Linoleic acid lowers LDL cholesterol without a proportionate displacement of saturated fatty acid

We tested the specificity of the plasma cholesterol-lowering effect of linoleic acid in a comparison of linoleate-rich and saturated fatty acid-rich foods. Twelve mildly hypercholesterolemic men and women ate the two diets for three weeks each in a random cross-over design, after a two-week baseline period. A linoleic acid-rich supplement was added to the baseline diet so that the saturated and monounsaturated fatty acid content did not change significantly. Despite the consequent increase in total fat intake, the linoleate-rich diet (23 per cent energy from polyunsaturated fatty acids) significantly lowered plasma total and low-density lipoprotein (LDL) cholesterol (-8 per cent and -14 per cent respectively), while high-density lipoprotein (HDL) cholesterol rose 8 per cent. The direction of these changes was similar in all 12 subjects. Compared with a supplement that raised dietary saturated fatty acids to 30 per cent energy, the linoleate acid-rich diet gave lower total cholesterol (-14 per cent), LDL cholesterol (-18 per cent) and HDL cholesterol (-12 per cent) concentrations. Linoleic acid lowers LDL cholesterol even when saturated fatty acids are not significantly displaced and substantially more when there is such displacement.     

Food safety and health effects of canola oil.

Canola oil is a newly marketed vegetable oil for use in salads and for cooking that contains 55% of the monounsaturated fatty acid; oleic acid, 25% linoleic acid and 10% alpha-linolenate [polyunsaturated fatty acid (PUFA)], and only 4% of the saturated fatty acids (SFAs) that have been implicated as factors in hypercholesterolemia. It is expressed from a cultivar of rapeseed that was selectively bred from old varieties in Canada to be very low in erucic acid–a fatty acid suspected to have pathogenic potential in diets high in the original rapeseed oil in experimental animals. Canola oil is free of those problems. It is the most widely consumed food oil in Canada, and has been approved for Generally Recognized as Safe (GRAS) status by the Food and Drug Administration (FDA) of the United States Department of Health and Human Services. The fatty acid composition of canola oil is consistent with its use as a substitute for SFAs, in meeting the dietary goals recommended by many health associations: an average diet containing about 30% of calories as fat made up of less than 10% SFAs, 8-10% PUFAs in a ratio of linoleic to linolenic acids between 4:1 and 10:1, the remainder being monounsaturated fatty acids. No single oil meets these current recommendations for ratios of PUFA/monounsaturated/polyunsaturated fatty acid ratios as the sole source of cooking and salad oil.     

Polyunsaturated meat and dairy products in fat-modified food patterns for hyperlipidemia.

Polyunsaturated meat and dairy products were compared with their saturated counterparts to determine their usefulness in a fat-modified diet for hyperlipidemic persons and their spouses. These polyunsaturated animal products were produced by feeding cattle a supplement of oil droplets coated with denatured protein. As a result, the polyunsaturated fatty acid content was 27 to 28 per cent of the meat fat and butterfat; saturated fatty acids (C12:0 to tc16:0) were 18 to 19 per cent. Of the eleven free-living subjects three were normocholesteremic, three had type IIa hyperlipidemia and five had type VI (IIb). In the fourteen-week study, an adjustment period of three weeks was followed by two consecutive experimental periods of four weeks each, then by a three-week follow-up period. During the adjustment period, participants continued to follow their usual eating patterns. During both experimental periods all followed the same prescribed fat modified food pattern using polyunsaturated margarine and oil. Five participants ate polyunsaturated beef and dairy products during the first experimental period and their saturated counterparts in the second; six participants ate saturated products first, then polyunsaturated. During the follow-up period, all participants selected all their own food. Serum cholesterol levels in five participants who had not previously followed a fat-modified diet were reduced by 18 per cent with polyunsaturated animal products and 11 per cent with saturated products. Serum cholesterol in six participants, previously on a fat-modified diet, was not significantly changed with polyunsaturated products. In ten of eleven participants, serum cholesterol levels were an average of 6 per cent lower with polyunsaturated products than with saturated products. It is concluded that polyunsaturated animal products are suitable for use in fat-modified food patterns for reducing hyperlipidemia, with some restrictions in the amount of polyunsaturated animal fat and with the inclusion of polyunsaturated oil and margarine.     

