Fats So? Understanding The Metabolism Of Dietary Fats And Their Impact On Health
Published on 20 October 2009 in Food, health and wellbeing
Introduction
Inappropriate diets are seen as an important cause of heart disease, and may underlie up to 30% of deaths from this disease. The diets of people in Scotland and the north of England are perceived as less healthy than in the south and this factor has been suggested as one reason for higher death rates in the north.
Heart disease remains one of the major causes of premature death in the UK. Aside from debilitating effects on the quality of life it is also a major financial burden to the NHS and the economy. Moreover, the observed decline in heart disease incidence since the 1980s has slowed due to the increasing incidence of major risk factors, like obesity, hyperlipidaemia and diabetes mellitus.
Although treatments for heart disease continue to be developed and improved, the proportion of people dying from the most acute form of the disease (myocardial infarction or heart attack) remains high. Preventing heart disease must, therefore, remain our priority. Improving diet and lifestyle is a critical component of the strategy to decrease risk of getting heart disease in the population.
Key Points
Compelling evidence from metabolic studies, prospective cohort studies and clinical trials in the past decades indicates that at least 2 dietary strategies relating to fat intake are effective in preventing heart disease: substitution of non-hydrogenated unsaturated fats for saturated and trans-fats, and increasing the consumption of n-3 fatty acids from fish, fish oil supplements and plant sources. However, not all saturated fatty acids, trans-fatty acids or n-3 fatty acids are having similar effects on health outcomes, and thus we need to learn how individual dietary fatty acids, rather then classes of dietary fats, work.
The effects of diet on heart disease can be mediated through multiple biological pathways other than just elevating blood cholesterol levels, heightening the need to find more intermediate end points as markers of heart disease risk. We are currently developing such novel markers which could, for example, be assessed in blood or urine, and may be used to assess the effectiveness of dietary trials for the prevention of disease.
Research Undertaken
The understanding of how dietary compounds are likely to influence the risk of heart disease has grown substantially owing to studies investigating the molecular mechanisms that play a role in the development of heart disease, as well as the execution of carefully controlled dietary intervention studies.
However, although dietary lipids and fatty acids have been implicated in both cause and prevention of heart disease, their exact roles and mechanisms of action remain unclear. We aim to understand how dietary lipids such as those from fish and fish oils (n-3 fatty acids) or fatty acids present in dairy products (like conjugated linoleic acids or CLA) can influence the development of heart disease. By doing this we have learned that not all n-3 fatty acids from fish or fish oil work in a similar way. For example, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the most important n-3 fatty acids in fish and fish oil, differentially affect inflammation processes and blood platelet function in the human body.
Similarly, we found that different forms of CLA can have quite different effects. The form of CLA found in natural sources such as dairy products (cis9,trans11 CLA) may protects against plaque formation, decrease inflammation, improve insulin sensitivity and improve blood platelet function. Whereas another form of CLA (trans10,cis12 CLA), which is present in CLA supplements available over the counter and via the internet, may aggravate insulin insensitivity and plaque formation.
Policy Implications
The information we provide may facilitate the refinement of current nutrition guidelines on healthy fats and heart disease,
Assessing the beneficial or not so beneficial properties of dietary fatty acids (which are often major components of important Scottish food products) may eventually provide opportunities to produce novel food products that are processed to contain or not to contain such fatty acids.
Author
Dr. Baukje de Roos b.deroos@abdn.ac.uk
