More than twelve million people worldwide die annually from CVD, which is now the leading cause of death in Europe (British Heart Foundation Statistics, 2004). The most important type of CVD, in terms of mortality and morbidity, is CHD. Elevated total cholesterol (TC), LDL-cholesterol and triacylglycerols (TG) and low HDL-cholesterol are associated with an increased risk of coronary events (Kannel et al. 1979; Martin et al. 1986; Assmann et al. 1996; Austin et al. 1998). It is well accepted that even small changes in blood lipid profiles can have important benefits for public health. A decrease in TC is associated with a reduction in the risk of CHD for all age-groups (Law et al. 1994). In general, a 1% decrease in TC is associated with a 1–2% reduction in risk. Furthermore, a 1% decrease in LDL-cholesterol has been estimated to reduce the risk of major coronary events by 1·7% (4S study; Pedersen et al. 1998). Moreover, the relationship between the risk of heart disease and blood cholesterol levels is continuous and shows no threshold effect (MRFIT study; Dolecek, 1992).
Data from long-term primary and secondary intervention studies show that the risk of CHD is reduced when individuals change from a diet high in saturated fats to one high in PUFA (Dayton & Pearce, 1969; Leren, 1970; Turpeinen, 1979; Hjermann et al. 1981; Miettinen et al. 1983; Jousilahti et al. 1998). Four large prospective cohort studies have shown a protective effect of total PUFA on CHD risk (Dolecek, 1992; Ascherio et al. 1996; Hu et al. 1997; Pietinen et al. 1997). The Nurses' Health Study (Hu et al. 1997), for example, indicates that replacement of 5% of the energy from saturated fatty acids (SFA) by PUFA could lower the risk of heart disease by 46%. Part of the effect is almost certainly as a result of the beneficial effects on the blood lipid profile. However, it is not clear what proportion of the effect is attributable to the decrease in SFA or to the increase in PUFA.
SFA and unsaturated fatty acids have different effects on the balance of cholesterol-carrying lipoproteins in the blood (Keys, 1965; Hegsted et al. 1993; Clarke et al. 1997; Howell et al. 1997; Finnegan et al. 2003; Mensink et al. 2003). Several studies have evaluated the effectiveness of blood-cholesterol-lowering diets high in PUFA and low in SFA on coronary morbidity and mortality (Dayton et al. 1969; Leren, 1970; Turpeinen et al. 1979; Miettinen et al. 1983; Frantz et al. 1989). Overall, these studies have shown that diets low in SFA (8–9% energy) and high in PUFA (14–21% energy) reduce LDL-cholesterol levels by 13–15%, which is associated with a 25–43% reduction in CHD events. In general, SFA increase TC, LDL-cholesterol and TG, while MUFA and PUFA decrease TC, LDL-cholesterol and TG. Although both PUFA and MUFA lower TC:HDL-cholesterol, the effect of PUFA on TC and LDL-cholesterol is slightly superior to that of MUFA.
Worldwide mortality from heart disease is expected to continue to increase as a result of the ageing of the population and lifestyle changes linked to urbanisation, industrialisation and globalisation (World Health Organization, 2003). Physicans and healthcare professionals recommend individuals to change their diet to be low in saturated and trans-fats and higher in unsaturated fats to reduce their risk of CHD. Food manufacturers can contribute to this change by modifying the composition of food products. The present paper will review how advances in modern fat technology have allowed, for example, Unilever to update margarine and spread compositions in line with the latest scientific evidence.
Hippolyte Mège-Mouriès invented margarine in 1869 as a butter substitute. The Jurgens family purchased the patent 2 years later and started to manufacture margarine. At this time The Netherlands did not have patent legislation, thus it did not take long before a local competitor, van den Bergen, also started to produce margarine. After years of fierce competition the companies joined forces, resulting in a merger and the start of the Margarine Union in 1927. The Margarine Union signed an agreement with Lever Brothers 2 years later and became Unilever. The original beef-fat and milk recipe was adapted as new fats became available or cheaper and as a result of new technologies, such as fat hydrogenation and refrigeration. The drive behind these early innovations was to benchmark margarine with butter, both in appearance, structure, flavour and nutrition. Margarine was formulated to contain a similar level of fat, vitamin A and vitamin D to butter.
In the 1960s physicians and healthcare professionals began to recommend the use of oils rich in PUFA in order to decrease the saturated fat intake of patients with heart disease. However, individuals found it difficult in practice to exchange SFA for PUFA fats in their diet. Physicians, health care professionals and governmental organisations in The Netherlands concluded that there was a need for intervention at a population level and approached Unilever about the development of a margarine that was low in SFA but high in PUFA.
To make a margarine that was low in SFA but high in PUFA was a technical challenge for the food industry, as the particular fatty acids in margarine are an integral part of the structure of the product. Margarine is an emulsion of small water droplets in liquid oil stabilised by a structure of solid fat crystals (see Fig. 1). The solid fat crystals form a sponge-like structure that holds the oil in the product. The amount of solid fat crystals and their size, shape and mutual interaction, will influence the structure, hardness and texture of the product.
Many fats and oils from seeds, such as soyabean oil, sunflower-seed oil and rapeseed oil, are high in PUFA and low in SFA (see Fig. 2). However, these oils are too low in solids in the temperature range 10–35°C to give consistency to margarine. Tropical oils such as palm oil, palm-kernel oil and coconut oil are higher in solids but they are also high in SFA. Alternatively, by altering the solid-phase characteristics of the oil (see Fig. 1), a low-SFA oil can be modified to provide more solids. The melting point of unsaturated oils and fats can be increased with hydrogenation, a process that converts unsaturated C=C bonds in the fatty acid groups of the TG to saturated C – C bonds, i.e. turning an unsaturated fat into a saturated fat. It was subsequently found that if the reaction is stopped when only some of the double bonds have reacted with H2 (partial hydrogenation) the products have different extents of saturation. Thus, the selection of the oil or fat, controlling the extent of saturation and optimising processing conditions such as H2 pressure, oil temperature, the choice of the catalyst, gives the partial hydrogenation technique the flexibility to produce fat-phase components with the desired characteristics from a range of oils. By applying this technology Unilever scientists were able to use a minimum of solid fat (SFA) to structure a maximum level of PUFA-rich liquid oil.
In 1960 Unilever developed the first blood-cholesterol-lowering product, Becel, which contained 50–55% PUFA and could be used in place of butter in the diet. Originally, the product was distributed via pharmacies and during the first 3 years it could only be bought on medical prescription.
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