Elevated plasma fibrinogen caused by inadequate alpha-linolenic acid intake can be reduced by replacing fat with canola-type rapeseed oil.

The effects of canola-type rapeseed oil (RSO) on serum lipids, plasma fibrinogen, lipid oxidation and fatty acids were studied in three groups of subjects, two of which had not been consuming fish in their habitual diets. Forty-two volunteers (35 women, 7 men, 16-62 years) replaced fat with RSO for 6 weeks in a parallel design. The average cholesterol and fibrinogen concentrations were 5.0 mmol/l and 2.6 g/l, respectively. The intake of alpha-linolenic acid (alpha-LLA) was doubled. Efficient competitive inhibition by alpha-LLA was seen as a decrease in long-chain (LC) n-6 PUFA at 3 weeks. Elevated fibrinogen (2.6-3.9 g/l) decreased by 0.95 g/l at 6 weeks. Docosahexaenoic acid (22:6n-3) in plasma phospholipids increased at low fibrinogen levels only. The associations and changes in plasma C18 and LC PUFA followed the competitive and metabolic principles of the body, and especially in the case of n-3 PUFA according to the recycling pathway.

Safety aspects and cholesterol-lowering efficacy of low fat dairy products containing plant sterols.

OBJECTIVE: The aim of this study was to investigate whether a plant sterol mixture would reduce serum cholesterol when added to low fat dairy products in subjects with hypercholesterolaemia, and to examine the effects of the mixture on the serum plant sterol and fat-soluble vitamin levels. DESIGN: A parallel, double-blind study. SETTING: The study was performed in three different locations in Finland. SUBJECTS: In total, 164 mildly or moderately hypercholesterolaemic subjects participated in the study. METHODS: The subjects were randomly divided into two groups: a plant sterol group and a control group. The subjects consumed the products for 6 weeks after a 3-week run-in period. The targeted plant sterol intake was 2 g/day in the sterol group. RESULTS: During the treatment period, there was a 6.5% reduction in serum total cholesterol in the sterol group while no change was observed in the control group (P<0.0005). Serum low-density lipoprotein (LDL) cholesterol was reduced by 10.4% in the sterol group and by 0.6% in the control group (P<0.00005). There was no change during the trial in serum high-density lipoprotein (HDL) cholesterol or triacylglycerol concentrations. The HDL/LDL cholesterol ratio increased by 16.1% in the sterol group and by 4.3% in the control group (P=0.0001). Serum plant sterol levels increased significantly (P=0.0001) in the sterol group. None of the fat-soluble vitamin levels decreased significantly when changes in serum total cholesterol were taken into account. The hypocholesterolaemic effect of sterol administration was not influenced by apolipoprotein E phenotype. CONCLUSIONS: Yoghurt, low-fat hard cheese and low-fat fresh cheese enriched with a plant sterol mixture reduced serum cholesterol in hypercholesterolaemic subjects and no adverse effects were noted in the dietary control of hypercholesterolaemia.

Hypolactasia & lactose intolerance among three ethnic groups in Malaysia.

BACKGROUND & OBJECTIVES: Prevalence of adult-type hypolactasia is known to vary among different countries and in different ethnic populations in the same country. The present study was undertaken to evaluate the prevalence of hypolactasia and lactose intolerance in three different ethnic populations living in similar environmental conditions in Malaysia. The correlation between different symptoms and lactose intolerance test was also studied. METHODS: A total of 300 Malaysian subjects from three different ethnic populations: Malays, Chinese and Indians (100 volunteers in each group, 18-49 yr old working or studying in a University) were included. Urine galactose excretion and gastrointestinal symptoms were measured after lactose intake (50 g). RESULTS: Based on galactose excretion, 88 per cent of the Malays, 91 per cent of the Chinese and 83 per cent of the Indians were hypolactasic. The differences were statistically not significant. When the symptoms were also considered, prevalence of lactose intolerance appeared to be significantly lowest among the Indians. When the subjects were divided into low, middle and high galactose excretion groups some correlation was found between the symptoms and galactose excretion. INTERPRETATION & CONCLUSION: There was no clear association between hypolactasia and gastrointestinal symptoms in all the study groups. However, the lactose intolerance was high in all the study groups indicating the increasing demand for low lactose dairy products in the Asian countries.

