High consumption of fish oil may benefit cardiovascular health

Eating fish in amounts comparable to those of people living in Japan seems to impart a protective factor that wards off heart disease, according to an international study funded by the National Institutes of Health (NIH) and led by the University of Pittsburgh Graduate School of Public Health.

Middle-aged Japanese men living in Japan had lower incidence of coronary artery calcification, a predictor of heart disease, than middle-aged white men living in the United States, likely due to the significantly higher consumption of omega-3 fatty acids found in fish. The findings will be published in the March 6, 2014 issue of the journal Heart.

"Multiple studies have looked at the effect of fish oil on cardiovascular health, with mixed results," said lead author Akira Sekikawa, M.D., Ph.D., associate professor of epidemiology at Pitt Public Health. "Previous studies investigated substantially lower intake of omega-3 fatty acids than what people in Japan actually get through their diet. Our study seems to indicate that the level of marine-derived omega-3 fatty acids consumed must be higher than previously thought to impart substantial protection."

Marine-derived omega-3 fatty acids, which are found in fish, especially oily fish, as well as in squid and krill, may help to reduce inflammation and slow the formation of fatty plaques in arteries.

Researchers at Pitt partnered with scientists in Japan, Hawaii and Philadelphia to follow nearly 300 men for five years, tracking multiple factors that affect cardiovascular health, including cigarette smoking, the level of cholesterol in the blood and alcohol consumption, as well as their rates of diabetes and high blood pressure.

After accounting for risk factors for heart disease, the U.S. men had three times the incidence of coronary artery calcification as the Japanese men. Meanwhile, the levels of marine-derived omega-3 fatty acid in the blood were more than 100 percent higher in the Japanese than in the white men.

"The vast difference in heart disease and levels of marine-derived omega-3 fatty acid are not due to genetic factors," said Dr. Sekikawa. "When we look at Japanese Americans, we find that their levels of coronary artery calcification are actually higher than that of the rest of the U.S. population."

The average dietary intake of fish by Japanese people living in Japan is nearly 100 grams each day, which the American Heart Association considers 1 ½ servings. The average American eats about 7 to 13 grams of fish a day, or about one serving a week.

Heart disease is the leading cause of death in the U.S. and globally, according to the World Health Organization. However, Japan bucks this trend, with cancer as the leading cause of death.

"I am not encouraging Americans to start consuming massive amounts of fish, which may have harmful contaminants, such as mercury, in their flesh," said Dr. Sekikawa. "However, our findings indicate that it is worthwhile to take another look at the effect of marine-derived omega-3 fatty acids on heart disease, particularly when consumed at higher rates than previously investigated."

Fish oil supplements may protect the heart in stressful situations

Fish oil may help the heart beat mental stress

The omega 3 fatty acids in fish oil have long been thought to protect against cardiovascular disease—so much so that the American Heart Association currently recommends eating at least two servings of fish a week, particularly fatty varieties rich in omega 3s. However, the mechanism behind this protective effect still remains a mystery.

In a new study, scientists led by Jason R. Carter of Michigan Technological University shed light on this phenomenon by providing evidence that fish oil might specifically counteract the detrimental effects of mental stress on the heart. Their findings show that volunteers who took fish oil supplements for several weeks had a blunted response to mental stress in several measurements of cardiovascular health, including heart rate and muscle sympathetic nerve activity (MSNA), part of the "fight or flight" response, compared to volunteers who took olive oil instead. The results may explain why taking fish oil could be beneficial to the heart and might eventually help doctors prevent heart disease in select populations.

The article is entitled "Fish Oil and Neurovascular Reactivity to Mental Stress in Humans." It appears in the May, 2013 edition of the American Journal of Physiology – Regulatory, Integrative, and Comparative Physiology, published by the American Physiological Society.

Methodology

Carter and his colleagues worked with 67 adult volunteers. At the beginning of the study, each volunteer underwent a battery of tests to assess cardiovascular function, including heart rate, blood pressure, MSNA, and blood flow through the forearm and calf. These tests were performed first when the volunteers were at rest, and then again while they were performing a mental arithmetic test while the investigator encouraged them to hurry, a situation designed to induce acute mental stress. The study subjects were then nearly equally assigned to take either 9 grams of fish oil per day or 9 grams of olive oil, a placebo that hasn't been shown to have the same beneficial cardiovascular effects as fish oil. None of the volunteers were aware of which supplement they were taking. After 8 weeks of this intervention, the study subjects underwent the same tests again.

Results

The researchers found that test results didn't change between the two groups of study subjects when they were at rest. However, results for the volunteers who took fish oil and those who received the placebo differed significantly for some of the tests during the mental stress. Those in the fish oil group showed blunted heart rate reactivity while they were stressed compared to those who took olive oil. Similarly, the total MSNA reactivity to mental stress was also blunted in the fish oil group.

Importance of the Findings

These results show that fish oil could have a protective effect on cardiovascular function during mental stress, a finding that adds a piece to the puzzle on why taking fish oil helps the heart stay healthy, the authors suggest. Future studies might focus on the effects of taking fish oil for longer time periods and examining this effect on older populations or people with cardiovascular disease.

"Overall," the study authors say, "the data support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans and suggest important physiological interactions between fish oil and psychological stress that may contribute to disease etiology."

Omega-3 fatty acids appear to protect damaged heart after heart attack

Taking omega-3 fatty acids appeared to lower inflammation and guard against further declines in heart function among recent heart attack survivors already receiving optimal standard care, according to results from a randomized, controlled trial presented at the American College of Cardiology's 64th Annual Scientific Session in San Diego (2015).

Patients in the study taking 4 grams of prescription-only omega-3 fatty acid capsules daily for six months after a heart attack were significantly more likely to show improvements in heart function compared to patients taking a placebo. Heart function was measured by an expansion of the left ventricular endsystolic volume index. Patients taking omega-3 fatty acids also had significantly less evidence of fibrosis -- a thickening or scarring of the areas of the heart remote from the heart attack, which can develop when the surviving heart muscle works harder and under high pressure to compensate for the damage to the heart. The data suggests that patients who were able to mount a substantial change in levels of omega-3 fatty acids in their blood derived the most benefit.

