Fat, Sugar, Whole Grains and Heart Disease: 50 Years of Confusion.

During the 1970s some investigators proposed that refined carbohydrates, especially sugar and a low intake of dietary fiber, were major factors in coronary heart disease (CHD). This suggestion was eclipsed by the belief that an excess intake of saturated fatty acids (SFA) was the key dietary factor, a view that prevailed from roughly 1974 to 2014. Findings that have accumulated since 1990 inform us that the role of SFA in the causation of CHD has been much exaggerated. A switch from SFA to refined carbohydrates does not lower the ratio of total cholesterol to HDL-cholesterol in the blood and therefore does not prevent CHD. A reduced intake of SFA combined with an increased intake of polyunsaturated fatty acids lowers the ratio of total cholesterol to HDL-cholesterol; this may reduce the risk of CHD. The evidence linking carbohydrate-rich foods with CHD has been steadily strengthening. Refined carbohydrates, especially sugar-sweetened beverages, increase the risk of CHD. Conversely, whole grains and cereal fiber are protective. An extra one or 2 servings per day of these foods increases or decreases risk by approximately 10% to 20%.

Denis Burkitt and the origins of the dietary fibre hypothesis.

For more than 200 years the fibre in plant foods has been known by animal nutritionists to have significant effects on digestion. Its role in human nutrition began to be investigated towards the end of the 19th century. However, between 1966 and 1972, Denis Burkitt, a surgeon who had recently returned from Africa, brought together ideas from a range of disciplines together with observations from his own experience to propose a radical view of the role of fibre in human health. Burkitt came late to the fibre story but built on the work of three physicians (Peter Cleave, G. D. Campbell and Hugh Trowell), a surgeon (Neil Painter) and a biochemist (Alec Walker) to propose that diets low in fibre increase the risk of CHD, obesity, diabetes, dental caries, various vascular disorders and large bowel conditions such as cancer, appendicitis and diverticulosis. Simply grouping these diseases together as having a common cause was groundbreaking. Proposing fibre as the key stimulated much research but also controversy. Credit for the dietary fibre hypothesis is given largely to Burkitt who became known as the 'Fibre Man'. This paper sets out the story of the development of the fibre hypothesis, and the contribution to it of these individuals.

Guar gum and similar soluble fibers in the regulation of cholesterol metabolism: current understandings and future research priorities.

The hypocholesterolemic effects associated with soluble fiber consumption are clear from animal model and human clinical investigations. Moreover, the modulation of whole-body cholesterol metabolism in response to dietary fiber consumption, including intestinal cholesterol absorption and fecal sterol and bile acid loss, has been the subject of many published reports. However, our understanding of how dietary fibers regulate molecular events at the gene/protein level and alter cellular cholesterol metabolism is limited. The modern emphasis on molecular nutrition and rapid progress in 'high-dimensional' biological techniques will permit further explorations of the role of genetic polymorphisms in determining the variable interindividual responses to soluble fibers. Furthermore, with traditional molecular biology tools and the application of 'omic' technology, specific insight into how fibers modulate the expression of genes and proteins that regulate intestinal cholesterol absorption and alter hepatic sterol balance will be gained. Detailed knowledge of the molecular mechanisms by which soluble fibers reduce plasma cholesterol concentrations is paramount to developing novel fiber-based "cocktails" that target specific metabolic pathways to gain maximal cholesterol reductions.

Hacia una definición de fibra alimentaria / Alimentary fiber definition

La fibra alimentaria (FA) ha sido un tópico de considerable interés para los nutricionistas y médicos en estos últimos 35 años. Este artículo presenta un análisis sobre la definición de fibra alimentaria y la controversia que existe al respecto, así como las nuevas propuestas que han surgido para incluir en su definición. La FA fue definida como: todos los polisacáridos no almidones más la lignina, que no pueden ser digeridos o absorbidos en el intestino delgado humano. Esta definición no incluye otros componentes vegetales tales como: polifenoles, proteínas resistentes y almidones resistente, los cuales son también resistentes a la digestión. Para muchos investigadores, la definición de FA aun no esta concluida o completa. Las investigaciones epidemiológicas han indicado, la posible relación entre las enfermedades más comunes en las modernas sociedades occidentales y la fibra alimentaria.

