Scholarly article on topic 'Hypolipidemic effect of fat spreads containing flaxseed oil'

Hypolipidemic effect of fat spreads containing flaxseed oil Academic research paper on "Agriculture, forestry, and fisheries"

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{Hyperlipidemia / Cholesterol / "Flaxseed oil" / "Fat spreads" / "Omega-3 fatty acid"}

Abstract of research paper on Agriculture, forestry, and fisheries, author of scientific article — M.A. El-Waseif, H.H. Abd El-Dayem, H.A. Hashem, S.A. El-Behairy

Abstract The hypolipidemic effect of fat spreads containing flaxseed oil (rich plant source of longchain omega-3 polyunsaturated fatty acid) represents the aim of the present study. Such effect was biologically evaluated through assessment of four biochemical parameters that reflect the blood serum lipid profile, namely total cholesterol, low- and high-density lipoproteins and triglyceride levels during a feeding experiment for 8 successive weeks using male albino rats. Eight fat spreads containing 20%, 40%, 60% and 80% total fat were used; of these, four spreads were formulated using palm and flaxseed oils while the other four treatments were prepared by palm and soybean oils at the same concentrations. Results showed that fat spreads containing flaxseed oil exerted reducing effect on total cholesterol, LDL levels, TC/HDL and LDL/HDL ratios at higher rates compared with those containing soybean oil or pharmaceutical product especially after 8weeks of feeding experiment. Levels of HDL in animals administered the studied fat spreads were lowered at significant to insignificant different rates. Flaxseed oil exerted its beneficial effect when it was incorporated into formulation at high amounts since G6 (FPB3, containing 29.5% flaxseed oil) and G8 (FPB4, containing 39% flaxseed oil) animal groups exerted higher/comparative levels of HDL after 8weeks of feeding compared to the initial concentration. Concerning triglycerides levels, all studied groups (except G8, FPB4) and controls showed significant higher levels at the end of feeding experiment compared to initial concentration. On the other hand, animals received the highest% of flaxseed oil (G8, FPB4) exerted its healthy effect as triglycerides levels were decreased from 104.3mg/dL at zero time to 92.7mg/dL after 4weeks of feeding with decreasing rate of 11.1%, another reducing effect was noted after 8weeks as triglycerides levels were significantly decreased to 79.7mg/dL (decreasing rate of 23.6%).

Academic research paper on topic "Hypolipidemic effect of fat spreads containing flaxseed oil"

Annals of Agricultural Science (2014) 59(1), 17-24

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Faculty of Agriculture, Ain Shams University Annals of Agricultural Science

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ORIGINAL ARTICLE

Hypolipidemic effect of fat spreads containing flaxseed oil

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M.A. El-Waseif a *, H.H. Abd El-Dayem a, H.A. Hashem a, S.A. El-Behairy b

a Department of Food Science and Technology, Faculty of Agriculture, Al-Azhar University, Nasr City, Cairo, Egypt b National Organization for Drug Control and Research, Giza, Egypt

Received 2 September 2013; accepted 13 March 2014 Available online 6 August 2014

KEYWORDS

Hyperlipidemia; Cholesterol; Flaxseed oil; Fat spreads; Omega-3 fatty acid

Abstract The hypolipidemic effect of fat spreads containing flaxseed oil (rich plant source of long-chain omega-3 polyunsaturated fatty acid) represents the aim of the present study. Such effect was biologically evaluated through assessment of four biochemical parameters that reflect the blood serum lipid profile, namely total cholesterol, low- and high-density lipoproteins and triglyceride levels during a feeding experiment for 8 successive weeks using male albino rats. Eight fat spreads containing 20%, 40%, 60% and 80% total fat were used; of these, four spreads were formulated using palm and flaxseed oils while the other four treatments were prepared by palm and soybean oils at the same concentrations. Results showed that fat spreads containing flaxseed oil exerted reducing effect on total cholesterol, LDL levels, TC/HDL and LDL/HDL ratios at higher rates compared with those containing soybean oil or pharmaceutical product especially after 8 weeks of feeding experiment. Levels of HDL in animals administered the studied fat spreads were lowered at significant to insignificant different rates. Flaxseed oil exerted its beneficial effect when it was incorporated into formulation at high amounts since G6 (FPB3, containing 29.5% flaxseed oil) and G8 (FPB4, containing 39% flaxseed oil) animal groups exerted higher/comparative levels of HDL after 8 weeks of feeding compared to the initial concentration. Concerning triglycerides levels, all studied groups (except G8, FPB4) and controls showed significant higher levels at the end of feeding experiment compared to initial concentration. On the other hand, animals received the high-est% of flaxseed oil (G8, FPB4) exerted its healthy effect as triglycerides levels were decreased from 104.3 mg/dL at zero time to 92.7 mg/dL after 4 weeks of feeding with decreasing rate of 11.1%, another reducing effect was noted after 8 weeks as triglycerides levels were significantly decreased to 79.7 mg/dL (decreasing rate of 23.6%).

