Clinical Hemorheology and Microcirculation 35 (2006) 251–255 IOS Press
251
Phytosterols in milk as a depressor of plasma cholesterol levels: Experimental evidence with hypercholesterolemic Portuguese subjects Sonia Gonçalves a,∗ , A. Vasco Maria b , A.S. Silva a , J. Martins-Silva a and C. Saldanha a a
Instituto de Biopatologia Química, Unidade de Biopatologia Vascular, Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, 1649-028 Lisboa, Portugal b Instituto de Medicina Preventiva, Faculdade de Medicina, 1649-028 Lisboa, Portugal Abstract. Plant sterols have been reported to decrease plasma concentrations of cholesterol without any side effects. To evaluate the effects on plasma cholesterol concentrations and the hemorheological parameters, we performed a study with hypercholesterolemic patients (n = 19) treated with phytosterol-enriched milk (2 g/day). Hypercholesterolemic patients (n = 15) of matched age drinking equal type of milk but without phytosterols were used as control group. Concentrations of total cholesterol, HDL-C, LDL-C and hemorheological parameters were measured in the beginning, after 15 and 30 days of milk intake. After 15 days of beverage intake, hypercholesterolemic subjects treated with phytosterol-enriched milk showed a significant decrease in plasma concentrations of total cholesterol and LDL-C by 9.62% (p < 0.05) and 12.20% (p < 0.05), respectively. After 30 days, a little increase in the total cholesterol and LDL-C concentrations were observed. In the hypercholesterolemic control group there were nonsignificant changes between plasma concentrations of total cholesterol, HDL-C and LDL-C during the study. The evaluation of plasma viscosity and erythrocyte aggregation shows no changes statistically significant during the study for both groups studied. The results obtained during the study show a positive effect with the phytosterol-enriched milk as plasma cholesterol-lowering as combined treatment for hypercholesterolemia. Keywords: Hypercholesterolemia, phytosterols, LDL-C, HDL-C, functional food, plasma viscosity, erythrocyte aggregation
1. Introduction Atherosclerosis is a complex process influenced by a group of risk factors, including the LDL-C concentration as the most important. Deposition of cholesterol, cholesterol esters and others lipids in the artery wall leads to narrowing and hardening of the artery, which in turn may lead to atherosclerosis and increased risk of forming blood clots (thrombosis) [1]. Trials using drugs therapy have demonstrated remarkable reductions in CHD events, especially in patients with hypercholesterolemia [2,3]. Recently, studies show that more robust reduction appears when the therapy is accomplished by increasing phytosterol consumption in the daily diet [1,4–6]. The mechanism of action is not clear, but it is accepted that phytosterols are thought to displace cholesterol from bile acid micelles and/or co-precipitate cholesterol in the intestinal lumen, thereby limiting its uptake [1,7]. *
Corresponding author. E-mail:
[email protected].
1386-0291/06/$17.00 2006 – IOS Press and the authors. All rights reserved
252
S. Gonçalves et al. / Phytosterols in milk as a depressor of plasma cholesterol levels
Cholesterol is a fatty substance that forms deposits in the blood vessel. Artery-clogging plaques may form when, among others factors, cholesterol concentrations become too high, so that blood vessels become blocked and are unable to supply blood to the heart or brain, triggering a heart attack or stroke. Plant sterols have been reported to decrease plasma concentrations of cholesterol without any side effects. The aim of this work is to show the effect of phytosterol milk containing in the lipid profile and hemorheological parameters of the subjects with hypercholesterolemia. 