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Introduction
Hypercholesterolemia is one of the main risk factors for cardiovascular diseases (CVDs) (Korpela et al. , 2006). Recent dietary guidelines recommend limiting the consumption of foods high in saturated fat and cholesterol to reduce the risk of CVD (Lecerf, 2009; Attuquayefio and Stevenson, 2015). CVD is the leading cause of death worldwide and its prevention continues to be a significant challenge (Karami, et al. , 2012; Siri-Tarino, et al. , 2010). The link between dietary fat and CVD risk has attracted much attention because the differential effect of fatty acids on gene expression has been established (Khodadadi, et al. , 2008). It is assumed that many of the atherogenic or cardioprotective effects of dietary fatty acids are mediated through the control of gene expression.
Milk fat is generally known as consistently enhancer of plasma cholesterol level (Haug et al. , 2007). Therefore, it is believed that the intake of high fat dairy products would be associated with CVD risk. However, inconsistent atherogenic effects with different severities have been reported by previous studies probably due to the use of different dairy products (Pereira, 2014).
High-fat dairy products such as butter increase serum cholesterol levels. Butter contains significant amounts of saturated long chain fatty acids including palmitic and myristic acid which are inducer of hypercholesterolemia and enhancer of low-density lipoprotein cholesterol (LDL-C) level more stronger than other fatty acids (Lecerf, 2009). Accordingly, lesser butter and saturated fatty acids (SFA) consumption has been recommended in different dietary guidelines although very recent prospective studies have questioned association between all types of SFA and CVD (Siri-Tarino et al. , 2010; Chowdhury et al. , 2014). In fact conflicting evidences have been reported on the correlation of high-fat dairy product and higher risk of CVD (Crichton et al. , 2010; Ohlsson, 2010; Hjerpsted et al. , 2011; Aune et al. , 2013). For instance, a very recent meta-analysis study by Engel and Tholstrup (2015) has shown no association between the intake of butter and CVD.
Usually the results obtained from investigations that utilized individual fatty acids are not exactly in line with the results of studies used habitual diets because ordinary foods contain several other nutrients which may synergistically or contrarily interfere with the effects of fatty acids. It is...