Determination of trans fatty acid levels by FTIR in processed foods in Australia

Health authorities around the world advise 'limiting consumption of trans fatty acid', however in Australia the trans fatty acid (TFA) content is not required to be listed in the nutrition information panel unless a declaration or nutrient claim is made about fatty acids or cholesterol. Since there is limited knowledge about trans fatty acid levels in processed foods available in Australia, this study aimed to determine the levels of TFA in selected food items known to be sources of TFA from previously published studies. Food items (n=92) that contain vegetable oil and a total fat content greater than 5% were included. This criterion was used in conjunction with a review of similar studies where food items were found to contain high levels of trans fatty acids. Lipids were extracted using solvents. Gravimetric methods were used to determine total fat content and trans fatty acid levels were quantified by Attenuated Total Reflectance Fourier Transform Infrared spectroscopy. High levels of trans fatty acids were found in certain items in the Australian food supply, with a high degree of variability. Of the samples analysed, 13 contained greater than 1 g of trans fatty acids per serving size, the highest value was 8.1 g/serving. Apart from when the nutrition information panel states that the content is less than a designated low level, food labels sold in Australia do not indicate trans fatty acid levels. We suggested that health authorities seek ways to assist consumers to limit their intakes of trans fatty acids.     

Proceedings: Present and proposed regulations affecting the marketing of prudent diet foods

When the questions of the relationship of diet and heart disease are considered, even those most committed must admit a controversy. In the past, the Food and Drug Administration took a position specifically forbidding any kind of statements on fat and fatty acids. Although there are no definitive studies which have demonstrated beyond doubt that a diet modification in the general public with respect to fat and cholesterol is desirable, the Agency has modified its position so that patients may better identify such foods when a “prudent” diet has been recommended by their physicians. This product identification is achieved through labeling where the total fat content, the cholesterol, and saturated and polyunsaturated fatty acids may be stated. No other statements may be made that implicitly or explicitly claim a value in preventing or treating heart or artery diseases. Responsibility for the education and use of the information by the consumer will remain with the individual physician, health educator, and health organizations.     

Exchanging partially hydrogenated fat for palmitic acid in the diet increases LDL-cholesterol and endogenous cholesterol synthesis in normocholesterolemic women

Partial hydrogenation of oil results in fats containing unusual isomeric fatty acids characterized by cis and trans configurations. Hydrogenated fats containing trans fatty acids increase plasma total cholesterol (TC) and LDL-cholesterol while depressing HDL-cholesterol levels. Identifying the content of trans fatty acids by food labeling is overshadowed by a reluctance of health authorities to label saturates and trans fatty acids separately. Thus, it is pertinent to compare the effects of trans to saturated fatty acids using stable isotope methodology to establish if the mechanism of increase in TC and LDL-cholesterol is due to the increase in the rate of endogenous synthesis of cholesterol. Ten healthy normocholesterolemic female subjects consumed each of two diets containing approximately 30% of energy as fat for a fourweek period. One diet was high in palmitic acid (10.6% of energy) from palm olein and the other diet exchanged 5.6% of energy as partially hydrogenated fat for palmitic acid. This fat blend resulted in monounsaturated fatty acids decreasing by 4.9 % and polyunsaturated fats increasing by 2.7%. The hydrogenated fat diet treatment provided 3.1% of energy as elaidic acid. For each dietary treatment, the fractional synthesis rates for cholesterol were measured using deuterium-labeling procedures and blood samples were obtained for blood lipid and lipoprotein measurements. Subjects exhibited a higher total cholesterol and LDL-cholesterol level when consuming the diet containing trans fatty acids while also depressing the HDL-cholesterol level. Consuming the partially hydrogenated fat diet treatment increased the fractional synthesis rate of free cholesterol. Consumption of hydrogenated fats containing trans fatty acids in comparison to a mixtur e of palmitic and oleic acids increase plasma cholesterol levels apparently by increasing endogenous synthesis of cholesterol.     

Variability in the trans fatty acid content of foods within a food category: implications for estimation of dietary trans fatty acid intakes.

