# Functional Yogurt: Types and Health Benefits
## 1 Introduction  
With increasing interest and concern regarding healthy nutrition, a more conscious consumer profile is emerging [1, 2]. This awareness among consumers is driving the development of the nutritional and functional properties of products in the food sector and fostering the creation of diverse new products [3]. Functional foods are defined as those that provide health benefits beyond basic nutritional values [4, 5]. These foods are recognized for their potential to offer different health benefits, including antioxidant properties, anti-inflammatory effects, digestive system support, immune system enhancement, heart health improvement, or the prevention of cardiovascular and chronic diseases [6, 7].  
Milk and dairy products are prominent in the functional food sector because of their contents of fats, proteins, carbohydrates, minerals, and vitamins [8, 9]. Milk contains both micronutrients and macronutrients, including various bioactive compounds, especially lactoferrin, immunoglobulin, lactoperoxidase, and oligosaccharides [10, 11, 12, 13]. The health benefits associated with enhancing the characteristics of these components have been investigated in numerous studies [14, 15]. In particular, glycoproteins play significant roles, such as modulating immune responses by demonstrating antibacterial and antiviral capacities and exerting neuroprotective effects against neurological diseases [16, 17, 18, 19]. In terms of these functions, the importance of consuming milk and dairy products is highlighted.  
At this point, yogurt can be considered one of the most essential dairy products because of its rich bioactive content [20, 21]. This food is obtained by enhancing the functional andnutritional properties of milk through fermentation [22; 23; 24]. Owing to fermentation, the content and nutritional properties of milk, along with its sensory properties, primarily its texture, are modulated [25]. In addition to the benefits provided by milk, yogurt has additional characteristics [26; 27].  
Over the past decade, the production of different types of yogurts has increased. Probiotic, prebiotic, and symbiotic yogurts are widely produced and consumed, notably to support gut health and the digestive system [28; 29; 30; 31]. In addition, yogurt is produced from different materials to support various functions [32; 33; 34]. For example, plant-based materials, including fruits, vegetables, leaves, grains, seeds, or various food additives, are used to produce different kinds of yogurt [35; 36]. Additionally, for consumers who have issues with consuming milk and dairy products, lactose-free and easy-to-digest products are also being produced [37]. In this context, yogurt made from A2 milk, known as the natural form of milk, presents a new approach to functional yogurt types [38].  
With the growing interest in the consumption of functional foods, the health benefits and functionalities of food products are determining factors in consumers' decisions to choose or reject certain products [39]. With the addition of certain materials, functional yogurt not only provides a range of health benefits to consumers through the fermentation of milk but also enhances these benefits [23]. Among components beneficial to human health that may be included in yogurt are probiotic bacteria, dietary fibers, which are considered prebiotics; various fruits and vegetables; and other plant parts, such as leaves and seeds [40; 41]. Thus, yogurt with an enhanced functional content can benefit gut health, the digestive system, and other systems [7; 42; 43; 44; 45; 46]. Additionally, these foods have been found to exhibit antioxidant, anti-inflammatory, and antidiabetic properties.  
In this sense, the evolution of yogurt from the past to the present and the various types of functional yogurt have been investigated. Additionally, the effects of yogurt consumption on both healthy and diseased individuals have been extensively examined.