Butter was replaced by olive oil in a controlled 100 g fat diet in order to study the effect of saturated fats (SAFA) versus monounsaturated fats (MUFA) on small-bowel sterol excretion in eleven healthy ileostomates. Bile acids and neutral sterols were measured by gas-liquid chromatography. Net cholesterol excretion (excretion minus intake) was 84 +/- 25 mg/24 h (mean +/- SE) on the SAFA diet and increased to 218 +/- 32 mg/24 h on the MUFA diet (P less than 0.01). The bile acid excretion tended to be somewhat lower on the MUFA diet, but this was significant only for chenodeoxycholic acid. Net sterol excretion (the sum of excretion of net cholesterol and bile acids) was significantly lower on the SAFA diet than on the MUFA diet (443 +/- 60 and 529 +/- 58 mg/24 h, respectively). The immediately increased excretion of cholesterol from the small bowel could thus explain the serum cholesterol-lowering effect of a change from a SAFA-rich to a MUFA-rich diet, though the mechanism for this change is still unclear.

The effect of a fat-modified diet with 1100 kcal (4600 kJ) on the reduction of body weight and body fat was studied. A low-carbohydrate, high-fat diet with predominant animal fat (diet T) was compared with a low-carbohydrate, high-fat diet with predominant vegetable fat (diet P). Diet T was composed of 52.1% of the energy as fat, 20.7% as protein and 27.2% as carbohydrates. Diet P was composed of 54.1% of the energy as fat, 18.9% as protein and 27.0% as carbohydrates. More than two-thirds of the fat in diet T was butter, in diet P margarine. The study was carried out with 30 subjects (8 men) over two 21-day periods. With diet T, men had a mean weight loss of 7.1 kg = 338 g/d, of which 3.2 kg = 152 g/d were proved to be body fat, while women had a mean weight loss of 4.4 kg = 210 g/d, of which 2.3 kg = 110 g/d were proved to be body fat. With diet P, men had a mean weight loss of 7,6 kg = 362 g/d, of which were 3.9 kg = 186 g/d body fat, while women lost 3.8 kg = 181 g/d of body weight on average, of which were 2.0 kg = 95 g/d body fat. An improvement of blood pressure was also found. Significant differences of the reduction of body weight and body fat between the diet with mostly animal fat and the diet with mostly vegetable fat were not found.

Intake of trans fatty acids unfavorably affects blood lipoproteins. As margarines are a major source of trans, claims for the advantages of margarines over butter need to be scrutinized. Here we review dietary trials that directly compared the effects of butter and margarine on blood lipids. We identified 20 studies in which subjects had stable body weights, and margarine and butter were exchanged in the diet at constant energy and fat intake. We calculated the changes in average blood lipid levels between study diets (49 comparisons) as a function of the percentage of calories as margarine substituted for butter. Replacing 10% of calories from butter by hard high-trans stick margarines lowered total serum cholesterol by 0.19, LDL by 0.11, and HDL by 0.02 mmol/l, and did not affect the total/HDL cholesterol ratio. Soft low-trans tub margarines decreased total cholesterol by 0.25 and LDL by 0.20 mmol/l, did not affect HDL, and decreased the total/HDL cholesterol ratio by 0.20. Based on the total/HDL cholesterol ratio, replacement of 30 g of butter per day by soft tub margarines would theoretically predict a reduction in coronary heart disease risk of 10%, while replacement of butter by hard, high-trans margarines would have no effect. Replacing butter by low-trans soft margarines favorably affects the blood lipoprotein profile and may reduce the predicted risk of coronary heart disease, but high-trans hard margarines probably confer no benefit over butter.

The cross-sectional association between consumption of various fats (eg, butter, olive oil, and vegetable oil) and risk factors for coronary heart disease was analyzed in a sample of 4903 Italian men and women 20 to 59 years of age. The intake of fats was ascertained by an interviewer-administered questionnaire. Increased consumption of butter was associated with significantly higher blood pressure and serum cholesterol and glucose levels for men; in women only the association with glucose reached statistical significance. In both sexes consumption of olive oil and vegetable oil was inversely associated with serum cholesterol and glucose levels and systolic blood pressure. These findings were adjusted for confounding effects of other risk factors for cardiovascular disease. These cross-sectional findings from a large population sample suggest that consumption of butter may detrimentally affect coronary risk factors, while polyunsaturated and monounsaturated fats may be associated with a lower coronary risk profile.

