DHA / EPA (Omega 3)

DHA & EPA Omega 3 Fatty Acids Clinical Report Summary

Written Exclusively for MyNutritionStore.com by Rachel Parker

 

Omega-3 fatty acids, DHA and EPA, from fish oil are an effective treatment for high blood pressure, elevated blood triglycerides and increased mortality after an initial heart attack, according to numerous peer reviewed clinical studies (1, 2, 3, 4, 5, 6, 7). DHA and EPA come from fish oils and are essential for dietary health. Many people in North America have a diet lacking in omega-3 fatty acids, which results in a heightened risk of health problems like stroke and heart attack (2, 3). Omega-3 helps balance out another essential fatty acid, Omega-6, with its anti-inflammatory properties. DHA and EPA have performed so well in clinical studies that the American Heart Association has recommended fish oil as a dietary supplement. The group suggests taking one gram a day for cardio protection and 2 to 4g a day to reduce blood triglycerides, a condition that can lead to heart attack (1, 2). DHA and EPA supplements are considered safe in healthy people when taken at doses of 3g a day or less (1). People who have high cholesterol should consult a doctor before taking omega-3 because the supplement tends to slightly elevate low- density lipoprotein (LDL) or bad cholesterol (1, 5, 7). Omega-3, in high doses, may also inhibit the action of anticoagulant or blood thinning drugs.  

 

DHA & EPA Omega 3 Fatty Acids Overview

 

Omega-3 fatty acids, found in the oils of some fish and plants, are polyunsaturated fats essential for good health. The three most nutritionally important omega 3 fatty acids are alpha-linolenic acid; eicosapentaenoic acid (EPA), which is considered most important for cardiovascular health; and docosahexaenoic acid (DHA), which is most important for nerve tissue, including the retina. Alpha-linolenic acid is commonly found in walnuts and flaxseeds while DHA and EPA come from oils found in fatty fish like mackerel, salmon and tuna. All of these essential fatty acids must be included in a healthy daily diet; however, only the efficacy of fish oils, DHA and EPA, will be presented in this report. The importance of dietary omega-3 fatty acids has urgently come to the attention of scientists in the last 30 years, especially DHA and EPA. Research has found that people in North America have a diet drastically lacking in omega-3 acids and heavy in omega-6 acids. Omega-6 fatty acid, found in meat and vegetable oils, is also essential for good health but there is too much of it in the average diet (1). Researchers estimate that North Americans consume omega-6 to omega-3 at a ratio of 16:1 but this ratio should be 4:1, according to many nutritionists (2). Omega -6 fatty acids tend to be more inflammatory, while omega-3 acids are the opposite so researchers have found that an imbalance of essential fatty acids contributes to deadly heath conditions like heart attack, stroke and coronary heart disease (2, 3). Because of this, many scientists and doctors have recommended that people eat more fish or take supplements of DHA and EPA, as fish oil supplements outperform their vegetarian counterparts (1, 2, 3). Even the American Heart Association endorses DHA and EPA supplements for people with certain health conditions (1).

 

Safe Use of DHA & EPA Omega 3 Fatty Acids

 

Omega-3 fatty acids, DHA & EPA, have a low rate of side effects and are generally regarded as safe at doses of 3 grams a day or less for two years (1). People who have high cholesterol levels should consult a doctor before taking omega-3 as the supplement may slightly raise LDL, or bad, cholesterol when taken in high doses (1, 6). Pregnant or lactating women should also consult a doctor because there have been few studies conducted within this group. High doses of omega-3 (over 3g a day) may also inhibit the action of anticoagulant or blood thinning drugs (1).  

 

DHA & EPA Omega 3 Fatty Acids Key Clinical Studies

 

Research into the health benefits of DHA and EPA started in 1972 when a researcher discovered that the Inuit people of Greenland had significantly lower cholesterol and triglyceride levels despite eating a diet high in protein and fat, predominately from consuming fish (2, 3). Since then, hundreds of human studies have examined the impact of DHA and EPA on health conditions like heart disease, arthritis and Alzheimer's disease (1, 2, 3). Many of these studies are significant and after review the strongest clinical evidence supports DHA and EPA use for three specific conditions: to prevent heart attacks in people who have had one before, decrease high blood triglycerides and lower elevated blood pressure (4, 5, 6, 7).

