Effect of Norwegian fish powder on risk factors for coronary heart disease among hypercholesterolemic individuals.

BACKGROUND AND AIM: Numerous studies suggest an association between high intake of fatty fish and reduced risk of coronary heart disease. Very long-chain omega-3 fatty acids are thought to be responsible for the benefits observed, though other fatty fish components may act in concert with them. Norwegian fish powder is a dry herring product that contains essential amino acids, marine omega-3 fatty acids, vitamins and minerals. The aim of the present study was to determine whether it has beneficial effects on risk factors for coronary heart disease in man. METHODS AND RESULTS: A single center, randomized, double-blind, parallel-treatment study was carried out for 12 weeks. Subjects with primary hypercholesterolemia were randomly allocated to 10 g fish powder or placebo (20 tablets/day). Participants were instructed to follow National Cholesterol Education Program (NCEP) Step I Diet during a 4-week diet run-in phase and during the study. Concentrations of lipids, lipoproteins, hemostatic variables and endothelial cell markers were determined before and after supplementation. Our data showed that the fish powder supplement was well tolerated. A significant decrease and increase respectively were observed in plasma alpha-linolenic acid (p = 0.03) and docosahexaenoic acid (DHA) (p = 0.03). Concentrations of lipids, lipoproteins, homocysteine, factor VII, fibrinogen, tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI)-1, soluble intercellular adhesion molecule (ICAM)-1, P-selectin and interleukin (IL)-8 were not beneficially affected. CONCLUSIONS: Fish powder supplementation does not seem an effective approach to improve risk factors for coronary heart disease in hypercholesterolemic subjects following the NCEP Step I Diet.

Racemization kinetics of aspartic acid in fish material under different conditions of moisture, pH, and oxygen pressure.

The racemization kinetics of aspartic acid in heat-treated whole herring have been studied under conditions of treatment comparable to those that may occur in processing of fish meal. D-Aspartic acid content in the samples has been measured by RP-HPLC with precolumn automatic derivatization. The major parameters affecting the rate of racemization of aspartic acid k(Asp) have been demonstrated to be temperature (elevation of temperature from 95 to 120 degrees C resulted in an increase of k(Asp) from 0.46 to 3.39x10(-3) min(-1)), moisture of the raw material (reduction of the moisture content of the raw material from 80 to 15% lowered k(Asp) measured at 95 degrees C from 0.46 to 0.06x10(-3) min(-1)), and to a lesser extent, pH (k(Asp) at 95 degrees C was lowered from 0.46 to 0.37x10(-3) min(-1) following a decrease of pH from 7.0 to 4.0). No significant effects on the racemization rate of aspartic acid was observed for reducing the oxygen pressure to 0.8%. The results from the present study show that the content of D-aspartic acid in fish material is a function of heat exposure and may be used to predict the thermal history of fish meal.

Fish lipids: more than n-3 fatty acids?

Recent studies have shown that marine oils rich in long-chain (C20 and C22) fatty acids (i.e. certain natural marine oils and partially hydrogenated fish oil) may affect the haemostatic balance in a favourable way with regard to coronary heart disease. Such fats have also been found to increase the content of EPA (eicosapentaenoic acid = C20:5 n-3) and to decrease the content of arachidonic acid (C20:4 n-6) in blood lipids, thus affecting the ratio of C20:4 n-6 to C20:5 n-3 in a favourable way with regard to eicosanoid production. It is therefore likely that the positive effects of long-chain monoenoic fatty acids on haemostasis are due to increased synthesis of long-chain essential n-3 fatty acids. According to recent theories the final steps in the synthesis of long-chain essential fatty acids occur in the peroxisomes, which also have a controlling function in essential fatty acid synthesis. Long-chain monoenoic fatty acids are known to enhance peroxisomal beta-oxidation. An hypothesis is therefore advanced that marine oils rich in long-chain monoenoic fatty acids improve haemostasis in a favourable way with regard to coronary heart disease through increased peroxisomal beta-oxidation and increased synthesis of long-chain n-3 fatty acids.

trans fatty acids. 5. Fatty acid composition of lipids of the brain and other organs in suckling piglets.

