by Lorena Sanchez, Scientific Project Manager, Sprÿng Powered by Ynsect, France
The global obesity crisis, a health concern of epidemic proportions for humans, is sadly affecting our companion animals too. According to the Association for Pet Obesity Prevention, 59 percent of dogs and 61 percent of cats worldwide are currently obese — a figure that has risen over the past decade by 169 percent for cats and 158 percent for dogs. Although factors such as breed and neuter status can predispose certain animals to obesity, the broad extent of the trend suggests that owner-related factors, such as diet choice and feeding practices, are largely responsible. Compared to healthy animals, obese pets have lower vitality, as well as increased pain and emotional disturbance. Life expectancy is reduced by approximately 1.5 years for both cats and dogs, and there are numerous associated health risks including cancer, inflammation, diabetes (particularly for cats), high blood pressure, kidney disease and respiratory disease. Such serious health concerns carry a financial consequence for the pet owner in increased medical expenses, and pet obesity is estimated to account for 20 percent of pet insurance claims.
Strategies for combatting pet obesity
Fortunately, there is evidence that much of this is reversible.Studies have shown that obese pets that follow a supervised weight loss program can regain their vitality, and that restricting food intake can both increase life expectancy and delay the onset of chronic disease. To achieve such success, owners must increase their pet’s physical activity, and modify their own (often long-standing) feeding practices. This will typically involve both a moderation of the quantity of food (for example, reducing the number of treats offered), and understanding what constitutes a quality diet: a low-calorie, high-fiber, high in protein of good quality, and low-fat diet is a safe and effective way to lose or maintain weight in pets.
Recent studies on obese rats and mice suggest that a particularly good source of dietary protein for combatting obesity may be mealworm protein.
The global market for dietary insect protein is quite young but growing rapidly—it is expected to reach US$1.74 billion by 2028, and pet food applications account for 75 percent of this. Originally, the primary incentive for exploring insect protein as an alternative to animal protein was environmental: insect farming requires significantly less water and is less land-dependent than conventional livestock; its GHG production is lower; and insects have a low feed conversion ratio, which means they convert low-protein ingredients to high-protein ingredients very efficiently. Now there is increasing evidence to suggest that consuming mealworm protein may not only be beneficial for the environment, but also for health.
Mealworm protein reduces fat accumulation and total lipid content
A growing body of research on rodent models of obesity has demonstrated that including mealworm protein the diet has a marked anti-obesity effect. In a recent study from Kelly Swanson’s group, mice were fed a high fat diet, with casein as the protein source. Once the mice had become clinically obese, some of the obese mice continued on the same diet, while others were fed similar diets in which the protein source was replaced by Sprÿng’s mealworm protein. After eight weeks, the mice whose diet included the mealworm protein slowed their weight gain. Elsewhere, numerous studies on genetically obese rats and mice have demonstrated that animals fed a diet with mealworm meal as the protein source produce visibly less fat tissue than animals fed their standard casein diet. What’s more, within the fat tissue, the fat cells themselves (adipocytes) are smaller. This effect can be reproduced in the laboratory by growing adipocytes in vitro, and adding an extract of mealworm: the treated adipocytes are not only smaller, but—significantly—their production of triglycerides is reduced by 70 percent. Triglycerides are a type of lipid molecule, formed in the liver from fatty acids: the more fat tissue in the body, the more fatty acids are carried to the liver in the blood, and the more triglycerides are produced. Furthermore, high triglyceride levels are often associated with high levels of other lipids, including cholesterol. This total lipid content is an important indicator of obesity-related ill health: in dogs, hyperlipidemia has been linked to gastrointestinal dysfunction such as vomiting and diarrhea, seizures, and cloudy eyes; in cats, skin lesions and peripheral neuropathies are common; and pancreatitis can also result. In the studies on obese rats, the total lipid content in the liver was reduced by 60 percent in rats fed mealworm protein; and the total lipid content in blood plasma was reduced by almost two-thirds.
Beneficial health effects of mealworm cuticle
What is it about the insect meal that causes this reduction of lipid production? The answer might be chitin, a polysaccharide found in mealworm cuticle (comprising the exoskeleton). To test the hypothesis that mealworm cuticle reduces lipid production in rats, obese rats were fed a normal casein diet to which ground insect cuticle was added, and indeed, this diet produced many of the same lipid-reducing effects as the diet in which casein was completely replaced by mealworm meal. Specifically, there was a decrease in the production of several proinflammatory lipids associated with fatty liver disease (ceramides, glycosylceramides, and sphingomyelin). Additionally, several changes to gut microbiota were observed, including significant increases in Actinobacteria—known to have anti-inflammatory effects and to counteract fatty liver disease—as well as Lactobacillaceae and Bifidobacteria, both known to alleviate accumulation of lipids in the liver. These observed microbiota changes may lead to a reduction in proinflammatory lipid production in the liver.
Part of the beneficial effect of chitin may reflect its function as a dietary fiber, it is already well understood that increasing dietary fiber is part of a strategy for combatting pet obesity. Numerous weight control products already available on the market, for both cats and dogs, include a greater number and variety of fiber sources than maintenance kibbles products. When using insect meal as a protein source in pet food, such as Sprÿng’s Protein70 and WetPro15, the high-quality protein comes with supplementary dietary fiber in the form of chitin.
Whatever the precise mechanism, there is no question that including mealworm protein in the diet is beneficial in counteracting obesity, at least in rodents. While future research on cats and dogs is necessary, these findings are already very promising for a future in which it seems likely that the use of insect protein in pet food will continue to rise, although the initial motivation may have been environmental, it seems our beloved companions may end up healthier, and be around for longer, as a consequence.
