Marja Mutanen

Dietary trans fatty acids increase conjugated linoleic acid levels in human serum

Conjugated linoleic acid (CLA), fatty acids with 18 carbon atoms and two conjugated cis/trans double bonds, have shown anticarcinogenic effects in experimental studies. We determined the proportion of CLA (the sum of cis-9, trans-11 and trans-9, cis-11 CLA) of total fatty acids in the diets and serum samples of healthy subjects who consumed for 5 weeks a diet high in saturated fatty acids mainly from dairy fat, followed by 5 weeks on a diet high (8.7% of energy, en%) in trans fatty acids from partially hydrogenated vegetable oil (40 subjects) or a similar diet high in stearic acid (9.3 en%, 40 subjects). All diets contained equal amounts of fat and cis-monounsaturated and cis-polyunsaturated fatty acids. The fatty acid compositions of the pooled diets and fasting serum samples drawn at the end of the diet periods were analyzed by gas chromatography, and CLA was identified by comparison with a standard of C18:2 conjugated dienes. The proportions of CLA in the dairy fat, trans fatty acid, and stearic acid diets were 0.37, 0.04, and 0.10% of total methylated fatty acids, respectively. The corresponding mean (SD) proportions in serum were 0.33 (0.07)% after the dairy fat diet, higher, 0.43 (0.12)%, P < 0.001, after the trans fatty acid diet, and lower, 0.17 (0.06)%, P < 0.001, after the stearic acid diet. The difference between dairy fat and stearic acid diets was explained by different dietary intakes but increased amounts of CLA not present in the diet were incorporated into serum lipids during the trans fatty acid diet. CLA in human tissues is partly derived from the diet but part of it may be formed by conversion from dietary trans fatty acids.

Dairy products and metabolic effects in overweight men and women: results from a 6-mo intervention study

BACKGROUND Some epidemiologic studies have suggested inverse relations between intake of dairy products and components of the metabolic syndrome. OBJECTIVE The objective was to investigate the effects of an increased intake of dairy products in persons with a habitually low intake on body composition and factors related to the metabolic syndrome. DESIGN Middle-aged overweight subjects (n = 121) with traits of the metabolic syndrome were recruited in Finland, Norway, and Sweden and randomly assigned into milk or control groups. The milk group was instructed to consume 3-5 portions of dairy products daily. The control group maintained their habitual diet. Clinical investigations were conducted on admission and after 6 mo. RESULTS There were no significant differences between changes in body weight or body composition, blood pressure, markers of inflammation, endothelial function, adiponectin, or oxidative stress in the milk and the control groups. There was a modest unfavorable increase in serum cholesterol concentrations in the milk group (P = 0.043). Among participants with a low calcium intake at baseline (<700 mg/d), there was a significant treatment effect for waist circumference (P = 0.003) and sagittal abdominal diameter (P = 0.034). When the sexes were analyzed separately, leptin increased (P = 0.045) and vascular cell adhesion molecule-1 decreased (P = 0.001) in women in the milk group. CONCLUSIONS This study gives no clear support to the hypothesis that a moderately increased intake of dairy products beneficially affects aspects of the metabolic syndrome. The apparently positive effects on waist circumference and sagittal abdominal diameter in subjects with a low calcium intake suggest a possible threshold in relation to effects on body composition.

Effects of a monounsaturated rapeseed oil and a polyunsaturated sunflower oil diet on lipoprotein levels in humans.