The effects of dietary trans fatty acids on the fatty acid composition of the brain in comparison with other organs were studied in 3-wk-old suckling piglets. In Experiment (Expt.) 1 the piglets were delivered from sows fed partially hydrogenated fish oil (PHFO) (28% trans), partially hydrogenated soybean oil (PHSBO) (36% trans) or lard (0% trans). In Expt. 2 the piglets were delivered from sows fed PHFO, hydrogenated fish oil (HFO) (19% trans) or coconut fat (CF) (0% trans) with two levels of dietary linoleic acid (1 and 2.7%) according to factorial design. In both experiments the mother's milk was the piglets' only food. The level of incorporation of trans fatty acids in the organs was dependent on the levels in the diets and independent of fat source (i.e., PHSBO, PHFO or HFO). Incorporation of trans fatty acids into brain PE (phosphatidylethanolamine) was non-detectable in Expt. 1. In Expt. 2, small amounts (less than 0.5%) of 18:1 trans isomers were found in the brain, the level being slightly more on the lower level of dietary linoleic acid compared to the higher. In the other organs the percentage of 18:1 trans increased in the following order: heart PE, liver mitochondria PE, plasma lipids and subcutaneous adipose tissue. Small amounts of 20:1 trans were found in adipose tissue and plasma lipids. Other very long-chain fatty acids from PHFO or HFO (i.e., 20:1 cis and 22:1 cis + trans) were found in all organ lipids except for brain PE. Dietary trans fatty acids increased the percentage of 22:5n-6 in brain PE.(ABSTRACT TRUNCATED AT 250 WORDS)

Trans fatty acids. 4. Effects on fatty acid composition of colostrum and milk.

trans Isometric fatty acids of partially hydrogenated fish oil (PHFO) consist of trans 20:1 and trans 22:1 in addition to the trans isomers of 18:1, which are abundant in hydrogenated vegetable oils, such as in partially hydrogenated soybean oil (PHSBO). The effects of dietary trans fatty acids in PHFO and PHSBO on the fatty acid composition of milk were studied at 0 (colostrum) and 21 days postpartum in sows. The dietary fats were PHFO (28% trans), or PHSBO (36% trans) and lard. Sunflower seed oil (4%) was added to each diet. The fats were fed from three weeks of age throughout the lactation period of Experiment 1. In Experiment 2 PHFO or "fully" hydrogenated fish oil (HFO) (19% trans), in comparison with coconut oil (CF) (0% trans), was fed with two levels of dietary linoleic acid, 1 and 2.7%, from conception throughout the lactation period. Feeding trans-containing fats led to secretion of trans fatty acids in the milk lipids. Levels of trans 18:1 and trans 20:1 in milk lipids, as percentages of total cis + trans 18:1 and cis + trans 20:1, respectively, were about 60% of that of the dietary fats, with no significant differences between PHFO and PHSBO. The levels were similar for colostrum and milk. Feeding HFO gave relatively less trans 18:1 and trans 20:1 fatty acids in milk lipids than did PHFO and PHSBO. Only low levels of cis + trans 22:1 were found in milk lipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Trans fatty acids. 3. Fatty acid composition of the brain and other organs in the newborn piglet.

