Effects of fatty acids on insulin secretion

As well as evidence for FFA modulation of energy metabolism and insulin action at cellular level, there is also increasing evidence to support the view that the amount and type of fatty acids influence the secretion of insulin, and in particular, modulate glucose-stimulated insulin secretion (GSIS). This appears to be an important physiological response which ensures insulin secretion is enhanced in situations where glucose uptake and oxidation could otherwise be compromised owing to inhibitory...

Saturated and trans fatty acids in the diet

Dietary fats largely consist of triglycerides, molecules with three fatty acids esterified to a glycerol backbone. Fatty acids are classified on the basis of their chain length, the number of double bonds in the molecule, the position of the first double bond from the methyl end and the configuration of the double bonds (trans or cis). Accordingly, fatty acids are categorised as saturated, (cis)-monounsaturated, trans and polyunsaturated (Fig. 1.1). Saturated fatty acids (SAFAs) have no double...

Reducing fats in raw meat

Moloney, Teagasc, Grange Research Centre, Ireland 13.3 Breeding effects on the fat content and composition of meat 13.4 Dietary effects on the fat content and composition of meat 13.5 Strategies for improving the fat content and composition of meat 13.6 Implications for the food processor 13.8 Sources of further information

Evidence from human intervention studies saturated versus unsaturated fatty acids

Dietary intervention studies investigating effects of dietary fatty acids on insulin sensitivity have produced inconclusive results (Table 2.2). Many studies have been of short duration and have used small subject numbers (Popp-Snijders et al, 1987 Heine et al, 1989 Fasching et al, 1991 Garg et al, 1992 Christiansen et al., 1997 Brynes et al., 2000 Ryan et al., 2000 Lauszus et al., 2001 Louheranta et al., 2002 Summers et al., 2002 Gerhard et al., 2004). However, the KANWU study, which used a...

Conclusions lipidgene interactions and personalized nutrition

The literature reviewed in this chapter has shown that the influence of dietary lipids (fat, cholesterol) on metabolic markers and risk factors is markedly influenced by genetic polymorphisms in humans. Current recommendations (to limit total and saturated fat, to reduce cholesterol and to increase monounsaturated and n-3 polyunsaturated fat intake) must be reinforced in a way that reflects the reality of how consumers prepare and eat meals today. However, dietary recommendations that have been...

MUFA and cardiovascular risk

Diet, and especially its fat content, can have a varying influence upon cardiovascular risk factors and on mechanisms related to the onset and progression of atheroma plaques. The final aim of preventing and treating coronary arteriosclerosis is to reduce the risk of new heart attacks and mortality from them. In spite of this, research studies into the effects of dietary intervention on the clinical course of the disease are few in number and have only provided significant results in secondary...

Evidence from animal studies

Animal studies have shown that high-fat diets reduce insulin sensitivity (Huang et al., 2004 Marotta et al., 2004), and that they may lead to damage of the pancreas and impaired insulin secretion (Huang et al., 2004). There are also data from animal studies that suggest that dietary fat quality may influence insulin action. Table 2.1 shows a summary of a selection of studies that have investigated the effects of different dietary fatty acids on markers of insulin action in animal models....

Energy balance

Body fatness is probably the principal modifiable risk factor for the development of diabetes and metabolic syndrome. Traditionally, hypocaloric diets intended for weight loss are high in CHO and low in fat. A common perception is that dietary fat of any kind is fattening, while low-fat diets have slimming properties. Thus, in spite of the accumulating evidence of the cardiovascular health benefits of diets high in MUFAs, nutrition experts are still reluctant to recommend them as an alternative...

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Mono per 5 Poly per 5 Carb per 5 Trans per 2 Fig. 1.4 Difference in observed risk for coronary heart disease when saturated fatty acids are iso-energetically replaced with monounsaturated fatty acids (Mono), polyunsaturated fatty acids (Poly), carbohydrates (Carb) or trans fatty acids (Trans). Data from the Nurses' Health Study (Hu et al., 1997). slightly superior. Replacing SAFAs with carbohydrates, i.e. lowering the total fat content of the diet, does not improve the total to HDL cholesterol...

Genetic influences on the uptake and absorption of cholesterol

Cholesterol is essential for all mammalian cells, and nearly all tissues of the body have the ability to produce cholesterol necessary for the formation of cell membranes. Cellular cholesterol requirements are met through de novo synthesis and uptake of plasma lipoproteins. In humans, plasma lipoproteins transport two sources of cholesterol cholesterol derived from diets and that endogenously synthesized by the liver and other tissues. While LDL seems to transport both dietary or...