© 2014 Production and hosting by Elsevier B.V. on behalf of Faculty of Agriculture, Ain Shams

University.

* Corresponding author. Tel.: +20 01004951889. E-mail addresses: m_elwaseif@yahoo.com, melwaseif@gmail.com (M.A. El-Waseif).

Peer review under responsibility of Faculty of Agriculture, Ain-Shams University.

Introduction

Hyperlipidemia, also known as hyperlipoproteinemia or dyslipidemia, is an abnormal elevation of lipid levels in the blood stream. These lipids include cholesterol, cholesterol

http://dx.doi.org/10.1016/j.aoas.2014.06.003

0570-1783 © 2014 Production and hosting by Elsevier B.V. on behalf of Faculty of Agriculture, Ain Shams University.

compounds, phospholipids and triglycerides, all carried in blood as large molecules called lipoproteins. There are three types of hyperlipidemia namely hyperlipoproteinemia (elevated levels of lipoprotein in blood), hypercholesterolemia (high cholesterol) and hypertriglyceridemia (high triglycerides level in blood). Hyperlipidemia affects lipid production, transportation in blood stream and/or deposition in body cell (Carrero et al., 2004; Sies et al., 2005).

Increased consumer awareness of diet and health has resulted in higher demand for functional foods. In fat spreads market, two trends are emerging, i.e. enrichment with omega-3 fatty acids and the reduction in trans fatty acids (TFAs). However, there are currently significant technical gaps in the effective delivery of both omega-3 fatty acids and spreads which are genuinely low in trans fatty acids (Timon, 2010). The spread fat industry is working diligently in creating new varieties of spread fats that will produce more healthful fat.

Intake of high amounts of TFAs has been positively correlated with increased risk of coronary heart disease, inflammation, and cancer (Pande and Akoh, 2013). The major dietary sources of TFAs are products formulated with partially hydro-genated fats such as margarines, shortenings, bakery products, and fast foods (Wahle and James, 1993; Willet et al., 1993). The oils rich in polyunsaturated fatty acids (PUFAs) cause a decrease in "bad" cholesterol and triglycerides concentrations. Also, the omega-3 (rn-3) fatty acids (such as linolenic acid) in oils can increase the level of circulating good cholesterol (Khan et al., 2010).

Ng et al. (1992) and Choudry et al. (1995) declared that palm olein and olive oil have similar beneficial cholesterol modulating effects in protecting humans against cardiovascular diseases. Palm olein (rich in both fatty acids C16:0 and C18:1 represents about 40% and 43% of total fatty acids, respectively) and olive oil (rich in C18:1 fatty acids, about 77% of total fatty acids) have comparable effects on total cholesterol, low- and high-density lipoproteins cholesterol (LDL and HDL) as well as LDL/HDL ratio.

Omega 3-fatty acids have a high nutritional status, its consumption has been reported by Tou et al. (2011) to improve health by reducing the risk of cardiovascular disease, obesity, diabetes, inflammation, and several neurological diseases. But their use in food products is limited due to their susceptibility to lipid oxidation (Choo et al., 2007). Also, fish oil (as source of omega-3) incorporation into fat spreads (especially at high %) resulted in increasingly fishy flavor and decreased sensory quality (Kolanowski et al., 2004).

Lipid flaxseed composition makes it an important source of omega 3 fatty acids, especially a-linolenic acid (ALA) which may constitute up to 52% (Gutierrez et al., 2010) and 59.02% (El-Waseif et al., 2013) of the total fatty acids. Morris (2006) stated that flaxseed oil is a potentially vegetable important source of omega-3 as it is relatively stable to oxidation compared to fish oils.

Consumption of food products (such as fat spreads) enriched with flaxseed oil as a source of omega-3 PUFA represents an easy delivery system of such fatty acids into the human body and significantly improves the level and profile of PUFA in the diet and in human body tissues. In addition, Grune et al. (2001) and Grundt et al. (2003) demonstrated that the bioavailability of omega-3 from enriched intake was comparable with the bioavailability of the acids from capsule supplements.

