Fish oils in hypertriglyceridemia: a dose-response study

Article Abstract:

Fish oils from marine fish contain the n-3 fatty acids, which reportedly lower blood lipids such as cholesterol; this may in turn reduce the risk of developing coronary heart disease (CHD). Several previous studies reported that the addition of fish or fish oil supplements to the diet led to reductions in blood lipids. More specifically, with fish oil consumption the circulating level of triglycerides was lowered by 20 to 60 percent in normal individuals and by up to 81 percent in patients with elevated triglycerides. In the current study, 10 adults with hypertriglyceridemia (elevated blood triglycerides) were given three different doses of fish oils, supplying 4.5, 7.5 and 12 grams n-3 fatty acids per day. Each dose was consumed by each subject for six weeks. Significant reductions in both total cholesterol and triglycerides were obtained for each subject on all the fish oil doses. The effectiveness of the different doses was comparable, indicating that the lowest dose may be preferable. In addition, the level of low-density-lipoprotein (LDL) cholesterol increased significantly, by 23 and 28 percent, with the two higher amounts of fish oils. Since this may raise CHD risk, the lowest dose again appears most effective. One known side effect of fish oils is an increased tendency towards bleeding; this was observed only while subjects took the highest dose. The authors conclude that fish oil supplementation in the amount of 4.5 grams of n-3 fatty acids (15 milliliters fish oil) per day significantly reduced total cholesterol and triglycerides while tending to raise LDL and high-density-lipoprotein (HDL) cholesterol, in patients with hypertriglyceridemia. It should be noted that all subjects were also following a low-fat, low-cholesterol diet. Studies of the effects of fish oils over longer periods are needed in order to establish the optimal dose. (Consumer Summary produced by Reliance Medical Information, Inc.)

Care and treatment, Hyperlipidemia

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N-3 fatty acid effects on lipids, lipoproteins, and apolipoproteins at very low doses: results of a randomized controlled trial in hypertriglyceridemic subjects

Article Abstract:

Studies with human subjects and laboratory animals have suggested that consumption of fish oils may reduce the risk of atherosclerosis, which is the accumulation of fatty plaques inside large and medium-sized arteries, such as the coronary arteries. The substances in fish oils that appear to offer these health benefits are the omega-3, or n-3, fatty acids. Most human studies have used fish oil supplements in high doses (up to 30 grams per day), but the impact of low doses, which have fewer side effects, has not been thoroughly evaluated. Twenty-five adults with hypertriglyceridemia (elevated blood triglycerides) were studied: 10 people took 2.2 grams n-3 fatty acids daily; 7 took 1.1 grams daily; and 8 consumed olive oil, which was considered a placebo treatment. The study period lasted 20 weeks. Compared with baseline values, significant increases in low-density lipoprotein (LDL) cholesterol and a related substance, LDL-apolipoprotein B, occurred in the group taking 2.2 grams n-3 fatty acids. Both groups taking n-3 fatty acids experienced clinically significant increases in LDL apolipoprotein B, compared with the placebo group. These effects not only lacked health benefit, but were considered potentially harmful; the very low doses of fish oils may have increased the risk for coronary artery disease in these hypertriglyceridemic patients. However, the interpretation of these data is complex because fish oils exert their influence on risk of heart disease through various mechanisms. While the increase in LDL cholesterol is not desirable, other effects that were not measured here may have offset this trend and the total impact of the fish oils could still have been beneficial. In addition, the fish oil groups experienced minor reductions in blood triglyceride levels. (Consumer Summary produced by Reliance Medical Information, Inc.)

Prevention, Dosage and administration, Diet therapy, Omega-3 fatty acids, Omega 3 fatty acids, Hyperlipoproteinemia

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Dietary-fish effects on serum lipids and apolipoproteins, a controlled study

Article Abstract:

Research has established that elevated levels of certain blood lipids, such as cholesterol, increase the risk of developing coronary heart disease (CHD). Blood lipids are in turn influenced by the fats consumed in the diet. One specific type of fat, the n-3 polyunsaturated fatty acids found in marine fish, may improve the blood lipid profile and thereby reduce the risk of CHD. Eighty-four healthy men, aged 20 to 45 years, took part in a study conducted at three sites in the Netherlands and Norway. For six weeks, the men ate a daily supplement of either mackerel paste (to provide fish oils) or meat paste. Urine tests were used to determine whether the men were consuming the supplement as directed; the average compliance was 80 percent. The levels of various blood lipids were tested. Total cholesterol and low-density lipoprotein (LDL) cholesterol did not change, and high-density lipoprotein (HDL) cholesterol increased by an equal amount in the two groups. Blood triglycerides (TGs) were reduced in the fish paste group, but the potential benefit of this decrease is questionable. Levels of apolipoproteins, substances that transport lipoproteins in the blood, were only slightly altered and only in subjects from one of the three study sites. Analysis of cholesterol esters and triglycerides showed that the content of n-3 fatty acids increased in the fish paste group only. This finding may constitute an advantage in terms of lower CHD risk for the fish group. But given the lack of improvement in the other blood lipids, particularly LDL- and HDL-cholesterol, the results were disappointing because they failed to demonstrate a conclusive link between fish consumption and reduced CHD risk. (Consumer Summary produced by Reliance Medical Information, Inc.)

Heart attack, Apolipoproteins

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