 

1. Blood Pressure and Omega-3 - DHA & EPA

 

Numerous studies have found that supplemental DHA and EPA can lower blood pressure, especially in patients who are hypertensive, or have high and unsafe levels of blood pressure (1. 2, 4). One study, from the Johns Hopkins School of Medicine, examined several of these studies for bias and efficacy. A total of 17 trials were examined and overall omega-3 polyunsaturated fatty acids were found to reduce total blood pressure. However the biggest benefit was found in hypertensive patients not yet receiving treatment. In this group, blood pressure dropped significantly: 5.5 mm Hg for systolic BP and 3.5 mm Hg for diastolic BP (2, 4). Studies with higher doses of omega-3 yielded more dramatic drops and most studies lasted three months or less. Please see the study abstract below for more details (4):   

Does supplementation of diet with 'fish oil' reduce blood pressure? A meta-analysis of controlled clinical trials. Appel LJ et al.

BACKGROUND: Several lines of evidence suggest that supplementation of diet with omega-3 polyunsaturated fatty acids (omega-3 PUFA), commonly referred to as fish oils, may reduce blood pressure (BP). However, most clinical trials of omega-3 PUFA supplementation have been of insufficient size to detect relevant BP changes. METHODS: We conducted a meta-analysis of 17 controlled clinical trials of omega-3 PUFA supplementation. To estimate an overall effect of omega-3 PUFA supplementation on BP, we calculated the net BP change in each trial (BP delta in omega-3 PUFA group minus BP delta in control group), which was then weighted according to the inverse of the variance. RESULTS: In the 11 trials that enrolled normotensive individuals (n = 728), omega-3 PUFA supplementation led to significant reductions of systolic BP (SBP) and diastolic BP (DBP) in two and one trials, respectively. In the six studies that enrolled untreated hypertensives (n = 291), significant reductions of SBP and DBP were present in two and four trials, respectively. Weighted, pooled estimates of SBP and DBP change (mm Hg) with 95% confidence intervals were -1.0 (-2.0 to 0.0) and -0.5 (-1.2 to +0.2) in the trials of normotensives, and -5.5 (-8.1 to -2.9) and -3.5 (-5.0 to -2.1) in the trials of untreated hypertensives. In 13 of 17 studies, trial duration was less than 3 months. Doses of omega-3 PUFA tended to be high (average dose > 3 g/d in 11 trials). The magnitude of BP reduction was greatest at high BP but was not significantly associated with dose of omega-3 PUFA. Side effects, most commonly eructation and a fishy taste, occurred more frequently in omega-3 PUFA participants than in control participants (28% vs 13%, P < .001). CONCLUSIONS: Our analyses indicate that diet supplementation with a relatively high dose of omega-3 PUFA, generally more than 3 g/d, can lead to clinically relevant BP reductions in individuals with untreated hypertension. However, use of omega-3 PUFA as antihypertensive therapy will require demonstration of long-term efficacy and patient acceptability of lower doses.

 

2. Triglycerides and Omega-3 - DHA & EPA

 

Triglycerides are plasma lipids or blood fats similar to cholesterol. And just like cholesterol, elevated blood triglycerides are also associated with a high risk of coronary heart disease (5). Some people have high triglyceride levels because of poor diet, others because of family history. Clinical studies show that omega-3 supplements can reduce blood lipids in people who have high serum triglycerides, otherwise known as hypertriglyceridemia, by 30-50% (3, 5,). This type of research has gotten the attention of the American Heart Association. The group recommends omega-3 DHA & EPA supplements to reduce blood triglycerides in some people at a dose of 2 to 4g a day (1). Scientists are still investigating how DHA & EPA alter blood lipids but it seems that DHA is more of the catalyst. One study tested DHA and EPA separately against placebo corn oil. More than 200 men were given one of these oils for seven weeks of treatment. In the end both DHA and EPA decreased blood triglycerides over placebo but the change was greatest in the DHA group: 26%. Other tests indicate stronger chemical activity in DHA for more information she the study abstract as below (3, 5, 6):

Highly purified eicosapentaenoic acid and docosahexaenoic acid in humans have similar triacylglycerol-lowering effects but divergent effects on serum fatty acids. Grimsgaard S et al.

To compare the effects of highly purified ethyl ester concentrates of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on serum lipids, apolipoproteins, and serum phospholipid fatty acids in humans, we conducted a double-blind, placebo-controlled, parallel design intervention study. Healthy nonsmoking men (n = 234) aged 36-56 y were randomly assigned to dietary supplementation with 3.8 g EPA/d, 3.6 g DHA/d, or 4.0 g corn oil/d (placebo) for 7 wk. Serum triacylglycerols decreased 26% (P < 0.0001) in the DHA group and 21% (P = 0.0001) in the EPA group compared with the corn oil group. Although not significant, net decreases in serum triacylglycerols were consistently greater in the DHA group across all quartiles of baseline triacylglycerol concentrations. Serum high-density-lipoprotein cholesterol increased 0.06 mmol/L (P = 0.0002) in the DHA group. In the EPA group, serum total cholesterol decreased 0.15 mmol/L (P = 0.02) and apolipoprotein A-I decreased 0.04 g/L (P = 0.0003). In the DHA group, serum phospholipid DHA increased by 69% and EPA increased by 29%, indicating retroconversion of DHA to EPA. In the EPA group, serum phospholipid EPA increased by 297% whereas DHA decreased by 15%, suggesting that EPA is not elongated to DHA in humans. The serum phospholipid ratio of n-3 to n-6 fatty acids increased in both groups, whereas the relative changes in n-6 fatty acids suggested possible alterations in liver desaturation activity in the DHA group. We conclude that both DHA and EPA decrease serum triacylglycerols, but have differential effects on lipoprotein and fatty acid metabolism in humans.