"Giving a high dose of omega-3 fatty acids soon after a heart attack appears to improve cardiac structure and heart functioning above and beyond the standard of care," said Raymond W. Kwong, M.D., M.P.H, director of cardiac magnetic resonance imaging at Brigham and Women's Hospital in Boston and the study's senior author. "Because this is a unique group of patients with remarkably high adherence to [guideline-directed] treatments for acute myocardial infarction already, we feel fairly confident that the benefits from this therapy are additive. The implications of this study could be fairly large."

An estimated 720,000 Americans have heart attacks each year. After a heart attack, the heart can remodel or reorganize itself to maintain or improve function. In some cases, the heart may undergo adverse changes such as enlargement of the heart, decreased pumping ability or added cardiac strain that can predispose someone to heart failure and arrhythmias later in life.

Although earlier studies have shown that omega-3 fatty acids may lower the risk of irregular heartbeats and death from a heart attack, research has not consistently shown a benefit. Kwong said his research is the first to use quantitative cardiac imaging to look at how omega-3 fatty acids might actually protect the heart after a major heart attack.

Researchers randomized 374 patients recovering from a heart attack and receiving standard treatment to take either 4 grams of omega-3 fatty acids or a placebo; groups were balanced in terms of location of the infarct--anterior or non-anterior--and age. Blood work and cardiac imaging were analyzed at two to four weeks post-heart attack and again at six months. Compared to previous research, this study used a much higher dose of omega-3 fatty acids, 4 grams compared to 1 gram daily, and a small amount of corn oil, which does not contain fatty acids, as the placebo.

By using cardiac magnetic resonance imaging, researchers were able to look at changes in patients' hearts and see the disease process before and after treatment. Adverse changes in left ventricular remodeling and function, in addition to the worsening of fibrosis, were used as surrogates for poor outcomes after heart attack.

Patients taking the omega-3 fatty acids were 39 percent less likely to show a deterioration of heart function as compared to patients taking a placebo. The analysis also looked at key markers of systemic inflammation, which were also more likely to be improved in those taking the fish oil. In particular, the percent reduction in ST2, a marker of the severity of adverse cardiac remodeling and tissue fibrosis, was substantially greater in the treatment arm after six months.

"Omega-3 fatty acids may have anti-inflammatory effects and also promote better cardiac healing," Kwong said. "This is important because other anti-inflammatory agents, including steroids and NSAIDS, have failed to make a difference after myocardial infarction." Patients in the study who had a 5 percent increase in the amount of omega-3 fatty acid in their blood seem to have the best chance of improving heart function.

"If this becomes a useful therapy, it seems a 5 percent increase in the serum level of omega-3 fatty acids correlates with a 10 percent improvement in left ventricular remodeling," he said. In this study, most (92 percent) of patients randomized to fish oil increased omega-3 fatty acid by at least 5 percent, compared with less than half (42 percent) of patients receiving placebo.

Kwong said the higher-dose omega-3 fatty acids was not found to be associated with any major safety issues, such as increased bleeding. "It's a very well-tolerated therapy," he said, adding that it is unlikely patients could get the amount of omega-3 fatty acids from diet alone. He said the daily 4 gram dose is roughly equivalent to someone eating a large, 8-ounce serving of salmon every day for six months.

For many years, the American College of Cardiology and the American Heart Association have recommended that people eat fish rich in omega-3 fatty acids at least twice a week because of its potential heart benefits.

Kwong said most North Americans do not follow this advice, while Japanese populations with higher levels of omega-3 and an otherwise similar risk profile to North Americans have lower risks of heart disease and sudden cardiac death. The increase in the omega-3 blood content of many patients in Kwong's study at six months was similar to levels found in Japanese populations with a diet very rich in omega-3 fatty acids.

Fatty fish such as salmon, tuna, trout and sardines contain the most omega-3 fatty acids. Fatty acids are a key component of cell membranes and they help with cell signaling, proper immune function and may also improve cognitive functioning. This study is limited in that it did not investigate the association between omega-3 fatty acids and cardiac events after heart attack; assessing this relationship would require a large group of patients over many years. It also did not evaluate this treatment immediately after having a heart attack.

A fish a day keeps the doctor away

Most people, whether healthy or having cardiovascular disease (CVD), would benefit from regular consumption of oily fish, concluded speakers at the EuroPRevent 2012 meeting. While eating whole fish undoubtedly offers the optimum approach for increasing omega-3 intakes in both primary and secondary prevention, delegates heard, supplements have a major role to play in increasing omega-3 intakes for people who do not like fish. The EuroPRevent 2012 meeting, held 3 May to 5 May 2012 in Dublin, Ireland, was organised by the European Association for Cardiovascular Prevention and Rehabilitation (EACPR), a registered branch of the European Society of Cardiology (ESC).

The symposium " A fish a day keeps the doctor away" (1) centred on the cardiovascular disease (CVD) benefits of the long chain highly unsaturated omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in the flesh of oily fish, such as salmon, mackerel, herring, trout and sardines. In the round table debate speakers attempted to unravel the current confusion where initial studies showed eating fish/taking omega 3 supplements delivered CVD benefits, but more recent studies with supplements failed to reproduce these effects.

"Omega-3 fatty acids are really important to human health, whether you're talking about CVD, brain or immune health. Heath professionals have a key role to play in educating the public about the beneficial effects of including fish in their diets," said Philip Calder, a metabolic biochemist and nutritionist from the University of Southampton, UK.

The latest European Guidelines on Cardiovascular Disease Prevention in Clinical Practice, also launched at the EuroPRevent 2012 meeting, recommend that people should eat fish at least twice a week, one meal of which should be oily fish (2). For people opting for supplements, warned Calder, it is best to take pharmaceutical grade preparations of omega-3 oils since not all over the counter preparations contain the same dose of the fatty acids. "It's important that health professionals give clear guidance around the need for patients to take 1g of omega-3 a day to achieve any beneficial effects.

With over the counter brands containing different concentrations there's a danger people may not be receiving sufficient intakes," said Calder.