OBJECTIVE: Currently, the published information on trans fatty acid composition of foods is incomplete and of questionable accuracy. Detailed fatty acid analysis of over 200 foods was undertaken for the purpose of determining the variability in trans fatty acid content among foods within a product category, and the significance of this variability to the estimation of trans fatty acids intakes from analysis of dietary intake data. METHODS: The analysis of food fatty acids used gas-liquid chromatography with 100 m capillary columns and standardized methodologies for food sampling, fat extraction, separation and quantification of trans fatty acid isomers. For the purposes of this report, trans refers to all non-naturally occurring isomers including trans, cis-trans, geometric and positional isomers. RESULTS: The results show that the amount of trans fatty acids varies considerably among foods within a category, reflecting differences in the fats and oils used in the manufacturing or preparation process. For example, the range of trans fatty acids in 17 brands of crackers was 23 to 51% total fatty acids, representing differences of from 1 to 13 g trans fatty acids per 100 g cracker. The large errors that may arise in estimates of the trans fatty acid intake of an individual are illustrated by analyses of the potential trans fatty acid intake in a sample diet, for each food as calculated using the minimum and maximum values for trans fatty acids within a given category. The results of these analyses show estimates of trans fatty acid intake from a low of 1.4 to 25.4 g a day for the same diet. CONCLUSION: This study shows that the wide variability in trans fatty acid content of different foods may result in large errors in the estimation of trans fatty acid intake of individuals and, potentially, groups.     

Influence of the reformulation of ingredients in bakery products on healthy characteristics and acceptability of consumers

Bakery products are highly consumed by children and adults and as cereal-derived foods are considered a fundamental part of a balanced diet, but they are usually high in sugar and saturated and trans fat and low in fibre. This study aimed to develop four different bakery products (cookies, croissants, Spanish muffins and Spanish sponge cake) with healthier properties, such as lower fat and sugar content, healthy fatty acid profile and higher fibre content. Margarine and sunflower oil were replaced with high oleic sunflower oil, and inulin was also added. After the modifications, a significant reduction of fat content and kilocalories in all cases, an increment of monounsaturated fat and a decrease in saturated fatty acids in three products were observed. The sensory analysis resulted similar results in both recipes for cookies and lower acceptability in sponge cake, croissants and muffins. Purchase intention only decreased in sponge cake.     

trans Fatty acids in human milk are inversely associated with concentrations of essential all-cis n-6 and n-3 fatty acids and determine trans, but not n-6 and n-3, fatty acids in plasma lipids of breast-fed infants.

BACKGROUND: Human milk fatty acids vary with maternal dietary fat composition. Hydrogenated dietary oils with trans fatty acids may displace cis n-6 and n-3 unsaturated fatty acids or have adverse effects on their metabolism. The effects of milk trans, n-6, and n-3 fatty acids in breast-fed infants are unclear, although n-6 and n-3 fatty acids are important in infant growth and development. OBJECTIVE: We sought to determine the relations between trans and cis unsaturated fatty acids in milk and plasma phospholipids and triacylglycerols of breast-fed infants, and to identify the major maternal dietary sources of trans fatty acids. DESIGN: We collected milk from 103 mothers with exclusively breast-fed 2-mo-old infants, blood from 62 infants, and 3-d dietary records from 21 mothers. RESULTS: Mean (+/-SEM) percentages of trans fatty acids were as follows: milk, 7.1 +/- 0.32%; infants' triacylglycerols, 6.5 +/- 0. 33%; and infants' phospholipids, 3.7 +/- 0.16%. Milk trans fatty acids, alpha-linolenic acid (18:3n-3), arachidonic acid (20:4n-6), docosahexaenoic acid (22:6n-3) (P < 0.001), and linoleic acid (18:2n-6) (P = 0.007) were each related to the same fatty acid in infant plasma phospholipids. Milk trans fatty acids were inversely related to milk 18:2n-6 and 18:3n-3, but not to milk or infant plasma 20:4n-6 or 22:6n-3. trans Fatty acids represented 7.7% of maternal total fat intake (2.5% of total energy); the major dietary sources were bakery products and breads (32%), snacks (14%), fast foods (11%), and margarines and shortenings (11%). CONCLUSIONS: There were comparable concentrations of trans fatty acids in the maternal diet, breast milk, and plasma triacylglycerols of breast-fed infants. Prepared foods were the major dietary source of trans fatty acids.     

Fatty acids and retinyl esters of rat milk: effects of diet and duration of lactation

