Several clinical studies have shown that plant stanol esters are effective agents that lower cholesterol. The ability to lower cholesterol with dietary plant stanol ester has been shown to be sustained for periods up to 12 months, but how soon the full cholesterol lowering effect of plant stanol esters can be obtained, is still unclear.
Plant sterols (also known as phytosterols) are found naturally in a range of plant sources. The term phytosterols covers plant sterols and plant stanols.
Phytosterols are plant sterols structurally similar to cholesterol that act in the intestine to lower Cholesterol absorption. They have been shown to lower cholesterol in studies using fat-containing foods, such as margarine or mayonnaise.
Vegetarians, particularly vegans, generally have the highest intakes of dietary phytosterols.
The highest concentrations of phytosterols are found in unrefined plant oils, including vegetable, nut and olive oils. Nuts, seeds, whole grains and legumes are also good dietary sources of phytosterols.
In most previous studies the vast proportion of reduction in cholesterol has been reported to occur within 2â€“3 weeks, but the effects of plant stanol esters probably appear sooner than that.
In one study the maximal cholesterol-lowering effect was obtained within a week of dietary plant stanol ester use. The authors concluded that low-fat yoghurt enriched with plant stanol esters lowers within 1 week LDL cholesterol to the same extent as oil-based products. (Atherosclerosis 2002, 160:205-213).
In another study of a specific patient group of colectomized (colon removal) patients, a significant reduction in blood serum cholesterol was found already after one day of stanol ester use but a steady state was reached within just one week. (Am J Clin Nutr 2000, 71:1095-1102).
However, as far as we know, short-term cholesterol-lowering effects of plant stanol esters have not been studied at several repeated time points within short period of time in a real target group for use of stanol ester-enriched products, i.e. hypercholesterolemic (high cholesterol) subjects.
Therefore, in the present study our aim was to find out the time needed to obtain the full cholesterol-lowering effect of plant stanol esters with a daily dose of 2.0 g stanols in healthy, hypercholesterolemic (high cholesterol) subjects.
Altogether 11 mildly to moderately hypercholesterolemic (high cholesterol) subjects (10 men and 1 women) were recruited to the study from subjects participated the former studies carried out at the Department of Clinical Nutrition, University of Kuopio in Finland.
The study lasted three weeks including six visits to the study unit. Participants started the study in two batches so that one started a week later than the other batch.
For 14 days the participants consumed the test margarine daily and during this period the fasting blood samples were taken at the beginning of the experimental period (0 day) and at days 4, 8 and 15 (meaning 3, 7 and 14 days after the initiation of test margarine consumption, respectively).
The main results of the present study with high cholesterol participants were that the significant decrease in blood serum LDL cholesterol concentrations was achieved already after one week of the initiation of stanol ester margarine consumption, and that no additional cholesterol-lowering effect was obtained between the 8th and 15th days. A cholesterol reduction of -9.9% and -10.2%, respectively.
Our findings agree with the findings of Mensink and collegues in which the full cholesterol-lowering effect was reached within one week with stanol ester use.
These results are also in line with the values of two weeks of our dose-response study, where blood serum LDL cholesterol was reduced significantly by 10.5%, 11.2%, 17.4% and 17.4% with the daily stanol dose of 0.8 g, 1.6 g, 2.4 g and 3.2 g respectively, compared to the control participants who consumed no plant stanols. (FASEB Journal 2002, 16:A609).
Our study can be criticized because of the lack of the control group. It is clear that the fatty acid modification contributes to the serum cholesterol reduction, but this takes place after a few week consumption.
Therefore, the changes in blood serum cholesterol concentrations in the present study can be ascribed to plant stanol ester use despite the lack of the control group.
Furthermore, these results can be ascribed to plant stanol ester use, since the compliance of subjects was good according to the follow-up diaries and weighted returned tubs.
In addition, the changes in blood serum plant sterol and stanol concentrations reveal the good compliance.
Moreover, our results are supported by results from the studies of Mensink and collegues (Atherosclerosis 2002, 160:205-213) and Miettinen and collegues (Scand J Clin Lab Invest 1981, 41:353-360).
The cholesterol lowering effect of plant stanol esters is based on their ability to inhibit cholesterol absorption effectively from the small intestine.
Structure-specific effects of individual phytosterol constituents have recently been shown where saturated phytosterols are more efficient compared to unsaturated compounds in reducing cholesterol levels. (Life Sci 1995, 57:195-206).
In the present study, blood serum phytosterol/total cholesterol ratio decreased significantly already within 4 days indicating that intestinal cholesterol absorption reduces rapidly after the initiation of the stanol ester consumption.
This supports the finding that the cholesterol-lowering effect of stanol esters appears very soon after the initiation of their consumption.
During the follow-up period the returning of blood serum cholesterol to the initial values began rapidly after termination of the consumption of plant stanol esters.
However, one week after study completion the LDL cholesterol value was still 5% lower than the initial value indicating that full return to the initial values after use of the plant stanol ester enriched-margarine does not take place within one week.
This finding supports the finding of previous studies in which the returning to baseline has been found to occur after two to three weeks of the termination.
Therefore, consumption of products enriched with stanol esters should be regular in order to receive sustainable cholesterol lowering effects.
In addition to that it should be taken into account that although a clinically significant benefit can be reached already within one week with plant stanol ester use, a steady state in blood serum cholesterol concentrations is usually attained within 3â€“4 weeks.
Therefore, blood serum cholesterol values are reasonable to follow for at least that time, especially if there is a need to match cholesterol-lowering drug therapy with the use of dietary plant stanol esters.
Extracted and adapted from: Maarit Hallikainen, Essi Sarkkinen, Ingmar Wester and Matti Uusitupa. Short-term LDL cholesterol-lowering efficacy of plant stanol esters. BMC Cardiovascular Disorders 2002, 2:14doi:10.1186/1471-2261-2-14. Â© 2002 Hallikainen et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the (http://creativecommons.org/licenses/by/2.0).
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