Canada Goose Deutschland Outlet Camp unten Kapuzen Parka Braun Dietary Fats and Health
A significant part of this review is dedicated to the current advances in nutrition science on the relation between dietary fat consumption and health outcomes, including obesity and cardiovascular disease. For easier understanding of the current document, written for a somewhat more advanced reader, it may be worthwhile to first read Facts on Fats: The Basics.
1. Why are dietary fats important?
Facts on Fats: The Basics describes the role of fats in taste perception and the importance of fats in a number of food technology applications. From a nutritional point of view, dietary fats are important for several health related aspects and for optimal functioning of the human body. Dietary fats are not just a source of energy; they function as structural building blocks of the body, carry fat soluble vitamins, are involved in vital physiological processes in the body, and are indispensable for a number of important biological functions including growth and development. The importance of dietary fats is explained in more detail below.
The membranes around the cells in our body physically separate the inside from the outside of the cell, and control the movement of substances in and out of the cells. They are mainly made of phospholipids, triglycerides and cholesterol (see Facts on Fats: The Basics). Both length and saturation of the fatty acids from phospholipids and triglycerides affect the arrangement of the membrane and thereby its fluidity. Shorter chain fatty acids and unsaturated fatty acids are less stiff and less viscous, making the membranes more flexible. This influences a range of important biological functions such as the process of endocytosis in which a cell wraps itself around a particle to allow its uptake.1
The brain is very rich in fat (60%) and has a unique fatty acid composition; docosahexaenoic acid (DHA) is the major brain fatty acid. The lipids of the retina also contain very high concentrations of DHA.2
Our bodies cannot produce the polyunsaturated fatty acids (PUFA) linoleic acid (LA) and alpha linolenic acid (ALA) as described in Facts on Fats the Basics. Without these essential fatty acids some vital functions would be compromised, thus they must be provided by the diet. LA and ALA can be converted to longer chain fatty acids and compounds with hormone like or inflammatory properties (such as prostaglandins or leukotrienes, respectively). As such, essential fatty acids are involved in many physiological processes such as blood clotting, wound healing and inflammation. Although the body is able to convert LA and ALA into the long chain versions arachidonic acid (AA), eicosapentaenoic acid (EPA), and, to a lesser extent, to docosahexaenoic acid (DHA), this conversion seems limited.3 The longer chain fatty acids EPA and DHA are said to be „conditionally essential“ and it is recommended to consume direct sources of these particular long chain fatty acids. The richest source of EPA and DHA is oily fish, including anchovy, salmon, tuna and mackerel. See Facts on Fats the Basics for a more complete overview of the most common fatty acids and foods in which they can be found.
Dietary cholesterol helps to maintain a stable pool of cholesterol, but cholesterol is also synthesised by the liver. The human body regulates its cholesterol status. When the cholesterol intake is very low (as in vegans who consume no animal products), both gut absorption and synthesis increase. When cholesterol intake is high, the body’s synthesis is suppressed and excretion via bile salts is increased. The amount of cholesterol, which passes daily through the small intestine, which is the sum of dietary cholesterol and produced cholesterol, is between 1 and 2 g.2 The average cholesterol intake in Europe is 200 300 mg/day, meaning that the body’s production is significantly higher. The blood cholesterol level is the net result of the absorption in the gut and the synthesis in the liver, minus the excretion via the faeces (as cholesterol, bile salts and products resulting from bacterial transformation) and the use of cholesterol by cells.4
2. These are being reviewed every few years, and form the basis for the national dietary recommendations and for health related policy actions based on review of the scientific literature,
and after consultation with panels of scientific experts.
The extrapolation from the scientific literature to actual dietary recommendations can differ between organisations and/or countries. The reason can be that the recommendations were issued at a later point in time, after newer research findings became available, or that study findings were interpreted slightly differently. heart disease, cancer, or death for which different consumption levels being beneficial/harmful, into population based recommendations. supplements versus whole foods).
Consequently, converting the outcomes from different studies into one general recommendation that targets the general population is a challenge. Moreover, there is no standardised methodology to define dietary recommendations, and background documentation does not always clearly specify the procedures that were used. More transparency in the evaluation of the scientific evidence used to set recommendations would therefore be desirable.6 This is being tackled by initiatives for harmonisation, such as the EU funded EURRECA project.7
Dietary recommendations for fats
Historically, dietary recommendations focussed on the prevention of nutrient deficiencies. These guidelines are meant to advise people on a healthy diet that ensures adequate intakes of all nutrients. More recently, with higher prevalence of obesity and chronic diseases, nutrition recommendations have shifted to address food overconsumption and prevention of chronic (metabolic) diseases. saturated fat replaced by unsaturated fat), or changing the type in combination with an overall reduction of fat are protective against cardiovascular events. For reasons described above, these recommendations somewhat differ per organisation/country. It is important to keep in mind that these dietary reference values are derived for population groups and not specifically for individuals. Personal needs may vary depending on a number of personal and lifestyle related factors. This means that it is advised that 20 35% of the total daily energy intake should come from dietary sources of fats. As described in section 2, fat has many essential biological functions, so the total consumption should not be lower than 15 20%. Moreover, diets that are low in fat (20%E) may adversely affect blood lipids by lowering HDL and increasing triglycerides, and may lead to an inadequate intake of essential fatty acids.6 The upper limit for fat intake aims to ensure that people do not consume too many daily calories as fat, since it is the most energy dense macronutrient.
The recommendations for total fat intake are further subdivided in advised intakes for the specific fatty acids.6 Read Facts on Fats the Basics for more information on the molecular structure and nomenclature of fatty acids.
The recommendations for trans fatty acids (TFA) are mainly to keep the intake either as low as possible, or below 1%E.6 It has been convincingly shown that TFA adversely affect blood lipids and increase subsequent CVD risk.24 In contrast to 10 15 years ago, the vast majority of the food products analysed recently for TFA content in Western Europe, do not contain high levels of TFA, and do not pose a major health risk. Instead, they have set recommendations for the specific fatty acids, including the n 3 fatty acids ALA, EPA, DHA and EPA+DHA, and the n 6 fatty acids LA and in some cases also AA.6 These recommendations vary considerably among the different countries, organisations, and consumer age groups, and are expressed either in ‚%E‘ or in ‚g/day‘ (Table 2). The reason for these differences may be because some organisations have focussed on avoiding deficiencies while others have established the recommendations in order to prevent chronic diseases. When they do, the advice is to not exceed 300 mg/day.6 The most recent scientific publications point out that in healthy individuals, dietary cholesterol has little impact on blood cholesterol levels (see box Cholesterol).
3. How much dietary fat do we consume?
Monitoring consumption levels of dietary fats in the population, and evaluating to what extent people adhere to the dietary guidelines is important to assess the effectiveness of recommendations.