Effects of vitamin E on the toxicity of oxidized LDL on endothelial cells in vitro in smokers vs nonsmokers on diets rich in fish.

OBJECTIVE: To clarify whether supplementation of vitamin E can alter the low density lipoprotein (LDL) oxidation properties and thereby affect endothelial cell function and prostacyclin production in smokers compared to nonsmokers on diets rich in fish in a pilot study. DESIGN: The LDL of six smokers and six nonsmokers on habitual high fish diet was isolated before and after an 8-week supplementation of vitamin E (800 IU/day). LDL was oxidized by incubation with CuSO4. Cytotoxicity of LDL oxidized to different degrees on endothelial cells was investigated in vitro in these two groups. SETTING: Helsinki University Central Hospital; Institute of Biomedicine, Pharmacology, University of Helsinki. RESULTS: At baseline, the rate of oxidation was higher in nonsmokers than in smokers. The lag phase increased significantly after the supplementation of vitamin E both in smokers and nonsmokers. Native LDL dose dependently tended to reduce the viability of endothelial cells in vitro more markedly when isolated from smokers than from nonsmokers. Vitamin E supplementation had no beneficial effect on the cytotoxicity of oxidized LDLs in endothelial cell culture. On the other hand, simultaneous administration of Trolox, the water-soluble analogue of vitamin E, attenuated the LDL cytotoxicity on endothelial cells. The vitamin E supplementation to LDL donors attenuated the increase in prostacyclin production both in smokers and nonsmokers. CONCLUSION: Supplementation of LDL donors (healthy male volunteers on habitual fish diet) with vitamin E increased the lag phase of LDL oxidation, but, on the other hand, did not influence in vitro cytotoxicity of LDL, or prostacyclin production.

Effect of ingesting sour milk fermented using Lactobacillus helveticus bacteria producing tripeptides on blood pressure in subjects with mild hypertension.

Angiotensin-converting enzyme (ACE) is important in the regulation of blood pressure (BP). Two tripeptides that inhibit ACE, isoleucyl-prolyl-proline (Ile-Pro-Pro) and valyl-prolyl-proline (Val-Pro-Pro), have been isolated from certain sour milks. The aim of the study reported was to evaluate the effect on BP in subjects with mild hypertension of a new sour milk containing tripeptides. The initial number of subjects was 60 (36 men, 24 women). Among the criteria for inclusion in the study were systolic BP (SBP) between 140 and 180 mmHg and/or diastolic BP (DPB) between 90 and 110 mmHg, without antihypertensive drug therapy. There were two study periods with a washout period between. All subjects were given 1.5 dl per day of a placebo (regular sour milk) or of the active product, a milk that had been fermented with Lactobacillus helveticus bacteria and contained 2.4-2.7 mg of Ile-Pro-Pro and 2.4-2.7 mg of Val-Pro-Pro per 1.5 dl. In the first phase, SBP fell 16 mmHg from baseline in the active group, 2 mmHg more than in the placebo group (P=0.0668) and no difference in DBP (P=0.92). There was a statistically significant downward trend both in SBP and DBP (P=0.0001). During the second phase, SBP fell 11 mmHg in the active group (P=0.008). The reduction in SBP was significantly larger in active than placebo group (P=0.012). In the crossover analysis combining both phases, SBP fell on average 2.6+/-15.9 mmHg more on the active product compared with the placebo product, but this difference was not statistically significant (P=0.3111). The difference in DBP, 1.0+/-8.3 mmHg between the two test products was not significant either (P=0.4431). In conclusion, the ingestion of sour milk fermented by L. helveticus bacteria and that containing ACE inhibitory tripeptides seems to lower BP modestly.