As recommended by the American Heart Association, beneficial health effects could be gained for people with high triglycerides (blood fat) when they were supplemented with 1.5-3 g of flaxseed oil per day, the increased use of omega rn-3 fatty acids is a powerful example of one such nutritional therapeutic strategy that may produce significant cardiovascular benefits (Kris-Etherton et al., 2003; Rodriguez et al., 2010).

The present study was designed to evaluate the effect of oral ingestion of edible spreadable fats containing flaxseed oil (at four different concentrations) on blood serum lipid profile. Four parameter levels, namely total cholesterol, HDL, LDL and triglycerides during feeding experiment for 8 weeks using albino rats, were measured.

Materials and methods

Materials

Refined, bleached and deodorized palm and soybean oils were obtained from Arma Food Industries, 10th of Ramadan City, Egypt. Flaxseeds (Linum usitatissimum L.), variety Sakha 1, free from garden cress and weed seeds were obtained from Fiber Crops Research Section, Field Crops Research Institute, Agriculture Research Center, Giza, Egypt. Other materials used as additives including stabilizers (corn starch, sodium alginate and whey protein powder); emulsifying agents (skimmed milk powder, soybean lecithin and glycerol monos-tearate); antioxidant (ascorbyl palmitate); preservative (potassium sorbate) and flavor (butter flavor) were used in formulation of fat spreads.

Methods

Extraction of flaxseed oil

Flaxseed oil was extracted from crushed seeds using a hydraulic press (10,000 Lb/inch2 for 1 h at room temperature) as described by Ustun et al. (1990). The resultant oil was filtered through a fine cloth, filled in dark brown bottles and stored at deep freezing temperature (—18 0C) until use.

Preparation of fat spreads

Eight fat spreads (blends) containing 20%, 40%, 60% and 80% total fat were formulated, according to procedures of Cheng et al. (2008) and Lumor et al. (2010) with minor modifications. El-Waseif et al. (2013), in previous work, described the details of formulation procedure followed. Four treatments were formulated using palm and flaxseed oils, the other four treatments contained palm and soybean oils (as a control treatments).

Biochemical experiment

Animals and negative control treatment

Sixty-six adults male albino rats (body weight 120-140 g); obtained from the farm of National Organization for Drug Control and Research, Giza, Egypt; were housed in screen bottomed aluminum cages in rooms maintained at 25 ± 1 0C with alternating cycles of light and dark of 12 h duration. The rats were fed on the control diet basal diet (composed of; g/100 g diet; casein 10.0, cotton seed oil 5.0, salt mixture 4.0, vitamin mixture 1.0 and maize starch as carbohydrate source, 80.0).

Salt mixture was consisted of (g/1Kg): CaCo3 (543.0), MgCo3 (25.0) MgSo4 (16.0) NaCl (69.0) KCl (112.0) KH2Po4 (212.0) FePo4 4H2O (20.50) KI (0.08) MnSo4 (0.35) Naf (1.00) Al2(So4)3 K2So4 (0.17) Cusou (0.90) (Mendel and Wakeman, 1937). Vitamin mixture (Campell, 1961) composed of (per ech kg of basal diet): vit. A (200 I.U.), vit. D (100 I.U.), vit. E (10 I.U.), vit. K (0.5 mg), choline chloride (200 mg), inositol (25 mg), niacin (4mg) thiamine (0.5 mg), riboflavin (1.0 mg), pyridoxine (0.4 mg), pantothenic (0.4) P. amino benzoic acid (10.0 mg), B12 (2.0 mg), biotin (0.02 mg) folic acid (0.02 mg) and cellulose to make 1 kg. The diet was freshly prepared every week and was stored in a refrigerator at 10 0C.

After seven consecutive days of feeding on basal diet (adaptation period), the blood samples (—ve control treatment) were withdrawn from retro bulbar venous plexus of each rat following the procedure of Schermer (1967). Collected blood sample was placed in a dry and clean centrifuge tube and allowed to clot (undisturbed) for 1-2 h at 37 oc. The serum was removed using a Pasteur pipette and centrifuged for 10 min. at 3000 r.p.m. to remove any suspended red blood cells. The clean nonhemolyzed supernatant serum was pipetted into a Wassermann tube and kept at freezing temperature (—18 oc) until analysis.