Eating oily fish may prove more beneficial than taking capsules of omega-3. "This is because fish contain all sorts of other nutrients like vitamin D, selenium and iodine that may also be beneficial against CVD. And we don't have the final proof that the benefits from eating fish come from the omega-3," said Daan Kromhout, from Wageningen University, The Netherlands. "Fish, it needs to be remembered, don't provide a total panacea against CVD. As well as consuming fish, people need to eat healthy diets, not smoke and be physically active."

Conflicting trials of omega-3

The first association between omega-3 consumption and incidence of CVD was found in epidemiological studies in the late 1970s when Danish investigators Bang and Dyerberg discovered the incidence of myocardial infarction (MI) was ten times higher among the Danish population than Greenland Inuits. "At the time the Greenland Inuits ate diets of whale and seal meat that were exceptionally high in omega-3 fatty acids," said Erik Berg Schmidt, from Aalborg University Hospital, Aarhus, Denmark. "The findings went contrary to the dogma of the time that animal fats were harmful and led to the hypothesis that omega-3 fatty acids reduce vascular disease."

Omega-3 fatty acids are a family of naturally occurring polyunsaturated fatty acids named according to the position of the double bonds within their hydrocarbon chain. Since mammals lack enzymes to insert the double bond in the omega-6 or omega-3 position, they need to obtain these fatty acids from their diets. EPA and DHA enter the food chain through marine phytoplankton and pass through fish.

The initial trials showing a benefit for omega-3 in the secondary prevention of patients with established CVD were:

The Diet and Reinfarction Trial (DART), 1989, in 2,033 men who had suffered an MI showed a 29% reduction in all-cause mortality among those who received advice to add two fatty fish meals per week (300 g of oily fish) or to take fish oil capsules providing an equivalent intake of marine omega-3 (3).

The Gruppo Italiano per lo Studio della Sopravvienza nell'Infarto (GISSI) Prevenzione trial, 1999, which enrolled 11,324 patients within three months of an MI, showed that marine omega-3 fatty acids (885 mg EPA+DHA per day) lowered the risk of the combined primary outcome of death and non-fatal cardiovascular events by 15% (4).

The JELIS study, 2007, which involved 18,645 Japanese patients with hypercholesterolaemia, with or without pre-existing coronary artery disease, showed that long-term use of 1.8 g of purified EPA daily lowered the risk of the combined primary outcome of death and non-fatal cardiovascular events by 15% (5).

However, in 2010, three large trials - Alpha Omega, OMEGA, and SU.FOLOM3 – all failed to confirm the benefits of omega-3 fatty acids supplements on CVD events.

Each of these later studies, said Berg Schmidt, had issues related to the marine omega-3 fatty doses used, the exact mix of EPA and DHA, the lag between when the MI occurred and initiating omega-3 fatty acid treatment, the use of newer invasive and non-invasive strategies, the length of follow-up and sample size, which in some cases was too small to show a beneficial effect.

Fish intake in primary prevention

Following the first epidemiological observations in Greenland Inuits, Kromhout told delegates, prospective cohort studies carried out in European, American, Japanese, and Chinese populations also showed inverse associations between fish consumption and CVD morbidity and mortality.

Recently a Danish cohort study from Aalborg found that when levels of omega-3 fatty acids were measured in an adipose biopsy taken from the buttocks of 57 053 subjects, a negative dose response was found with the risk of acute MI(6). "But there've been no trials of eating fish in healthy people because you'd need too many participants to reach a conclusion for the trial to be feasible," explained Kromhout.

The only real way to look for benefits in primary prevention, he added, is to investigate the effects on intermediate endpoints. One such study by Matthew Pase, from the NICM Centre for Study of Natural Medicines and Neurocognition, Melbourne, Australia, reviewing data from 10 clinical trials involving 550 participants, found omega-3 fatty acids reduced pulse wave velocity by an average of 33 % and arterial compliance by 48 % (7).

The mechanism of action of Omega-3 fatty acids

Omega-3 fatty acids, explained Calder, can exert a variety of actions on cell physiology and function. "They're anti-inflammatory and might therefore decrease the inflammatory processes within the vessel wall, which are recognised as major contributors to atherosclerosis," he said.

Indeed, recent studies by Calder and colleagues showed that the incorporation of EPA into advanced plaques was associated with a decreased expression of various matrix metalloproteinases (MMPS), proteins which have been implicated in plaque cap thinning and increased vulnerability to rupture.

Omega-3 fatty acids are also known to have an anti-arrhythmic effect. The presence of omega-3 fatty acids in cardiomyocyte membrane phospholipids decreases electrical excitability and modulates the activity of ion channels (e.g. sodium, potassium and calcium, effects that are claimed to promote electrical stability in the cell and prevent arrhythmias. It is also known that omega-3 fatty acids are potent triglyceride lowering agents.

One issue that has hindered studies exploring the mechanisms of action of omega-3, added Calder, is that the amounts of EPA and DHA vary between the different commercial preparations of omega-3. "This is important because EPA and DHA don't always have the same actions," he said.

"With investigators using different doses it's been hard to produce consistent effects. To properly unravel the mechanisms we need to adopt a strategic multidisciplinary approach where everyone uses the same dose and relative amounts of EPA and DHA" said Calder.

References

1. A fish a day keeps the doctor away – 14.00 to 15.30 Friday 4th May. Symposium. Liffey Hall 1 Lecture Room

2. European Guidelines on Cardiovascular Disease Prevention in Clinical Practice. EHJ 2012. Doi: 10.1093/eurheartj/ehs092

3. Burr ML, Gilbert JF, Holliday RM, et al. Effects of changes in fat, fish and fibre intakes on death and myocardial reinfarction: diet and reinfarction trial (DART). Lancet 1989; 344:757-61.

4. GISSI-Prevenzione Investigators. Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Lancet 1999; 354: 447-55.

5. Yokoyama M, Origasa H, Matsuzaki M, et al. Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label blinded endpoint analysis. Lancet 2007; 369:1090-98.

