Calcium and Osteoporosis

The multibillion dollar dairy industry has been greatly involved in nutritional education in the USA.  Unfortunately they are not unbiased.  They promoted for years the 4 basic food groups, with one being a dairy group.  We will look at the facts, please try to look objectively.  It is hard when we grow up believing "every body needs milk".

The intestines regulate how much calcium is absorbed.  This is to prevent too much calcium from being absorbed.  People with a parathyroid hormone imbalance or bone cancer have developed too much calcium in the blood and died.  Normally  20-30 percent of the calcium ingested in food is usually absorbed. If one is on a low calcium diet then up to 40 or 50% may be absorbed.    Persons who take in less calcium also tend to excrete less calcium in the urine.  

A  diet, as recommended in some "diet books", of high protein, and low carbohydrates will cause a total body calcium loss that will cause osteoporosis (decreased bone mass and calcium poor bones).  If one is on a high protein diet there is a greater excretion of calcium in the urine.

Although there is evidence to believe that adding calcium and Vit. D to the western diet is helpful in preventing some osteoporosis ( and this should be done in those at risk) this is not the solution as the calcium pill sellers and the dairy industry would have us believe. 

The intuits consume 2500mg (600 to 1200mg is average in USA) of calcium daily and have one of the highest rate of osteoporosis in the world.  Their protein intake is 3 to 5 time the average American at 250 to 400mg per day.

From the Department of Nutrition, Harvard School of Public Health we quote;

"Dietary protein increases urinary calcium losses and has been associated with higher rates of hip fracture in cross-cultural studies. ... In this prospective study, usual dietary intake was measured in 1980 in a cohort of 85,900 women, aged 35-59 years, who were participants in the Nurses' Health Study. A mailed food frequency questionnaire was used and incident hip (n = 234) and distal forearm (n = 1,628) fractures were identified by self-report during the following 12 years. Information on other factors related to osteoporosis, including obesity, use of postmenopausal estrogen, smoking, and physical activity, was collected on biennial questionnaires. Dietary measures were updated in 1984 and 1986. Protein was associated with an increased risk of forearm fracture (relative risk (RR) = 1.22, 95% confidence interval (Cl) 1.04-1.43, p for trend = 0.01) for women who consumed more than 95 g per day compared with those who consumed less than 68 g per day. A similar increase in risk was observed for animal protein, but no association was found for consumption of vegetable protein. Women who consumed five or more servings of red meat per week also had a significantly increased risk of forearm fracture (RR = 1.23, 95% Cl 1.01-1.50) compared with women who ate red meat less than once per week.  " (1)

As research paper from the School of Pharmacy and Biomedical Sciences, University of Portsmouth, England reports;

"Osteoporosis-related bone fractures are a significant cause of mortality and morbidity, with women being particularly affected. ... An adequate supply of calcium is essential to attain maximum bone mass, and adult intakes below about 500 mg/day may predispose to low bone mass. Supplementation with calcium may conserve bone at some skeletal sites, but whether this translates into reduced fracture rates is not clear. Chronically low intakes of vitamin D--and possibly magnesium, boron, fluoride and vitamins K, B12, B6 and folic acid (particularly if co-existing)--may pre-dispose to osteoporosis. Similarly, chronically high intakes of protein, sodium chloride, alcohol and caffeine may also adversely affect bone health. The typical Western diet (high in protein, salt and refined, processed foods) combined with an increasing sedentary lifestyle may contribute to the increasing incidence of osteoporosis in the elderly." (2)

90% of the calcium in the body is stored in in the bones and there is a balance between the blood calcium and the bone calcium.  It is a dynamic relationship.  Calcium and phosphorus are regulated by the parathyroid hormone and are in balance normal, however if one high, the other is low. Therefore, overeating of calcium can cause the essential mineral phosphorus to be seriously depressed. Conversely, drinking sodas with a  high phosphorus content can upset the balance of calcium in the body.

Researcher at the University of Wisconsin preformed the following study:  A study group of healthy young adult males were given a controlled diet of 1400 mg of calcium per day.  The amount of protein varied in their diets from 48 grams to 141 grams.  The results in brief; the 48 gram group gained 10mg of calcium per day,  the high protein group (141 grams) lost 84 mg of calcium per day.  (Just as we would predicate). (3)

Many green vegetable are excellent sources of calcium included are Collards, Kale, Mustard green and broccoli.  Beans, figs, and tofu are also good sources.

In Summary we can conclude;
The amount of calcium needed to maintain strong bone is dependent on the amount of protein in our diet.  The higher the protein (especial animal protein) the more calcium we require.  This is because a high protein diet cause a urine loss of calcium.   There is a point where no amount of ingested calcium will compensated for urine loss caused by a high protein diet (your intestines can only absorb a finite amount).

Every body does not need the high protein, high phosphate, and high salt drink called milk.  Save it for baby cows.

Other factors in osteoporosis are high intakes of salt, alcohol, tobacco, caffeine and a sedentary lifestyle

1. Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA.  Am J Epidemiol 1996 Mar 1;143(5):472-9

2. School of Pharmacy and Biomedical Sciences, University of Portsmouth, England, UK.   Br J Biomed Sci 1994 Sep;51(3):228-40

3. Weimar Institute, Tidings, Summer 1999