Effects of a high virgin olive oil diet on the promotion stage of dimethylbenz(alpha)anthracene-induced mammary carcinogenesis in rats were investigated in comparison with those of a high corn oil diet. Animals were randomly placed into 4 groups: control, fed a normolipidic control diet (3% corn oil); M, fed a high corn oil diet (20%); O, fed a high olive oil diet (3% corn oil plus 17% olive oil); and MO, fed the high olive oil diet after 33 days of high corn oil diet. Whereas the high corn oil diet clearly stimulated the mammary carcinogenesis, reducing the latency time and increasing the tumor incidence, multiplicity and volume, the high olive oil diet led to a lower tumor incidence than in the former group, a latency time similar to that of the control and lower tumor multiplicity and volume even than in the control group. Moreover, the histopathological features of the adenocarcinomas in olive oil groups were compatible with a greater degree of differentiation. These data suggest that the high virgin olive oil diet would have acted as a negative modulator of the experimental mammary carcinogenesis conferring to the tumors a more benign clinical behavior and a lower histopathological malignancy in comparison with the control and high corn oil diets.

Eur J Nutr. 2001 Aug;40(4):161-7
Impact of diets containing corn oil or olive/sunflower oil mixture on the human plasma and lipoprotein lipid metabolism.
Wagner KH, Tomasch R, Elmadfa I.
Institute of Nutritional Sciences, University of Vienna, Austria.

BACKGROUND: The effects of monounsaturated fatty acids (MUFA) rich diets compared to those that are rich in polyunsaturated fatty acids (PUFA) as well as the effects of an intake of single oils compared to oil mixtures are controversially discussed and results are contradictory. AIM OF THIS STUDY: To evaluate the effects of a plant oil-mixture (olive/sunflower oil; saturated/monounsaturated/polyunsaturated (S/M/P) = 14:69:17) high in oleic acid but also showing a moderate content of polyunsaturated fatty acids (PUFA) in comparison with a single, PUFA rich corn oil (S/M/P = 13:33:54) used in a normal, balanced diet on human plasma and lipoprotein metabolism. METHODS: The double-blind designed study comprised 28 healthy, non-smoking young men aged between 19 and 31 years. After two weeks of adjustment (mixed, balanced diet: 11.6 MJ average, average fat intake approximately 105 g/d), the design included a two week test period in which a diet with 80 g corn oil/d vs a mixture of 68 g olive- and 12 g sunflower oil/d (total 80 g) as the main fat source was given, followed by a crossover after two weeks. Compliance and ingestion of diets were monitored by assessing the fatty acid pattern in LDL and by determination of alpha- and gamma-tocopherol in plasma and LDL. Results Diets were well incorporated due to the significant changes in plasma- and LDL-tocopherol levels and the significant different average ratio of oleic acid to linoleic acid in LDL. The PUFA-rich corn oil diet was able to reduce low density lipoprotein (LDL) cholesterol from adjustment to T2 significantly (p < 0.01), which was also confirmed by a trend after cross over (p=0.15). Total cholesterol (only after cross over at T3), total triglycerides (TG) and very low density lipoprotein (VLDL)-TG were significantly lower at T2 after the corn oil diet than after the mixed oil diet. Total high density lipoproteins (HDL) and HDL cholesterol remained unchanged by both diets. CONCLUSIONS: The results show that during the intervention of two weeks for each diet and the following cross over the corn oil diet had more influence on lipoprotein metabolism than the MUFA-rich diet. The hypocholesteremic effect of the PUFA-rich diet must also be connected with the high amount of unsaponifiable substances, mainly phytosterols in the corn oil.

