Throughout the last decade, obesity has been growing into the main nutritional disease not only in humans, but also in companion animals. Over the years, studies have reported values between 20–40 percent with regards to obesity in the studied population (McGreevy et al., 2005; Gossellin et al., 2007). More recent studies have reported percentages of approximately 44 percent with regards to occurrence of obesity in dogs (Mao et al., 2013; Alonso et al., 2017), demonstrating a progressive and disturbing increase of this condition.
Pet obesity: a serious condition
Its development is directly or indirectly associated with increased risk of other conditions, such as cardiorespiratory, orthopedic alterations and metabolic disorders such as reduced glucose tolerance, type 2 diabetes in felines, hyperlipidemia (Gayet et al., 2004; Brunetto et al., 2011) and reduced life expectancy (Kealy et al., 2002).
The mechanisms involved in the development of many of the mentioned alterations rely on the characterization of adipocytes as members of an active endocrine tissue (Balistreri et al., 2010). Therefore, adipose tissue also participates in mechanisms of inflammation and immunity, with production and release of a wide range of pro-inflammatory factors such as interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and suppression of anti-inflammatory factors such as adiponectin as well as other cytokines.
Weight loss can reduce these changes, the severity of complications and even normalize the alterations acquired by overweight status. The success of treatment depends on the promotion of weight loss and effective maintenance of lean weight; thus, it is necessary to induce a negative energy balance state by means of caloric restriction (Cloetens et al., 2012; Floerchinger et al., 2015). Satiety plays a major role during this process concerning the animal and its owner, since the manifestation of hunger, which consequently leads the animal to seek and beg for food, often compromises the continuation of the program (Weber et al., 2007).
Researching beta-glucans and their effects on obese dogs
Beta-glucans are polysaccharides composed of glucose monomers linked together by β-glycosidic bonds. Due to their complex mechanism of action in an organism, several effects have already been associated with their supplementation: modulation of the immune response (Li et al., 2006; Zaine, 2014), reduction of the inflammatory response (Beynen and Legerstee, 2010; Beynen et al., 2011; Silva et al., 2015), and modulation of glucose (Vetvicka and Oliveira, 2014; Silva et al., 2015) and lipids (Andrade et al., 2016) metabolism. However, the effects of beta-glucans on glycemic control are poorly understood in dogs, and no studies that evaluated the addition of this polysaccharide in glycemic parameters of obese dogs are available.
A recent study carried out at the School of Veterinary Medicine and Animal Science – University of São Paulo (Brazil) evaluated the effects of purified beta-glucans from yeast S. cerevisiae (MacroGard, Biorigin, Brazil) on metabolic parameters and hormones related to satiety of obese dogs. Fourteen privately owned dogs were split into two experimental groups: obese dogs (group A) with body condition score (BCS) 8 or 9/9 and lean dogs with ECC 5/9 (group B), according to the Laflamme (1997) scoring system. Group A later became group C after the supplementation with beta-glucans.
Research results
Dietary beta-glucans led to important changes in glycemic variables (basal and mean blood glucose), cholesterol and triglycerides, since groups B and C did not present any statistical difference for these parameters, while group A (obese without supplementation) presented higher values for them. The addition of beta-glucans has also promoted a reduction of basal insulin concentrations in the obese group (C), although these values remained higher than those found in group B (P < 0.05).
Appetite regulating hormone GLP-1 (see Figure 1) was affected by the supplementation with beta-glucans. The lean and obese dogs (before supplementation) had lower circulating concentrations of GLP-1 (p <0.05). These results could explain why some dogs of group C presented leftovers throughout the study and decreased begging behavior for food, as reported by the owners.
[FIGURE 1]
FIGURE 1: According to research results, appetite regulating hormone GLP-1 was affected by the dogs’ food being supplemented with beta-glucans.
In conclusion, these are pioneering results of extreme importance, since it supports the idea of beta-glucans as a possible solution to be included in diets formulated for obesity control, as well as for maintenance after weight loss, due to its effects on metabolism and appetite control.
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