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Supplementation of postmenopausal women with fish oil rich in eicosapentaenoic acid and docosahexaenoic acid is not associated with greater in vivo lipid peroxidation compared with oils rich in oleate and linoleate as assessed by plasma malondialdehyde and F(2)-isoprostanes.

BACKGROUND: Although the replacement of dietary saturated fat with unsaturated fat has been advocated to reduce the risk of cardiovascular disease, diets high in polyunsaturated fatty acids (PUFAs) could increase lipid peroxidation, potentially contributing to the pathology of atherosclerosis. OBJECTIVE: The objective of this study was to examine indexes of in vivo lipid peroxidation, including free F(2)-isoprostanes, malondialdehyde (MDA), and thiobarbituric acid reacting substances (TBARS), in the plasma of postmenopausal women taking dietary oil supplements rich in oleate, linoleate, and both eicosapentaenoic acid and docosahexaenoic acid. DESIGN: Fifteen postmenopausal women took 15 g sunflower oil/d, providing 12.3 g oleate/d; safflower oil, providing 10.5 g linoleate/d; and fish oil, providing 2.0 g EPA/d and 1.4 g DHA/d in a 3-treatment crossover trial. RESULTS: Plasma free F(2)-isoprostane concentrations were lower after fish-oil supplementation than after sunflower-oil supplementation (P: = 0.003). When plasma free F(2)-isoprostane concentrations were normalized to plasma arachidonic acid concentrations, significant differences among the supplements were eliminated. Plasma MDA concentrations were lower after fish-oil supplementation than after sunflower-oil supplementation (P: = 0.04), whereas plasma TBARS were higher after fish-oil supplementation than after sunflower oil (P: = 0.003) and safflower oil (P: = 0.001) supplementation. When plasma MDA concentrations were normalized to plasma PUFA concentrations, significant differences were eliminated, but TBARS remained higher after fish-oil supplementation than after sunflower oil (P: = 0.01) and safflower-oil (P: = 0.0003) supplementation. CONCLUSIONS: With fish-oil supplementation, there was no evidence of increased lipid peroxidation when assessed by plasma F(2)-isoprostanes and MDA, although plasma TBARS was higher than with sunflower-oil and safflower-oil supplementation.

Aged↗

Meat, fat, and their subtypes as risk factors for colorectal cancer in a prospective cohort of women.

The authors investigated the association of intakes of meat and fat with colorectal cancer in a prospective cohort of women in the United States. Between 1987 and 1989, 45,496 women completed a 62-item National Cancer Institute/Block food frequency questionnaire, and during 386,716 person-years of follow-up, there were 487 incident cases of colorectal cancer. The authors used Cox proportional hazards regression to estimate relative risks and 95% confidence intervals for total meat, red meat, white meat, processed meat, and well-done meat intakes, as well as for total fat, saturated fat, and unsaturated fat. Relative risks for increasing quintiles of total meat and red meat consumption indicated no association with colorectal cancer (relative risk for high compared with low quintile = 1.10, 95% confidence interval: 0.83, 1.45) for red meat. For total fat, there was also no association with increasing quintiles of consumption (relative risk for high compared with low quintile = 1.14, 95% confidence interval: 0.86, 1.53). Additionally, none of the other subtypes of either meat or fat showed any association with colorectal cancer. This study provided no evidence of an association between either meat or fat (or any of their subtypes) and colorectal cancer incidence, but the authors cannot rule out the possibility of a modest association.

Age Distribution↗

Dietary fatty acids on the control of glucose-6-phosphate dehydrogenase and malic enzyme in the starved-refed rat.

The role of dietary unsaturated fat in the control of hepatic glucose-6-phosphate dehydrogenase (G6PD) (EC 1.1.1.49) and malic enzyme (ME) (EC 1.1.1.40) was studied in rats subjected to one or two cycles of starvation-refeeding. Rats starved and refed a control (5% corn oil) diet showed a threefold increase in G6PD activity and a twofold increase in ME activity compared to ad libitum-fed rats. After a second cycle of starvation-refeeding G6PD and ME activities showed fourfold and threefold increases, respectively, as compared to ad libitum-fed rats. Feeding rats diets containing 8% linoleic acid (as triglycerides) prevented the increase in G6PD and ME activities upon starvation-refeeding, diets with oleic, palmitic, and stearic acis when fed did not prevent this increase. Feeding rats various combinations of linoleic, linolenic and oleic acids following starvation prevented the additional increase in G6PD and ME activities after a second starvation-refeeding cycle; however, linoleic acid fed alone during the first refeeding prevented the additional increase in ME activity but not in G6PD activity. It is suggested that the dietary control of these enzymes involves one or more specific polyunsaturated fatty acids.

