Las grasas y aceites en la nutrición humana: algo de su historia / Fats and oils in the human nutrition: an historical overview

Las grasas y aceites, también identificadas como materias grasas, constituyen la forma mayoritariamente comestible de los lípidos. Actualmente muestran un gran desarrollo tecnológico y nutricional, aunque su utilización en la alimentación y en usos domésticos comenzó hace muchos siglos. La Revolución Industrial significó un salto cuantitativo en el conocimiento de las materias grasas. El francés Eugene Chevreul fue el iniciador de la investigación científica en grasas y aceites. Jean-Baptiste Dumas en Francia y Justus Liebig, en Alemania, dieron origen a los primeros conceptos sobre la importancia nutricional de las grasas y aceites. Hypolitte Mége-Mouriés desarrollo un procedimiento para obtener un producto similar a las actuales margarinas. El alemán Franz Knoop fue el descubridor del proceso bioquímico de metabolización de los ácidos grasos conocido como beta oxidación. Los norteamericanos George y Mildred Burr descubrieron la esencialidad de los ácidos grasos, y las investigaciones de los ingleses Haslan y Chick, en forma independiente, caracterizaron las primeras lipoproteínas. Este trabajo resume en forma no exhaustiva los primeros descubrimientos relacionados con el rol nutricional de las grasas y de los aceites.

Fats and oils, also identified as fats, are the main components of edible lipids. The technological and the nutritional knowledge of fats and oils is at present very well developed, however the utilization of fats as foods or for domestic uses was initiated many centuries ago. The named Industrial Revolution represented a significant quantitative development in the knowledge of fats and oils. The French Eugene Chevreul was probably the first scientific who studied the properties of fats and oils. Another French citizen, Jean-Baptiste Dumas together with the German scientist Justus Liebig, were the first researchers who intended to explain the nutritional properties of fats. The French pharmacist Hypolitte Mége-Mouriés was involved in the preparation of the first fat emulsion which resembles a margarine. The German scientist Franz Knoop described the biochemical process known as beta oxidation of fatty acids. George and Mildred Burr, both American scientists, were the first to describe the essentiality of fatty acids, and the English Haslan and Chick independently isolated the first lipoproteins. The present description review, although not exhaustively, the main discoveries about the nutritional role of fats and oils.

Social worlds, actor-networks and controversy: the case of cholesterol, dietary fat and heart disease.

Knowledge which links dietary fat and cholesterol to coronary heart disease (CHD) has been controversial for more than forty years. While policies advocating fat and cholesterol restriction are now deeply ingrained in affluent western societies, the scientific 'facts' on which they are supposedly based are highly contested. Applying concepts from actor-network theory and the symbolic interactionist social worlds approach, I argue that knowledge and dietary recommendations relating to cholesterol, fat and CHD are the outcome of complex social negotiations which can only be understood in their cultural, commercial and political contexts. Policies were framed in the 1960s before 'proof' of their efficacy was available. Since then, ambiguous experimental results have been shaped to support the policies. I argue that, despite its many attractive features, actor-network theory cannot adequately deal with protracted controversies. Social worlds theory provides a much more useful framework for investigating long debates in which the 'facts' remain elusive.

Estimation of historical exposures to machining fluids in the automotive industry.

A retrospective exposure assessment study in the automotive parts industry conducted in conjunction with a cancer mortality and respiratory morbidity study [Kennedy et al. (1989): Am J Ind Med 15:627-641; Eisen et al. (1992): Am J Ind Med 22:809-824; Tolbert et al. (1992): Scand J Work Environ Health 18:351-360] describes exposure to different types of machining fluids and selected components that may contribute to the conditions investigated. A dataset of 394 industrial hygiene measurements made between 1958 and 1987 was used to estimate past machining fluid levels using a linear statistical model. The effects of different plants, machining fluid types, machining operations, and time periods were examined in the model. Separate analyses examined the effects of different sampling and analysis methods and other measurement variables. Machining fluid levels prior to 1970 were generally two to five times higher than subsequent measurements. The arithmetic mean exposure of all measurements taken before 1970 was 5.42 mg/m3. Arithmetic means for different subgroups ranged from 0.59 to 20.28 mg/m3, depending upon plant, machining fluid, and operation. The arithmetic mean exposure after 1980 was 1.82 mg/m3 with subgroups ranging from 0.45 to 2.79 mg/m3. Changes in exposure levels generally corresponded with reported changes in plant environments such as installation of enclosures and local exhaust ventilation on machines.

Tallow and the time capsule: Claude Bernard's discovery of the pancreatic digestion of fat.

In 1848, Claude Bernard discovered that pancreatic secretion could emulsify and saponify fatty substances. He would eventually attribute these reactions to an enzyme that was later named 'pancreatic lipase'. This essay has three goals: 1) to examine Bernard's previously overlooked research on the pancreas; 2) to explore the equally ignored history of lipid digestion and metabolism; 3) to reconstruct Bernard's discovery of pancreatic lipase through a parallel analysis of his laboratory notebooks and his publications. This method reveals a discrepancy between the sequence and motivation of events as they were reported by Bernard in his publications and as they appear in his laboratory notebooks.

Blood as the earliest drug, its substitutes, preparations and latest position.

Blood was soul and Redness its active principle when red substances were rich in soul-content. But soul was a substance whence blood became a drug which donated soul to treat wounds and incurable diseases. Its redness as life-force, but also as substance, could prolong life. A drug made from human blood could treat serious wounds and as a life saving drug was also a drug of fertility. The latest use of blood appears as syrup haemoglobin while the latest use of human blood would be blood transfusion.