to analyze your diet every now and then to make sure you are keeping your protein intake at approximately 5–6% of the calories needed to maintain a healthy bodyweight. This is the best way to ensure the maintenance of healthy, strong bones. Here is a Diet Analyzer spreadsheet I created to analyze the protein, fat, carbohydrate, calories, and calcium content in grams of fruit, nuts, and vegetables. You can add other foods to this spreadsheet by copying information from the link to the USDA at the bottom of the spreadsheet. However, don't be surprised to see your protein intake immediately skyrocket to 10%, 15%, or more if you add grains, legumes, and animal foods to your diet. See the bottom table.

5–6% Protein, Raw, Vegan Sample Menus:

Calories from Protein in Grain, Legume, and Animal Foods:

References: 

Arnett, T. R. (2008). Extracellular pH regulates bone cell function. The Journal of Nutrition, 138, 415S-418S.

Boutenko, V. (2005). Green for Life. Raw Family Publishing.

Brown, S. E., & Jaffe, R. (2000). Acid-alkaline balance and its effect on bone health. International Journal of Integrative Medicine, 2.

Campbell, T. C. (2008). RDA's: Time to peel back the labels. Retrieved November 8, 2009 from http://www.tcolincampbell.org

Campbell, T. C., & Campbell, II, T. M. (2006). The China study: Startling implications for diet, weight loss, and long-term health. Dallas, TX: BenBella.

Get Health Care Solutions (2009). Melvin Page, D.D.S. Retrieved November 22, 2009 from http://gethealthcaresolutions.com/blog/?p=16

Hegsted, M., Schuette, S. A., Zemel, M. B., et al. (1981). Urinary calcium and calcium balance in young men as affected by levelof protein and phosphorus intake. Journal of Nutrition, 111, 553–562.

Hindhede M. (1920). The effect of food restriction during war on mortality in Copenhagen. Journal of the American Medical Association, 74, 381–382. 

Ho-Pham, L. T., Nguyen, P. L. T., Le, T. T. T., Doan, T. A. T., Tran, N. T., & Nguyen, T. V. (2009). Veganism, bone mineral density, and body composition: A study in Buddhist nuns. Osteoporosis International.

Lanham-New, S. A. (2008). The balance of bone health: Tipping the scales in favor of potassium-rich, bicarbonate-rich foods. Journal of Nutrition, 138, 172S–177S.

Lanou A. J. (2006). Bone health in children. BMJ, 333, 763–764.

Margen, S., Chu, J., Kaufmann, N., & Calloway, D. (1974) Studies in calcium metabolism. 1. The calciuretic effect of dietary protein. American Journal of Clinical Nutrition, 27, 584–589.  

McCarty, M. F., Barroso-Aranda, J., & Contreras, F. (2009). The low-methionine content of vegan diets may make methionine restriction feasible as a life extension strategy. Medical Hypotheses, 72, 125–128.

Murray, C., Lopez, A., Chin, B., Feehan, D., Hill, K. (2006). Estimation of potential global pandemic influenza mortality on the basis of vital registry data from the 1918–20 pandemic: a quantitative analysis. The Lancet 368, 2211–2218.

Nationmaster.com. (2009). Mortality statistics>Osteoporosis with pathological fracture (per capita) (most recent) by country. Retrieved December 9, 2009 from 
http://www.nationmaster.com/graph/mor_ost_wit_pat_fra_percap-
osteoporosis-pathological-fracture-per-capita.

Paterson, C. R. (1978). Calcium requirements in man: a critical review. Postgrad Medical Journal, 54, 244–248.

Recker, R. R., & Heaney, R. P. (1985). The effect of milk supplements on calcium metabolism, bone metabolism and calcium balance. American Journal of Clinical Nutrition, 41, 254–263.

Small, R. E. (2005). Uses and limitations of bone mineral density measurements in the management of osteoporosis. Medscape General Medicine, 7.

Vegetarians in Paradise. (2009). Calcium basics. Retrieved November 22, 2009 from http://www.vegparadise.com/calcium.html

World Health Organization. (2003). Diet, nutrition and the prevention of chronic diseases. Geneva, SW.

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