 

3. Heart Attack and Omega-3 - DHA & EPA

 

Omega-3 fatty acids increase the life expectancy of people who have had a heart attack, according to several published clinical studies (1, 2, 7). This was first discovered in a 1989 study called the Diet and Reinfarction Trial (DART) that investigated more than 2,000 male patients who had just suffered a heart attack. Half the group was advised to eat fish twice a week, the other half given no such recommendation. After 2 years, the fish group had a 29% reduction in mortality or death (1). A few years later, scientists in Italy went a step further and investigated omega-3 supplements in heart attack patients. More than 11,000 patients were assigned to take omega-3, vitamin E, a combination of both supplements or nothing at all for three and a half years. At the end of treatment, patients taking omega-3 had an overall reduction in mortality rate by 20% and 30% reduction in cardio vascular deaths (1, 2, 7). Researchers believe that omega-3 can stabilize the contraction of heart cells and reduce the chance of arryhythmia or irregular heart beat (2). Specific details can be found in the study abstract (7): 

Early protection against sudden death by n-3 polyunsaturated fatty acids after myocardial infarction: time-course analysis of the results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-Prevenzione. Marchioli R et al.

BACKGROUND: Our purpose was to assess the time course of the benefit of n-3 polyunsaturated fatty acids (PUFAs) on mortality documented by the GISSI-Prevenzione trial in patients surviving a recent (<3 months) myocardial infarction. METHODS AND RESULTS: In this study, 11 323 patients were randomly assigned to supplements of n-3 PUFAs, vitamin E (300 mg/d), both, or no treatment (control) on top of optimal pharmacological treatment and lifestyle advice. Intention-to-treat analysis adjusted for interaction between treatments was carried out. Early efficacy of n-3 PUFA treatment for total, cardiovascular, cardiac, coronary, and sudden death; nonfatal myocardial infarction; total coronary heart disease; and cerebrovascular events was assessed by right-censoring follow-up data 12 times from the first month after randomization up to 12 months. Survival curves for n-3 PUFA treatment diverged early after randomization, and total mortality was significantly lowered after 3 months of treatment (relative risk [RR] 0.59; 95% CI 0.36 to 0.97; P=0.037). The reduction in risk of sudden death was specifically relevant and statistically significant already at 4 months (RR 0.47; 95% CI 0.219 to 0.995; P=0.048). A similarly significant, although delayed, pattern after 6 to 8 months of treatment was observed for cardiovascular, cardiac, and coronary deaths. CONCLUSIONS: The early effect of low-dose (1 g/d) n-3 PUFAs on total mortality and sudden death supports the hypothesis of an antiarrhythmic effect of this drug. Such a result is consistent with the wealth of evidence coming from laboratory experiments on isolated myocytes, animal models, and epidemiological and clinical studies.

 

DHA & EPA Omega 3 Fatty Acids References

 

1. Covington M. Omega-3 fatty acids. Am Fam Physician. 2004; 70(1): 133-140.
2. Schwalfenberg G, Omega-3 fatty acids. Can Fam Physician. 2006; 52(6): 734-740.
3. Harris HS. n-3 Fatty acids and serum lipoproteins: human studies. Am J Clin Nutr. 1997; 65(suppl): 1645S-1654S).
4. Appel LJ. Does supplementation of diet with 'fish oil' reduce blood pressure? A meta-analysis of controlled clinical trials. Arch Intern Med. 1993; 153(12) : 1429-1438.
5. Oh RC, Lanier JB. Management of Hypertriglyceridemia. Am Fam Physician. 2007; 75(9): 1365-1371.
6. Grimsgaard S et al. Highly purified eicosapentaenoic acid and docosahexaenoic acid in humans have similar triacylglycerol-lowering effects but divergent effects on serum fatty acids. Am J Clin Nutr. 1997; 66(3): 649-659.
7. Marchioli R. Early protection against sudden death by n-3 polyunsaturated fatty acids after myocardial infarction: time-course analysis of the results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-Prevenzione. Circulation. 2002; 105(16): 1874-1875.