This review of corn oil provides a scientific assessment of the current knowledge of its contribution to the American diet. Refined corn oil is composed of 99% triacylglycerols with polyunsaturated fatty acid (PUFA) 59%, monounsaturated fatty acid 24%, and saturated fatty acid (SFA) 13%. The PUFA is linoleic acid (C18:2n-6) primarily, with a small amount of linolenic acid (C18:3n-3) giving a n-6/n-3 ratio of 83. Corn oil contains a significant amount of ubiquinone and high amounts of alpha- and gamma-tocopherols (vitamin E) that protect it from oxidative rancidity. It has good sensory qualities for use as a salad and cooking oil. Corn oil is highly digestible and provides energy and essential fatty acids (EFA). Linoleic acid is a dietary essential that is necessary for integrity of the skin, cell membranes, the immune system, and for synthesis of icosanoids. Icosanoids are necessary for reproductive, cardiovascular, renal, and gastrointestinal functions and resistance to disease. Corn oil is a highly effective food oil for lowering serum cholesterol. Because of its low content of SFAs which raises cholesterol and its high content of PUFAs which lowers cholesterol, consumption of corn oil can replace SFAs with PUFAs, and the combination is more effective in lowering cholesterol than simple reduction of SFA. PUFA primarily lowers low-density-lipoprotein cholesterol (LDL-C) which is atherogenic. Research shows that PUFA has little effect on high-density-lipoprotein cholesterol (HDL-C) which is protective against atherosclerosis. PUFA generally improves the ratio of LDL-C to HDL-C. Studies in animals show that PUFA is required for the growth of cancers; the amount required is considered to be greater than that which satisfies the EFA requirement of the host. At this time there is no indication from epidemiological studies that PUFA intake is associated with increased risk of breast or colon cancer, which have been suggested to be promoted by high-fat diets in humans. Recommendations for minimum PUFA intake to prevent gross EFA deficiency are about 3% of energy (en%). Recommendations for prevention of heart disease are 8-10 en%. Consumption of PUFA in the United States is 5-7 en%. The use of corn oil to contribute to a PUFA intake of 10 en% in the diet would be beneficial to heart health. No single source of salad or cooking oil provides an optimum fatty acid (FA) composition. Many questions remain to be answered about the relation of FA composition of the diet to various physiological functions and disease processes.

Olive oil is an integral ingredient of the Mediterranean diet and accumulating evidence suggests that it may have health benefits that include reduction of risk factors of coronary heart disease, prevention of several varieties of cancers, and modification of immune and inflammatory responses. Olive oil appears to be an example of a functional food, with varied components that may contribute to its overall therapeutic characteristics. Olive oil is known for its high levels of monounsaturated fatty acids and is also a good source of phytochemicals including polyphenolic compounds, squalene, and alpha-tocopherol.

OBJECTIVE: This study investigates the potential role of olive oil and other added fats used for seasoning or cooking on ovarian carcinogenesis. METHODS: We analyzed data from a multicentre case-control study conducted between 1992 and 1999 in Italy, including a total of 1031 incident with a first diagnosis, histologically confirmed epithelial ovarian cancer cases and 2,411 hospital controls with acute, non-malignant and non-gynecological conditions. The subjects' usual diet was investigated through a validated food-frequency questionnaire, including specific questions aimed at assessing added fat intake patterns. RESULTS: After allowance for study centre, year at interview, age, education, parity, oral contraceptive use, and total energy intake, a reduced risk of ovarian cancer was observed for high intake of olive oil (odds ratio (OR) = 0.68, 95% confidence interval (CI) 0.50-0.93 for the highest quintile of intake, compared to the lowest one) and for a group of specific seed oils (i.e. sunflower, maize, peanut, and soya) (OR = 0.59, 95% CI 0.46-0.76). No significant associations were observed for mixed seed oils, butter, and margarine. CONCLUSIONS: The present study suggests a favorable effect of olive oil and other vegetable oils on ovarian cancer in this Italian population.

In the Mediterranean basin, olive oil, along with fruits, vegetables, and fish, is an important constituent of the diet, and is considered a major factor in preserving a healthy and relatively disease-free population. Epidemiological data show that the Mediterranean diet has significant protective effects against cancer and coronary heart disease. We present evidence that it is the unique profile of the phenolic fraction, along with high intakes of squalene and the monounsaturated fatty acid, oleic acid, which confer its health-promoting properties. The major phenolic compounds identified and quantified in olive oil belong to three different classes: simple phenols (hydroxytyrosol, tyrosol); secoiridoids (oleuropein, the aglycone of ligstroside, and their respective decarboxylated dialdehyde derivatives); and the lignans [(+)-1-acetoxypinoresinol and pinoresinol]. All three classes have potent antioxidant properties. High consumption of extra-virgin olive oils, which are particularly rich in these phenolic antioxidants (as well as squalene and oleic acid), should afford considerable protection against cancer (colon, breast, skin), coronary heart disease, and ageing by inhibiting oxidative stress.

longside the French paradox, the REGICOR Study (Girona, Spain) has shown another paradox in the Mediterranean area: a high prevalence of cardiovascular risk factors with low incidence of myocardial infarction in the population of Girona, Spain. The antioxidant effects associated with olive oil consumption could explain part of this 'Mediterranean Paradox'. Virgin olive oils processed by two centrifugation phases and with low fruit ripeness have the highest levels of antioxidant content. The total content of phenolic compounds (PC) from virgin olive oil could delay LDL oxidation. The content and nature of olive oil PC have a high influence in the antioxidant capacity of an olive oil. PC from diet could bind human LDL in non-supplemented volunteers. PC from virgin olive oil could bind LDL and tyrosol is bioavailable in humans from ingestion of virgin olive oil in its natural form.