The effects of high oleic acid rapeseed oil compared with polyunsaturated fats on serum lipoprotein levels are largely unknown. Therefore, we fed 30 women and 29 men a baseline diet rich in saturated fat, which was followed by a diet rich in high oleic and low erucic acid rapeseed oil (total energy content of fat, 38%; saturates, 12.4%; monounsaturates, 16%; n-6 polyunsaturates, 6%; and n-3 polyunsaturates, 2%) and one rich in sunflower oil (total energy content of fat, 38%; saturates, 12.7%; monounsaturates, 10%; n-6 polyunsaturates, 13%; and n-3 polyunsaturates, 0%). The oils were incorporated into mixed natural diets that were dispensed in a random order for 3.5 weeks each in a blinded crossover design. The diet composition was confirmed by analysis of duplicate diets. Both test diets reduced serum total cholesterol (TC) and low density lipoprotein (LDL) cholesterol levels from baseline, the monounsaturated rapeseed oil diet more than the polyunsaturated sunflower oil diet (TC: -15% versus -12%, p less than 0.01; LDL cholesterol: -23% versus -17%, p less than 0.01). Very low density lipoprotein (VLDL) cholesterol and total, VLDL, and LDL triglyceride levels were lower during the sunflower oil diet compared with the rapeseed oil diet. Total high density lipoprotein (HDL) cholesterol levels remained unchanged by both diets. The consumption of rapeseed oil resulted in a more favorable HDL2 to LDL cholesterol ratio (0.43 +/- 0.19 versus 0.39 +/- 0.18, p less than 0.01) and an apolipoprotein A-I to B ratio (3.0 +/- 1.4 versus 2.4 +/- 1.6, p less than 0.001) than did the sunflower oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Persistence of probiotic strains in the gastrointestinal tract when administered as capsules, yoghurt, or cheese

Most clinical studies of probiotics use freeze-dried, powdered bacteria or bacteria packed in capsules. However, probiotics are commercially available in various food matrices, which may affect their persistence in the gastrointestinal tract. The objective of the study was to compare oral and faecal recovery during and after administration of a combination of Lactobacillus rhamnosus GG and LC705, Propionibacterium freudenreichii subsp. shermanii JS, and Bifidobacterium animalis subsp. lactis Bb12 as capsules, yoghurt, or cheese. This randomized, parallel-group, open-label trial (n=36) included a 4-week run-in, 2-week intervention, and 3-week follow-up period. Participants consumed 10(10)cfu/day of probiotic combination and provided saliva and faecal samples before, during, and after the intervention. Strain-specific real-time PCR was used to quantify the strains. L. rhamnosus GG was the only probiotic strain regularly recovered in saliva samples. During the intervention period it was recovered in the saliva of 88% of the volunteers at least once. No difference was found between the yoghurt and cheese groups. At the end of the intervention, L. rhamnosus GG and LC705 counts were high in faecal samples of all product groups (8.08 and 8.67log(10) genome copies/g, respectively). There was no matrix effect on strain quantity in faeces or the recovery time after ceasing the intervention. For P. freudenreichii subsp. shermanii JS and B. animalis subsp. lactis Bb12, a matrix effect was found at the end of the intervention (P<0.01 and P<0.001, respectively) and in the recovery time during follow-up (P<0.05 for both). Yoghurt yielded the highest faecal quantity of JS and Bb12 strains (8.01 and 9.89log(10) genome copies/g, respectively). The results showed that the administration matrix did not influence the faecal quantity of lactobacilli, but affected faecal counts of propionibacteria and bifidobacteria that were lower when consumed in cheese. Thus, the consumption of probiotics in yoghurt matrix is highly suitable for studying potential health benefits and capsules provide a comparable means of administration when the viability of the strain in the capsule product is confirmed.

Dietary determinants of serum paraoxonase activity in healthy humans

The associations between habitual diet and a variety of markers of lipid peroxidation or oxidative stress in a group of 95 healthy comparatively young Finnish volunteers (24 male and 71 females) were investigated. The habitual diet of the subjects was evaluated with a 3-day food record. The following biochemical parameters related to lipid peroxidation or oxidative stress were measured: lagtime of Cu2+ induced LDL oxidation in vitro, lipid hydroperoxides and Schiff bases produced during the LDL oxidation test, malondialdehyde measured as thiobarbituric acid-reactive substances from native LDL and Cu2+ oxidized LDL, serum paraoxonase (PON) activity. Serum PON activity showed most constantly associations with habitual diet. PON activity correlated negatively (r=-0.31 to -0.37) with intake of vegetables, total and water-soluble fiber, as well as intake of beta-carotene. Highly significant difference (P=0.005) in PON activity between lowest (<135 g/day) and highest (>256 g/day) vegetable intake quartiles was found. Malondialdehyde levels showed conflicting associations with diet. The results suggest that the significantly lower PON activity associated with high vegetable intake needs to be studied further.

