“UNDERSTANDING CLAYS: THEIR ORIGIN, FORMATION & LOCATION”
Improved Milbond-TX® (IMTX) is one of several inert clay-based mycotoxin binders sold commercially. Since the introduction of IMTX to the world-wide animal and feed industries in 1992, tens of thousands of tons have been successfully used as a dietary additive to prevent losses in animal performance commonly associated with aflatoxin B1 (AFB1). The question is often asked, “Why is IMTX such an effective binder of AFB1?” It would be so easy to simply respond by saying, “The ability of IMTX to bind AFB1 so effectively is due to the properties associated with a specific Family of clays called “Smectite” to which IMTX belongs.” However, nothing would be learned by this simple answer. So, in this issue of Milwhite’s Journal and in the next issue clays are discussed in a manner that promotes understanding and learning. This approach should provide enough background information about clays so that it will be easier to understand and appreciate the exact mechanisms involved when IMTX sequesters AFB1 in an animal’s digestive tract. The mechanisms involved in sequestering AFB1 will be the topic of discussion in the next issue of Milwhite’s Journal.
All clays consist of elements (atoms) combined with other elements to form compounds known as “minerals”. Rocks are made of minerals and clays are formed when rocks are weathered. Simply speaking, the rocks that are eroded to form clays are combinations of different elements and there are 92 different elements associated with the earth’s crust. Minerals have known compositions and unique crystalline structures. Because there are so many possible combinations of elements when they bind together geologists have discovered and classified over 4,000 minerals each with a different name, chemical composition and atomic structure. The same is true for clays, in that, as rocks erode into their basic mineral elements different clays form as these elements recombine or the parent mineral is dramatically altered. Therefore, the elements which comprise the mineral makeup of a clay and directly responsible for a clay’s crystalline structure are a reflection of the elements in the parent mineral of a particular rock. Unless someone is a geologist by training, understanding the nomenclature and the elemental makeup of all the different minerals is very confusing and overwhelming to say the least.
Of the 92 elements in the earth’s crust only 8 are found in large quantities and make up 98% of the crust. These elements are, in order of abundance, oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium. Oxygen, silicon and aluminum are the most abundant and these three alone make up approximately 85% of the earth’s crust. The reason oxygen is so abundant is because as other elements combine with oxygen they form oxides. For example, aluminum bound to oxygen is known as alumina (Al2O3) and silicon bound to oxygen is known as silica (SiO2) which is better known as “quartz”. Crystals of SiO2 can range in size from very large to very small as in “sand”. It is unbelievable, but the largest quartz crystal ever to be discovered was approximately 20 feet long and weighed more than 48 tons. In nature, minerals are found in various degrees of purity. If one or more minerals are associated with a crystal of SiO2 a completely different mineral is formed that has a different name with a different crystalline structure and different physical properties. Minerals containing silica are known as “silicates” and are the largest group of minerals. When minerals containing alumina and silica combine they are referred to as “aluminosilicates”. In nature, the crystalline structure of aluminosilicate ores is usually associated with water. When this occurs the clays are referred to as “hydrated aluminosilicates” with a general formula of Al2O3SiO2H2O. When other elements such as sodium and calcium are involved with such a clay they are referred to as a hydrated sodium calcium aluminosilicate or better known simply as “HSCAS”. It is because of the properties of HSCAS that they possess a high capacity to bind with AFB1. Also, HSCAS clays ordinarily contain other minerals in small amounts. IMTX is classified as HSCAS clay.
Geologically speaking, clays are formed over millions of years in the earth’s outer layer (i.e., crust) from the erosion of rocks, as previously mentioned. The eroded material (clay) can be found located in two places in reference to its parent rock. The clay deposit that required millions of years to form can be found very close to its parent rock or varying distances from its parent rock. The location of clay, in reference to its parent rock, gives rise to the name of the two main types of clay. Residual or “primary” clays, as they are sometimes called, are those clays that remain at or near their site of formation. Sedimentary or “secondary” clays are carried by wind, water or glaciers varying distances from where they are formed.
In fact, shale is the most abundant type of clay-rich sedimentary rock on earth and is found world-wide in sedimentary basins where it was deposited millions of years ago. Some of these basins are very large and give rise to many of the world’s richest shale oil and natural gas deposits. These deposits were formed as a result of sedimentary clay material traveling over and covering lake beds and sea bottoms that were rich in algae. Then, after millions of years, as the algae and other organic material decomposed, formed the natural gas and shale oil deposits that are so valuable today.
As stated previously, IMTX is an inert clay-based material and there are indeed essential characteristics associated with certain clays, especially those belonging to the Smectite Family, which make them efficient mycotoxin binders. The Smectite Family consists of many different types of clay which are sometimes referred to as “clay species” within this Family. Smectite clays are known to possess two main properties that are responsible for them being efficient binders of AFB1. These properties are a high cation exchange capacity and large surface area. In fact, some clays in the Smectite family have been shown to have as much as 8 times more of these two properties than other types of clays. Two examples of Smectite clays are Bentonite and Montmorillonite which are very similar in their chemical and physical properties. In fact, they are so similar with regard to their properties that they are often considered to be the same clay. Thus, their names are often used interchangeably and synonymously. In some instances authors have promoted confusion in their articles written about the ability of different clays to bind AFB1 because they used Smectite, Montmorillonite and Bentonite synonymously. All that needs to be remembered is when either of these names is used the authors are referring to a clay having similar properties which result in their ability to bind AFB1.
A major characteristic of clays in the Smectite Family that contributes to their ability to bind AFB1 is that Smectites are considered phyllosilicate clays because their structure is associated with defined layers often resembling plates, flakes or leaves stacked on top of one another. In fact, the term “phyllo” is Greek in origin, means “leaf”, and is still used today to define a middle-eastern pastry consisting of tissue-thin layers of dough that becomes flaky when baked. Once stacked, spaces exist between the crystalline layers. If the clay’s layers are wide enough apart molecules of different sizes and possessing an ideal conformation may easily enter the spaces. In the next issue of Milwhite’s Journal the mechanisms of AFB1 binding will be discussed along with other interesting information about clays.
Note: The information in this issue of Milwhite’s Journal was compiled by Dr. Orlando Osuna, Director of Health Science at Milwhite, Inc. and Dr. Richard Miles, Professor Emeritus, University of Florida, Gainesville, FL, USA.