Dietary studies of children from a biracial population: intakes of fat and fatty acids in 10- and 13-year olds

Dietary intakes of fat and fatty acids were examined in children randomly selected from a biracial community, Bogalusa, LA. Between two 10-yr-old groups examined 3 yr apart, temporal trends of 1) higher intakes of polyunsaturated fatty acids, linoleic and linolenic acids, and 2) lower intakes of animal fat, saturated fatty acids, and palmitic acid were documented. No racial differences were found, and the only difference between sexes was for myristic acid (boys greater than girls). Longitudinal comparisons of a cohort of 148 children examined at both 10 and 13 yr showed higher intakes over time of unsaturated fatty acids, polyunsaturated fatty acids, vegetable fat, oleic, linoleic, and linolenic acids, and lower intakes of cholesterol, saturated fatty acids, animal fat, and myristic acid. The percentage of energy intake from fat, saturated fatty acids and polyunsaturated fatty acids was quite similar to other reports of US children and adults. Few children's intakes of cholesterol, fat, and fatty acids were compatible with current recommendations for prudent diets. Patterns of dietary fat and fatty acid intake of Bogalusa children reflect reported food market trends of increased use of vegetable fats.     

Ten-year incidence of coronary heart disease in the Honolulu Heart Program. Relationship to nutrient intake

Nutrient intake was determined in over 8000 men of Japanese ancestry residing on the island of Oahu. Nutrient determination took place at the initial examination during the years 1965-1968. This report relates nutrient intake to the risk of developing coronary heart disease in the 10 years subsequent to the initial examination. Men who developed coronary heart disease had a lower average intake of calories, carbohydrates, starch, and vegetable protein than men who remained free of coronary heart disease. Men who developed coronary heart disease also had a higher mean intake of percentage of calories from protein, fat, saturated fatty acids, and polyunsaturated fatty acids than men who remained free of coronary heart disease. These men also had a significantly lower mean percentage of calories from carbohydrates and a higher mean ingestion of cholesterol per 1000 calories than men who remained free of coronary heart disease. In multivariate analyses including age, systolic blood pressure, serum cholesterol, cigarettes smoked per day, and physical activity index, carbohydrates, vegetable protein, percentage of calories from saturated fatty acids, and percentage of calories from polyunsaturated fatty acids are no longer significantly related to incidence.     

Effects of dietary trans fatty acids on blood pressure in normotensive subjects.

Consumption of essential fatty acids of the (n-6) series may affect blood pressure in man. Trans fatty acids in the diet interfere with the metabolism of essential fatty acids in rats. We therefore measured the effect of dietary trans fatty acids on blood pressure in 25 men and 34 women. Each subject consumed, in random order, three mixed natural diets, each for three weeks. The composition of the three diets was similar, except for 10.4 per cent of energy, which was provided by either oleic acid, trans fatty acids, or saturated fatty acids. The intake from polyunsaturated fatty acids was 3.4 per cent on the saturated-fat diet and 4.6 per cent on the other two diets. On the oleic-acid diet systolic blood pressure was 113 +/- 12.8 mmHg and diastolic blood pressure 66 +/- 8.3 mmHg, on the trans-fatty-acid diet 112 +/- 12.2 mmHg and 67 +/- 8.1 mmHg, and on the saturated-fat diet 112 +/- 12.6 mmHg and 67 +/- 8.1 mmHg. No significant differences were observed in blood pressure levels between the three diets. We conclude that neither trans nor saturated fatty acids influence blood pressure levels in normotensive subjects relative to oleic acid.     