Induction of hyperlipidemia

According to Gone et al. (1989), hyperlipidemia in rats was done by feeding on an animal high fat diet contained 20% coconut oil and 1% cholesterol, the used high fat diet contained cholic acid (0.5%) to enhance the central absorption of lipids. After 2 months of feeding, the occurrence of hyper-lipidemia was assessed by determining the lipid parameters in blood serum of treated animals.

Feeding experiment

Hyperlipidemic rats were randomly classified into eleven equal groups (each comprises 6 rats) in addition to the negative control group. Rats were treated for 8 weeks by nine different formulas as follows:

1. Negative control (basal diet) (—ve).

2. Positive control group ( + ve).

3. SPB1 = Soybean-Palm oils blend (20%).

4. FPB1 = Flaxseed-Palm oils blend (20%).

5. SPB2 = Soybean-Palm oils blend (40%).

6. FPB2 = Flaxseed-Palm oils blend (40%).

7. SPB3 = Soybean-Palm oils blend (60%).

8. FPB3 = Flaxseed-Palm oils blend (60%).

9. SPB4 = Soybean-Palm oils blend (80%).

10. FPB4 = Flaxseed-Palm oils blend (80%).

11. Pharmaceutical product (contains 1000 mg of fish oil; EPA (Eicosapentaenoic acid), C20:5 omega-3 and DHA (Docosahexaenoic acid), C22:6 omega-3, 30%).

Fat spreads were given orally to the ratat a daily dose of (1.8 g/kg of body weight) throughout the feeding period (8 weeks). During such period, rats were individually weighted and blood samples were collected at time intervals of 0, 4 and 8 weeks.

Determination of serum lipid parameters

According to Tzang et al. (2009) serum lipid parameters, namely serum total cholesterol (TC), triacylglycerol (TAG), and high density lipoprotein cholesterol (HDL) were measured by using commercial kits (Randox Laboratories Ltd., Antrim, UK, BT294QY). For HDL, serum was precipitated by addition of phosphotungstic acid in the presence of magnesium ions. After centrifugation (3000 g for 10 min), the cholesterol concentration in HDL fraction was determined by using the TC commercial kit (Randox Laboratories Ltd., Antrim, UK, BT294QY). Those methods are based on measuring of colored end-products at 500 nm. LDL concentration was calculated according to the formula of Beena and Prasad (1997).

Statistical analysis

One-way analysis of variance using SPSS 16.0 for windows was performed on all experimental data sets. Post-hoc multiple comparisons were carried out by Duncan analysis to determine significant differences between sample means at 5% level.

Results and discussion

When lipid levels in the blood serum were abnormally elevated, it is important to bring such levels under control. This is done more safely with changing dietary habits by increasing the consumption of diets low in total fat, saturated and cholesterol. The present study was aimed to evaluate the influence of flaxseed oil supplemented dietary on experimentally induced hyperlipidemia in rats. Eight formulated fat spreads containing different percentages of total fat %s (namely 20%, 40%, 60% and 80%) were tested as lowering agents for hyperlipidemia in the rats. Tested animals were orally ingested the fat spread at dose equivalent to the dose recommended by Kris-Etherton et al. (2003) for human beings (1.5-3.0 g/day). The effect of each spread was evaluated by assessment of total cholesterol, HDL, LDL and triglycerides concentrations in blood serum of manipulated animals in comparison with pharmaceutical preparation of omega-3.

Body weight

The hyperlipidemic rats and the manipulated groups were weighted at the beginning (initial weight) and after 8 weeks of feeding. The results are summarized in Table 1.

Tested rats showed varied values of average initial weight ranged between 125.3 and 154.3 g (Table 1). Significant (P < 0.05) increases in body weight of all studied rats (at varying %s) were observed since their average values were reached to 157.0-187.5 g at the end of feeding experiment.

In comparison with the initial body weight, average weight of hyperlipidemic fed rats (+ control, G10) was increased by 21.64% at the end of feeding experiment. While the negative control group (G11) exhibited an increase by only 5.51% in the same period. Simultaneously, weight of hyperlipidemic and manipulated rat groups was increased significantly at different levels (18.34-35.0%) as a result of applying the feeding program. Positive control group (G10) as well as rats belonged to G9 group (received the pharmaceutical product contains fish oils, EPA and DHA by 81 mg 1 day as recommended by

Table 1 Average body weight gain of rats fed as affected by fat spread formulations for 8 weeks.