The effects of dietary trans fatty acids on tissue fatty acid composition were studied in newborn piglets delivered from sows fed partially hydrogenated fish oil (PHFO) (28% trans) or partially hydrogenated soybean oil (PHSBO) (36% trans) in comparison with lard (0% trans) from 3 wk of age and through gestation in Experiment 1, or fed PHFO or "fully" hydrogenated fish oil (HFO) (19% trans) in comparison with coconut oil (CF) (0% trans) with two levels, 1 and 2.7%, of dietary linoleic acid from conception through gestation in Experiment 2. The piglets were sampled immediately after delivery, without having access to mothers' milk. Incorporation of trans fatty acids into brain PE (phosphatidylethanolamine) were non-detectable or very low (less than 0.1%). The incorporation of 18:1 trans into heart-PE, liver mitochondria-PE, total plasma lipids and adipose tissue was low, and 20:1 trans was not detected. Dietary trans fatty acids had no consistent effects on the overall fatty acid composition of the different tissue lipids. It is concluded that trans fatty acids from PHFO, HFO and PHSBO have no significant effects on the fatty acid accretion in the fetal piglet.

Trans fatty acids. 1. Growth, fertility, organ weights and nerve histology and conduction velocity in sows and offspring.

Effects of dietary trans fatty acids on the pre- and postnatal growth and development in pigs were studied with special emphasis on nervous tissue. In experiment 1, female pigs were fed partially hydrogenated fish oil (PHFO) (28% trans) or soybean oil (PHSBO) (36% trans), in comparison with lard (0% trans) from weaning (3 wk) through the first reproduction cycle (up to 2 yr). In experiment 2, female pigs were fed two fish oils (33 and 19% trans) in comparison with coconut oil (0% trans) in diets with low and high levels of linoleic acid (18:2n-6 cis, cis) from gestation until their offspring were three wk old. Compared with the trans-free fats, the trans-containing fats had no effect on growth and development, feed consumption and utilization or on the weight of the brain, heart, kidneys, liver, lungs or spleen in the adult sows and their offspring. No effects from the experimental fats were found on histology and conduction velocity of the peroneal nerve. An increased number of the sows fed PHFO had fertility problems compared with those fed lard and PHSBO in Expt. 1, but no similar effects were seen in Expt. 2. It is concluded that consumption of trans fatty acids with 18-22 carbon atoms from PHFO and with 18 carbon atoms from PHSBO at levels that were 5 to 12 times higher than those normally consumed by humans had no detrimental effects on female pigs or their offspring during pregnancy and lactation.

Trans fatty acids. 2. Fatty acid composition of the brain and other organs in the mature female pig.

Female pigs were fed from three wk of age and up to two years a diet containing partially hydrogenated fish oil (PHFO, 28% trans monoenoic fatty acids), partially hydrogenated soybean oils (PHSBO, 36% trans fatty acids) or lard. No consistent differences were found between PHFO and PHSBO with regard to incorporation of trans fatty acids in organ lipids, but trans incorporations were highly organ-specific. No trans fatty acids were detected in brain phosphatidylethanolamine (PE). The incorporation of monoenoic trans isomers, as a percentage of total cis + trans, in other organs was highest in subcutaneous adipose tissue and liver mitochondria PE, followed by blood lipids with the lowest level in heart PE. The percentage of trans isomers compared with that of dietary lipids was consistently lower for 20:1, compared with 18:1 in organs from PHFO-fed pigs. The only effect of dietary trans fatty acids on the fatty acid pattern of brain PE was an increased level of 22:5n-6. Heart PE and total serum lipids of pigs fed the hydrogenated fats contained higher levels of 18:2n-6, and these lipids of the PHFO-fed group also contained slightly elevated amounts of 20:3n-6, 18:3n-3 and 20:5n-3. Liver mitochondria PE of the PHFO group also contained higher levels of 20:3n-6 and 22:5n-6. Dietary trans fatty acids caused a consistent decrease of saturated fatty acids compensated by increased levels of monoenes.(ABSTRACT TRUNCATED AT 250 WORDS)

Feeding of partially hydrogenated fish oils to rats in comparison with partially hydrogenated soybean oil and refined rapeseed oil: a combined chronic oral toxicity and carcinogenicity study with in utero phase.