Analysis of macrocomponents and fatty acids in the market basket of male adolescents in The Netherlands

During a period of 2 1/2 years, every 3 months 221 different food items forming a "market basket" were purchased, prepared, and classified into 23 food commodity groups. The "market basket" was based on a study of the dietary intake of 18-year-old men. In the (homogenized) food groups, the contents of protein, fat, and available carbohydrates were determined as well as the fatty acid composition. The mean daily amounts of the macrocomponents (as a percentage of the mean daily energy value of the total diet) were 14% for protein, 35% for fat, 47% for total available carbohydrates, and 4% for alcohol. The total diet contained 24 gm dietary fiber. The fatty acid composition of the Dutch male adolescents' diet resembles the fatty acid composition of the Dutch "national diet" and the typical American diet: approximately 15% of total calories as saturated fatty acids, 5% as polyunsaturated fatty acids (PUFA), and a polyunsaturated to saturated fatty acids ratio of 0.33. The results, as compared with the recommendations for a healthy diet, show that a decreased consumption of saturated fat, a higher consumption of PUFA, a higher dietary fiber intake, and a higher consumption of complex carbohydrates would be advisable for male Dutch adolescents.     

Food safety and health effects of canola oil

Canola oil is a newly marketed vegetable oil for use in salads and for cooking that contains 55% of the monounsaturated fatty acid; oleic acid, 25% linoleic acid and 10% alpha-linolenate [polyunsaturated fatty acid (PUFA)], and only 4% of the saturated fatty acids (SFAs) that have been implicated as factors in hypercholesterolemia. It is expressed from a cultivar of rapeseed that was selectively bred from old varieties in Canada to be very low in erucic acid--a fatty acid suspected to have pathogenic potential in diets high in the original rapeseed oil in experimental animals. Canola oil is free of those problems. It is the most widely consumed food oil in Canada, and has been approved for Generally Recognized as Safe (GRAS) status by the Food and Drug Administration (FDA) of the United States Department of Health and Human Services. The fatty acid composition of canola oil is consistent with its use as a substitute for SFAs, in meeting the dietary goals recommended by many health associations: an average diet containing about 30% of calories as fat made up of less than 10% SFAs, 8-10% PUFAs in a ratio of linoleic to linolenic acids between 4:1 and 10:1, the remainder being monounsaturated fatty acids. No single oil meets these current recommendations for ratios of PUFA/monounsaturated/polyunsaturated fatty acid ratios as the sole source of cooking and salad oil.     

Nutrient analysis of Exchange Lists for Meal Planning. I. Variation in nutrient levels.

Using available food composition data, individual Exchange Lists within the revised Exchange Lists for Meal Planning were evaluated for calories; protein; fat; calcium; phosphorus; iron; sodium; potassium; vitamin A; thiamin; riboflavin; niacin; ascorbic acid; saturated, oleic, and linoleic fatty acids; cholesterol; and crude fiber. Mean values, standard deviations, and ranges are reported for the above nutrients. Mean values agreed well with those suggested in the booklet for grams of carbohydrates, protein, and fat and for calories for all lists except milk. However, a wide range in values exists for food within each Exchange List.     

Calories, fat and cholesterol: intake patterns in the US population by race, sex and age.

Nutrient intakes were investigated for Blacks and Whites using data from the NHANES II survey (1976-80). Intake of energy, total fat, saturated fat, dietary cholesterol, P/S ratio, and per cent of calories derived from total and saturated fat are examined by sex and age, both in absolute terms and per unit of body weight. For most age and sex categories, Blacks are found to have a lower intake of energy and fats than Whites; however, Blacks have a consistently higher intake of dietary cholesterol. The ratio of polyunsaturated fats to saturated fats is higher in females than in males, but all age-sex groups are substantially below recommended levels. Per cent of calories from total and saturated fat are similar in most age-sex groups. Possible explanations of the observed patterns include activity level and metabolic differences.     

Foods predictive of nutrient intake in Chinese diet in Taiwan: I. Total calories, protein, fat and fatty acids.