6. Joensen AM, Overvad K, Dethlefsen C et al. Marine n-3 Polyunsaturated Fatty Acids in Adipose Tissue and the Risk of Acute Coronary Syndrome. Circulation. 2011;124:1232-8

7. Pase MP, Grima A, Sarris J, et al. Do long-chain n-3 fatty acids reduce arterial stiffness? A meta-analysis of randomised controlled trials. British Journal of Nutrition 2011; 106:974-80

Farmed Salmon Raises Blood Levels of Omega-3s

People who eat farm-raised salmon can increase their intake of beneficial omega-3 fatty acids to levels that may help reduce their risk of heart disease, according to studies by U.S. Department of Agriculture (USDA) scientists.

The studies by Agricultural Research Service (ARS) nutritionist Susan Raatz and physiologist Matthew Picklo address concerns about whether farm-raised salmon have less available omega-3s than salmon caught in the wild.

Two omega-3 fatty acids—EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)—are abundant in oily fish such as salmon, tuna, mackerel, and herring. Consuming 250 milligrams daily of EPA and DHA—the amount in a 3-ounce farmed salmon fillet—has been associated with reduced heart disease risk.

The scientists evaluated a group of 19 healthy human volunteers who were provided three different portion sizes of farm-raised Atlantic salmon. Each volunteer was assigned to consume two weekly servings of one of the three portion sizes of salmon for a four-week period. After a "blood-clearing" break of four to six weeks, a different portion size was served, followed by another break. Then the third portion size was served, so that each volunteer had tested all three portion sizes.

The raw weights of the salmon portions fed to the volunteers were 90 grams (about 3.2 ounces), 180 grams (about 6.3 ounces), and 270 grams (about 9.5 ounces). The Dietary Guidelines for Americans recommend consuming 8 ounces of seafood weekly.

Blood was collected from each of the 19 subjects to mark fatty acid levels and other heart disease risk indicators at the beginning and end of each treatment. The results showed that EPA blood levels doubled after the volunteers consumed the 6.3-ounce portions and increased nearly threefold after they consumed the 9.5-ounce portions. Also, based on the blood indicators, DHA levels were elevated by about 50 percent, regardless of portion size.

Farm-raised Salmon Retains Healthy Omega-3s When Baked

U.S. Department of Agriculture (USDA) nutritionist Susan Raatz, physiologist Matthew Picklo, and cooperators have found that farm-raised Atlantic salmon maintains its healthy levels of omega-3 fatty acids when baked.

While eating seafood rich in omega-3 fatty acids is known to reduce risk of heart disease, it has not been known whether baking causes loss of omega-3s in farm-raised Atlantic salmon. The team also examined the extent to which baking Atlantic salmon alters healthful fatty acids through oxidation that leaves unhealthy compounds, such as toxic omega-3 oxidation byproducts.

The researchers demonstrated that baking salmon to the proper temperature does not decrease its content of beneficial omega-3 fatty acids. They found that baking actually decreases the presence of fatty acid oxidation byproducts. Preparing the fish based on restaurant and safety guidelines—to a tender-but-safe 145 degrees Fahrenheit rather than overcooking—was a key factor, according to authors.

This research was published in the Journal of the Academy of Nutrition and Dietetics.

Fish consumption and dietary omega-3 fatty acid supplements may help prevent heart disease

Literally hundreds of clinical trials, including some that have gained widespread attention, have been done on the possible benefits of omega-3 fatty acids for the prevention of heart disease – producing conflicting results, varied claims, and frustrated consumers unsure what to believe.

A recent analysis done by scientists in the Linus Pauling Institute at Oregon State University, published in the Journal of Lipid Research, has sorted through many of these competing findings, and it helps to explain why so many of the studies seem to arrive at differing conclusions.

The review concludes that both fish consumption and dietary omega-3 fatty acid supplements may still help prevent heart disease; that some fatty acids, from certain sources, are more effective than others; that these compounds may have enormous value for serious health problems other than heart disease; and that the very effectiveness of modern drug therapies for heart disease may be one explanation for the conflicting findings on the benefits of omega-3 fatty acids.

“After decades of studying omega-3 fatty acids, it’s clear that they have value in primary prevention of heart disease,” said Donald Jump, author of the analysis, a principal investigator in the Linus Pauling Institute, and professor in the OSU College of Public Health and Human Sciences.

“It’s less clear how much impact fish oils have in preventing further cardiovascular events in people who already have heart disease,” Jump said. “The studies done several decades ago showed value even for that patient population, but the more recent studies are less conclusive. We believe that one explanation is the effectiveness of current state-of-the-art treatments now being offered.”

Some of the earliest work that raised interest in omega-3 fatty acids was done in the 1970s with Greenland Inuits, who ate large amounts of fish and were found to have unusually low levels of cardiovascular disease. But, Jump said, millions of people now at risk for cardiovascular disease take medications such as statin drugs for high cholesterol; fibrates for high triglycerides; anti-thrombotics to thin their blood; and other drugs with anti-inflammatory or anti-arrhythmia effects.

Fish oils can have positive effects on virtually all of these same cardiovascular risk factors, Jump said, but so can the drugs.

“Some of the early studies done on fish oil were prior to so many effective medications being widely available and heavily used,” Jump said. “And people often forget that nutrients, like fish oils, are less potent than prescription drugs, and often have their best value when used for extended periods.

“When so many people in these studies are taking a regimen of medications to address the same issues that fish oil might also affect, it’s easy to understand why any added benefit from the fish oils is more difficult to detect,” he said.

The point, Jump said, is not that omega-3 fatty acids have no value – they do. But for studies of their value in cardiovascular disease, which are often done when patients are taking other medications, that value is less clear.

A wide body of other research, he says, makes it clear that omega-3 fatty acids also have health benefits that go beyond cardiovascular disease. They have been shown to improve visual acuity; improve cognitive function and reduce dementia; reduce inflammation and perhaps some types of cancer, such as colon cancer; and reduce total mortality.

Among the findings of this review:

- An important type of omega-3 fatty acid for human health is DHA, which is the predominant omega-3 fatty acid that accumulates in tissues.