Treatment Initial body weight* (g) Body weight after 8 weeks* (g) Body weight gain (%)

Negative control (-) (G11) 148.8 ± 6.01b 157.0 ± 5.51a 5.51

Positive control ( + ) (G10) 129.4 ± 5.17b 157.4 ± 5.17a 21.64

Pharmaceutical product (G9) 152.7 ± 1.60b 180.7 ± 1.60a 18.34

SPB1 (G1) 148.6 ± 10.48b 182.3 ± 10.27a 22.68

FPB1 (G2) 141.0 ± 13.31b 173.5 ± 10.71a 23.05

SPB2 (G3) 154.3 ± 11.62b 187.5 ± 9.91a 21.52

FPB2 (G4) 149.7 ± 6.86b 177.2 ± 19.83a 18.37

SPB3 (G5) 130.0 ± 11.22b 175.5 ± 5.73a 35.00

FPB3 (G6) 125.3 ± 10.01b 166.4 ± 8.12a 32.80

SPB4 (G7) 126.0 ± 17.84b 166.9 ± 11.58a 32.46

FPB4 (G8) 125.3 ± 10.09b 162.1 ± 13.42a 29.37

Values with different small letters in the same row are significantly different (P < 0.05). % was calculated relative to the initial. SPB1 = Soybean-Palm oils blend (20%). SPB2 = Soybean-Palm oils blend (40%). SPB3 = Soybean-Palm oils blend (60%). SPB4 = Soybean-Palm oils blend (80%). FPB1 = Flaxseed-Palm oils blend (20%). FPB2 = Flaxseed-Palm oils blend (40%). FPB3 = Flaxseed-Palm oils blend (60%). FPB4 = Flaxseed-Palm oils blend (80%). Each value represents the mean weight of 6 rats ± SD.

its pamphlet) increased in weight by 21.64 and 18.34%, respectively, while rats of other groups fed on fat spreads showed comparable higher %s (18.37-35.0%). Among rat groups received tested fat spreads, G5 (SPB3) group exerted the highest increase % (35.00%). On the other hand, the lowest increase level was found for G4(FPB2) group (18.37%).

In general, body weight gain of rat groups fed on high fat diet was increased at higher levels compared to those fed on basal diet. Rats administered fat spreads containing flaxseed oil showed somewhat less body weight gain %s compared to the corresponding groups fed on spreads formulated with soybean oil (except for those fed on spreads of 20% total fat). Vijaimohan et al. (2006) found similar conclusions as they reported that using high fat diet caused high body weight gain compared to basal diet. Also, using flaxseed oil in the formulation of spreads (compared to soy bean oil) caused significant lowering effect on body weight gain. Body weight was increased (at the end of the feeding experiment) by 18.37%, 32.80% and 29.37% when FPB2, FPB3 and FPB4 respectively, were used for feeding while the corresponding spreads (SPB2, SPB3 and SPB4) showed values of 21.52%, 35.0% and 32.38% respectively, (Table 1). The same results reveal that levels of body weight increase were high in rat groups fed on fat spreads containing the highest total fat% (60% and 80%) than groups received fat spread of less total fat content (20% and 40%). These observations could be related to the high content of rn-3 fatty acid (ALA) in fat spreads of high fat content as reported by Vijaimohan et al. (2006) and Tzang et al. (2009).

Serum lipid parameter

Serum lipid profile (levels of total cholesterol, LDL, HDL and triglycerides as mg/dL in blood serum) as affected by oral ingestion of the eight formulated fat spreads for 8 successive weeks was studied, the obtained results were recorded in Table 2.

Total cholesterol

As a result of feeding experiment, total cholesterol concentration was increased insignificantly in the negative control group (G11). On the other hand, significant decrease was noted in the treatments of positive control (G10) and G9 group that received the pharmaceutical product. Also, rat groups manipulated with tested fat spreads showed significant (P < 0.05) lower total cholesterol concentration after 8 weeks of feeding program. Concentration reducing was happened at different rates and was pronounced than that showed by G9 group (in most cases).

Fat spreads containing flaxseed oil exerted reducing effect of total cholesterol level at higher rates compared with those containing soybean oil, especially at the end of feeding experiment. G7 and G8 groups (administered SPB4 and FPB4 spreads) exhibited concentrations of 94.8 ± 2.1 and 117.5 ± 8.5 mg/dL, respectively, at the beginning of the experiment and decreased to 80.2 ± 4.8 and 70.3 ± 1.0 mg/dL, respectively (decreasing rates of 15.40% and 40.17%, respectively) after 8 weeks of feeding experiment (Table 2).