Dietary consumption data obtained by food weighing for 539 households in Taiwan in 1980-1981 were used to search for foods predictive of nutrient intake. The average per capita nutrient intake in each household was calculated for total calories, protein, fat and fatty acids (saturated fatty acids, oleic acid and unsaturated fatty acids). Stepwise multiple regression analysis was carried out to reveal the relative importance of each of 405 food items in the dietary survey data for predicting nutrient intake. We found that as few as seven to 20 food items could account for a large proportion of the variability of macronutrient intake in this population. These lists of foods were the minimum needed to categorize an individual's nutrient intake for epidemiological studies in Taiwan. The types and amounts of cooking oils (important predictors of fat and calories) added to the dishes were found to vary from family to family, and should be considered in designing dietary questionnaires for Chinese in other societies.     

Cholesterol, saturated fatty acids, polyunsaturated fatty acids, sodium, and potassium intakes of the United States population

The USDA's 1977-1978 Nationwide Food Consumption Survey was utilized to assess dietary intake levels of cholesterol, fatty acids, sodium, and potassium by several age/sex groups of the U.S. population. Results indicated that mean cholesterol intakes for all male age groups of 12 yr and older exceeded 300 mg/day while the mean intakes of females and children were less than 300 mg/day. However, approximately 30% of each age group of adult females exceeded 300 mg cholesterol per day and only about one-third of the adult males had average intakes of less than 300 mg/day. Between 39% and 44% of total kilocalories were obtained from fat consumption with saturated fatty acids contributing 13-15%, polyunsaturated fatty acids contributing 5-6% and oleic acid contributing 12-14% of total kilocaloric intake. We found that 90% of children ages 6-11 yr and adult females had saturated fatty acids intakes of less than 40 gm/day; 90% of all men had intakes of less than 55 gm/day. At least 90% of all age/sex groups averaged intakes of polyunsaturated fatty acids of less than 26 gm/day. Average daily sodium intakes for each age/sex group (excluding table salt) were within the limits considered safe and adequate. However, approximately 4% of each age group of adult females and about 25% of each of the three younger adult male groups had average sodium intakes of 4000 mg/day or more. Average daily potassium intakes were somewhat low, ranging from 1584 mg/day for children ages 0-5 yr to 2735 mg/day for males ages 51-64 yr.     

Effect of 6 dietary fatty acids on the postprandial lipid profile, plasma fatty acids, lipoprotein lipase, and cholesterol ester transfer activities in healthy young men

BACKGROUND: There is increasing evidence that postprandial triacylglycerol-rich lipoproteins may be related to atherogenic risk. OBJECTIVE: The objective was to investigate the effect of individual fatty acid intakes on postprandial plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acids, and preheparin lipoprotein lipase and cholesterol ester transfer protein (CETP) activities. DESIGN: Six test fats high (approximately 43% by wt) in stearic acid, palmitic acid, palmitic + myristic acid, oleic acid, elaidic acid (trans 18:1), and linoleic acid were produced by interesterification. After having fasted for 12 h, 16 healthy young men were served the individual test fats incorporated into meals (1 g fat/kg body wt) in random order on different days separated by washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after the meals. RESULTS: Different responses to the test-fat meals were observed for plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acid concentrations, and lipoprotein lipase and CETP activities (diet x time interaction: 0.001 < P < 0.05). Intake of the long-chain saturated fatty acids stearic and palmitic acids resulted in a relatively lower lipemic response than did intake of the unsaturated fatty acids, probably because the saturated fatty acids were absorbed less and at a lower rate; therefore, the lipemic response took longer to return to postabsorptive values. CONCLUSIONS: Fatty acid chain length and degree of saturation appear to affect the extent and duration of lipemia and affect hepatic output indirectly. These effects may not be mediated via effects on lipoprotein lipase and CETP activities.     

Effect of hydrogenated fat on the plasma cholesterol and triglyceride levels of man.