This study was initiated to explore the quantitative and qualitative differences in milk total fatty acids and milk retinyl esters when either hydrogenated or nonhydrogenated fat is fed during pregnancy and lactation. Rats were fed diets containing 10% by weight of corn oil or partially hydrogenated corn oil. Milk was collected on d 1, 8 and 14 of lactation and analyzed for protein, total fatty acids, fatty acid pattern, and retinyl ester pattern. Whereas diet produced no quantitative differences in milk protein or total fatty acids, the pattern of milk fatty acids varied significantly. Rats fed corn oil produced milk having more medium-chain saturated fatty acids, less long-chain monoenoic fatty acids, and more polyunsaturated fatty acids compared to those fed hydrogenated corn oil. Rats fed hydrogenated corn oil produced milk fat having 21-26% of the trans fatty acid, elaidic acid. Significant differences were also observed with duration of lactation: medium-chain fatty acids increased three to fourfold between d 1 and 8, where cis-monoenes and polyunsaturated fatty acids declined. The pattern of milk retinyl esters strongly reflected, but was not identical to, that of total milk fat. Comparing d 14 milk from rats fed corn oil with that from rats fed hydrogenated corn oil, medium-chain esters of retinol constituted 24 and 11% of total retinyl esters, whereas saturated long-chain fatty acid esters constituted 52 and 44%, respectively. trans Fatty acid esters of retinol comprised 24% of vitamin A esters in milk of rats fed hydrogenated fat. These data provide evidence that the composition of milk retinyl esters, as well as that of total milk fat, is determined both by the type of fatty acids from diet and from diet-related differences in de novo synthesis of fatty acids within the mammary gland and other tissues.     

Regulatory frameworks for functional foods and dietary supplements

An understanding of the legal and regulatory requirements for foods, including dietary supplements and so-called functional foods, helps to focus attention on the special challenges that exist, which range from safety determinations to claim substantiation and consumer understanding. This article provides an overview of the Food and Drug Administration's regulatory framework for these products; it also highlights issues that are emerging and will require consideration and dialog.     

The effect of dietary trans alpha-linolenic acid on plasma lipids and platelet fatty acid composition: the TransLinE study

OBJECTIVE: To collect (i) baseline data and (ii) execute a large multicentre study examining the effect of trans alpha-linolenic acid on its incorporation into plasma lipids and on risk factors for coronary heart disease. DESIGN: Male volunteers were recruited and the habitual diet assessed by a 4-d weighed record. Fatty acid composition of plasma and platelet lipids were determined by gas chromatography at baseline. After a 6 week run-in period on a trans 'free' diet, male volunteers were randomised to consume 0.6 % of energy trans alpha-linolenic acid or to continue with a diet 'low' in trans alpha-linolenic acid for 6 weeks. SETTING: Three European university research departments supported by the research and development departments of the food industry. Subjects: Male volunteers (88) recruited by local advertisement. METHODS: Replacement of 30 % of the fat of the habitual diet by margarine, oil and foods. Rapeseed oil was deodorised especially to produce the trans 'free' and 'high' trans foods for this study. The incorporation and conversion of trans alpha-linolenic acid into plasma lipids and platelets was assessed by gas chromatography and dietary compliance was verified by 4-d weighed record. Results: Less trans alpha-linolenic acid isomers are incorporated into human plasma lipids in French volunteers than in Dutch or Scottish volunteers consuming their habitual diets. Trans 'free' alpha-linolenic acid-rich oil can be produced by careful deodorization during refining. The 'high' trans diet provided 1410+/-42 mg/d trans isomers of alpha-linolenic acid, whilst the 'low' trans group consumed 60+/-75 mg/d. The change in plasma lipid and platelet fatty acid composition documented that trans linolenic isomers are incorporated and converted to a trans isomer of eicosapentaenoic acid. Only the 15-trans alpha-linolenic acid is incorporated into plasma cholesteryl esters. The group consuming low trans diet had a slightly higher intake of fat, especially saturated and monounsaturated fat. CONCLUSIONS: Trans 'free' rapeseed oil, rich in alpha-linolenic acid, can be produced by careful deodorization. Dietary records show good compliance. Dietary trans isomers of alpha-linolenic acid are incorporated in plasma lipids and converted to long-chain polyunsaturated fatty acids. Their effects on risk factors for coronary heart disease and their metabolism will be reported elsewhere. Sponsorship: European Commission (FAIR 95-0594 grant). European Journal of Clinical Nutrition (2000) 54, 104-113     

Intake of trans fatty acid-rich hydrogenated fat during pregnancy and lactation inhibits the hypophagic effect of central insulin in the adult offspring