Animals↗

Dietary lipids and immune function.

The influence of dietary lipids on immune function has come under serious study only within the past two decades. It is clear from whole-animal studies that obesity and consumption of diets high in fat, particularly unsaturated fat, depress immunocompetence and enhance risk for serious infectious disease and cancer. In vitro systems, cell cultures and the tools of molecular biology are moving nutrition and immunology closer together with promise of significant benefits.

Animals↗

Mediterranean diet and cancer risk.

Various aspects of the Mediterranean diet are considered favourable with regard to cancer risk. These aspects were analysed using data from a series of case-control studies conducted in northern Italy between 1983 and 2001 on over 12,000 cases of 20 cancer sites and 10,000 controls. For most epithelial cancers, the risk decreased with increasing vegetable and fruit consumption, with odds ratios (OR) between 0.3 and 0.7 for the highest versus the lowest tertile. Subjects reporting frequent red meat intake showed ORs above unity for several common neoplasms. Conversely, fish (and consequently, n-3 fatty acids) tended to be another favourable dietary indicator. Wholegrain food intake was related to reduced risk of several types of cancer, particularly of the upper digestive tract, probably on account of its high fibre content. Fibres were in fact found to be protective with regard to colorectal and other selected cancers. In contrast to wholegrain, refined grain intake, and consequently glycaemic load, was associated with an increased risk of different types of cancer, including those of the upper digestive tract, colorectum, breast and endometrium. These results thus suggest that a low-risk diet for cancer entails increasing vegetables and fruit, reducing meat, but also refined carbohydrate consumption. Furthermore, olive oil and other unsaturated fats, which may be a unique common characteristic of the Mediterranean diet, should be preferred to animal and saturated fats. A score summarizing the major characteristics of the Mediterranean diet was inversely and consistently related to the risk of selected cancer sites. Regular consumption of pizza, one of the most typical Italian foods, showed a reduced risk of digestive tract cancers. Pizza could however simply be an indicator of a typical Italian diet.

Case-Control Studies↗

Primary prevention of diabetes: what can be done and how much can be prevented?

Although it is widely believed that type 2 diabetes mellitus is the result of a complex interplay between genetic and environmental factors, compelling evidence from epidemiologic studies indicates that the current worldwide diabetes epidemic is largely due to changes in diet and lifestyle. Prospective cohort studies and randomized clinical trials have demonstrated that type 2 diabetes can be prevented largely through moderate diet and lifestyle modifications. Excess adiposity is the most important risk factor for diabetes, and thus, maintaining a healthy body weight and avoiding weight gain during adulthood is the cornerstone of diabetes prevention. Increasing physical activity and reducing sedentary behaviors such as prolonged TV watching are important both for maintaining body weight and improving insulin sensitivity. There is increasing evidence that the quality of fat and carbohydrate plays a more important role than does the quantity, and thus, public health strategies should emphasize replacing saturated and trans fats with unsaturated fats and replacing refined grain products with whole grains. Recent studies have also suggested a potential role for coffee, dairy, nuts, magnesium, and calcium in preventing diabetes. Overall, a healthy diet, together with regular physical activity, maintenance of a healthy weight, moderate alcohol consumption, and avoidance of sedentary behaviors and smoking, could nearly eliminate type 2 diabetes. However, there is still a wide gap between what we know and what we practice in the field of public health; how to narrow that gap remains a major public health challenge.

Alcohol Drinking↗

Postprandial lipemia and lipoprotein lipase in the rabbit are modified by olive and coconut oil.

Feeding a 14% coconut oil/0.5% cholesterol (CNO/chol) diet to rabbits resulted in plasma triglycerides that were, on average, 15 times higher than basal levels. Plasma triglycerides in rabbits fed a 14% olive oil/0.5% cholesterol (OO/chol) diet were significantly below baseline levels. Differences in postprandial triglyceride response and postheparin plasma lipoprotein lipase activity (LPL) in various feeding conditions were studied to determine the mechanism of the hypertriglyceridemia. Postprandial triglyceride responses after the first high fat/cholesterol meal were more prolonged in CNO/chol rabbits than in OO/chol rabbits; postprandial triglyceride responses after chronic CNO/chol feeding were significantly greater compared to OO/chol rabbits. When long-term CNO/chol rabbits were given one OO/chol or corn oil/chol meal, postprandial triglyceride peaks were greatly diminished, suggesting that these unsaturated fat meals may alter triglyceride clearance capacity. LPL activity was 400% higher than basal levels in chronically fed OO/chol rabbits but changed very little in chronically fed CNO/chol rabbits. Twenty-four hours after a single OO/chol meal was fed to chow-fed rabbits, LPL doubled; one CNO/chol meal was associated with only a 40% increase. Feeding a single OO/chol or corn oil/chol meal to chronically fed CNO/chol rabbits resulted in a 30% to 50% increase in LPL by 24 hours. Thus, the hypertriglyceridemia in CNO/chol rabbits may result in part from a decreased clearance capacity due to a lack of increase in LPL activity, while increased LPL may be partially responsible for the hypotriglyceridemia observed in OO/chol feeding. Aortic cholesterol was substantially higher in CNO/chol rabbits. Triglyceride was approximately eight times greater in livers from CNO/chol-fed rabbits than in those fed OO/chol, but liver cholesterol was only about one-third as much as that in OO/chol rabbits.