Partially hydrogenated fish oils (PHFO) have been widely used in human food products for many years, particularly in Europe, North and South America and in South Africa. Animal studies, mainly with rapeseed oil, suggested that erucic acid might be responsible for morphological changes in the myocardium. It was suggested that other members of the docosenoic (22:1) family of fatty acids might produce similar effects to those ascribed to erucic acid. Certain PHFO can contain relatively high levels of these other isomers. Thus it was decided to evaluate PHFO of differing 22:1 levels in comparison with partially hydrogenated soybean oil (PHSBO) and refined rapeseed oil (LEAR) in a rat life span study, preceded by a breeding period in which the experimental lipids were fed to male and female parents. Two commercially produced PHFO were selected to represent the lower (PHFO-L) and upper (PHFO-U) range of 22:1 contents, 4.3 and 13.8%, respectively. A third test oil was prepared from a 50:50 blend of these (PHFO-M) to provide and intermediary 22:1 level. The control PHSBO and LEAR contained 0 and 1.0% 22:1, respectively. These experimental oils were included in semi-purified diets at 8 and 16%, respectively, in the breeding and life span periods of the study, together with 4% of oil mixtures providing essential fatty acids (EFA). Specific pathogen free (SPF). Wistar weanling rats, 200 of each sex, provided the subjects for the breeding period. Sufficient numbers of offspring were obtained in suitable condition from each treatment group to allow selection of a total of 555 weanlings for allocation to the five dietary treatments of the life span period of the study. For the life span period of the study, which was terminated after 107 to 110 weeks of treatment, 50 subjects were allocated to each of the PHSBO, PHFO-L and PHFO-U dietary groups, and 50 males to each of the LEAR and PHFO-M groups. The remaining subjects were allocated to sub-groups for sacrifice four days or 26 weeks after introduction of the life span period diets. All life span group subjects were weighed and had their food intakes recorded, and were subjected to clinical examination, routinely. At designated stages, ophthalmoscopic examination of all subjects was carried out, and samples of blood and urine were obtained from sub-groups for laboratory analysis. All decedent and terminated life span group subjects were subjected to post mortem examination, with weighing of 16 organs.(ABSTRACT TRUNCATED AT 400 WORDS)

Availability of selenium in fish meal in comparison with soybean meal, corn gluten meal and selenomethionine relative to selenium in sodiumselenite for restoring glutathione peroxidase activity in selenium-depleted chicks.

We assayed the availability of selenium in feeds and selenomethionine relative to selenium in sodium selenite for restoring blood serum glutathione peroxidase activity in selenium-depleted chicks. The contents of total selenium (determined by neutron activation analyses) were for eight samples of capelin fish meal, 1.34, two samples of mackerel fish meal, 6.17, one sample of solvent-extracted soybean meal, 0.42, and one sample of corn gluten meal, 0.54 ppm in dry matter. The availability of the selenium (relative to selenium in selenite=100%) in capelin fish meal was 48.0 (38.5--60.0), mackerel fish meal, 34.1 (32.3--35.8), soybean meal, 17.5, corn gluten meal, 25.7, and in selenomethionine, 78.3%.

A biological assay for determination of availability of selenium for restoring blood plasma gluthathione peroxidase activity in selenium-depleted chicks.

This study was undertaken to develop an assay for the determination of biological availability of selenium. In a preliminary experiment, commercial male, White Leghorn chicks had significantly reduced glutathione peroxidase activity in blood plasma after 7 days of depletion on a selenium-deficient (0.04 ppm of Se) diet. Selenium-depleted chicks fed graded levels of selenium (0.02--0.10 ppm in steps of 0.02 ppm) for 9 days had glutathione peroxidase activity in blood plasma which was linearly, highly correlated with dietary selenium content. In three subsequent experiments, chicks were fed a selenium-deficient diet for 7 days and were then distributed into groups of five chicks each. The standard diets, which contained 0.02, 0.04, 0.06, 0.08 and 0.10 ppm of selenium added as NaHSeO3, and the test diets, which contained three levels of each test substance and provided selenium supplements within the standard range, were each fed to three groups of chicks for 9 days. The dose parameter was selenium, in the standard groups added as NaHSeO3 and in the test groups provided by the selenium present in the test substance. The response parameter was blood plasma glutathione peroxidase activity. Statistical analyses of the results utilizing four fish meals as test substances revealed that the assay complied with the requirements for statistical and fundamental validity.

