Oxidation of PUFAs, as well as sugars, produces various aldehydes which are known to initiate or intensify several diseases, such as cancer, asthma, type 2 diabetes, atherosclerosis and endothelial dysfunction [20].
Micronutrients
Vitamins and minerals are nutrients that are found in small amounts in most foods and are essential, in minute amounts, for normal metabolic function.
Vitamins are a group of organic compounds that cannot be synthesised by humans and should be provided by the diet; otherwise their deficiency could cause adverse health conditions. While vitamins have few chemical similarities, their metabolic functions have been defined in 1 of 4 general groups: (i) membrane stabilisers, (ii) hydrogen and electron donors and acceptors, (iii) hormones, and (iv) coenzymes [8]. They also have important roles in gene expression in humans. Vitamins are classified into 2 groups based on their solubility: fat-soluble and water-soluble. The main functions and dietary sources of vitamins are presented in Table 2; with more details provided in Chapter 6. The fat-soluble vitamins are absorbed passively by intestinal mucosae in the presence of fat. This group of vitamins is mainly found in the lipid portions of the cells such as membranes and lipid droplets. Fat-soluble vitamins are excreted with faeces via the enterohepatic circulation [8]. The water-soluble vitamins are also mainly absorbed by passive diffusion, except for vitamin B1 (thiamine) which is absorbed by a sodium-dependent transport mechanism and vitamin C which is absorbed by both passive diffusion and sodium-dependent active transport. Vitamin B12, a collective term for a group of cobalt-containing compounds known as corrinoids, is absorbed by active transport in the terminal ileum after binding to salivary haptocorrin and “intrinsic factor” (a protein cofactor secreted by the parietal cells of the stomach). The water-soluble vitamins are not stored in significant amounts in the body and are excreted in the urine [8].
In nutrition, minerals are a group of inorganic elements that cannot be made by the body and are necessary for a variety of functions, including: the formation of bones and teeth, as essential constituents of body fluids and tissues, as components of enzyme systems and for normal nerve function. Based on the quantity needed by the body, minerals have been categorised into 2 major groups: macrominerals with a requirement of =100 mg/day and microminerals (trace elements) with a requirement of <15 mg/day, which include ultra-trace elements that are necessary at a level of µg/day, although specific requirements have not been established for some of them (Table 3) [8]. Minerals take up 4–5% of the body weight of an average adult. Although macrominerals occur mainly in the ionic state in the food and the body, some minerals also exist as components of organic compounds such as phospholipids and haemoglobin. They are usually absorbed in the ionic state, with heme iron being exceptional, by an active transport mechanism. The unabsorbed minerals are excreted in the faeces [8]. For more detail, the reader is referred to Chapters 3, 4 and 5.
Table 2. Vitamins – key information
Diet, Nutrition and Oral Health
Oral and systemic well-being is fundamentally linked with diet and nutrition. In this context, diet denotes the local actions of foods on oral tissues and includes the composition of food, its consistency, and the pattern and frequency of eating. In contrast, nutrition describes the systemic effects of nutrients on the development, regeneration and repair of tissues [21].
There is a synergistic multidirectional relationship between oral health and nutrition and diet.
Oral infectious diseases, as well as acute, chronic, and terminal systemic diseases with oral manifestations, influence the ability to eat and consequently to achieve an adequate diet and attain nutrient balance. Equally, nutrition and diet can impact the development and status of the oral cavity and the progression of oral diseases. The impact of diet and nutrition on oral health is discussed in Chapters 7–13, and the impact of oral health on diet and nutrition in Chapter 14.
Nutrition influences the teeth primarily during their formation; whereas bone and the soft tissues of the mouth respond promptly to nutritional imbalance, as they are continuously being renewed [21]. At the pre-eruptive stage, deficiencies of energy, protein, calcium, phosphorus, iodine, iron and vitamins A, C, and D can affect tooth development. Diet and intake of nutrients continue to influence tooth development and mineralisation after tooth eruption. In addition, due to the rapid rate of tissue turnover of the oral mucosa, deficiencies of some nutrients such as vitamins B2, B12, C, and folate as well as iron and zinc may initially be reflected in the mouth.
Primary dietary factors and eating patterns associated with dental caries risk include the form of the food (e.g., solid, liquid), the frequency of consumption of fermentable foods such as sugars/starch-based diets and the duration of exposure of the teeth to these fermentable products. On the other hand, dental caries, tooth loss (edentulism) and removable prostheses (dentures) can have a major impact on dietary habits and diet composition, thereby impacting the general health and quality of life of the affected individuals. An inability to chew certain foods, such as steak, whole grains, fruit and vegetables, due to untreated painful dental caries and tooth loss, may lead to inadequate intake of protein, dietary fibre, vitamins and minerals [22].
Dental erosion is associated with acids of intrinsic (gastrointestinal) and extrinsic (dietary and environmental) origin. Acidic foods may contain one or more of: acetic, ascorbic, carbonic, citric, malic, oxalic, phosphoric and tartaric acids. An important factor influencing the erosive potential of acidic foods and drinks is eating habits, such as the length of time that an acidic drink remains in the mouth (e.g., swishing the drink around the mouth, night-time bottle feeding). Individuals with a healthier lifestyle that includes diets high in acidic fruits and vegetables may have higher incidences of dental erosion [23]. Consumption of soft drinks and chewing vitamin C tablets have been reported to be significantly associated with the development of dental erosion, with approximately 2.4- and 1.2-fold increased risk, respectively [24]. On the other hand, milk and yogurt provide important sources of dietary calcium, phosphate and casein, which are known to protect enamel [24]. The relationship between diet and dental erosion is discussed in Chapter 9.
Table 3. Daily requirements of specific elements