A high linoleic acid diet increases oxidative stress in vivo and affects nitric oxide metabolism in humans

Abstract Evidence from in vitro studies shows that increased intake of polyunsaturated fatty acids leads to increased oxidative stress, which may be associated with endothelial damage. We measured the urinary levels of 8-iso-PGF 2α and nitric oxide metabolites as well as plasma slCAM-1 levels from healthy subjects after strictly controlled diets rich in either linoleic acid (LA, C18:2 n-6) or oleic acid (OA, C18:1 n-9). Thirty-eight volunteers (20 women and 18 men, mean age 27 years) consumed a baseline diet rich in saturated fatty acids (SFA) for 4 weeks and were then switched to either a high LA diet (11.5 en%) or a high OA diet (18.0 en%) also for 4 weeks. During the LA and OA diets, nearly all food was provided for the whole day. A control group of 13 subjects consumed their habitual diet throughout the study. Urinary excretion of 8-iso-PGF 2α was significantly increased after the LA diet (170 vs 241 ng/mmol creatinine, P =0.04), whereas the urinary concentration of nitric oxide metabolites decreased (4.2 vs 2.6 mg/mmol creatinine, P =0.03). No significant changes were seen in the OA group. Significant differences between the LA and control group were found for both 8-oxo-PGF 2α ( P =0.03) and NO ( P =0.02), whereas the OA and LA groups did not differ with respect to any parameter. Also plasma slCAM-1 remained unchanged in both groups throughout the study. In conclusion, the high-LA diet increased oxidative stress and affected endothelial function in a way which may in the long-term predispose to endothelial dysfunction.

Functional food science and the cardiovascular system.

Cardiovascular disease has a multifactorial aetiology, as is illustrated by the existence of numerous risk indicators, many of which can be influenced by dietary means. It should be recalled, however, that only after a cause-and-effect relationship has been established between the disease and a given risk indicator (called a risk factor in that case), can modifying this factor be expected to affect disease morbidity and mortality. In this paper, effects of diet on cardiovascular risk are reviewed, with special emphasis on modification of the plasma lipoprotein profile and of hypertension. In addition, dietary influences on arterial thrombotic processes, immunological interactions, insulin resistance and hyperhomocysteinaemia are discussed. Dietary lipids are able to affect lipoprotein metabolism in a significant way, thereby modifying the risk of cardiovascular disease. However, more research is required concerning the possible interactions between the various dietary fatty acids, and between fatty acids and dietary cholesterol. In addition, more studies are needed with respect to the possible importance of the postprandial state. Although in the aetiology of hypertension the genetic component is definitely stronger than environmental factors, some benefit in terms of the development and coronary complications of atherosclerosis in hypertensive patients can be expected from fatty acids such as alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid. This particularly holds for those subjects where the hypertensive mechanism involves the formation of thromboxane A2 and/or alpha 1-adrenergic activities. However, large-scale trials are required to test this contention. Certain aspects of blood platelet function, blood coagulability, and fibrinolytic activity are associated with cardiovascular risk, but causality has been insufficiently proven. Nonetheless, well-designed intervention studies should be initiated to further evaluate such promising dietary components as the various n-3 and n-6 fatty acids and their combination, antioxidants, fibre, etc. for their effect on processes participating in arterial thrombus formation. Long-chain polyenes of the n-3 family and antioxidants can modify the activity of immunocompetent cells, but we are at an early stage of examining the role of immune function on the development of atherosclerotic plaques. Actually, there is little, if any, evidence that dietary modulation of immune system responses of cells participating in atherogenesis exerts beneficial effects. Although it seems feasible to modulate insulin sensitivity and subsequent cardiovascular risk factors by decreasing the total amount of dietary fat and increasing the proportion of polyunsaturated fatty acids, additional studies on the efficacy of specific fatty acids, dietary fibre, and low-energy diets, as well as on the mechanisms involved are required to understand the real function of these dietary components. Finally, dietary supplements containing folate and vitamins B6 and/or B12 should be tested for their potential to reduce cardiovascular risk by lowering the plasma level of homocysteine.

