giovedì 7 giugno 2012

Debunking the calcium myth

7/06/2012 - Lorenzo Acerra

After promising better bone health by bringing calcium intake estimates to three times the levels they used to be, the dairy industry's indisputed claims are now on the verge of disintegration. The dairy industry's forte totters! Bischoff-Ferrari (2010) and Warensjo (2010) recently confirmed preliminary results obtained by Cummings (1997), which showed that the risk of hip fracture doubled as people began to use calcium supplements.

It is the bones protein matrix, which is called collagen, that accounts for flexibility and prevention of fractures. Increasing the calcium ratio does nothing to increase bone's health or balance. On the contrary, a level of calcium higher then 800 mg / day will worsen the collagen index and therefore contribute to bone fractures.

UK health authorities have already taken the decision to leave the wagon of the "calcium paradigm". They lowered the estimate of calcium daily need to 700 mg (Institute of Health, 2011). In 1995 UK scientists from the Cambridge University experimented with increasing daily calcium intakes in lactating Gambian mothers, whose standard base vegan diet was giving them 285 mg of calcium a day. Interestingly, it was observed that the supplementation did not made the calcium levels of the mother's milk increase, nor the bone mineralization improve. They interpreted this as an indication that 285 milligrams was exactly what nature asked for to maintain their bone health. The authors of this study had to acknowledge that the daily calcium requirements seemed to be very low, at a level of about 300 mg a day, above which more calcium intake does not bring benefits.

In 1998 Finch proposed that modern methods for calculating the daily calcium needs are flawed because what happens at higher intakes is "passive absorption", which doesn't seem to lead to higher calcium intake in the bones. For this same reason the official estimates of the daily intake of calcium had been set in 1948 to a level of 300 mg (Food and Nutrition Board, US, 1948).

In 1951 Hegsted observed that calcium requirements appeared to be so low that it was not possible to find groups of people or individuals who did not satisfy it through merely drinking of water or consumption of vegetables and grains. There is a very efficient system in the body which helps us to retain and recycle the calcium even at very low levels of intake (Nicolls 1939, Ellis 1933, Basu 1939, Potgieter 1940). As our intake of calcium increases, the body simply treats it as a waste product (Leitch 1937, Owen 1940, Sherman 1920 e 1947). The action of our gastrointestinal hormones is such that it generally prevents that the circulating calcium levels increase too much. Regulating mechanisms are important because they prevent a build up of calcium in the blood such that would cause deposition of calcium in organs, muscles, joints and vascular tissues. And when this happens, an healthy thyroid gland makes a further effort to down-regulate the levels of the circulating calcium by increasing the elimination through the kidney tubules.

So, the "calcium paradigma" has failed. Well, let's see if those who are still on that wagon can explain the following SIX PARADOXES. The first one: Fontana (2005) demonstrated that caucasian raw vegans had a better bone health and lower bone fracture risk compared with the general population, even though they had quite a low calcium income. Couldn't this be due to the higher vitamin C income these people got from raw foods? Vitamin C is known to support several types of enzimatic activities that are useful to the bone collagen. The collagen is what remains of a naked bone which ahs been put in an acid bath. We now know that it is the flexible matrix of the collagen that prevents fractures.

THE SECOND PARADOX - As the consumption of dairy products has doubled and even tripled in recent times in Western countries, the incidence of bone fractures has increased proportionally (Van Hemert 1990, Nydegger 1991, Fujita 1992, Lau 1993a, Parkkari 1996, Lippuner 1997, Lips 1997, Versluis 1999).

THE THIRD PARADOX - Initially it was tought that the association between higher bone fractures and increased dairy consumption was just an insignificant coincidence, and that the Western epidemics of bone fractures could be simply explained in terms of genetic susceptibility of some populations. However, it was later ascertained that the incidence of bone fractures would increase also in those African, Chinese or Indian groups who would suddenly increase their dairy consumption (Smith 1966, Barss 1985, Abelow 1992, Ju 1993, Kin 1993, Russell-Aulet 1993, Lau 1993b, Rowe 1993, Feskanich 1997, Memon 1998, Ho 1999, Schwartz 1999).

THE FOURTH PARADOX - The Harvard Nurses' Health Study followed >75,000 women for 12 y, and a second prospective study in Sweden followed 60,689 women for 11 y. Both studies not only demonstrated that dairy consumption does not contribute to bone health, but actually that it increased the risk of bone fractures! (Feskanich 1997, Michaëlsson 2003). Further, 2 meta-analyses of studies of milk or dairy consumption and fracture risk have shown no reduction in risk with higher intakes of milk, dairy, or total dietary calcium (Bischoff-Ferrari 2007, Kanis 2005).

Here is what prof. Lanou (University of North Carolina) has to say about it: "Although cow milk has been widely recommended in Western countries as necessary for growth and bone health, evidence collected during the past 20 years shows the need to rethink strategies for building and maintaining strong bones. Osteoporotic bone fracture rates are highest in countries that consume the most dairy, calcium, and animal protein. Most studies of fracture risk provide little or no evidence that milk or other dairy products benefit bone. Bones are better served by attending to calcium balance and focusing efforts on increasing fruit and vegetable intakes, limiting animal protein, exercising regularly, getting adequate sunshine or supplemental vitamin D, and getting approximately 500 mg Ca/d from plant sources." Kanis (2005) also concluded from his observations that a low intake of milk is not associated with any marked increase in fracture risk and that the use of this risk indicator is of little or no value in case-finding strategies.

THE FIFTH PARADOX - A typical clinical case with kidneys stones has been presented by Annemarie Colbin, PhD: "For years a young woman had to go to the hospital to have calcium deposits reamed out of her ureter (the tube that brings urine from the kidnes to the bladder), as they kept forming regularly. Once they put a tube from her kidneys to her bladder to allow the urine to flow while her ureter healed; within a day or two there were calcium deposits in the tube. The doctors at the hospital were stumped. I asked her, "How much milk do you drink?" "Oh," she replied, "about a quart a day." "Even in the hospital?" "Yes." "Did anyone inquire about this?" "No." I suggested that she totally stop consuming milk. When I saw her a few years later, she'd had no recurrences of the problem, had a new baby, and was in fine health.

THE SIXTH PARADOX - Inadequate mineralization of the bone did not respond to increasing the calcium intake according to observations by Hannon (1934), Liu (1935), Maxwell (1935), Steggerda (1946), Snapper (1950) and Hegsted (1951), Stearns (1951).





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