Morphological changes and fatty acid composition in hearts from pigs fed rapeseed oil, fish oil, partially hydrogenated fish oil, partially hydrogenated soybean oil and lard.

Female pigs, fed diets in which 42% of the caloric intake came from either rapeseed oil, fish oil, partially hydrogenated fish oil, partially hydrogenated soybean oil or lard, were killed after one week, five weeks, six months and one year. Type of fat or length of feeding did not affect the cardiac content of total fat which was normal in all animals. The fatty acid pattern of tissue triglycerides only partly reflected the fatty acid pattern of diets. The relative amounts of C22:1 and C20:1 were greatest after six months and levelled off during the following six months. The content of C22:1 in cardiac triglycerides never exceeded one fifth of the dietary concentration. Microscopic lipidosis was found in some pigs after one week, five weeks and six months. Minor heart lesions consisting of focal necrosis of muscle cells were found after one week and more frequently after six months and one year. No relationship between incidence and severity of the heart lesions and any particular type of fat in the diet could be found.

Comparison of lipid status in the hearts of piglets and rats on short term feeding of marine oils and rapeseed oils.

A series of 4 experiments with piglets and one experiment with rats has been conducted to establish the cardiac lipid status of weanling (3 weeks old) male animals fed fats with different contents of docosenoic fatty acids. Experimental fats were rapeseed oil (RSO) (48.0% 22:1), refined fish oil (RFO) (14.6% 22:1), partially hydrogenated fish oil (PHFO) (14.3% 22:1) and lard (0% 22:1) combined with sunflower seed oil (SFO) in different proportions in diets with 21% total fat. Lipidosis could not be detected in piglets as increased heart weights, by chemical assay for myocardial contents of triglycerides, or by accumulation of docosenoic fatty acids or nonesterified fatty acids (NEFA). In rats, diets with RSO at a level of 16% increased myocardial triglyceride and docosenoic fatty acid contents about 7 times while the effect on cardiac NEFA was inconsistent. Histological examinations of the hearts revealed stainable intracellular fat droplets in some piglets fed 16% RSO for 8 to 13 days, but not after 2, 4 and 6 and 16, 19 and 22 days of feeding. After 10 days of feeding, mild to moderate histological lipidosis was found in piglets fed diets containing 2% or more of 22:1 fatty acids, with no significant difference between RSO, RFO and PHFO in this respect. The same diets in rats gave about 5 times more histological lipidosis than in piglets. This is attributed to a difference in species response, the rat reacting in a more pronounced manner than the piglet. The cardiac lipidosis no-effect level in piglets corresponded to a daily intake of docosenoic fatty acids of 0.4 g per kg body weight. Mild lipidosis was also found in a few animals on docosenoic acid-free diets.

A chick assay for determination of available iron from biological material and its application to fish protein concentrates.

A dose response assay for the assessment of available iron in biological materials using chicks as experimental animals is described. Day-old chicks were fed on an iron-deficient diet for 2 to 3 weeks at which time the hematocrit had decreased to about 20%. After this depletion period, the standard groups were fed graded levels of iron sulphate up to a maximum level of 30 ppm iron. The test groups were fed two levels of biological material giving a total dietary iron concentration within the standard range. The response was measured by hemoglobin concentration (g/100 ml), and the dose by the consumption of iron per gram of body weight gain. Contents of available iron (relative to iron sulphate-iron) in the test substances were calculated from the dose response regression equations obtained on the standard groups, and hemoglobin (g/100 ml), feed consumption and body weight gain in the test groups. Statistical evaluation of the data revealed that the assay complied with the requirement for statistical and fundamental validity. Results from application of the method on six different samples of fish protein concentrate (FPC) are reported.