Referência:
Verbrugghe A, Hesta M, Van Weyenberg S, Papadopoulos GA, Gommeren K, Daminet S, Bosmans T, Polis I, Buyse J, Janssens GP. The glucose and insulin response to isoenergetic reduction of dietary energy sources in a true carnivore: the domestic cat ( Felis catus). Br J Nutr. 2010 Jul;104(2):214-21. doi: 10.1017/S0007114510000358. Epub 2010 Mar 2. PMID: 20193098.
Resumo:
Insulin resistance is a state in which greater than normal insulin concentrations are required to elicit a quantitatively normal glucose response in the body, tissues and cells(1). Insulin resistance and consequent hyperinsulinaemia are associated with a cluster of abnormalities, such as hypertension, dyslipidaemia and central obesity, which increase cardiovascular risk. This cluster is referred to as the metabolic syndrome(1, 2). In individuals who are unable to compensate for reduced insulin sensitivity, impaired glucose tolerance and overt diabetes might occur because of the prolonged and increased demand on β-cells to secrete insulin(1, 3).
A critical role for the quantity and quality of dietary carbohydrates in the pathogenesis of this disorder has been postulated by the ‘carnivore connection’ theory(1, 3, 4). During the Ice Ages, our ancestors consumed high-protein (HP), low-carbohydrate (LC) diets, and since the brain, fetus and mammary gland all have specific needs for glucose, metabolic adaptations were necessary to adapt to low glucose intake. Therefore, resistance to the glucose-lowering effects of insulin offered survival and reproductive advantages. The event of the agricultural revolution augmented the amount of digestible carbohydrates, and the industrial revolution was responsible for changing the quality of carbohydrates. These evolutionary changes in carbohydrates, meaning the introduction of high-glycaemic index foods, can worsen insulin resistance and can be linked to the development of type 2 diabetes(1, 4).
Over the last decades, as in humans, the diet of strictly carnivorous domestic cats changed from HP, LC prey(5) to commercial diets, often containing moderate to high amounts of highly digestible carbohydrates. As in humans, these dietary changes are held responsible for the recent increase in incidence of feline insulin resistance and diabetes mellitus(3, 6).
Several human studies(7–10) as well as rodent studies (rats(11) and mice(12)) demonstrated that glucose tolerance and insulin sensitivity could benefit from HP, LC diets. In healthy cats, high-carbohydrate (HC) diets are suggested to impair glucose tolerance(13). However, the hypothesis that HC diets lead to β-cell exhaustion was contradicted by Slingerland et al. (14), since feeding a HC diet resulted in increased glucose-induced insulin secretion during hyperglycaemic glucose clamps. Yet, this could be the first step towards β-cell exhaustion, but long-term consequences were not investigated. It can, however, not be disclaimed that HC diets might be an indirect risk factor for diabetes by promoting obesity. Hoenig et al. (15) suggested that cats with the same energetic intake are more prone towards obesity and insulin resistance when fed a low-protein (LP), HC diet in comparison with a HP, LC diet. In contrast, high-fat (HF), LC diets were also shown to impair glucose tolerance(16, 17) as well as to induce weight gain(16).
A plausible explanation for the lack of agreement among these studies is that the effect of increasing one energy source (1) was often confounded with the decrease of other energy sources; or (2) often meant an increase on top of an already high level of this energy source.
The present study deals with these aspects by applying a pairwise reduction of one energy source, and therefore enables the identification of the separate effect of each energy source by looking at the effect of its reduction to minimal amounts. This method has been shown to be effective in demonstrating single energy source effects on metabolism in poultry(18).
Palavras-chave: carboidratos, carnívoro, resistência insulínica, gatos