2. Materials and methods 2.1. Subjects and protocol Thirty-seven (aged 30–45 y) hypercholesterolemic patients (LDL cholesterol > 130 mg/dl) were selected. Nineteen subjects were treated with phytosterol-enriched milk (2 mg/day), the other eighteen were used as control group (milk without phytosterols). Both groups had drunk the milk during thirty days. In all cases, subjects were instructed to maintain the same dietary intake during the study. The hypercholesterolemic patients were advised to continue their prescribed medications. 2.2. Analysis Blood samples were collected from subjects before breakfast on days 0, 15 and 30 of the trial. Plasma concentrations of total cholesterol, HDL- and LDL-cholesterol were determinate. Plasma viscosity was measured with the Harkness method [8], and erythrocyte aggregation index (EAI) was determinate as reported before [9]. 2.3. Statistical methods The data were evaluated by using t-Student method (two tails paired with a level of significance P < 0.05). 3. Results For hypercholesterolemic patients the trial was performed using two groups: the hypercholesterolemic subjects treated with non-enriched milk (HNEM) and the hypercholesterolemic subjects treated with phytosterol-enriched milk (HPEM). Tables 1 and 2 show the results of lipid profile obtained for both groups after 15 and 30 days of milk intake, respectively. In the hypercholesterolemic group treated with non-enriched milk, no changes statistically significant were found in their total cholesterol, HDL-C and LDL-C concentrations after 15 and 30 days of beverage intake, i.e. the lipid profile was not significant altered during the trial. In the hypercholesterolemic group treated with phytosterol-enriched milk a significant reduction between the total cholesterol and LDL-C concentrations after 15 and 30 days of the milk intake was observed . Total cholesterol concentrations were significantly decreased from 245 mg/dl to 223 mg/dl after 15 days of phytosterol-milk intake and from 248 mg/dl to 229 mg/dl after 30 days of the trial. The results obtained after the evaluation of LDL-C concentrations shows significant differences after 15 and 30 days of milk intake. Diminishes from 156 mg/dl to 138 mg/dl after 15 days of milk intake were observed and
S. Gonçalves et al. / Phytosterols in milk as a depressor of plasma cholesterol levels
253
Table 1 Effect of non-enriched and phytosterol-enriched milk on mean of total cholesterol, HDL-, LDLcholesterol concentrations of hypercholesterolemic subjects after fifteen days of intake. i initial value, f final value Parameter Total cholesterol (mg/dl) HDL-C (mg/dl) LDL-C (mg/dl) ∗
P < 0.05, ∗∗ P > 0.05.
Non-phytosterol milk i253 ± 37∗∗ f 247 ± 34 52 ± 7∗∗ 52 ± 7 166 ± 31∗∗ 156 ± 28
Phytosterol milk 245 ± 37∗ 223 ± 33 63 ± 16∗∗ 58 ± 13 156 ± 37∗ 137 ± 36
Table 2 Effect of non-enriched and phytosterol-enriched milk on mean of total cholesterol, HDL-, LDLcholesterol concentrations of hypercholesterolemic subjects after thirty days of milk intake Parameter Total cholesterol (mg/dl) HDL-C (mg/dl) LDL-C (mg/dl) ∗
P < 0.05, ∗∗ P > 0.05.
Non-phytosterol milk i255 ± 38∗ f 239 ± 45 52 ± 8∗∗ 51 ± 9 166 ± 33∗ 146 ± 40
Phytosterol milk 248 ± 38∗ 229 ± 29 62 ± 15∗∗ 61 ± 14 157 ± 38∗ 143 ± 26
Fig. 1. Effect of non-enriched and phytosterol-enriched milk on mean of plasma viscosity in hypercholesterolemic subjects (NS no significative).
from 157 mg/dl to 143 mg/dl after 30 days of the trial. We also performed an evaluation of the plasma viscosity and erythrocyte aggregation index. The results obtained are shown in Figs 1 and 2. The initial plasma viscosity and EAI mean values are not significantly different between groups. After the evaluation of the hemorheological parameters a nonsignificant decrease was observed for both groups after the milk intake.
254
S. Gonçalves et al. / Phytosterols in milk as a depressor of plasma cholesterol levels
Fig. 2. Effect of non-enriched and phytosterol-enriched milk on mean of erythrocyte aggregation index in hypercholesterolemic subjects (NS no significative).