Animals↗

Nutritional factors and risk of incident dementia in the PAQUID longitudinal cohort.

PURPOSE: The aim of this study was to present a summary of the results obtained in the PAQUID study regarding wine consumption, fish and seafood consumption and vitamin A and E plasma concentrations. METHODS: This study was carried out from the PAQUID (Personnes Agees QUID) cohort, an epidemiological study on cognitive and functional aging after 65 years in Southwestern France. The relationship between nutritional factors and risk of incident dementia was measured using logistic regression or Cox proportional hazards models on different subsamples of the cohort. RESULTS: Among 2950 initially non-demented subjects, moderate drinkers had a decreased relative risk of developing a dementia in the subsequent 8 years (RR=0.56) compared to non-drinkers. In a sub-sample of 1416 subjects, those who ate fish or seafood at least once a week had a significant reduced risk of incident dementia adjusted for age and sex (RR=0.66). Lastly, a nested casecontrol study was performed among 182 subjects. Adjusted for confounders, the risk of dementia was significantly increased for the lowest vitamin E concentration compared to the highest one (OR=2.54). DISCUSSION: These results are in agreement with a possible protective role of a diet rich in poly-unsaturated fats and antioxidant components. However, confounding factors such as education and lifestyle may be involved and should be further explored.

Aged↗

Effects of dietary fatty acids on the early stages of neoplastic induction in the rat pancreas. Changes in fatty acid composition and development of atypical acinar cell nodules.

Diets enriched with fat, especially unsaturated fat, promote experimental pancreatic carcinogenesis, but little is known of the effects of individual fatty acids. The effect of stearic and oleic acid on pancreatic fatty acids and atypical acinar cell nodules (preneoplastic lesions) was studied in 14-day-old weanling male Leeds strain rats (n = 60) given the carcinogen azaserine. Rats were allocated to one of six groups: untreated controls (n = 10), 20% stearic acid diet (n = 10), 20% oleic acid diet (n = 10), carcinogen alone (n = 10), carcinogen plus 20% stearic acid diet (n = 10) or carcinogen plus 20% oleic acid diet (n = 10). Azaserine was administered by intraperitoneal injection in a dose of 30 mg/kg at 2, 3 and 4 weeks of age. When total lipid extracts of pancreas were examined, there was an increase in stearic acid in the stearic acid fed group and an increase in oleic acid in the oleic acid fed group, irrespective of carcinogen treatment. The relative content of all other pancreatic fatty acids was suppressed by feeding oleic acid. At 26 weeks, the number and volumetric indices of pancreatic atypical acinar cell nodules was increased only in rats given azaserine and oleic acid. The enhancing effect of oleic acid on pancreatic carcinogenesis may be associated with pancreatic fatty acid changes.

Animals↗

Distributional shape of nutrition data.

Nutrition data from 111 undergraduate college students (51 males and 60 females, ranging in age from 17 to 24) were studied with respect to the shape of the underlying probability distributions. Three-day averages for total energy, percent protein, percent saturated fat, percent unsaturated fat, percent complex carbohydrates, percent refined carbohydrates, cholesterol, sodium, vitamin C, and iron (measured in milligrams) were computed, and their distributions were compared with the normal (Gaussian) distribution. The distribution of values of sodium for females and, to a lesser extent, cholesterol for females and of cholesterol and vitamin C for males, differed from the normal distribution. The remaining distributions appeared to be reasonably close to normal in shape. It is recommended that nutrition researchers verify the normal distribution assumptions prior to applying parametric techniques to their data and that they use nonparametric (distribution-free) techniques to analyze their data whenever those assumptions are not valid.