A group of 33 adult males was fed for 21 days a formula diet that supplied 38 per cent of their calories as fat. The fatty acid composition of the diet was 25 per cent saturates, 16 per cent polyunsaturates and 58 per cent monounsaturates. All of the unsaturated acids were in the cis configuration. The subjects were then divided into two groups. One group of 17 men continued on the same diet. In the diet of the remaining subjects, 80 per cent of the dietary fat was replaced with a hydrogenated fat. Over 60 per cent of the monounstaurated acids and approximately one-half of the polyunsaturated acids of the diet of this latter group were in the trans configuration. Except for the presence or absence of trans acids, the fatty acid intakes of the two groups were the same. Over the 4-week period that the two diets were consumed, the group receiving the hydrogenated fat showed no change in plasma cholesterol or triglyceride levels relative to the subjects consuming the unhydrogenated fat. It is concluded that the effect of a hydrogenated fat on blood lipid level is determined by its fatty acid composition and this effect is not altered by the isomeric form of the unsaturated acids.     

Effect of source of dietary fats on serum glucose,insulin, and gastric inhibitory polypeptide responses to mixed test meals in subjects with non-insulin dependent diabetes mellitus.

We recently demonstrated that normal subjects given mixed test meals of varying fatty acid composition showed significantly greater serum insulin responses to meals enriched with polyunsaturated fat as compared to those in which the fat content was derived from saturated fatty acids. To determine if a similar phenomenon occurs in subjects with non-insulin dependent diabetes mellitus (NIDDM), serum glucose, insulin, C-peptide, and gastric inhibitory polypeptide (GIP) responses to three mixed test meals of varying fatty acid composition were assessed in twelve subjects with NIDDM. Baseline means (+/? SEM) fasting serum glucose concentration was 205 +/? 15 mg/dl and mean glycosylated hemoglobin was 8.5 +/? 0.5%. Fatty acids in the test meals were either saturated fats, or polyunsaturated fats derived from vegetables or fish. Each test meal provided 40% of the subjects' calculated daily caloric requirement and contained approximately 45% carbohydrate, 40% fat, and 15% protein. No appreciable differences in serum glucose, insulin, and C-peptide responses occurred during the three mixed test meals. Although GIP values were higher in the saturated fat and the vegetable meals when compared to the fish meal, the differences did not reach statistical significance. The inability of NIDDM subjects to evoke a greater insulin response to polyunsaturated fatty acids than to saturated fatty acids suggests another pathogenetic factor contributing to their glucose intolerance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fatty acid composition and arachidonic acid intake of selected Saudi foods

Twenty-eight Saudi Arabian common foods were analyzed for their fatty acid contents by gas-liquid chromatography using capillary column. The predominant fatty acids were oleic, palmitic, linoleic and stearic acids. The polyunsaturated to saturated fats ratio (P:S) as well as the n-3:n-6 ratio were generally not compatible with recommended values. Assessment of C20:4 (n-6) content in those foods showed a noticeable variation ranging from 9 mg/100 gm in beef sirloin to 256 mg/100 g in kannad fish. Eicosapentaenoic acid (C20:5) n-3 content was highest in kannad (925 mg/100 g). Applying C20:4 (n-6) values determined in this work to Saudi Balanced Sheet, the mean C20:4 (n-6) intake for a Saudian was estimated as approximately 115 mg/day.     

Fatty acid composition and arachidonic acid intake of selected Saudi foods

Twenty-eight Saudi Arabian common foods were analyzed for their fatty acid contents by gas-liquid chromatography using capillary column. The predominant fatty acids were oleic, palmitic, linoleic and stearic acids. The polyunsaturated to saturated fats ratio (P:S) as well as the n-3:n-6 ratio were generally not compatible with recommended values. Assessment of C20:4 (n-6) content in those foods showed a noticeable variation ranging from 9mg/100 gm in beef sirloin to 256 mg/ 100 g in kannad fish. Eicosapentaenoic acid (C20:5) n-3 content was highest in kannad (925 mg/100 g). Applying C20:4 (n-6) values detemined in this work to Saudi Balanced Sheet, the mean C20:4 (n-6) intake for a Saudian was estimated as ~115 mg/day.     