At the end of the feeding experiment, the bad cholesterol (LDL) concentration in the negative control (G11) group was increased significantly as a result of feeding on basal diet; while in G9 and G10 (positive control) groups, the level of the same parameter was lowered significantly after 8 weeks of feeding (P < 0.05). When the eight fat spreads were administered orally to tested rats, significant decreases were observed for groups up to 4 weeks of feeding. Furthermore, another significant reducing effect (at varied %s) was noted during the period from the fourth to the eighth week of feeding.

The same results (Table 2) declared that incorporation of flaxseed oil into the formulated fat spreads exerted its marked lowering effect on LDL concentration in blood serum of tested rats. This finding was observed in comparison with either

Table 2 Effect of fat spreads on the blood serum lipid parameters of hyperlipidemic male albino rats.

Treatment schedule (N :

Total cholesterol mg/dL*

LDL mg/dL*

HDL mg/dL*

Triglycerides mg/dL*

0 Time

4 weeks

8 weeks

0 Time

4 weeks

8 weeks

0 Time

4 weeks

8 weeks

0 Time

4 weeks

8 weeks

G11 (-) 68.3 ± 1.6a 68.5 ± 1.9a 70.0 ± 1.8a 23.1 ± 1.1b 24.8 ± 1.3b 27.1 ± 1.1a 32.2 ± 2.1a 30.4 ± 1.5ab 29.3 ± 1.2b 64.8 ± 1.5b 66.7 ± 1.5ab 68.0 ± 2.1a

G10 ( + ) 114.3 ± 6.12a 108.7 ± 2.1b 107.7 ± 2.3b 57.1 ± 3.3a 52.0 ± 5.5b 50.5 ± 4.3c 34.0 ± 2.1a 30.4 ± 1.8b 30.3 ± 1.7b 116.0 ± 13.3b 131.3 ± 14.3ab 134.3 ± 14.4a

G9 (Ph) 110.3 ± 8.5a 91.7 ± 6.8b 79.3 ± 5.2c 59.9 ± 2.4a 39.1 ± 2.3b 25.9 ± 5.4c 31.8 ± 2.9a 30.5 ± 4.8a 28.5 ± 6.8a 93.0 ± 3.0c 110.5 ± 7.7b 124.7 ± 14.7a

G1 (SPB1) 107.3 ± 5.4a 88.8 ± 4.3b 85.5 ± 16.7b 61.3 ± 1.6a 35.2 ± 5.8b 26.8 ± 6.0c 31.1 ± 1.3a 29.4 ± 2.5a 26.2 ± 6.0a 74.3 ± 8.6c 121.2 ± 8.1b 162.8 ± 17.5a

G2 (FPB1) 123.0 ± 13.3a 102.1 ± 11.1b 65.5 ± 6.1c 71.7 ± 4.1 a 43.3 ± 2.3b 28.4 ± 4.8c 32.7 ± 2.9a 31.3 ± 3.2a 28.0 ± 4.8a 94.7 ± 0.82b 137.5 ± 19.0a 156.5 ± 19.9a

G3 (SPB2) 116.3 ± 19.3a 102.8 ± 12.8ab 95.0 ± 14.2b 65.3 ± 4.4a 49.7 ± 3.1b 41.5 ± 4.3c 35.3 ± 1.6a 33.6 ± 0.9a 29.2 ± 3.3b 78.7 ± 10.8b 97.3 ± 13.8ab 121.7 ± 38.5a

G4 (FPB2) 119.8 ± 6.0a 99.5 ± 4.9b 82.0 ± 3.9c 62.8 ± 2.4a 43.0 ± 2.0b 29.4 ± 5.8c 34.7 ± 1.6a 32.7 ± 2.6ab 28.0 ± 6.4b 111.7 ± 17.2a 119.0 ± 16.7a 124.3 ± 18.8a

G5 (SPB3) 115.8 ± 2.1a 96.2 ± 1.7b 95.0 ± 23.9b 56 ± 1.9a 33.0 ± 1.4b 36.4 ± 3.0c 39.8 ± 2.3a 36.0 ± 2.1b 28.8 ± 2.5c 99.0 ± 2.4b 135.8 ± 30.9a 149.2 ± 36.9a

G6 (FPB3) 101.7 ± 3.2a 84.5 ± 2.6b 73.2 ± 13.9c 51.1 ± 2.3a 30.6 ± 1.6b 18.2 ± 1.8c 31.0 ± 1.8a 32.7 ± 1.9a 32.8 ± 1.8a 98.0 ± 11.6b 106.2 ± 2.1ab 113.3 ± 8.0a