OBJECTIVE: Using rats we examined whether maternal intake of hydrogenated fat rich in trans fatty acids affects brain fatty acid profile, hypothalamic content of insulin receptor and insulin receptor substrate-1 proteins, and the hypophagic effect of centrally administered insulin in 3-mo-old male progeny. METHODS: Throughout pregnancy and lactation, Wistar rats ate isocaloric/normolipidic diets with soybean oil (control) or soybean oil-derived hydrogenated fat (trans diet) as a fat source. Upon weaning, the trans offspring continued on the trans diet (trans group) or were switched to a control diet (trans-control group). RESULTS: Compared with control rats, trans rats had lower brain levels of eicosapentaenoic acid. Compared with trans rats, trans-control rats had increased levels of total polyunsaturated fatty acids and arachidonic acid and decreased levels of trans fatty acids, saturated fatty acids, and monounsaturated fatty acids. Insulin receptor and insulin receptor substrate-1 levels were significantly lower (44% and 38%, respectively) in trans than in control rats. In trans-control rats, insulin receptor was 26% lower (P < 0.05), whereas insulin receptor substrate-1 was 50% lower, than in control rats. Insulin decreased 24-h feeding in control (27%) and trans (38%) rats but failed to do so in trans-control rats. The latter group had increased serum glucose levels. CONCLUSIONS: The data suggest that the early (intrauterine/perinatal) exposure to hydrogenated fat rich in trans fatty acids programmed the hypothalamic feeding control mechanisms. As young adults, only trans-control animals showed loss of insulin-induced hypophagia, indicating that the mismatch between early and later nutritional environments was relevant. However, the trans group also showed signs of altered appetite signaling mechanisms, suggesting that the early adaptations may have deleterious consequences later in life.     

Changes in the content and forms of vitamin K in processed foods

High intake of trans fatty acids has been linked to deleterious health effects including increased risk of cardiovascular disease. Since 2006, the Food and Drug Administration requires companies to label the trans fatty acid content of foods. This has resulted in an overall decrease of commercially-hydrogenated oils in the food supply. Hydrogenation of vitamin K (VK)-rich plant oils changes the form and content of VK. It is not known if changes in use of hydrogenated oil in the U.S. food supply resulted in a change in the forms and amount of VK in processed foods. To test this, we compared 253 foods for total and individual forms of VK in foods analyzed pre- and post-2006 as part of the U.S. Department of Agriculture (USDA) Nutrient and Food Analysis Program. Overall, foods identified as rich sources of the hydrogenated form of VK pre-2006 (dihydrophylloquinone; dK) had lower amounts of dK post-2006 with a concomitant increase in the parent form of VK, phylloquinone. However, the range of dK was large within foods, suggestive of a wide range of current practices regarding use of hydrogenated oils in the U.S. food supply.     

The application of medium-chain fatty acids: edible oil with a suppressing effect on body fat accumulation

The bulk of fatty acids found in our diets consists of long-chain fatty acids (LCFA), which are molecules containing 12 or more carbon atoms. In contrast, medium-chain fatty acids (MCFA) are composed of 8-10 carbon atoms, and are found in palm kernel oil, among other types of foods. MCFA have attracted attention as being part of a healthy diet, because they are absorbed directly into the portal vein, transported rapidly to the liver for beta-oxidation, and thus increase diet-induced thermogenesis. In contrast, long-chain triacylglycerols are absorbed via the intestinal lymphatic ducts and transported by chylomicrons through the thoracic duct into the systemic circulation. Because medium-chain triacylglycerols (MCT) containing solely MCFA have a few disadvantages when used for deep frying, we have developed a new kind of triacylglycerol product: medium- and long-chain triacylglycerol (MLCT). MLCT is produced by lipase-catalyzed enzymatic transesterification. Long-term clinical trials have demonstrated that MLCT and MCT result in less body fat accumulation in humans. MLCT oil has been approved as FOSHU (Food for Specified Health Use) for use as cooking oil with a suppressing effect on body fat accumulation.     

Proposed Changes in U.S.A. Regulations for Food Labeling

On November 17, 1999, the United States (U.S.A.) Food and Drug Administration (FDA) published a proposed rule that would allow for the declaration of trans fatty acids in nutrition labeling and would limit trans fatty acids wherever saturated fat limits are placed on nutrient content or health claims. Specifically, FDA proposed that the amount oftrans fat be included with that of saturated fat. The combined amount would be followed by an asterisk referring to a footnote specifying the amount of trans fats included in the total value. In addition, the agency proposed that the percent Daily Value shown be based on the combined amount of saturated and trans fatty acids. Other options for declaringtrans fatty acids were discussed and comments requested.FDA also published a notice on June 26, 2000, requesting comment on a Citizen Petition that requested: (1) the declaration of added sugars in nutrition labeling, (2) the development of a Daily Value for added sugars so that consumers would be informed of the proportion of a reasonable day's intake of added sugars that was provided by a serving of food, and (3) the revision of criteria pertaining to nutrient content and health claims to take added sugars into account.     