Adolescent↗

Effect of interviewer recording practices on nutrient intake--Bogalusa Heart Study.

Recording practices of interviewers who independently collected dietary recalls from children for the same 24-hour eating period were analyzed. For each duplicate pair, three aspects of recording were examined: name of foods, quantity assessed from child, and food identification number selected prior to nutrient analysis. There was a 76% agreement on recorded food names. For those matched foods, 87% were assigned the same food identification numbers. Differences regarding quantities of foods were greatest for liquids, meats, and sweets. Recalls were analyzed for nutrient content on the computerized Extended Table of Nutrient Values. A paired t-test statistic showed significant sequence effect, with total energy, sugar, fat, and unsaturated fat higher for the first interview. Significant differences in nutrient intake were noted for the interviewer pair with highest percentage of foods differing by name. After-school snack assessment was the most variable eating occasion. Entry-level criteria for trained interviewers are proposed to establish standardized interviewing techniques when applying the 24-hour recall tool to child respondents.

Child↗

Modifying effect of dietary fat on benzo[a]pyrene-induced respiratory tract tumours in hamsters.

Groups of 40 Syrian golden hamsters of both sexes were fed diets containing either 5% fat (control), 20% saturated fat (beef tallow) or 20% unsaturated fat (sunflower seed oil) from weaning and during the whole experimental period (up to 656 days). Respiratory tract tumours were induced by intratracheal instillation of benzo[a]pyrene attached to ferric oxide and suspended in saline. Mortality was slightly, but not statistically significantly higher in the high fat groups than in the low fat control group. Microscopic examination of the respiratory tract revealed an increased number of tumour bearing animals, an increased multiplicity of respiratory tract tumours and an increased total number of respiratory tract tumours in animals fed high fat diets. The tumour enhancing effect of fat was most pronounced in the high unsaturated fat group. Especially epidermoid papillomas, epidermoid carcinomas and combined epidermoid and adenocarcinomas contributed to the observed differences in tumour response amongst groups. It was concluded that dietary fat enhances benzo[a]pyrene-induced respiratory tract carcinogenesis in hamsters.

Adenocarcinoma↗

Effects of protected cyclopropene fatty acids on the composition of ruminant milk fat.

Unsaturated fatty acids can be protected from ruminal hydrogenation, and when fed to lactating ruminants, the constituent acids are incorporated into milk triacylglycerols. By this means, it has been possible to reduce the melting point of milk triglycerides and to make softer butter fat. This report shows that, by feeding small amounts of protected cyclopropene fatty acids, one is also able to make harder butter fat. Sterculia foetida seed oil, a rich source of cyclopropene fatty acids, was emulsified with casein and spray dried to yield a free flowing dry powder. When this material was treated with formaldehyde and fed to lactating goats(ca. 1 g cyclopropene fatty acids per day), there were substantial increases in the proportions of stearic acid and decreases in the proportions of oleic acid in milk fat. Similar results were obtained when the formaldehyde-treated supplements were fed to lactating cows (ca. 3 g cyclopropene fatty acids per day). The effect was considerably less apparent when the S. foetida seed oil-casein supplement was not treated with formaldehyde, suggesting that cyclopropene fatty acids are hydrogenated in the rumen as are other unsaturated fatty acids. The effect of feeding protected cyclopropene fatty acids on the stearic:oleic ratio in milk fat is probably due to cyclopropene-mediated inhibition of the mammary desaturase enzymes.

Animals↗

Quality of dietary fatty acids, insulin sensitivity and type 2 diabetes.

Epidemiological evidence and intervention studies clearly indicate that the quality of dietary fat influences insulin sensitivity in humans, in particular, saturated fat worsens it, while monounsaturated and omega-6 polyunsaturated fats improve it. Long chain omega-3 fatty acids do not seem to have any effect on insulin sensitivity, at least in humans. Moreover, there is also good epidemiological evidence that the quality of dietary fat may influence the risk of type 2 diabetes, again with saturated fat increasing and unsaturated fat decreasing this risk. No intervention study is available at the moment on this specific point, even if in the Finnish Diabetes Prevention Study the incidence of type 2 diabetes was reduced by a multifactorial intervention, which also included a reduction of saturated fat intake.

Clinical Trials as Topic↗

Dietary cholesterol and type of fat differentially affect cholesterol metabolism and atherosclerosis in baboons.

