MICA: Reducing cardiovascular disease risk through replacement of saturated fat in milk and dairy products

Within the UK, Europe and North America heart disease is the major cause of ill health and death. Diet has an important impact on heart disease risk and studies have shown that good dietary habits at a young age and throughout the lifespan can reduce the excessive economic and social burden associated with heart disease, by helping to prevent or delay its development. The Department of Health has dietary recommendations to reduce disease risk, principally a reduction in total saturated fat (hard fats found in processed and animal derived foods) intake. However currently, the UK population considerably exceeds this saturated fat target. Milk and milk products are one of the largest sources of dietary saturated fat, contributing about 30% of the total with cheese and butter contributing most. A common strategy to reduce saturated fat intake is to advise reduction or removal of milk and dairy products from the diet. However milk is an important food providing essential nutrients such as calcium, B vitamins and iodine, particularly important for children, young women and older adults and their reduction may lead to detrimental effects on nutritional status and health. In addition, evidence suggests that there are likely to be benefits of increased dairy food consumption such as milk in terms of lower blood pressure, reduced incidence of heart disease and some cancers, although there is limited evidence for cheese and butter. Thus simply reducing milk intake to reduce saturated fat consumption is likely to be counterproductive. Studies with humans where blood cholesterol has been measured suggest that replacing a proportion of the saturated fat in the diet with mono or polyunsaturated fats (typically found in vegetable oils) does improve their cardiovascular health value. There is now good evidence that changing the diet of the dairy cows can provide a sustainable means of producing milk with reduced saturates and increased monounsaturates, although because of the complex nature of dairy foods it cannot be simply assumed that such modified foods will reduce the risk of heart disease. Such changes to the diet of the dairy cow may also have environmental benefits as they are likely to reduce the amount of methane (a potent greenhouse gas) produced by the cow thus reducing the carbon footprint associated with milk production. This project will examine the health benefits of such modified milk and dairy products in controlled human and laboratory studies using traditional and new methods of assessing heart disease risk. In the first part of the project, dairy products with reduced saturated fats and increased monounsaturated fats will be produced by changing the cow's diet. A detailed human study will then be undertaken to assess the long and short-term effects of including these dairy products in the diet and individual meals. New, more valuable methods of assessing changes in the risk of heart disease will be included as these are thought to be more predictive than the traditional approaches relying on blood cholesterol. In the third part of this project we will complement the human studies by determining in the laboratory how the modified milk and commercial dairy products influence the health of human blood vessels, such as those found in the heart. Any benefits arising from this work will inform public health policy on optimum dietary strategies to prevent or delay the onset of heart disease.

UK exceeds dietary targets for SFA recommended for CVD risk reduction. Milk/milk products are one of the largest sources (30% of total SFA). Recent data show likely benefits of increased milk consumption in reduced CVD risk thus consuming less milk/products to lower SFA intake may be counterproductive. Recent studies by our group (funded by BBSRC DRINC) show the potential of dairy cow nutrition to produce reduced SFA and increased cis-MUFA milk in a sustainable fashion. The hypothesis that consumption of such low-SFA dairy foods will reduce CVD risk in those at increased risk, compared with normal dairy foods, via mechanisms to increase secretion of endothelial-derived vasodilators will be tested. Initially, reduced SFA/enhanced cis-MUFA milk, cheese and butter will be produced by cow dietary changes. These modified foods will be used in double-blind, randomised, controlled, crossover chronic and acute studies with adults at increased CVD risk (n=54) to assess their effects in the background diet (12-weeks) and in test meals on biomarkers of CVD. These will include traditional (lipids and blood pressure) and novel markers (vascular function, determined by flow mediated dilatation and stiffness, pulse wave velocity), postprandial lipids, biomarkers of inflammation and vascular function (cellular adhesion molecules, endothelial progenitor cells). Furthermore, this project will use a co-culture system (human aortic smooth muscle cells overlayered with endothelial cells) which more closely mimics physiological systems, to examine the responses to plasma isolated during the acute postprandial studies on gene expression and protein levels of biomarkers of vascular function and endothelial vasodilators (including nitric oxide), providing a novel insight into mechanisms of action of low-SFA dairy products. These studies will provide unique evidence to inform public health policy on sustainable food-based dietary recommendation for CVD risk reduction.

Given the widespread consumption of milk and dairy products and the fact that they are major contributors of saturated fatty acids (SFA) in the diet, this work will have a significant impact on a wide range of beneficiaries as diverse as the general public, food production and retailing industries, the NHS and UK agriculture. Modification of milk fat composition as proposed would remove some 70,000 tonnes/year of SFA from the UK food chain. This would be a true removal rather than a movement of the SFA into other food chain entry points. Key beneficiaries include:
The public: This research will impact on the development of novel dietary and food-based strategies to reduce the risk of CVD. CVD remains the main cause of mortality and morbidity in the UK/EU and the US and is rapidly becoming a major issue in countries such as China. It has major effects on quality of life. The public would thus benefit directly from the reduced CVD risk, but also financially since less public finance would be needed for health care. CVD is estimated to cost the EU economy directly and indirectly some 200 billion EUR per year and thus even small reductions in CVD risk would have major implications on health care costs.
The consumer: Availability of SFA reduced dairy products would give consumers of all ages greater healthy food choices, without the need for dairy food exclusion.
The NHS: Diet, a major moderator of CVD risk will play an increasingly important role and lipid quality is a crucial aspect of diet. This work would make the achievement of dietary SFA reduction targets more likely leading to reduced CVD risk. This would relieve considerable pressure on the NHS both financially and resource-wise. Crucially the effect would start in childhood and would thus be preventative throughout adulthood reducing the need for pharmaceutical (e.g. statins) intervention later in life. It would provide health professionals, including dieticians, with new tools for designing healthy diets.
Food production and retailing industries: Milk and dairy companies will benefit from increased uptake of their products and retail companies will benefit from increased sales. Both will benefit from a healthy food image. This proposal includes a commercial partner Milk Link which is the UK's largest producer of cheese and supplies all major food retailers, food processors and food service organisations. It also manufactures a wide range of dairy products including long life milk and cream, extended shelf life products, flavoured milks and milk powders. Milk Link has recently announced a merger with Arla Foods and this will mean that Milk Link will become part of one of Europe's leading dairy co-operatives and dairy food producers. These companies will benefit directly from new knowledge gained from being involved in the research and in the longer term as outlined above. Moreover, as this project complements a current BBSRC/DRINC grant, feedback of findings etc will occur through DRINC members which includes major companies involved with dairy products including Danone, Kraft Foods, Nestlé, Marks and Spencer and Unilever.
UK Agriculture: Whilst an increase in food production is necessary as population size increases, this must be done in ways which are sustainable and recognise the need for foods to be healthy. This work will provide opportunities for UK agriculture to achieve these aims. It will increase the need to produce home grown rapeseed, a sustainable product which will provide UK dairy farmers with feed inputs which produce healthier dairy products at a reduced carbon cost.
Government and related policy making bodies: These bodies are responsible for UK diet and health policy. They will benefit from information which can feed into future dietary policy aimed at reducing CVD risk. It will allow them to promote good health and well being through staple food intervention and provide better understanding of the link between food production and consumer health.