4. Discussion This study evaluated the effects of the milk enriched with phytosterols on the lipid profile and on the hemorheological parameters of hypercholesterolemic subjects. Many studies have reported spread breads and beverages as to be a good vehicle for the effective transport of phytosterols. In the present study hypercholesterolemic subjects treated with non-enriched milk show, after 15 and 30 days of administration, showed no change in their lipid profile. In contrast, the hypercholesterolemic subjects treated with phytosterol-enriched milk show, after 15 days of milk intake, reductions in the total cholesterol concentrations by 9.62% (p < 0.05) and 6.69% (p < 0.05) after 30 days of the trial. Reduction in LDLC concentrations was also obtained for this group, 12.20% (p < 0.05) after 15 days of milk intake and 8.68% (p < 0.05) after 30 days of treatment. Our results were consistent with earlier studies [6,10,11]. Phytosterols exhibit relatively little potential for toxicity because they are poorly absorbed [7,10,11]. Abnormalities in blood rheology, in particular elevated plasma fibrinogen level and blood viscosity, are regarded as a risk factor for the progression of atherosclerosis and for the occurrence of cerebrovascular diseases and ischemic heart diseases [12]. It has been reported that the values of hemorheologic parameters increase in patients with hyperlipoproteinemia. In the present study, hemorheological parameters were evaluated in order to find any adverse effects associated with the use of phytosterol-milk in the treatment of hypercholesterolemia. It has been established that in patients with ischemic heart disease the viscosity of the blood plasma and the aggregation activity of erythrocytes are increased, which increases the degree of circulatory disturbances. The hemorheological disturbance in patients with cardiovascular diseases is formed by changes in the protein, lipid, and electrolytic composition of the blood plasma [13]. This deterioration of the rheological properties of blood significantly influences the degree of microcirculatory disturbances and the development of complications of ischemic heart disease [13]. These abnormalities mentioned before were not observed during the present study. Not significant changes (decreases or increase) of plasma viscosity and EAI were observed after non-enriched and phytosterol-enriched milk therapy for the groups studied. As shown phytosterols have a potential cholesterol-lowering effect; their administration as dietary supplements in commercial products, as the milk, constitutes a non-pharmacological therapy to lower
S. Gonçalves et al. / Phytosterols in milk as a depressor of plasma cholesterol levels
255
blood cholesterol concentrations. Two main ways have been implemented in the treatment of hypercholesterolemia, dietary supplements and pharmacological agents (drugs). Here, we have demonstrated that phytosterols added to the milk have the property to interfere with cholesterol absorption, an effect especially important in the treatment of hypercholesterolemia but unfortunately without influences on hemorheological parameters. Acknowledgements This study was supported by grant from Lactogal S.A. of Portugal. We thank to Mrs. Carmo Fernandes, Mrs. Teresa Freitas and Mrs. Isabel Pedrinho for the technical support on and hemorheological parameters measurements. References [1] H. Tapiero, D.M. Townsend and K.D. Tew, Phytosterols in the prevention of human pathologies, Biomed. Pharmacotherapy 57 (2003), 321–325. [2] M. Shimizu, J. Koizumi, S. Miyamoto, H. Origasa and H. Mabuchi, Electrocardiographic events and cholesterol reduction with pravastatin in patients with hypercholesterolemia: the Hokuriku lipid coronary heart disease study – pravastatin atherosclerosis trial, Int. J. Cardiol. (2004), in press. [3] P.H. Jones, Low-density lipoprotein cholesterol reduction and cardiovascular disease prevention: the search for superior treatment, Am. J. Med. 116 (2004), 17S–25S. [4] M.H. Moghadasian and J.J. Frohlich, Effects of dietary phytosterols on cholesterol metabolism and atherosclerosis: clinical and experimental evidence, Am. J. Med. 107 (1999), 588–594. [5] M.H. Moghadasian, Pharmacological properties of plant sterols in vivo and in vitro observations, Life Sci. 67 (2000), 605–615. [6] N. Jong, M. Simojoki, T. Laatikainen, H. Tapanainen, L. Valsta, M. Latí-Koski, A. Uutela and E. Vartiainen, The combined use of cholesterol-lowering drugs and cholesterol-lowering bread spreads: health behavior data from Finland, Preventive Med. 39 (2004), 849–855. [7] W.H. Yokoyama, Plasma LDL cholesterol lowering by plants phytosterols in a hamster model, Trends Food Sci. Tech. 15 (2004), 528–531. [8] J. Harkness, A new instrument for measurement of plasma viscosity, Lancet 16 (1963), 280–281. [9] M. Rampling and G. Martin, A comparison of the myrenne erythrocyte aggregometer with older techniques for estimating erythrocyte aggregation, Clin. Hemorheol. 9 (1989), 41–46. [10] H.A.W. Neil, N.G.W. Meijer and L.S. Roe, Randomized controlled trial of use by hypercholesterolemic patients of a vegetable oil sterol-enriched fat spread, Atherosclerosis 156 (2001), 329–337. [11] A. Jong, J. Plat and R.P. Mensink, Metabolic effects of plant sterols and stanols (Review), J. Nutr. Biochem. 14 (2003), 362–369. [12] Y. Tsuda, K. Satoh, M. Kitadai, T. Takahashi, Y. Izumi and N. Hosomi, Effects of pravastatin sodium and simvastatin on plasma fibrinogen level and blood rheology in type II hyperlipoproteinemia, Atherosclerosis 122 (1996), 225–233. [13] N.A. Gorbunova, L.I. Ershova, Z.M. Likhovetskaya, G.N. Kurbanova, A.A. Postnikov and A.A. Bozhév, Hemorheology and erythrodieresis in patients with ischemic heart disease. Medical plasmapheresis, J. Eng. Phys. Thermophysics 76 (2003), 681–683.
View publication stats