This study was designed to determine the differences in cholesterol metabolism due to dietary cholesterol and type of fat in adult baboons. From weaning at 16 wk to 7-8 y of age, 80 baboons were fed one of four diets: high cholesterol (0.24 mg/kJ) or low cholesterol (0.0024 mg/kJ) with 40% of energy from saturated fat [polyunsaturated/saturated fatty acid ratio (P/S) = 0.37] or unsaturated fat (P/S = 2.1). High cholesterol and saturated fat independently raised serum lipoprotein and apolipoprotein concentrations to about the same extent. The liver cholesterol concentration of baboons fed high cholesterol diets was 23% higher than that of baboons fed low cholesterol. High dietary cholesterol also increased bile cholesterol concentration by 25%, the neutral steroid excretion rate by 66% and the bile acid excretion rate by 30%. With feeding of saturated fat, compared with unsaturated fat, liver cholesterol was 24% lower, bile cholesterol 26% lower and the neutral steroid excretion rate 12% lower. Dietary cholesterol greatly suppressed whole-body cholesterol synthesis, but type of fat did not affect cholesterol synthesis rate. These results suggest that dietary cholesterol and saturated fat increase plasma lipoprotein concentrations through different physiological mechanisms.

Animals↗

Dietary fatty acid intakes and the risk of ovulatory infertility.

BACKGROUND: Pharmacologic activation of the peroxisome proliferator-activated receptor gamma (PPAR-gamma) improves ovulatory function in women with polycystic ovary syndrome, and specific dietary fatty acids can affect PPAR-gamma activity. OBJECTIVE: The objective of the study was to assess whether the intakes of total fat, cholesterol, and major types of fatty acids affect the risk of ovulatory infertility. DESIGN: We conducted a prospective cohort study of 18 555 married, premenopausal women without a history of infertility who attempted a pregnancy or became pregnant between 1991 and 1999. Diet was assessed twice during follow-up by using a food-frequency questionnaire. RESULTS: During follow-up, 438 incidents of ovulatory infertility were reported. In logistic regression analyses, intakes of total fat, cholesterol, and most types of fatty acids were not related to ovulatory infertility. Each 2% increase in the intake of energy from trans unsaturated fats, as opposed to that from carbohydrates, was associated with a 73% greater risk of ovulatory infertility after adjustment for known and suspected risk factors for this condition [relative risk (RR) = 1.73; 95% CI: 1.09, 2.73]. Obtaining 2% of energy intake from trans fats rather than from n-6 polyunsaturated fats was associated with a similar increase in the risk of ovulatory infertility (RR = 1.79; 95% CI: 1.11, 2.89). In addition, obtaining 2% of energy from trans fats rather than from monounsaturated fats was associated with a more than doubled risk of ovulatory infertility (RR = 2.31; 95% CI: 1.09, 4.87). CONCLUSION: trans Unsaturated fats may increase the risk of ovulatory infertility when consumed instead of carbohydrates or unsaturated fats commonly found in nonhydrogenated vegetable oils.

Adult↗

Prospective study of fat and protein intake and risk of intraparenchymal hemorrhage in women.

BACKGROUND: -Dietary animal fat and protein have been inversely associated with a risk of intraparenchymal hemorrhage in ecological studies. METHODS AND RESULTS: In 1980, 85 764 women in the Nurses' Health Study cohort, who were 34 to 59 years old and free of diagnosed cardiovascular disease and cancer, completed dietary questionnaires. From these questionnaires, we calculated fat and protein intake. By 1994, after 1.16 million person-years of follow-up, 690 incident strokes, including 74 intraparenchymal hemorrhages, had been documented. Multivariate-adjusted risk of intraparenchymal hemorrhage was higher among women in the lowest quintile of energy-adjusted saturated fat intake than at all higher levels of intake (relative risk [RR], 2.36; 95% CI, 1.10 to 5.09; P:=0.03). For trans unsaturated fat, the corresponding RR was 2.50 (95% CI, 1.35 to 4.65; P:=0.004). Animal protein intake was inversely associated with risk (RR in the highest versus lowest quintiles, 0.32; 95% CI, 0.10 to 1.00; P:=0.04). The excess risk associated with low saturated fat intake was observed primarily among women with a history of hypertension (RR, 3.66; 95% CI, 1.09 to 12.3; P=0.04), but such an interaction was not seen for trans unsaturated fat or animal protein. These nutrients were not related to risk of other stroke subtypes. Dietary cholesterol and monounsaturated and polyunsaturated fat were not related to risk of any stroke subtype. CONCLUSIONS: Low intake of saturated fat and animal protein was associated with an increased risk of intraparenchymal hemorrhage, which may help to explain the high rate of this stroke subtype in Asian countries. The increased risk with low intake of saturated fat and trans unsaturated fat is compatible with the reported association between low serum total cholesterol and risk.

Adult↗