Ana Paula Boroni Moreira

Influence of a high-fat diet on gut microbiota, intestinal permeability and metabolic endotoxaemia

Lipopolysaccharide (LPS) may play an important role in chronic diseases through the activation of inflammatory responses. The type of diet consumed is of major concern for the prevention and treatment of these diseases. Evidence from animal and human studies has shown that LPS can diffuse from the gut to the circulatory system in response to the intake of high amounts of fat. The method by which LPS move into the circulatory system is either through direct diffusion due to intestinal paracellular permeability or through absorption by enterocytes during chylomicron secretion. Considering the impact of metabolic diseases on public health and the association between these diseases and the levels of LPS in the circulatory system, this review will mainly discuss the current knowledge about high-fat diets and subclinical inflammation. It will also describe the new evidence that correlates gut microbiota, intestinal permeability and alkaline phosphatase activity with increased blood LPS levels and the biological effects of this increase, such as insulin resistance. Although the majority of the studies published so far have assessed the effects of dietary fat, additional studies are necessary to deepen the understanding of how the amount, the quality and the structure of the fat may affect endotoxaemia. The potential of food combinations to reduce the negative effects of fat intake should also be considered in future studies. In these studies, the effects of flavonoids, prebiotics and probiotics on endotoxaemia should be investigated. Thus, it is essential to identify dietetic strategies capable of minimising endotoxaemia and its postprandial inflammatory effects.

Long-term aerobic swimming training by rats reduces the number of aberrant crypt foci in 1,2-dimethylhydrazine-induced colon cancer

We determined the effect of long-term aerobic swimming training regimens of different intensities on colonic carcinogenesis in rats. Male Wistar rats (11 weeks old) were given 4 subcutaneous injections (40 mg/kg body weight each) of 1,2-dimethyl-hydrazine (DMH, dissolved in 0.9% NaCl containing 1.5% EDTA, pH 6.5), at 3-day intervals and divided into three exercise groups that swam with 0% body weight (EG1, N = 11), 2% body weight (EG2, N = 11), and 4% body weight of load (EG3, N = 10), 20 min/day, 5 days/week for 35 weeks, and one sedentary control group (CG, N = 10). At sacrifice, the colon was removed and counted for tumors and aberrant crypt foci. Tumor size was measured and intra-abdominal fat was weighed. The mean number of aberrant crypt foci was reduced only for EG2 compared to CG (26.21 +/- 2.99 vs 36.40 +/- 1.53 crypts; P < 0.05). Tumor incidence was not significantly different among groups (CG: 90%; EG1: 72.7%; EG2: 90%; EG3: 80%). Swimming training did not affect either tumor multiplicity (CG: 2.30 +/- 0.58; EG1: 2.09 +/- 0.44; EG2: 1.27 +/- 0.19; EG3: 1.50 +/- 0.48 tumors) or size (CG: 1.78 +/- 0.24; EG1: 1.81 +/- 0.14; EG2: 1.55 +/- 0.21; EG3: 2.17 +/- 0.22 cm(3)). Intra-abdominal fat was not significantly different among groups (CG: 10.54 +/- 2.73; EG1: 6.12 +/- 1.15; EG2: 7.85 +/- 1.24; EG3: 5.11 +/- 0.74 g). Aerobic swimming training with 2% body weight of load protected against the DMH-induced preneoplastic colon lesions, but not against tumor development in the rat.

Main characteristics of metabolically obese normal weight and metabolically healthy obese phenotypes

In this review, the influence of fat depots on insulin resistance and the main characteristics of metabolically obese normal-weight and metabolically healthy obese phenotypes are discussed. Medline/PubMed and Science Direct were searched for articles related to the terms metabolically healthy obesity, metabolically obese normal weight, adipose tissue, and insulin resistance. Normal weight and obesity might be heterogeneous in regard to their effects. Fat distribution and lower insulin sensitivity are the main factors defining phenotypes within the same body mass index. Although these terms are interesting, controversies about them remain. Future studies exploring these phenotypes will help elucidate the roles of adiposity and/or insulin resistance in the development of metabolic alterations.

Fish oil ingestion reduces the number of aberrant crypt foci and adenoma in 1,2-dimethylhydrazine-induced colon cancer in rats

We determined the effect of fish oil (FO) ingestion on colonic carcinogenesis in rats. Male Wistar rats received 4 subcutaneous injections (40 mg/kg body weight each) of 1,2-dimethylhydrazine (DMH) at 3-day intervals and were fed a diet containing 18% by weight FO (N = 10) or soybean oil (SO, N = 10) for 36 weeks. At sacrifice, the colon was removed, aberrant crypt foci were counted and the fatty acid profile was determined. Intestinal tumors were removed and classified as adenoma or carcinoma. Liver and feces were collected and analyzed for fatty acid profile. FO reduced the mean (+/- SEM) number of aberrant crypt foci compared to SO (113.55 +/- 6.97 vs 214.60 +/- 18.61; P < 0.05) and the incidence of adenoma (FO: 20% vs SO: 100%), but carcinoma occurred equally in FO and SO rats (2 animals per group). The polyunsaturated fatty acid (PUFA) profile of the colon was affected by diet (P < 0.05): total omega-3 (FO: 8.18 +/- 0.97 vs SO: 1.71 +/- 0.54%) and total omega-6 (FO: 3.83 +/- 0.59 vs SO: 10.43 +/- 1.28%). The same occurred in the liver (P < 0.05): total omega-3 (FO: 34.41 +/- 2.6 vs SO: 6.46 +/- 0.59%) and total omega-6 (FO: 8.73 +/- 1.37 vs SO: 42.12 +/- 2.33%). The PUFA profile of the feces and liver polyamine levels did not differ between groups (P > 0.05). In conclusion, our findings indicate that chronic FO ingestion protected against the DMH-induced preneoplastic colon lesions and adenoma development, but not against carcinoma in rats.

