Читать книгу The Impact of Nutrition and Diet on Oral Health - Группа авторов - Страница 28

As the terms “minerals” and “elements” are often used interchangeably, a few clarifying definitions will be presented first: Minerals are naturally occurring, solid, inorganic, crystalline substances which can contain a wide range of elements, although some minerals contain only one element (e.g., gold, diamond [carbon]). Elements, on the other hand, are substances that cannot be chemically interconverted or broken down into simpler substances, with each element being distinguished by its atomic number (i.e., the number of protons in the nuclei of its atoms). In biological tissues or foods, minerals are defined as the inorganic residue after ashing, a process by which water and organic matter are removed through prolonged, extensive heating in the presence of oxidizing agents, such as oxygen. Depending on the abundance of individual elements within the ash, elements can be divided into macro-, micro- or (ultra-) trace elements. Depending on their physiological importance, these elements can be also, or further, divided into essential, non-essential and toxic elements, although Paracelsus’ pearl (gemstone, not a mineral) of wisdom – “All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing poison.” – must be borne in mind. These classifications are arguably somewhat arbitrary and perhaps highlight that our knowledge of the physiological importance of all naturally occurring elements is still evolving.

All macroelements (Ca, K, Na, P, Cl), the topic of this chapter, are essential as they fulfil a variety of biological functions. However, these elements have physiological importance only in their ionic state and are consumed primarily in the form of salts. Virtually all potassium and sodium salts are soluble, whereas most physiologically relevant calcium salts are sparingly, poorly soluble or insoluble. Although the solubility of salts is determined by the anion(s), of physiological importance are primarily cations. Table 1 summarizes the most common sources of macroelements in the diet.

In addition to macro- and other elements supplied to the oral cavity through topical application of oral care products [1], with calcium, fluoride and some inherently antimicrobial trace elements (see Chapter 4) being the most important in the present context, foods containing macroelements pass through the oral cavity on their way to the stomach. During mastication with simultaneous lubrication, solubilization, and enzymatic digestion by saliva [2], macroelements can be released to come into contact with the oral soft and hard tissues and intra-oral biofilms. Ingested macroelements pass through the stomach into the intestine where they can be absorbed and transported to other parts of the human body in serum. Some elements/substances also require the co-presence of other compounds to be absorbed, with the most important being calcium requiring vitamin D (see Chapter 6) [3]. As elements can interact with the oral cavity in several ways, a distinction can be made between their topical and systemic effects. Both depend on the element’s or compound’s bioavailability; that is, the proportion of a substance that has an active effect, which for topical effects is directly related to its solubility.

Despite the macroelements being present in a wide range of foods and in sufficient amounts, the consumption of (arguably questionable) dietary supplements to boost the nutritional value of one’s diet has become increasingly popular. From a nutritional perspective, dietary supplements can be differentiated from foods, although they are considered a category of food. These supplements often contain high doses of individual (macro-) elements as a bioavailable salt in tablet form, although concentrated solutions have also become commercially available recently. Matrix effects or potential incompatibilities with other ions or compounds (e.g., oxalate contained in rhubarb or other plant leaves reduces the bioavailability of calcium) have been mitigated. It goes without saying that tablets have exclusively systemic effects, whereas solutions have topical as well as systemic effects. While the diet itself has been implicated as a risk factor for a range of diseases and conditions (e.g. see Chapter 7 for sugar and dental caries and Chapter 9 for fruit juices/acidic drinks and dental erosion), the effect of dietary supplements, although somewhat unintentionally and indirectly related to their nutritional benefits (e.g., effects of calcium supplementation on tooth loss and periodontal disease – see below), has also been the subject of oral health research.