Summer 2001 Issue — Building and maintaining strong bones:
A case for balance in dietary mineral consumption

Eric Bastian Ph. D.

Director Research and Development, Glamia Foods Inc.

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Recently the importance of dietary calcium has increased because research has established that calcium is not only essential for bone growth and development, it is important for regulation of cell function, nerve conduction, muscle contraction, and blood coagulation (Food and Nutrition Board, 1989). In addition, calcium provides a protective role against osteoporosis, essential hypertension, gestational hypertension, hypercholesterolemia, certain cancers (colon and mammary) and possibly gallstones (Miller et al., 1994; Barger-Lux and Heaney, 1994; Moerman et al., 1994). The RDAs for calcium are shown below:

Several of the population segments mentioned above have low intake. These groups have been targeted for education and now have an increased awareness that calcium is critical, particularly in prevention of osteoporosis. Thus, calcium supplementation and fortification has become increasingly important and calcium is being incorporated into many food products around the world. Calcium supplements/fortificants are usually calcium salts such as calcium citrate, calcium lactate, calcium carbonate and calcium phosphate. In spite of the increased awareness of calcium, the dietary intake levels of calcium are still low for some segments of the US population (Hallfrisch and Muller, 1993; Morgan et al., 1985) and for many groups of people throughout the world (Hendrix et al., 1995); (Tranquilli et al., 1994).

In the hype that has surrounded calcium supplementation and fortification, one of the basic principles of nutrition balance has been neglected and overlooked. If one examines the composition of bone, one finds that bone is comprised of living cells that are embedded in a specialized mineral matrix, the mineral composition of bone is well understood and is shown below:

Obviously, to maintain proper composition of mineral in the bone, there must be adequate absorption and delivery of all bone minerals to bone sites in the human body. The scientific literature lacks substantial information concerning maintenance of appropriate dietary mineral balances, particularly in relation to bone health.

Phosphorus is required for bone growth and maintenance, but in the US, phosphorus is not an element that is lacking in the diet, in fact, when it occurs in the form of ortho and polyphosphates, it can actually impede the absorption of calcium. Thus most recommendations for phosphorus are to maintain dietary calcium: phosphorus ratio of 2:1 (even though the RDIs for calcium and phosphorus are equivalent at 1000mg/day). There are numerous studies on calcium and bone health, but few concerning the other minerals. The most disconcerting item concerning the dietary ratio of calcium to magnesium was discussed by Seelig (1993). She points out that to compensate for loss of Ca from osteoporotic bones, oral treatment with Ca is common. Because most of the calcium supplements deliver only calcium and none of the other bone building minerals such as magnesium, the effect of high Ca intakes on Mg requirements or on the importance of Mg in maintaining normal bone matrix is not considered. High dietary Ca/Mg ratios interfere with Mg absorption, because Ca and Mg share common intestinal absorption pathways (Alcock and MacIntyre, 1962; Heaton and Fourman, 1965). When Ca is elevated with respect to mg, ca competes with mg for the absorption pathways and hypomagnesaemia (low magnesium in the blood) results. Some early experimental studies (Cunningham, 1933; Orent et al. 1934, and Watchorn and McCane, 1937) were based on feeding rats diets with high Ca/Mg ratios. Even though vitamin D also was high in these diets, the rat bones became hyper mineralised (high calcium in the bone) and the bones became brittle. It is disturbing to note that follow up experiments in humans have not been done, especially given the tendenancy for segments of the US population, that consumed low Ca and are adjusting with Ca supplementation, also are consuming Mg well below recommended levels (USDA, 1980; Morgan et al., 1985; Abdulla et al., 1989). I again point out that the calcium supplements being consumed are in the form of calcium carbonate, calcium citrate, calcium lactate, and calcium phosphate, none of which contain any magnesium, potassium, zinc and other minerals required for good bone health. In considering the potential for high dietary Ca 9after supplementation with calcium salts) and low dietary mg in some segments of our population, Seelig (1993) says that, "This may be pertinent to the current encouragement of women to consume substantial amounts of Ca; regard is not given to probable low dietary Mg, as indicated by dietary surveys and the inadequate current RDA for Mg".

Hypomagnesmia exhibits other interesting phenomena, that of reducing the absorption of Ca, causing vitamin D to form hormonally inactive metabolites, and impairing the release of parathyroid hormone. (Heaton et al., 1964) both of which are involved in bone mineralization processes. Additionally, there is an increased need for magnesium when calcium and estrogen are used to treat osteoporosis (Seelig, 1990). Based on the available data, Celotti and Bignamini (1999) concluded that highly daily doses of calcium may be unsafe because of, "an imbalance in the ratio of calcium to magnesium" and they recommended that magnesium be supplemented along with calcium.

Along with recommending higher levels of Ca in the diet, nutrition researchers also are promoting increased levels of vitamin D, magnesium and potassium bicarbonate has been shown to reduce hypertension, prevent formation of kidney stones by suppressing excretion of calcium, and protect against osteoporosis by increasing renal retention of calcium and phosphorus (Morris et al., 1999). Again, the appropriate ratios of minerals for optimal bone health aren't readily apparent and, even though research is available showing the important of these minerals, the information seems to be swallowed up in the wave of calcium research and education. Just as Ca/Mg/K ratios have received little attention among researchers in the osteoporosis area, ratios of the required micronutrients also have received little attention. The effects of calcium supplementation with and without zinc, copper and manganese showed that bone less in postmenopausal women could be only partly arrested by Ca supplementation, but to fully maintain bone mass, trace minerals were required (Strause et al., 1994). Further evidence for the importance of trace minerals (Zn and Cu) has been given by Saltman and Strause (1993). One of the markers of osteoporosis is a loss of Zn from bone followed by excretion through the urine (Szathmari et al. 1993). Nonosteoporotic women showed substantially lower excretion levels of Zn. From the above discussion, I concluded that many minerals are required for optimal bone growth and health, but that the extreme focus on only calcium has, in a sense, inhibited the promotion of a balanced approach for mineral supplementation, particularly for segments of the population that are at risk for osteoporosis.

One mineral supplement that has been widely accepted in Asia and is recognized there as the "premier" bone building supplement is "milk calcium" (more accurately milk mineral). It has been recently shown by several studies that milk mineral contains, at least as far as we have information, the appropriate balance of minerals for optimal bone health. Milk has long been recognised as providing a great mineral balance for optimal bone health. However, as milk consumption has declined over the last two decades, many people are not getting the "balanced" dietary minerals that milk provides. Milk mineral is an ingredient that retains the mineral balance of milk while allowing for mineral supplementation into products that traditionally do not contain good rations of bone building minerals. TruCal is the first such product to be manufactured in the US. The composition of TruCal follows:

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