Regular intake of high-oleic peanuts improves fat oxidation and body composition in overweight/obese men pursuing a energy-restricted diet

Evaluate the effect of high‐oleic and conventional peanuts within a hypocaloric‐diet on energy metabolism and body composition.

Intestinal permeability measurements: general aspects and possible pitfalls

INTRODUCTION Disturbances of the gut barrier function have been related to a variety of diseases, including intestinal and extra-intestinal diseases. The intestinal permeability tests are considered useful tools for evaluating disease severity and to follow-up patients after a therapeutic intervention and indirectly assess barrier function. OBJECTIVE The aims of this review were to highlight the possible factors underlying higher intestinal permeability and the clinical conditions that have been associated with this in different age range; and also provide some insight into methodological aspects. RESULTS AND DISCUSSION Abnormal regulation of tight junction function is the main cause of altered intestinal barrier. The impaired barrier function results in higher permeation rates of administered probes through the intestinal mucosa. Lactulose and mannitol are one of the most commonly used probes. The innocuousness and easiness of intestinal permeability tests can be explored to expand the knowledge about the clinical situations in which intestinal barrier dysfunction can be an important feature. Many factors may influence the results of the test. Researchers and healthcare professionals should try to circumvent the possible pitfalls of the intestinal permeability tests to produce consistent evidences. The use of others markers of intestinal physiology may also contribute to understand the role of barrier function in different diseases.

High-oleic peanuts: new perspective to attenuate glucose homeostasis disruption and inflammation related obesity.

To evaluate the effects of acute and daily consumption of high‐oleic peanuts (HOP) on inflammation and glucose homeostasis in overweight/obese men.

Oral administration of sodium butyrate reduces chemically-induced preneoplastic lesions in experimental carcinogenesis

OBJETIVO: Avaliar o efeito da administracao oral de butirato de sodio na carcinogenese do colon. METODOS: A carcinogenese em ratos Wistar foi induzida com injecoes de 1,2-dimetilhidrazina na dose de 40mg/kg de peso corporal. A solucao de butirato de sodio (3,4%) foi oferecida ad libitum por 4 semanas (grupo butirato, n=16), em substituicao a agua (grupo controle, n=9). Os ratos foram sacrificados na 17a semana apos tratamento com a 1,2-dimetilhidrazina. Focos de criptas aberrantes e a expressao dos genes para o acido ribonucleico mensageiro (RNAm) das ciclinas D1 e E foram quantificadas no colon. Alteracoes no perfil de acidos graxos do colon, no figado, na gordura intra-abdominal e nas fezes foram analisadas. RESULTADOS: Uma significante diminuicao nos focos de criptas aberrantes foi encontrada no grupo que recebeu butirato. Nenhuma diferenca foi encontrada na expressao do RNAm das ciclinas D1 e E entre os grupos. Contudo, a ingestao de butirato diminuiu a quantidade de acido estearico e acido oleico na gordura intra-abdominal e do acido docosahexanoico no figado. Alem disso, o grupo butirato apresentou maior percentual de acido linoleico na gordura intra-abdominal, comparado com os ratos do grupo controle. CONCLUSAO: Os dados indicam que o uso de butirato reduz lesoes pre-neoplasicas em ratos e diminui as alteracoes no perfil de acidos graxos da gordura intra-abdominal e do figado, comumente encontradas na carcinogenese colonica.

Soybean Oil: How Good or How Bad in Comparison with Other Dietary Oils in the Context of Colon Cancer

Soybeans (Glycine Max) are one of the oldest crops cultivated around the world, and in Asia soyfoods have been consumed for more than 1000 years. The soybean was popularized because of its high content of protein and good percentage of lipids. World consumption of soybeans in 2008 was over 221 million metric tons, with approximately 50% of this supply coming from US production, where over 77 million ha are planted annually. Soybeans are desired in the market as a source of protein and oil. Nowadays, soy has a huge economic importance because the beans are very versatile and can be used not only for human and animal nutrition but also for industrial products (Clemente & Cahoon 2009). Many beneficial effects of soy components such as soy protein, isoflavones, phytosterols, inositol hexaphosphate and saponins have been suggested, including the beneficial role for inhibition of tumor development in animal models (Hawrylewicz, Zapata et al. 1995). This has stimulated, in only the last 30 years, soybean introduction into western cultures and diets as different sub-products (Golbitz 1995). These products are usually fermented (tempeh, miso, soy sauces, natto, fermented tofu) or non-fermented (fresh soybeans, whole dry soybeans, soy nuts, soy sprouts, whole-fat soy flour, soymilk, tofu, soy protein, soy oil). One of the most used nonfermented subproduct is the soybean oil. The oil represents approximately 20% of the grain and is influenced by both genotype and environmental factors, and in some countries this is the main sub-product utilized in the diet (Clemente & Cahoon 2009). Soybean oil is a representative source of lipids in human nutrition. There are proposed mechanisms that explain lipids involvement in cancer development, especially colorectal cancer (CRC). Thus, comparing soybean oil composition with other oils is a discussion that is relevant in the context of CRC, once this is a public health concern.