Dietary fats and the risk of coronary heart disease 141 Epidemiological studies and clinical trials

Cardiovascular diseases comprise many different disorders related to impaired blood flow, including disease of the heart (mostly coronary heart disease), the brain (ischaemic and haemorrhagic stroke) and peripheral blood vessels (e.g. deep vein thrombosis). Effects of dietary fats on the risk of coronary heart disease have been most widely studied and are established by both epidemiological studies and randomised controlled clinical trials. Of all cardiovascular diseases, a causal relationship...

Adverse effects of fatty acids on glucose and insulin

An increased supply of free fatty acids (FFAs) has been identified as a possible factor in the development of insulin resistance. Although elevated FFA levels are considered to be typical of the fasted state, in the case of subjects consuming high-fat diets, overspill of fatty acids into the circulation, following the breakdown of circulating fat, results in elevated FFA levels within the fed postprandial state also. Since most subjects on Westernised diets are in an almost continuous...

Dietary fats obesity diabetes and cancer

This chapter focuses on the effects of SAFA and TFA on CHD risk, because the evidence is most extensive and strong for this relationship. However, SAFA and TFA may also have other health effects. Next to CVD, the most important chronic diseases in Western societies for which a role of dietary fats has been suggested are obesity (and the resulting diabetes) and cancer. There has long been and still is debate about the role of the total amount of fat in the diet in the aetiology of obesity (Katan...

Dietary monounsaturated fat and cancer

The great interest during the past several decades on the relationship between diet and cancer derives from the large variations on rates of specific cancer among countries, coupled with the dramatic changes in the incidence of these conditions among populations emigrating to regions with different rates. Mediterranean populations are known to be partially protected against coronary heart disease and certain types of cancers (Trichopoulou and Critselis, 2004 La Vecchia, 2004). Their dietary...

Pathways in the coordination of cellular glucose and fat metabolism

Fatty Acid Beta Oxidation Cpt1

The metabolism of fat and carbohydrate are closely linked optimal oxidation of fat and conservation of glucose occur in the fed state and the opposite in the fasted state. Current theory identifies two major biochemical pathways as central components of this integrated coordination of energy metabolism. These are the glucose-fatty acid cycle first described in 1963 Randle et al., 1963 and the malonyl CoA carnitine palmitoyl transferase CPT -1 pathway which was suggested by the studies of...

Effects of fatty acids on insulin signalling pathways

In addition to their possible effects on the coordination of energy metabolism, FFAs may also have effects on the critical actions of insulin through, for example, the insulin signalling cascade. This cascade is essential for insulin-stimulated responses such as insulin-stimulated glucose uptake. The signalling cascade involves tyrosine phosphorylation of the insulin receptor substrate 1 IRS-1 protein and thereby stimulation of phosphatidyl inositol 3 kinase PI-3 kinase activity which is...

Epidemiological studies of dietary fatty acids insulin sensitivity and diabetes

Although many epidemiological and human experimental studies have investigated the role of dietary fatty acids in coronary heart disease CHD , and on cardiovascular risk biomarkers such as cholesterol, there are only a limited number of human studies that have investigated the role of dietary fat, specifically, in the development of insulin resistance. A number of prospective studies have focused on associations between dietary fatty acid intakes or plasma and tissue fatty acid compositions in...

Relevance of fatty acid modulation of GSIS in the pathogenesis of insulin resistance and type 2 diabetes

While on the one hand fatty acid-mediated increases in insulin secretion may be important in ensuring adequate insulin release in situations where both FFA and glucose are elevated, on the other hand chronic over-exposure to fatty acids could lead to hypersecretion of insulin and hyperinsulinaemia. Boden 1997 propose that in non-diabetic and moderately insulin-resistant subjects, FFA stimulation of gluconeogenesis is counteracted by the FFA stimulation of insulin secretion, and is thereby an...

LDL particle size

One of the untoward consequences of a prolonged residence time of TAG-rich lipoproteins in the circulation is enhanced lipid exchange between lipoprotein classes, leading to cholesterol depletion of LDL. These lipoprotein particles small, dense LDL, as opposed to large, buoyant LDL are prone to oxidation and enter the arterial wall more readily than larger particles, accelerating the development of atherosclerosis. LDL particle size and subclass pattern might be influenced by dietary fat. Until...