Isomeric fatty acids and tumorigenesis: a commentary on recent work

This article critically reviews the existing, although limited, literature concerning trans fatty acids and tumorigenesis. Neither epidemiological nor experimental studies published to date have demonstrated any valid association between trans fatty acid ingestion and tumorigenesis. A recent study showed that under controlled conditions, a fat with a high content of trans fatty acids did not promote the development of mammary tumors induced in rats by 7,12-dimethylbenz[a]anthracene to any greater extent than did a comparable fat with a high content of cis fatty acids. In addition, in this study a high trans fat was less tumor promoting than was a blend of fats that simulated the dietary fat composition of the United States and had a lower level of trans fatty acids. Another study using comparable cis and trans fats demonstrated that the high trans fat did not affect the growth and metastasis of implanted mammary tumors in mice relative to the high cis fat. Also, two recent studies reported no significant difference in the development of induced colon tumors in rats fed diets high in cis or trans fatty acids. The results of these and other studies are consistent with the conclusion that trans fatty acids are not uniquely related to tumor development.     

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.     

Isomeric fatty acids and tumorigenesis: A commentary on recent work

This article critically reviews the existing, although limited, literature concerning trans fatty acids and tumorigenesis. Neither epidemiological nor experimental studies published to date have demonstrated any valid association between trans fatty acid ingestion and tumorigenesis. A recent study showed that under controlled conditions, a fat with a high content of ‘trans fatty acids did not promote the development of mammary tumors induced in rats by 7,12‐dimethylbenz[a]anthracene to any greater extent than did a comparable fat with a high content of as fatty acids. In addition, in this study a high trans fat was less tumor promoting than was a blend of fats that simulated the dietary fat composition of the United States and had a lower level of trans fatty acids. Another study using comparable cis and trans fats demonstrated that the high trans fat did not affect the growth and metastasis of implanted mammary tumors in mice relative to the high cis fat. Also, two recent studies reported no significant difference in the development of induced colon tumors in ratsfed diets high in cis or trans fatty acids. The results of these and other studies are consistent with the conclusion that trans fatty acids are not uniquely related to tumor development.     

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.     

The role of fat in the diet – quantity,quality and sustainability

Dietary fat should supply at least 15% of food energy including 2.5% energy and 0.5% energy as linoleic acid and alpha‐linolenic acid respectively: docosahexaenoic acid may also need to be supplied in infants. The proportion of energy from fat is not linked to risk of obesity, cardiovascular disease and cancer. The total cholesterol/HDL cholesterol, which is the most robust lipid indicator of risk of coronary heart disease (CHD), is lowered by unsaturated fatty acids, increased by trans fatty acids and not affected by saturated fatty acids compared with carbohydrates. Using clinical outcomes as endpoints, trans fatty acids increase, polyunsaturated fatty acids decrease and monounsaturated and saturated fatty acids have no effect on CHD risk. Recent recommendations for the prevention of CHD suggest partial replacement of saturated with polyunsaturated fatty acids to give energy intakes in the range of 6–11% energy and a daily intake of 0.25 g long‐chain n‐3 polyunsaturated fatty acids. The recommendation to increase the intake of long‐chain n‐3 fatty acids needs to be considered against the backdrop of falling fish stocks; it is likely that a novel source will be needed in the future. The projected growth in world population will require more fat, mainly for food energy. The oil palm requires only one tenth of the land required by oil seeds to produce the same amount of oil. The impact of increased use of vegetable oils as biodiesel needs to be urgently reconsidered owing to the adverse environmental and economic consequences to people living in South East Asia.     

Home use of margarine is an important determinant of plasma trans fatty acid status: a biomarker study

The contribution of the home use of margarines, made with partially hydrogenated vegetables oils, to total trans fatty acid intake is difficult to determine using dietary assessment because food composition databases are incomplete for trans fatty acids; moreover, hidden fats in manufactured foods may be the predominant sources of trans fatty acids. The objective of our study was to determine, using plasma phospholipid trans fatty acid composition as a surrogate measure of exposure, whether the home use of margarine or butter is an important determinant of trans fatty acid status. We conducted a community-based (Dunedin, New Zealand), cross-sectional survey of people who consumed either margarine (n 65) or butter (n 64) but not both for home use. The levels of the 18:1 trans isomers commonly found in partially hydrogenated vegetable oils were all significantly higher in the plasma phospholipids of margarine compared with butter consumers, with the exception of 18:1n-7t, which did not differ. Among margarine consumers, the percentage of total fat from margarine was significantly correlated with levels of phospholipid 18:1n-6t, 18:1n-8t and 18:1n-12/9t isomers (r 0.57-0.63, P<0.001) but only weakly with 18:1n-7t (r 0.30, P=0.016). The intake of fat from fast foods, bakery products or meat and meat products was not associated with plasma phospholipid trans isomeric composition. The home use of margarine, made with partially hydrogenated vegetable oils, is an important determinant of trans fatty acid exposure in New Zealand.