- Plant-derived sources of these fatty acids, such as flaxseed oil or chia seeds, have less benefit than those from cold-water fish, because of differences in how the human body processes these nutrients.

- For individuals unwilling or unable to consume fish or fish-oil supplements, some products made from yeast or algae are high quality.

- It’s difficult to be certain of the amount of omega-3 fatty acids in farm-raised fish, since these fish require dietary omega-3 supplementation.

“We still believe the evidence is strong that the EPA and DHA content in heart tissues and blood is important to health and to the prevention of cardiovascular disease,” Jump said. “To meet the current recommendations for primary prevention of cardiovascular disease, individuals are advised to consume 200-300 milligrams of combined EPA and DHA per day.”

Mounting evidence of fish oil's heart health benefits

There is mounting evidence that omega-3 fatty acids from fish or fish oil supplements not only help prevent cardiovascular diseases in healthy individuals, but also reduce the incidence of cardiac events and mortality in patients with existing heart disease. A new study, published in the August 11, 2009, issue of the Journal of the American College of Cardiology, extensively reviews data from a broad range of studies in tens of thousands of patients and sets forth suggested daily targets for omega-3 consumption.

"This isn't just hype; we now have tremendous and compelling evidence from very large studies, some dating back 20 and 30 years, that demonstrate the protective benefits of omega-3 fish oil in multiple aspects of preventive cardiology," said Carl Lavie, M.D., F.A.C.C., medical director of Cardiac Rehabilitation and Prevention, Ochsner Medical Center, New Orleans, LA, and lead author of the article. "The strongest evidence of a cardioprotective effect of omega-3s appears in patients with established cardiovascular disease and following a heart attack with up to a 30 percent reduction in CV-related death."

Dietary intake of fish oil can also decrease the risk of atherosclerosis, arrhythmias, heart attack, sudden cardiac death and even health failure. Dr. Lavie adds that although there is a smaller benefit in reducing heart failure death—9 percent mortality benefit in a major recent randomized controlled trial—this is still very impressive given patients' grave prognosis.

"If we translate this finding, it means that we only need to treat 56 patients for four years to prevent one death," he said. "And we are talking about a very safe and relatively inexpensive therapy."

Most of the evidence for the cardioprotective benefits supports the use of DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), the long-chain fatty acids in the omega-3 family. According to Dr. Lavie, EPA and DHA work by getting into the membranes of cells and, in doing so, may help to improve the heart's electrical activity, vascular tone, plaque stabilization and blood pressure, among other benefits. Studies show that the reduction in CV events is inversely related to the tissue level EPA and, even more so, DHA.

Based on these findings, and because the body does not produce its own essential fatty acids, the authors recommend that healthy individuals should consume 500 mg daily of omega-3 fish oil containing EPA and DHA, and people with known heart disease or heart failure aim for at least 800 to 1,000 mg daily.

"There are clear health and heart benefits associated with increasing one's intake of foods that are rich in Omega-3s, including oily fish like salmon, sardines, trout, herring, and oysters" said Dr. Lavie "Patients should talk with their doctors about whether a fish oil supplement is needed to get the right amount and, in turn, benefit from the associated cardiovascular protection."

Dr. Lavie and his team came across only a few negative studies, including a recent one that showed no benefit in post-MI patients, but it has raised the possibility that omega-3 fatty acids may not provide as much additional protective benefits in low-risk patients already receiving extensive and rigorous post-MI therapies. "It was a one-year study that enrolled fewer than 4,000 patients and the majority were using aspirin, clopidogrel, statins, beta-blockers and ACE-inhibitors—the best of modern medicine," he said. "It may be that their risk was so low to start, that a larger study with longer follow-up would be required to better assess the true efficacy of omega-3 in such relatively low-risk patients."

Authors say further studies are needed to investigate and determine optimal dosages, as well as the relative ration of DHA and EPA that provides maximal heart protection in those at risk of cardiovascular disease, and in the treatment of atherosclerosis, arrhythmias and heart attacks.

Interestingly, culture has historically played a role; sometimes dubbed the "Eskimo factor," research shows cultures that have traditionally supported a diet rich in fish oil (Asian and Alaskan American populations) had a lower prevalence of cardiovascular disease and mortality, including a reduced prevalence of atherosclerosis and heart disease, compared to European and United States populations where consumption of fish is lower. Ironically, the introduction of Western dietary practices into Asian and Native American cultures may be diluting the cardioprotective benefits enjoyed by these populations by both reducing the overall intake of fish oils, as well as overwhelming its benefits with other deleterious dietary practices, including high intakes of saturated and trans fats and cholesterol.

Fish consumption and omega-3 fatty acid supplements may help prevent heart disease

A recent analysis done by scientists in the Linus Pauling Institute at Oregon State University, published in the Journal of Lipid Research, (November, 2012) has sorted through many of these competing findings, and it helps to explain why so many of the studies seem to arrive at differing conclusions.

Fish oils can have positive effects on virtually all of these same cardiovascular risk factors, Jump said, but so can the drugs.

Among the findings of this review:

- An important type of omega-3 fatty acid for human health is DHA, which is the predominant omega-3 fatty acid that accumulates in tissues.

- For individuals unwilling or unable to consume fish or fish-oil supplements, some products made from yeast or algae are high quality.

- It’s difficult to be certain of the amount of omega-3 fatty acids in farm-raised fish, since these fish require dietary omega-3 supplementation.

Couple of weekly portions of oily fish can help ward off stroke but fish oil supplements don't have the same effect

Eating at least two servings of oily fish a week is moderately but significantly associated with a reduced risk of stroke, finds a study published on bmj.com.

But taking fish oil supplements doesn't seem to have the same effect, say the researchers.

Regular consumption of fish and long chain omega 3 fatty acids has been linked with a reduced risk of coronary heart disease and current guidelines recommend eating at least two portions of fish a week, preferably oily fish like mackerel and sardines. But evidence supporting a similar benefit for stroke remains unclear.

So an international team of researchers, led by Dr. Rajiv Chowdhury at Cambridge University and Professor Oscar H. Franco at Erasmus MC Rotterdam, analysed the results of 38 studies to help clarify the association between fish consumption and risk of stroke or mini-stroke (transient ischaemic attack or TIA). Collectively, these conditions are known as cerebrovascular disease.