Dietary fatty acid composition influences the degree of human LDL oxidation, but has only minor effects on vascular tone in a bioassay system.

BACKGROUND AND AIM: Oxidized LDL has been detected in atherosclerotic vessels and presumed to be one of the major risk factors in atherosclerosis and cardiovascular diseases. The aims of the present study were to clarify whether the oxidation degree of LDL influences arterial tone and whether different long-lasting dietary habits have effects on biological variables. METHODS AND RESULTS: The lag phase of LDL oxidation was shorter (117 +/- 6 min) in the fish diet group than in the vegetarian (153 +/- 5 min) or the control diet group (152 +/- 10 min). The rat mesenteric arterial rings, which were preincubated with LDL oxidized to 1-30%, from the vegetarian and the fish diet groups showed (p < 0.05) decreased NA-induced maximal contraction forces when compared to the control diet. The LDL oxidation degrees of 31-60% and 61-90% had no effect on NA- and KCl-induced maximal contraction forces when compared to native LDL, nor were there differences between the diet groups. Endothelium-dependent and independent relaxation responses behaved similarly in all groups and were independent of the degree of oxidation. CONCLUSIONS: Dietary habits change the fatty acid composition of LDL, but have only minor effects on the vasoactive properties of oxidized LDL.

A long-term fish diet modifies the toxic properties of human partially oxidized LDL on vascular preparations in vitro.

Both LDL oxidation and LDL fatty acid composition affect vascular relaxation and contraction. The aim of this study was to investigate whether long-lasting dietary habits (vegetarian, fish and high saturated fat as a control group) can change those properties of partially oxidized LDL (ox-LDL) which are reflected in altered vascular responses measured with a bioassay. The effects of ox-LDL were investigated on rat mesenteric arteries. In endothelium intact arterial rings the contractile responses to noradrenaline (NA) tended to be diminished in the presence of ox-LDL derived from the fish diet group compared with the other groups. In the endothelium denuded arterial rings the contractile responses to NA and KCl were significantly enhanced by ox-LDL from the fish diet group compared with the control group. The ox-LDL from the fish diet group increased the diclofenac, L-NAME resistant relaxations to ACh compared to the control diet group suggesting the role of endothelium derived hyperpolarizing factor (EDHF). In conclusion, partially oxidized LDL from subjects living on a fish diet is biologically more vasoactive in bioassay systems than partially oxidized LDL from those living on vegetarian or saturated fatty acid containing diets. The impaired responses in vasoconstriction and improved vasodilation seem to be endothelium dependent.

Oxidized LDL from subjects with different dietary habits modifies atherogenic processes in endothelial and smooth muscle cells.

Low-density lipoprotein (LDL) activates a number of processes involved in atherogenesis and vasoconstriction. Evidence suggests that oxidation increases the atherogenicity of LDL. We investigated the effects of oxidized LDL (ox-LDL) on cytotoxicity, prostacyclin (PGI2), and cyclic guanosine-3',5'-monophosphate (cGMP) production in rat vascular smooth muscle cell (VSMC) and rat heart endothelial cell (EC) culture, as well as EC- and VSMC-mediated LDL oxidation. Native LDL (n-LDL) was isolated from subjects on three long-term diets with differing fatty acid content (control diet rich in saturated fat and vegetarian and fish diets). The Cu2+-catalyzed oxidation of n-LDL was monitored using conjugated diene formation and stopped at various time points to achieve 20%, 45%, 70%, and 100% levels of ox-LDL. The lag phase of oxidation by Cu2+ was shortest and thiobarbituric acid-reactive substance (TBARS) formation by VSMC-mediated oxidation was highest with n-LDL obtained from the fish diet group. There were no differences between the ox-LDLs obtained from the different diet groups in their cytotoxicity in EC culture. The degree of oxidation did not influence LDL cytotoxicity. In VSMC culture PGI2 production was increased by ox-LDLs from all diet groups. In EC culture only the extensively oxidized LDLs obtained from the vegetarian diet group were able to induce PGI2 production. The LDLs did not affect basal cGMP production in either EC or VSMC culture.