Dietary fiber (DF) has been a topic of considerable interest among nutritionists and physicians for the last 35 years. This work was basically focused on an analysis of the dietary fiber definition, the currently existing controversy and the new proposal to be included in such a definition. DF was defined as all nonstarch polysaccharides plus lignin, which are not digested or absorbed in the human digestive tract. This definition does not include other vegetable substances, such as, polyphenols, resistant protein or resistant starch, which are also resistant to digestion. For most researchers this definition is not yet complete. Epidemiological investigations, have suggested the possible relationship between the most common diseases in the modern Western societies and the dietary fiber.

Historical perspective as a guide for identifying and developing applicable methods for dietary fiber.

A review is presented describing the nature and evolving definition of dietary fiber. The historical development of the current definition is discussed as are the efforts to develop analytical methods to support food labeling regulations. Also considered are the characterization and quantitation of resistance starch, a dietary starch that does not digest in the small intestine, behaves like dietary fiber and therefore may have potential as a health-related ingredient in foods. The current status of AOAC methodology is discussed along with the possibility of updating the definition of dietary fiber. The potential impacts of changing the dietary fiber definition on analytical issues and on food composition databases are also considered.

Enteral nutrition in HPB surgery: past and future.

Perioperative nutrition has, during the past century, been transformed from a tool to provide calorie and nitrogen support to a tool to boost the immune system and increase resistance to complications. Despite all the progress in medicine and surgery, perioperative morbidity, the rate of infections, thrombosis, and the development of serosal adhesions has remained the same as long as can be judged, or at least during the past 80 years. Most prone to develop complications are persons above the age of 65 and persons with depressed immunity. About 80% of the immune system is localized in the gastrointestinal tract, which offers great opportunities for modulation through enteral nutrition. As the stomach has a tendency to develop postoperative paralysis, tube feeding is often necessary. In 1918, Andresen demonstrated the advantages of enteral nutrition, which already started on the operating table. Mulholland and colleagues and Rhoads and co-workers demonstrated, during the 1940s, certain advantages of enteral tube feeding. Also, the works by Alexander, Fischer, and Ryan, and their co-workers supported the value of early enteral feeding, and suggested enteral feeding as an effective tool to boost the immune system. It was, however, works published in the early 1990s, by Moore and colleagues and by Kudsk and colleagues, which made surgeons more aware of the advantages of early enteral nutrition. Surgery in the hepatobiliary pancreatic field is known to have a high rate of complications. Uninterrupted perioperative nutrition, i.e., nutrition during the night before, during surgery, and immediately after, offers a strong tool to prevent complications. It is essential that the nutrition also provides food for the colon, e.g., fiber and healthy bacteria (probiotics) to ferment the fiber and boost the immune system.

Effect of beta-glucan from oats and yeast on serum lipids.

Heart disease is the leading cause of death in the U.S. One way to reduce the risk of developing the disease is to lower serum cholesterol levels by making dietary changes. In addition to reducing intake of total fat, saturated fat, and dietary cholesterol, serum cholesterol can be further reduced by added fiber, especially from sources rich in beta-glucan. In this review, two sources of beta-glucan are described; one source is oats and the other yeast. Their chemical structures and physical properties are compared, and their effect on serum lipid levels is described. Oat beta-glucans are found in various breakfast cereals and snacks. Usually, several servings of these products are required to meet the Food and Drug Administration's claim of reducing the risk of heart disease. The yeast-derived fiber is a more concentrated source of beta-glucan than the oat product. It is currently being tested in a wide variety of food products.