The World Health Organisation has defined osteoporosis as the second-leading health care problem after cardiovascular disease, affecting more than 200 million women worldwide. Calcium plays a key role in prevention. Judy Davis looks at new patents for this mineral.
The poor solubility of many calcium compounds, particularly the more economical ones, leads to low absorption into the bloodstream as well as problems with incorporation into foods. Calcium compounds often impart a chalky, gritty mouth feel, off-flavours, and undesirable colouration. Researchers at General Mills are using encapsulation technology to overcome these problems.
According to its patent, the mineral is encapsulated in an edible oil that is contained within a glassy oligosaccharide matrix. The oil prevents adverse interaction between the mineral and the glass-forming oligosaccharide matrix as well as providing controlled time release. The oil and glassy matrix material provides a smooth mouth feel and eliminates the rough, gritty mouth feel associated with particulate or crystalline minerals such as calcium. Use of an oil, rich in medium-chain triglycerides, may enhance intestinal absorption of calcium, whilst inclusion of fructooligosaccharides or inulin in the oligosaccharide matrix not only increases the fibre content of the fortified food, but also promotes calcium absorption from the colon. Other vitamins and minerals also can be included in this encapsulation system. (PCT Patent Application WO 02/05667)
One of the more efficient ways of delivering calcium from supplements into the blood is through the formation of amino acid-calcium chelates. These complexes are soluble at and above pH levels of 7, such as are found in intestinal environments. They are absorbed through an active transport mechanism in which the amino acids serve as carriers. Once in the blood, the chelates form a mobile calcium pool capable of releasing calcium to meet metabolic demands.
The Tianjin, China-based Tianshi Group has developed a method for producing natural calcium supplements containing a high level of amino acid-calcium chelates and peptide-calcium chelates.
According to the patent, an acidic activation step is used to release free calcium ions from calcium hydrogen phosphate contained in the bone matrix. The released calcium chelates with amino acids and peptides to form the 'bio-organic' calcium product. Beta-cyclodextrin is used to eliminate any unwanted odour. (US Patent 6,342,252)
Soluble calcium salts are sometimes used to overcome grittiness problems typically associated with calcium fortification. When used for dairy products, however, soluble calcium salts interact with milk proteins, causing unwanted coagulation and sedimentation. In this case, carrageenans, pectins or other gums can be added to improve stability or reduce sedimentation, but these can cause viscosity problems.
Researchers at Nestlé have developed a calcium fortification system composed of a calcium salt with a hydrolysed polysaccharide derived from any negatively charged polysaccharide. The degree of polymerisation (DP) of the polysaccharide appears to be key in this invention, as it is chosen to enable complexation with calcium but prevent gelation and subsequent sedimentation of the complex during product storage. With pectin, for example, a lower DP reduces sedimentation and allows the addition of greater amounts of calcium. A DP of 1 to 10 seems preferable. The complexes are particularly suitable for making calcium-fortified milk, and their high stability enables them to be used in frozen, chilled or shelf-stable products. (US Patent 6,342,257)
Australia-based Anadis Ltd. has patented a composition aimed at treating metabolic bone disorders, including osteoporosis. The major actives are milk-derived casein calcium phosphopeptide and soy, or red clover-derived phytoestrogens. Casein phosphopeptides have been shown to increase calcium absorption—possibly by binding calcium and maintaining it in solution at neutral and alkaline pH<1/M>whilst phytoestrogens, such as diadzein or genistein, are thought to improve calcium retention in bone. The phosphopeptides and phyto-estrogens work in synergy to increase bone mass and reverse the effects of metabolic bone disease.
The product can be marketed as a nutraceutical supplement or formulated for individually packaged, daily drinkable 'shots.' (PCT Patent Application WO 01/87315)