Dietary habits affect the susceptibility of low-density lipoprotein to oxidation.

OBJECTIVE: To study, if there are differences in the fatty acid composition of low-density lipoprotein (LDL) in people eating three different long-standing habitual diets: vegetarian, high fish intake, or high saturated fat (milk fat) diet as a control group, and to study if these differences influence the oxidation susceptibility of LDL. DESIGN: Cross-sectional study using blood samples and a validated dietary frequency questionnaire with illustrations. SETTING: Helsinki University Central Hospital, Finland. SUBJECTS: The effect of three different types of long-standing diets of different fatty acid content (a strict vegetarian diet, n=11; a high fish intake diet, n=9; and a high saturated fat (milk fat) diet, controls, n=7) on the serum and LDL fatty acid content, and on the susceptibility of LDL to oxidation in vitro, was studied in healthy normocholesterolemic volunteers who had been on these diets for years. Oxidation of LDL was carried out by using CuSO4 as a pro-oxidant. RESULTS: There were no statistically significant differences in the serum lipids or lipoproteins, though the vegetarian group exhibited lowest mean values of total, high-density lipoprotein (HDL) and LDL cholesterol levels. Both the serum and LDL eicosapentaenoic, docosapentaenoic and docosahexaenoic acid proportions were highest in the fish and lowest in the vegetarian groups. Linoleic acid was highest among the vegetarians. In the fish group, the vitamin A concentration in serum was higher than in vegetarians and controls and beta-carotene lower than in controls, but in alpha-tocopherol, or lycopene concentrations there were no statistically significant differences. The lag phase of LDL oxidation was shortest (116 min) in the fish group and longest (165 min) in the vegetarian group, and the control group was between them (129 min). The mean oxidation percentage after 2.5 h of copper-induced oxidation was highest (44%) in the fish group and lowest (22%) in the vegetarian group and intermediate (31%) in the control group. CONCLUSION: Long-term dietary habits predict the fatty acid composition of serum and LDL, and influence the susceptibility of LDL to oxidation. In the fish group with the highest content of omega-3 fatty acids in LDL, the oxidation susceptibility of LDL was highest. In the vegetarian group with less omega-3 fatty acids in LDL, the LDL was more resistant to oxidation. SPONSORSHIP: Helsinki University Central Hospital.

Role of irritable bowel syndrome in subjective lactose intolerance.

It has been suggested that the symptoms of irritable bowel syndrome (IBS) may be wrongly attributed to lactose intolerance. We examined the relations among IBS, demographic factors, living habits, and lactose intolerance. On the basis of a lactose tolerance test with ethanol, 101 of the 427 healthy subjects studied were lactose maldigesters and 326 were lactose digesters. IBS was diagnosed by means of the Bowel Disease Questionnaire, according to the Rome criteria. The use of dairy products and symptoms experienced after their consumption were recorded. IBS was found in 15% of both the lactose maldigesters and lactose digesters. One-third of the subjects reported intolerance to dairy products containing < or = 20 g lactose. About half of this third were lactose maldigesters and about half were lactose digesters. As explanations for this subjective lactose intolerance, the logistic regression model estimated lactose maldigestion (odds ratio: 10.3; 95% CI: 5.2, 20.4), IBS (4.6; 2.1, 10.1), experience of symptoms other than gastrointestinal ones (2.3; 1.2, 4.5), and female sex (2.1; 1.1, 4.0). Characteristics common to both subjective lactose intolerance and IBS were female sex and the experience of abdominal pain in childhood (P < 0.01). Age, regularity of meals, and the amount of physical activity were not associated with either subjective lactose intolerance or IBS. Of the subjects with IBS, the percentage of lactose maldigesters was the same as in the whole study group (24%) but the number who reported lactose intolerance was higher (60% compared with 27%, P < 0.001). We showed a strong relation among subjective lactose intolerance, IBS, the experience of abdominal pain in childhood, and female sex.