G7 (SPB4) 94.8 ± 2.1a 84.5 ± 5.9b 80.2 ± 4.8b 41.6 ± 2.4a 30.2 ± 4.0b 24.3 ± 4.2c 34.0 ± 2.6a 33.9 ± 4.2a 34.2 ± 4.6a 94.5 ± 7.7b 102.0 ± 5.2ab 108.5 ± 8.0a

G8 (FPB4) 117.5 ± 8.5a 92.8 ± 13.5b 70.3 ± 1.0c 60.6 ± 3.4a 38.6 ± 3.5b 18.9 ± 2.2c 36.0 ± 2.8a 35.7 ± 3.3a 35.5 ± 3.6a 104.3 ± 10.5a 92.7 ± 8.8ab 79.7 ± 12.2b

Values with different small letters in the same row are significantly different (P < 0.05).

SPB1 = Soybean-Palm oils blend (20%).

SPB2 = Soybean-Palm oils blend (40%.

SPB3 = Soybean-Palm oils blend (60%).

SPB4 = Soybean-Palm oils blend (80%).

Ph = Pharmaceutical product.

FPB1 = Flaxseed-Palm oils blend (20%).

FPB2 = Flaxseed-Palm oils blend (40%).

FPB3 = Flaxseed-Palm oils blend (60%).

FPB4 = Flaxseed-Palm oils blend (80%).

* (M ± S.D) = Mean ± Std. Deviation.

Table 3 TC/HDL and LDL/HDL ratios of blood serum of male albino rats as affected by feeding fat spreads.

Treatment TC/HDL ratio LDL/HDL ratio

0 Time 4 weeks 8 weeks 0 Time 4 weeks 8 weeks

G11 (-) 2.12 2.25 2.38 0.68 0.73 0.82

G10 ( + ) 3.36 3.75 3.55 1.64 1.73 1.64

G9 (Ph) 3.47 3.01 2.78 1.85 1.31 0.91

G1 (SPB1) 3.45 3.26 3.02 1.93 1.49 1.09

G2 (FPB1) 3.77 3.26 2.34 2.00 1.38 0.77

G3 (SPB2) 3.29 3.25 3.06 1.85 1.60 1.45

G4 (FPB2) 3.45 3.04 2.93 1.74 1.34 1.02

G5 (SPB3) 2.91 2.67 3.30 1.63 1.32 1.28

G6 (FPB3) 3.28 2.58 2.23 1.60 0.99 0.62

G7 (SPB4) 2.79 2.49 2.34 1.29 1.11 0.76

G8 (FPB4) 3.26 2.60 1.98 1.25 0.80 0.54

SPB1 = Soybean-Palm oils blend (20%). FPB1 = Flaxseed-Palm oils blend (20%). SPB2 = Soybean-Palm oils blend (40%). FPB2 = Flaxseed-Palm oils blend (40%). SPB3 = Soybean-Palm oils blend (60%). FPB3 = Flaxseed-Palm oils blend (60%). SPB4 = Soybean-Palm oils blend (80%). FPB4 = Flaxseed-Palm oils blend (80%). Ph = Pharmaceutical product.

soybean oil or the pharmaceutical product tested. Using spreads containing flaxseed oil in feeding causing reducing of LDL level by 52.40-67.17% of the initial concentration compared to 34.81-52.5% and 32.37-55.93% for spreads contained soybean oil and pharmaceutical product, respectively.

The concentration of HDL (good cholesterol) in blood serum of rats belonged to G11, G10 and G9 groups (negative, positive controls and group received the pharmaceutical product, respectively) was reduced gradually after feeding for 8 weeks with decreasing levels of 9.0-10.88% of the initial concentration. Also, level of HDL in animals orally ingested the studied fat spreads diminished at significant to insignificant different rates. Flaxseed oil exerted its beneficial effect when it was utilized in formulation at high amounts since G6 (FPB3, containing 29.5% flaxseed oil) and G8 (FPB4, containing 39% flaxseed oil) exerted higher/comparative levels of HDL after 8 weeks of feeding compared to the initial concentration, (Table 2).