Magnesium and lipids in cardiovascular disease.

Carbohydrate intolerance is positively correlated with animal fat consumption and is more common in beef eating populations. In contrast, individuals consuming diets comprised of polyunsaturated fats have a lower incidence of diabetes mellitus. To test the hypothesis that dietary fats may influence carbohydrate metabolism, serum glucose, insulin, and gastric inhibitory polypeptide (GIP) responses to three mixed test meals of varying fatty acid composition were assessed in 12 normal subjects. Fatty acids in the meals were either saturated fats or polyunsaturated fats derived from vegetables or fish. Each test meal provided 40% of a subject's calculated daily caloric requirement and contained approximately 45% carbohydrate, 40% fat, and 15% protein. Serum insulin responses were 62% higher (p less than 0.01) after the fish and 39% higher (p less than 0.01) after the vegetable meals compared to the saturated fat meal. No significant differences in insulin responses were observed between the vegetable and fish meals. Serum glucose concentration was slightly higher (p less than 0.02) during the fish meal than with the vegetable or saturated fat meals. The GIP levels were comparable following the fish and vegetable meals and were 25% lower than those observed with the saturated fat meal. These findings suggest that diets enriched with polyunsaturated fatty acids augment insulin secretion significantly more than a diet comprised primarily of saturated fatty acids. The mechanism for this increased insulin secretion is unknown but did not appear to be mediated through differences in serum glucose values or through the insulin-otrophic effects of GIP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of low fat diets varying in P/S ratio on nutrient intakes, fecal excretion, blood chemistry profiles, and fatty acids of adult men

Twenty-three apparently healthy volunteers aged 35 to 60 years consumed closely monitored self-selected (SS) diets for five weeks followed by two low fat controlled diets (25% energy) for two six-week periods followed by another five-week SS diet. The two low fat diets, fed in a crossover design to one-half of the subjects per controlled diet period, had a polyunsaturated/saturated (P/S) fat ratio of either 0.3 or 1.0. Results are reported for bi-weekly measurements of energy and nutrients; blood profiles and plasma fatty acids; and for end-of-period values for stool characteristics. Blood chemistry profiles differed in the two groups. The low P/S diet produced significant increases not only in cholesterol, but in 16:0, 16:1, and percent saturated fatty acids and decreases in 18:2 and omega 6 fatty acids. The reverse was seen with the high P/S diet. The essential fatty acid (EFA) linoleic acid returned in the poststudy period to prestudy levels (all subjects), but arachidonic acid did not. The explanation for negative correlation between magnesium intake or excretion and percent plasma linoleic acid must await further research.     

Diet-related toxemia in pregnancy. I. Fat, fatty acids, and cholesterol.

Toxemia in pregnancy (preeclampsia)is characteristerized by a combination of at least two of the following clinical symptoms: hypertension, edema, and proteinuria. In three successive trials over three consecutive years, the dietary intake of a selected number of young pregnant women attending a Maternal and Infant Care Program at Tuskegee Institute were evaluated for total lipids, individual fatty acids, and cholesterol. Women with toxemia or with any of the individual symptoms were identified and women without toxemia or these symptoms served as controls. Results were variable from repetition to repetition in all but the toxemia group and the edema group. The consumption of total lipids and cholesterol was significantly greater in all three trials by both the toxemia and edema groups. Also, total saturated, monounsaturated, and polyunsaturated fatty acids were eaten in greater amounts. The greatest differences were in palmitic acid, stearic acid, oleic acid, and linoleic acid. The proportion of unsaturated fatty acids consumed in all groups was very low. All differences could be attributed primarily to breakfast and dinner meals and were found in the milk, meat, and egg food groups. Although satistical correlations were found between lipid intake and toxemia of pregnancy any specific relationship between the two is still unclear.