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

在英国、欧洲和北美，心脏病是导致健康不佳和死亡的主要原因。饮食对心脏病风险有重要影响，研究表明，在年轻时和整个生命周期良好的饮食习惯可以通过帮助预防或延缓心脏病的发展，减少与心脏病相关的过度经济和社会负担。卫生署提出了减少疾病风险的饮食建议，主要是减少饱和脂肪（加工食品和动物源性食品中发现的硬脂肪）的总摄入量。然而，目前，英国人口远远超过了饱和脂肪的目标。牛奶和奶制品是膳食饱和脂肪的最大来源之一，约占总量的30%，其中奶酪和黄油贡献最大。减少饱和脂肪摄入的一个常见策略是建议减少或从饮食中去除牛奶和乳制品。然而，牛奶是一种重要的食物，提供钙、B族维生素和碘等必需营养素，对儿童、青年妇女和老年人尤其重要，减少牛奶摄入可能会对营养状况和健康产生不利影响。此外，有证据表明，增加牛奶等乳制品的消费可能对降低血压、减少心脏病和某些癌症的发病率有好处，尽管对奶酪和黄油有益的证据有限。因此，简单地减少牛奶摄入量来减少饱和脂肪的消耗可能会适得其反。对人体进行的血液胆固醇测量研究表明，用单一或多不饱和脂肪（通常存在于植物油中）代替饮食中一定比例的饱和脂肪确实能提高心血管健康价值。现在有充分的证据表明，改变奶牛的饮食可以提供一种可持续的方式来生产减少饱和脂肪酸和增加单不饱和脂肪酸的牛奶，尽管由于乳制品的复杂性，不能简单地假设这种改良食品会降低患心脏病的风险。这种对奶牛饮食的改变也可能对环境有益，因为它们可能会减少奶牛产生的甲烷（一种强效温室气体）的数量，从而减少与牛奶生产相关的碳足迹。该项目将利用评估心脏病风险的传统和新方法，在受控的人体和实验室研究中检查这种改性牛奶和乳制品的健康益处。在该项目的第一部分，将通过改变奶牛的饮食来生产饱和脂肪减少和单不饱和脂肪增加的乳制品。随后将进行一项详细的人体研究，以评估在饮食和个人膳食中加入这些乳制品的长期和短期影响。新的、更有价值的评估心脏病风险变化的方法将被包括在内，因为这些方法被认为比依赖血液胆固醇的传统方法更具预测性。在该项目的第三部分，我们将通过在实验室中确定改性牛奶和商业乳制品如何影响人类血管（如心脏血管）的健康来补充人体研究。这项工作产生的任何好处都将为公共卫生政策提供最佳饮食策略，以预防或延缓心脏病的发作。

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.