Triglycerides

Compared to the initial concentration of triglycerides in blood serum, all studied rat groups (including the control with exception of G8 group, FPB4) showed significant higher levels at the end of feeding experiment (Table 2). On the other hand, fat spread treatment that contained the highest amount of flaxseed oil (39%) (G8, FPB4), compared of the other spreads containing flaxseed oil, exerted its healthy effect of triglycerides level since it decreased from 104.3 ± 10.5 mg/ dL at the beginning of feeding experiment to 92.7 ± 8.8 mg/ dL after four weeks of feeding with decreasing rate of 11.12%. Moreover, another reducing effect was noted after 8 weeks of feeding where triglycerides concentration was significantly diminished to 79.7 ± 12.2 mg/dL with decreasing rate of 23.58% (Table 2).

In general, the effects of flaxseed and flaxseed oil supplementation on plasma lipid have been controversial. Arjmandi et al. (1998) concluded that flaxseed oil has been shown to have inconsistent results with a few studies finding a modest reduction in triglycerides with large doses, but most with no effects. While, Tzang et al. (2009) showed hypocholesterolaemic effect of flaxseed oil compared to coconut oil and butter. Also, plasma triglycerides and cholesterol concentration in serum blood of mice were declined as the result of feeding diet containing flaxseed oil (Riediger et al., 2008). Cunnane et al. (1993) and Craig (1999) cited that flaxseed and its oil have decreasing effect in total cholesterol, LDL, LDL/HDL. On the other hand, Lucas et al. (2004) found that triglyceride concentration was higher in the flax-fed hamsters.

TC/HDL and LDL/HDL ratio

Results in Table 3 shows the effect of feeding rats on different fat spreads upon TC/HDL and LDL/HDL ratios. Values of the two calculated ratios were increased for positive (G10) and negative (G11) control animals. On the other hand, the corresponding values for rat group received the pharmaceutical product (G9) were decreased by 19.88% and 50.81%, respectively at the end of feeding experiment (after 8 weeks). Also, rat groups administered the different tested fat spreads exerted the same trend for the two calculated ratios (at varied rates). After 4 weeks of feeding experiment; TC/HDL ratio was decreased by 1.21-21.34% of its initial value, while LDL/HDL ratio was also diminished at relatively higher rates (13.51-38.12%). The same results declared that values of the calculated two ratios were gradually reduced parallel in manner with feeding experiment weeks.

In other words, the least values of the two calculated ratios were detected at the end of feeding experiment for all groups received the tested fat spreads. After 8 weeks of feeding, TC/ HDL and LDL/HDL ratios were decreased by 6.99-39.26 and 21.47-61.50%, respectively.

Spreads containing flaxseed oil (especially at high levels, 60% and 80% total fat) exhibited their appreciable effects compared to those containing soybean oil. Values of TC/ HDL ratio were reduced by 15.07-38.26% and 5.51-16.13% of its initial values (for flaxseed and soy bean oils formulated spreads), respectively, at the end of feeding experiment. LDL/HDL ratio showed the same trend (at higher %s) as its values were lowered by 41.38-61.50% and 21.47-43.52% for the same spreads, respectively, and at the same period of experiment. These findings were found in accordance with the results of Vijaimohan et al. (2006). Such observed reducing effects could be considered as one of the healthy benefits of alphalinolenic acid (ALA) on plasma lipids, so flaxseed oil (rich of ALA) could be used as a source of ALA to modify plasma lipids (Xu et al., 2012; Cunnane et al., 1993).

Flaxseed oil is a one of the richest sources of the plant-based rn-3 fatty acid. As recommended by Kris-Etherton et al. (2003) and Rodriguez et al. (2010), total intakes of 1.5-3.0 g/day of a-linolenic acid by human seem to be beneficial, especially for treatment and prevention of cardiovascular diseases. Such amount could be fulfilled by receiving fat spread containing flaxseed oil at amounts of 20-40, 20-30, 10-20 and 10 g/day of FPB1 (20% total fat), FPB2 (40% total fat), FPB3 (60% total fat) and FPB4 (80% total fat), respectively.

In conclusion, Flaxseed oil is a valuable source of various biologically active compounds (essential polyunsaturated fatty acids) which serve as basis for a number of effective drugs and prophylactic preparations as well as important nutritional additives. Flaxseed oil may be utilized as useful therapeutical safe food for hyperlipidemia through reducing hepatic lipids. As use of fat spreads enriched with flaxseed oil is considered as an easy delivery system of long chain omega-3 PUFA in the human body, using pure flaxseed oil in fat spread formulation can be considered as promise trend in the field of therapeutical fat spreads. These spreads characterize by relative high TUFAs content, especially the healthy fatty acid (omega-3, C18:3) and being free of trans fatty acids with good sensory properties.

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