Various studies have already shown that the fatty acid composition of dietary fat has different effects on hemostasis and platelet function. However, knowledge on this topic is incomplete. In the present study, fifty-eight healthy students received either a 4-week rapeseed oil [high content of monounsaturated fatty acids (MUFA) and high n-3/n-6 PUFA ratio], an olive oil (high content of MUFA, low n-3/n-6 PUFA ratio) or a sunflower oil (low content of MUFA, low n-3/n-6 PUFA ratio) diet. In each group, effects on hemostatic parameters were compared with a wash-in diet rich in saturated fatty acids with respect to intermediate-time effects on the hemostatic system and platelet function. With the olive oil diet, a reduction of coagulation factors VIIc, XIIc, XIIa, and Xc was found, whereas sunflower oil led to lower values of coagulation factors XIIc, XIIa, and IXc. In all study groups levels of plasmin-alpha2-antiplasmin were lower in week 4 than at baseline. Lower fibrinogen binding on platelets was found after the sunflower oil diet, whereas expression of CD62 and spontaneous platelet aggregation were slightly higher after the olive oil diet. However, given the major differences in the fatty acid compositions of the diets, the differences between the groups with respect to hemostasis tended to be small. Therefore, the clinical significance of the present findings remains to be evaluated.

In this highly controlled trial, 26 normolipidemic men (average age 28 years, range 18 to 60) were fed a baseline diet high in milk fat (MF) (fat 36% of energy, saturates 19%, monounsaturates 11%, polyunsaturates 4%), followed by a diet high in sunflower oil (SO) (fat 38% of energy, saturates 13%, monounsaturates 10%, polyunsaturates 13%) and another diet high in low erucic-acid rapeseed oil (RO) (fat 38% of energy, saturates 12%, monounsaturates 16%, polyunsaturates 8%). All diets were mixed natural diets with the same cholesterol contents. The baseline milk fat diet was given for 14 days and the oil diets for 24 days in a blind cross-over design. The platelet in vitro aggregation (slope %/min) induced by 1, 2 and 3 microM ADP and collagen (25 micrograms/ml PRP) was highly significantly (p less than 0.001) increased after both oil diets when compared with the results from the milk fat diet. The aggregation pattern determined by threshold collagen concentration confirmed increased collagen sensitivity of the platelets after the rapeseed oil diet (p less than 0.001). The enhancement of platelet aggregation was associated with increased in vitro platelet thromboxane production after the oil diets vs. the milk fat diet (p less than 0.05 after the sunflower oil diet and p less than 0.001 after the rapeseed oil diet).

Scientific evidence is accumulating that meat itself is not a risk factor for Western lifestyle diseases such as cardiovascular disease, but rather the risk stems from the excessive fat and particularly saturated fat associated with the meat of modern domesticated animals. In our own studies, we have shown evidence that diets high in lean red meat can actually lower plasma cholesterol, contribute significantly to tissue omega-3 fatty acid and provide a good source of iron, zinc and vitamin B12. A study of human and pre-human diet history shows that for a period of at least 2 million years the human ancestral line had been consuming increasing quantities of meat. During that time, evolutionary selection was in action, adapting our genetic make up and hence our physiological features to a diet high in lean meat. This meat was wild game meat, low in total and saturated fat and relatively rich in polyunsaturated fatty acids (PUFA). The evidence presented in this review looks at various lines of study which indicate the reliance on meat intake as a major energy source by pre-agricultural humans. The distinct fields briefly reviewed include: fossil isotope studies, human gut morphology, human encephalisation and energy requirements, optimal foraging theory, insulin resistance and studies on hunter-gatherer societies. In conclusion, lean meat is a healthy and beneficial component of any well-balanced diet as long as it is fat trimmed and consumed as part of a varied diet.