The 38 studies involved nearly 800,000 individuals in 15 countries and included patients with established cardiovascular disease (secondary prevention studies) as well as lower risk people without the disease (primary prevention studies). Differences in study quality were taken into account to identify and minimise bias.

Fish and long chain omega 3 fatty acid consumption was assessed using dietary questionnaires, identifying markers of omega 3 fats in the blood, and recording use of fish oil supplements. A total of 34,817 cerebrovascular events were recorded during the studies.

After adjusting for several risk factors, participants eating two to four servings a week had a moderate but significant 6% lower risk of cerebrovascular disease compared with those eating one or fewer servings of fish a week, while participants eating five or more servings a week had a 12% lower risk.

An increment of two servings per week of any fish was associated with a 4% reduced risk of cerebrovascular disease. In contrast, levels of omega 3 fats in the blood and fish oil supplements were not significantly associated with a reduced risk.

Several reasons could explain the beneficial impact of eating fish on vascular health, say the authors. For example, it may be due to interactions between a wide range of nutrients, like vitamins and essential amino acids, commonly found in fish. Alternatively, eating more fish may lead to a reduction in other foods, like red meat, that are detrimental to vascular health. Or higher fish intake may simply be an indicator of a generally healthier diet or higher socioeconomic status, both associated with better vascular health.

The differences seen between white and oily fish may be explained by the way they are typically cooked (white fish is generally battered and deep fried, adding potentially damaging fats).

Although there's a possibility that some other unmeasured (confounding) factor may explain their results, the authors conclude that "they reinforce a potentially modest beneficial role of fish intake in the cause of cerebrovascular disease."

In addition, they say their findings are in line with current dietary guidelines that encourage fish consumption for all; and intake of fish oils to people with pre-existing or at high risk of heart disease. They also support the view that future nutritional guidelines should be principally "food based."

In an accompanying editorial, authors from the Division of Human Nutrition at Wageningen University suggest that although it is "reasonable" to advise patients that eating one or two portions of fish per week could reduce the risk of coronary heart disease and stroke, any benefit of long chain omega 3 fatty acid supplementation is likely to be small. They say it is possible, however, that patients with additional risk factors such as diabetes may benefit.

Heart Failure Risk Lower in Women Who Often Eat Baked/Broiled Fish

The risk of developing heart failure was lower for postmenopausal women who frequently ate baked or broiled fish, but higher for those who ate more fried fish, in a study reported May 2011 in Circulation: Heart Failure, an American Heart Association journal.

In a large-scale analysis, women who ate the most baked/broiled fish (five or more servings/week) had a 30 percent lower risk of heart failure compared to women who seldom ate it (less than one serving/month).

Previous research has found that fatty acids (omega-3) in fish -- EPA, DHA and ALA -- may lower risk of cardiovascular disease by decreasing inflammation, resisting oxidative stress and improving blood pressure, cardiac and blood vessel function.

This study showed that they type of fish and cooking method may affect heart failure risk. The researchers found that dark fish (salmon, mackerel and bluefish) were associated with a significantly greater risk reduction than either tuna or white fish (sole, snapper and cod).

In a similar analysis, eating fried fish was associated with increased heart failure risk. Even one serving a week was associated with a 48 percent higher heart failure risk.

"Not all fish are equal, and how you prepare it really matters," said Donald Lloyd-Jones, M.D., Sc.M., senior author of the study. "When you fry fish, you not only lose a lot of the benefits, you likely add some things related to the cooking process that are harmful."

Other research has shown that frying increases the trans fatty acid (TFA) content of foods, which is associated with increasing risk for heart disease. In this study, however, the researchers did not find an association between TFA and heart failure risk.

Lloyd-Jones and his team examined self-reported dietary data from 84,493 postmenopausal women in the Women's Health Initiative Observational Study. They then divided study participants based on the frequency and type of fish consumption. Two groups of fish intake were defined: baked/broiled fish or fried fish. The baked/broiled fish group consisted of canned tuna, tuna salad, tuna casserole, white fish (broiled or baked), dark fish (broiled or baked) and shellfish (not fried). The fried fish group consisted of fried fish, fish sandwich and fried shellfish.

They conducted their analysis based on data from 1991 through August 2008. During an average follow-up of 10 years, 1,858 cases of heart failure occurred.

Most participants (85 percent) were Caucasian, 7 percent African-American and 3 percent Hispanic. Their average age was 63 at baseline.

Participants whose diets included more baked/broiled fish tended to be healthier and younger than their counterparts who ate fried fish. They were more physically active and fit, more educated and less likely to smoke, have diabetes, high blood pressure and heart disease (irregular heartbeat and coronary artery disease). Furthermore, their diets contained more fruits and vegetables, less unhealthy, saturated and trans fatty acids and more beneficial fatty acids, which are found in fish and in non-marine foods such as nuts, seeds and certain vegetable oils. Consumption of fried fish was associated with higher body mass index (a weight-to-height ratio), higher energy intakes (calories) and lower fiber consumption. Consumption of other fried foods besides fish was adjusted in the analysis.

While previous studies have linked omega-3 fatty acids to a decrease in some types of heart disease, their precise relationship to heart failure risk was unclear. Researchers sought to clarify the connection between fish and heart failure risk in postmenopausal women.

"Baking or broiling fish and eating it frequently seem to be part of a dietary pattern that is very beneficial for a number of things," said Lloyd-Jones, associate professor, preventive cardiologist and chair of the Department of Preventive Medicine at Northwestern University Feinberg School of Medicine in Chicago. "In this case, we demonstrated that it's associated with heart failure prevention. This suggests that fish is a very good source of lean protein that we ought to be increasing as a proportion of our diet and decreasing foods that contain less healthy saturated and trans fats."

The results of this study are consistent with previous findings in studies of older American and Swedish populations, he said, "but the new study adds the interesting results on darker fish. They also suggest that baked/broiled fish is associated with reduced risk of heart failure through mechanisms other than reducing risk for a heart attack, a precursor to heart failure in some people."