Lactobacillus rhamnosus LC705 Together with Propionibacterium freudenreichii ssp shermanii JS Administered in Capsules Is Ineffective in Lowering Serum Lipids

Objective: The aim of this study was to examine the effect of the administration of Lactobacillus rhamnosus strain LC705 and Propionibacterium freudenreichii ssp shermanii strain JS in capsules on serum cholesterol and triglyceride levels in mildly or moderately hypercholesterolemic men. Methods: Thirty-eight basically healthy men, mean age 42 years (range 24–55), mean cholesterol 6.2 mmol/L (5.3–8.2 mmol/L), participated in this double-blind, randomised, placebo-controlled, two-period crossover study with 4-week treatment periods. The subjects consumed daily two probiotic capsules containing viable Lactobacillus rhamnosus LC705 and Propionibacterium freudenreichii ssp shermanii JS (2 × 1010 colony forming units of each strain daily) or two placebo capsules. Serum lipids were assessed before the intervention, at the end of both 4-week treatment periods, and 2 weeks after the second treatment period. Dietary and lifestyle habits were carefully monitored. Results: All the subjects completed the study, and the probiotic capsules were well tolerated. Dietary habits and the intake of energy and nutrients, such as saturated fatty acids and cholesterol, did not differ between the treatment groups. No changes in total cholesterol, HDL cholesterol, LDL cholesterol or triglyceride levels were observed during the consumption of the probiotics compared to placebo. Conclusions: The administration of Lactobacillus rhamnosus LC705 and Propionibacterium freudenreichii ssp shermanii JS did not affect serum lipids.

Fats, lipids and blood coagulation.

Saturated and n-3 fatty acids, postprandial lipaemia, and the combined effects of fatty acids and lipid-lowering drugs have been of principal interest in recent studies in the field of dietary fats, lipids and haemostasis. The sex-specific effect of individual saturated fatty acids on coagulation factor VII activity has been discovered, and the significant effect of factor VII R353Q polymorphism on the postprandial response has also been found. An increased intake of n-3 fatty acids or fat reduction when combined with intensive lifestyle interventions may lead to reduced thrombotic potential in type 2 diabetic patients and obese individuals. Furthermore, positive effects on haemostasis by combined treatment with long-chain n-3 fatty acids and simvastatin indicate that n-3 fatty acids may be of some relevance with lipid-lowering drugs. The possible unfavourable effect of n-3 fatty acids on plasminogen activator inhibitor-1 activity is still a matter of dispute, but recent studies suggest that n-3 fatty acids, including α-linolenic acid, may have antithrombotic effects by enhancing protein C activity.

Promotion of intestinal tumor formation by inulin is associated with an accumulation of cytosolic β‐catenin in Min mice

Inulin, polydisperse β (2‐1) fructan, has been suggested to protect against colon carcinogenesis and is currently used in a number of food applications. However, the data regarding the role of inulin in intestinal carcinogenesis remains controversial since the results of our previous study suggested that inulin promotes intestinal tumor formation in Min mice, an animal model for intestinal cancer with a mutation in the Apc tumor suppressor gene (Carcinogenesis 2000;21:1167–73). In our present study, we further examined the effects of inulin on intestinal tumor formation in Min mice by carefully analyzing β‐catenin expression and cellular localization at 3 different time points during the tumorigenic process. Min mice were fed a high‐fat inulin‐enriched (10% w/w) diet or the high‐fat diet without any added fiber from the age of 6 weeks to the ages of 9, 12 or 15 weeks. The results showed that inulin significantly increased the number (by 20%) and especially the size (by 44%) of adenomas in the small intestine. At week 15, the promotion of tumor development was accompanied by an accumulation of cytosolic β‐catenin in the adenoma tissue. In the normal appearing mucosa, levels of membrane β‐catenin and PCNA were reduced in the inulin‐fed mice, possibly indicating impaired enterocyte migration. These data do not support the earlier suggestions on the cancer preventive effects of inulin and emphasize the need for further research and evaluation where health claims for inulin are concerned.