A long-term high-protein diet markedly reduces adipose tissue without major side effects in Wistar male rats

Abstract

Although there is a considerable interest of high-protein, low-carbohydrate diets to manage weight control, their safety is still the subject of considerable debate. They are suspected to be detrimental to the renal and hepatic functions, calcium balance, and insulin sensitivity. However, the long-term effects of a high-protein diet on a broad range of parameters have not been investigated. We studied the effects of a high-protein diet in rats over a period of 6 mo. Forty-eight Wistar male rats received either a normal-protein (NP: 14% protein) or high-protein (HP: 50% protein) diet. Detailed body composition, plasma hormones and nutrients, liver and kidney histopathology, hepatic markers of oxidative stress and detoxification, and the calcium balance were investigated. No major alterations of the liver and kidneys were found in HP rats, whereas NP rats exhibited massive hepatic steatosis. The calcium balance was unchanged, and detoxification markers (GSH and GST) were enhanced moderately in the HP group. In contrast, HP rats showed a sharp reduction in white adipose tissue and lower basal concentrations of triglycerides, glucose, leptin, and insulin. Our study suggests that the long-term consumption of an HP diet in male rats has no deleterious effects and could prevent metabolic syndrome.

High-protein diet during gestation and lactation affects mammary gland mRNA abundance, milk composition and pre-weaning litter growth in mice

“…Diets rich in protein can reduce food intake as previously shown in rodents (Lacroix et al, 2004). This satiating effect of protein might have also played a minor role in our study.…”

“…Thus, the HP group was also exposed to a lower carbohydrate intake (378 v. 600 g carbohydrates/kg diet) as compared to the C group. Generally, a high protein and a low carbohydrate diet was related to lower plasma glucose and insulin levels (Lacroix et al, 2004). In line with this, in dams fed an HP lactation diet plasma glucose concentrations at day 3 of lactation was lower (16.4 v. CC 20.7 mmol/l; P , 0.043; C. C. Metges et al (unpublished results)).…”

“…In obese and diabetic individuals, a higher utilization of fat reserves and improved glucose homeostasis was reported while subjected to diets containing higher protein contents (Farnsworth et al, 2003;Layman et al, 2003). Similar results were obtained in rats fed HP diets with reduced carbohydrate content (Jean et al, 2001; -E-mail: metges@fbn-dummerstorf.de Lacroix et al, 2004). Reports on the impact of an increased dietary protein intake during gestation and lactation on maternal and foetal/offspring health and development are scarce and the results obtained are inconsistent (Daenzer et al, 2002;Zhang et al, 2005;Thone-Reineke et al, 2006).…”

“…With HP intake, excess nitrogen needs to be disposed by urea synthesis and glucose must be synthesized de novo (Kuhla et al, 2010) which are highly energy consuming processes. Thus, high protein diets provide less net energy than isoenergetic Control diets (Johnston et al, 2002;Lacroix et al, 2004;Pichon et al, 2006), which is reflected in the lower fat pad mass of dams fed an HP diet during lactation. Maternal kidney mass responded to an HP diet with an increase and in particular in the dams fed an HP diet during gestation and lactation.…”

“…In addition, a higher relative kidney mass was observed in CHP and HPHP offspring which suggests a programming response to the maternal diet. Other authors reported that high dietary protein feeding increased absolute and relative mass of kidneys in rats and pigs due to increased glomerular filtration rate and cell hypertrophy (Schoknecht and Pond, 1993;Hammond and Janes, 1998;Murray et al, 1998;Lacroix et al, 2004).…”