In the United States, heart failure affects about 5.7 million people. Although the heart continues to function in this disease, it's unable to pump blood efficiently enough to meet the body's needs. Heart failure has many different causes, including smoking, high blood pressure, diabetes, overweight, lack of physical activity and poor diet. It's often treatable with lifestyle changes, medicine or surgery.

Moderate Fish Consumption May Lower Heart Disease Risk

Including fish in a balanced diet has long been associated with the prevention of heart disease, and scientists now believe that it can help preserve heart function in patients who have experienced heart failure. A new study in the Journal of Food Science (December, 2009) reports that moderate fish consumption can help reduce the risk of left ventricular systolic dysfunction (LVSD) in post acute coronary syndrome (ACS) patients.

Researchers from the University of Athens in Greece focused on demographical, nutritional, lifestyle, and medical factors combined with the risk of developing left ventricular dysfunction after nonfatal heart failure. The study included nearly one thousand patients who were hospitalized after ACS.

At the study’s conclusion, researchers noted that consuming fish one to two times per week was independently associated with a considerable reduction of the odds of developing LVSD. However, a higher consumption of fish did not result in further protection from the occurrence of LVSD.

Fish Oil May Protect Against Stroke

Research led by Hernan A. Bazan, MD, Assistant Professor of Surgery, Section of Vascular Surgery, at LSU Health Sciences Center New Orleans School of Medicine, has found that unstable carotid artery plaques - those in danger of rupturing and leading to a stroke - contain more inflammation and significantly less omega-3 fatty acids than asymptomatic plaques. This suggests that increasing the levels of omega-3 fatty acids in carotid artery plaques could either prevent strokes or improve the safety of treatment. This may be accomplished by increasing dietary intake of foods rich in omega-3 fatty acids. The study is in the journal, Vascular Pharmacology.

Our bodies produce only a small amount of omega-3 fatty acids, so most of what we need has to come from eating omega-3 fatty acid-rich foods like fish (salmon, tuna, trout, herring, etc.) or from supplements. Omega-3 fatty acids have been shown to protect against cardiovascular disease, particularly heart attack and sudden cardiac death. Dr. Bazan's team wanted to determine what the association might be with plaques in the carotid arteries, a common cause of strokes. Vulnerable plaques which can rupture in the carotid arteries may lead to transient ischemic attacks (TIAs), strokes, or vision loss by affecting the artery to the retina. The mechanisms leading to plaque rupture are still not fully understood but inflammation within the plaque is beginning to be recognized as an important cause of plaque rupture.

Dr. Bazan, an LSUHSC vascular/endovascular surgeon, in collaboration with researchers at Yale University and others at LSUHSC, analyzed plaques from 41 patients who underwent carotid endarterectomy (CEA) to remove plaque buildup in their arteries. Twenty-four patients were asymptomatic and 17 were symptomatic, having had neurological symptoms. All of the fats in the plaques were assessed with mass spectrometry, in collaboration with Dr. Song Hong at LSUHSC. The team was measuring the amounts of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) - the components of long-chain omega-3 polyunsaturated fatty acids. The plaques of asymptomatic patients contained more than twice as much DHA as the symptomatic patients, and about one and a half times as much EPA. Significantly less inflammation was also seen in the carotid atherosclerotic plaques from asymptomatic patients.

"In the future, a study to address whether supplementation with dietary omega-3 polyunsaturated fatty acids prevents carotid-related events in patients with moderate or high-grade carotid stenosis will help answer whether this is a formidable therapeutic target for the prevention of stroke," says Dr. Bazan.

According to the Centers for Disease Control and Prevention, stroke is the third leading cause of death in the United States, as well as a leading cause of serious long-term disability. About 795,000 strokes occur in the US each year and about 610,000 of these are first, or new, strokes. About 185,000 occur in people who have already had a stroke. Nearly 25 percent of strokes occur in people under the age of 65. Of all ischemic strokes occurring, carotid artery atherosclerotic plaques account for over a third of them. It has been noted for several decades that the southeastern United States has the highest stroke mortality in the country. It is not completely clear what factors might contribute to the higher incidence and mortality from stroke in this region.

Fish: Research Shows Novel Benefits of Fatty Acids in Arteries

New research from Columbia University Medical Center continues to shed light on the benefits of making fish a staple of any diet.

Fish are generally rich in omega-3 fatty acids, which have shown benefit in many health areas such as helping to prevent mental illness and delaying some of the disabilities associated with aging. Eating tuna, sardines, salmon and other so-called cold water fish appears to protect people against clogged arteries. Omega-3 fatty acids can also lower triglycerides, a type of fat often found in the bloodstream.

Now, a CUMC research team led by Richard J. Deckelbaum, M.D., Director of the Columbia Institute of Human Nutrition, has found that a diet rich in fish oils can prevent the accumulation of fat in the aorta, the main artery leaving the heart. The beneficial actions of fish oil that block cholesterol buildup in arteries are even found at high fat intakes.

The study was conducted in three separate populations of mice: one that was fed a balanced diet, one that was fed a diet resembling a “Western” diet high in saturated fat, and a third that was fed a high fish fat diet rich in omega-3 fatty acids.

Researchers in Dr. Deckelbaum’s laboratory, including Chuchun Liz Chang, a Ph.D. student in nutritional and metabolic biology, found that the fatty acids contained in fish oil markedly inhibit the entry of “bad,” or LDL, cholesterol into arteries and, as a result, much less cholesterol collects in these vessels.

They found that this is related to the ability of those fatty acids to markedly decrease lipoprotein lipase, a molecule that traps LDL in the arterial wall. This will likely prove to be important as a new mechanism which helps explain benefits of omega-3 fatty acids on heart health.

Dr. Deckelbaum advises those interested in increasing omega-3 intakes do so by either increasing fish intake or by using supplements that contain the “long-chain” fatty acids, EPA and DHA, which are found in cold water fish.

The research was published February 5, 2009 by the American Heart Association’s Arteriolosclerosis, Thrombosis and Vascular Biology, and is supported in part by grants from the National Institutes of Health.

