6
2. Beta lipoprotein-high density lipoprotein HDL
HDL is produced separately in the liver and in charge of bringing back excess cholesterol from body cell to liver in order to be excreted Almatsier 2003. As the
lower cholesterol content and cholesterol disposal function, HDL cholesterol is often called as the good cholesterol.
Although cholesterol is sufficient from endogenous biosynthesis, dietary cholesterol also contributes to the so-called exogenous cholesterol. Exogenous cholesterol is cholesterol obtained
from the gastrointestinal absorption of the food consumed. Increased consumption of dietary cholesterol by 200-750 mg will increase blood cholesterol levels as much as 5.4 - 5.8 mmolL
Bender 2000. Most of the cholesterol in the blood comes from the synthesis in the body which is about 1 gday and 0.3 gday from food Harper et al. 1988; Clarenburg 2001; Bachorik et al. 2001.
Total blood cholesterol can be measured through several ways; either a complete blood test performed by medical professional or by using cholesterol home test kit. The examples of cholesterol
home test kit can be seen in Figure 2. Although the test is not able to identify the levels of each of the components such as LDL or HDL cholesterol accurately and the variability of result may be higher
than complete blood test, the American Heart Association 2010 stated that the measurement is considerably useful to screen the risk of developing cardiovascular disease. However, to determine
the levels of each composition of blood cholesterol and triglyceride, it is preferable to do complete blood test performed by medical professional.
Figure 2. Example of commercially available cholesterol home test kit
http:www.priceinspector.co.uk
C. PLANT STEROLS
Plant sterols PS are plant compounds with similar structure and biological functions as cholesterol Parish et al. 2002 in Akoh Min 2002. The differences of these two types of sterols are
located on the side chain configuration and the degree of saturation Clifton 2002. More than 250 types of plant sterols have been isolated from plants Piironen et al. 2000. Piironen further explained
that the most common types of plant sterols found in plants are β-sitosterol, campesterol, and
stigmasterol. Β-sitosterol is the most dominant type of plant sterols, constitutes of 56-79 of the
plant sterols total consumption. Sitosterol is used to synthesize steroid sitosterol. Meanwhile, campesterol and stigmasterol has a proportion of 18 and 9, respectively. Saturated plant sterols
derivatives, which are less abundant in nature, are called plant stanols. Plant stanols constitutes about
7
9 of the total proportion of plant sterols in diet Piironen Lampi 2004. The structure of cholesterol and certain unstaturated of plant sterols showed in Figure 3.
Figure 3. Chemical structures of cholesterol and plant sterols fitosterol sitosterol, campesterol, dan stigmasterol
Plant sterols present in varying amounts in different kinds of plant based food with the highest plant sterols content found in vegetable oils and cereals Piironen et al. 2000. Plant sterols
concentrations lower than 100 mg100 g found in oil fraction of coconut, palm, olive, and avocado, while moderate concentrations 100-200 mg100 g were found in peanut oil, soy, hemp, and
sunflower seed. Sesame, canola, and corn oil contain plant sterols in higher concentration, between 200-400 mg100 g Phillips et al. 2002. While crude vegetable oils contain the highest amount of
plant sterols, the refining process leads to somewhat lower plant sterols levels Piironen Lampi 2004.
In cereals, plant sterols are highly localized within the kernel, while the highest amount is contained in germ and bran Piironen Lampi 2004. Piironen and Lampi further explained that the
cereal derived products, plant sterols content also depend primarily on vegetable oils and other ingredients added. Meanwhile, fruits and vegetables contain plant sterols in lower levels than the
other groups less than 200 mgkg fresh weight, which might be due to their higher water content. Nevertheless, Normen et al. 1999 stated that the role of food in total plant sterols intake depends on
the dietary pattern and the way they consumed, which food with small amounts of plant sterols can also significantly contribute to the total intake if consumed in large quantities.
D. PLANT STEROLS IN CHOLESTEROL LOWERING
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