Eating fish may explain very low levels of heart disease in Japan

Consuming large quantities of fish loaded with omega-3 fatty acids may explain low levels of heart disease in Japan, according to a study led by the University of Pittsburgh Graduate School of Public Health slated for the Aug. 5, 2008 issue of the Journal of the American College of Cardiology and available online. The study also found that third- and fourth-generation Japanese Americans had similar or even higher levels of atherosclerosis, or hardening of the arteries – a major risk factor for heart disease, compared to white Americans.

The very low rate of heart disease in Japan among developed countries has been puzzling. Death rates from coronary heart disease in Japan have been less than half of that in the U.S. This holds true even among Japanese men born after World War II who adopted a Western lifestyle since childhood, and despite the fact that among these same men, risk factors for coronary heart disease (serum levels of total cholesterol, blood pressure and rates of type 2 diabetes) are very similar among men in the U.S. Additionally, the rate of cigarette smoking, another major risk factor, has been infamously high in Japan.

"Our study suggests that very high levels of omega-3 fatty acids have strong properties that may help prevent the buildup of cholesterol in the arteries," said Akira Sekikawa, M.D., Ph.D., study lead author and assistant professor of epidemiology at the University of Pittsburgh Graduate School of Public Health. "Increasing fish intake to two times a week for healthy people is currently recommended in the U.S. Our study shows much higher intake of fish observed in the Japanese may have strong anti-atherogenic effect."

Fish consumption among the Japanese is one of the highest in the world. Japanese men consume an average of 100 grams, equivalent to about 3.75 ounces, of fish every day from early in life. Meanwhile, Americans typically eat fish less than two times a week.

"The Japanese eat a very high level of fish compared to other developed countries," said Dr. Sekikawa. "While we don't recommend Americans change their diets to eat fish at these quantities because of concerns about mercury levels in some fish, increasing intake of omega-3 fatty acids in the U.S. could have a very substantial impact on heart disease. Given the similar levels of atherosclerosis in Japanese Americans and white Americans, it also tells us that lower levels of heart disease among Japanese men are much more likely lifestyle related than a result of genetic differences," said Dr. Sekikawa.

Omega-3 fatty acids are a type of polyunsaturated fat found primarily in fish. The two most potent omega-3 fatty acids are known as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and are usually found in oily fishes, such as mackerel, salmon and tuna.

Taking Fish Oil Supplements

Do fish oil supplements just seem too … well … fishy?

The Mayo Clinic Health Letter explains some health benefits of this diet supplement and ways to overcome the occasional fishy aftertaste.

Fish oil supplements are especially good for those who want the heart health benefits of omega-3 fatty acids but don’t like to eat fish. Fish oil supplements often are prescribed for heart attack survivors; the supplements can help prevent future heart problems. They also are prescribed for people with high triglycerides, a type of fat in the blood.

Tips to avoid fishy aftertaste or burps include:

-- Swallow the capsule frozen. This slows the breakdown of fish oil in the stomach, often reducing fishy burps. The fish oil is still digested effectively.

-- Take the capsule at the beginning of a meal. Food traps the fish oil in the stomach, and mixing buffers the odor.

Try an “odorless” supplement. This type of coated capsule passes through the stomach and dissolves in the intestines.

Switch brands. A different brand may taste less fishy. For fish oil purists, some manufacturers make a pure omega-3 fatty acids product that doesn’t taste fishy, although it is likely to cost more than standard products.

Fried Fish Fuels Strokes

Eating a Southern staple, fried fish, could be one reason people in Alabama and across the "stroke belt" states are more likely than other Americans to die of a stroke, according to a study published in the December 22, 2010, online issue of Neurology, the medical journal of the American Academy of Neurology (AAN).

In the stroke belt states – Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Tennessee – the risk of dying from stroke is higher than in other parts of the country. In Alabama, the stroke death rate is 125 per every 100,000 people, against a national average of just 98 per 100,000.

The study was part of the long-running REGARDS (Reasons for Geographic And Racial Differences in Stroke) trial, led by George Howard, Dr. PH, at the University of Alabama at Birmingham. REGARDS enrolled 21,675 people over the age of 45 between January 2003 and October 2007, and continues to follow them for health events.

Studies have shown that the omega-3 fatty acids in fish, especially fatty fish, may reduce the risk of stroke, but other research has shown that frying fish leads to the loss of the natural fatty acids, the AAN said in a press release.

The American Heart Association recommends that people eat fish at least twice a week, with an emphasis on fatty fish. In the entire study, fewer than 1 in 4 participants consumed two or more servings of non-fried fish per week; people in the stroke buckle were 17 percent less likely to meet the recommendations than those in the rest of the country, the AAN said.

Moreover, the study showed that people in the stroke belt were 30 percent more likely to eat two or more servings of fried fish than those in the rest of the country.

"These differences in fish consumption may be one of the potential reasons for the racial and geographic differences in stroke incidence and mortality," Fadi Nahab, M.D., of Emory University, author of the current paper, said in an AAN press release.

"Our study showed that stroke belt residents, especially African-Americans, eat more fried fish than Caucasians and people living in the rest of the country," said Howard, professor and chair of the Department of Biostatistics in the School of Public Health at UAB.

The study found that blacks were more than three and a half times more likely to eat fried fish per week than whites, with an overall average of about one serving per week of fried fish for blacks compared to half of a serving for whites.

"One of the next steps in this research will be to determine if people who eat higher amounts of non-fried fish have less risk of stroke than people who don't eat a lot of fish or eat more fried fish," says Suzanne Judd, Ph.D., assistant professor of biostatistics at UAB and a study co-author.

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Omega-3 fatty acids appear to protect damaged heart after heart attack

Taking omega-3 fatty acids appeared to lower inflammation and guard against further declines in heart function among recent heart attack survivors already receiving optimal standard care, according to results from a randomized, controlled trial to be presented at the American College of Cardiology's 64th Annual Scientific Session in San Diego.

Health News Report

Monday, December 15, 2014

Fish/Fish Oil: Heart Attack and Stroke Benefits/Dangers