Fish oil - Health Benefits

Fish oil - Health Benefits

Fish is a good source of protein without the high saturated fat in fatty meat products.

The benefits and risks of eating fish oil still need to be defined by further research. Until there's compelling evidence that fish oil supplements (capsules) benefit overall cardiovascular health, the American Heart Association does not recommend their general use. Using fish oil capsules to lower high blood cholesterol levels is not recommended. Fish oil capsules are only recommended for a few patients with severely high triglycerides , who haven't responded well to treatment and are at increased risk of pancreatitis (inflammation of the pancreas). Background Public attention has recently focused on the value of fish and fish oils in the diet. Some studies have shown that people who regularly eat fish have lower rates of heart disease.

Current studies show that some benefits come from the fat content of fish. Fish are rich in omega-3 fatty acids. hese are a form of polyunsaturated fat that's chemically different from the omega-6 fatty acids found in most vegetable oils.

What are the effects of omega-3 fatty acids?

On blood fats (lipoproteins) Omega-3 fatty acids lower blood levels of triglyceride and very low-density lipoproteins (VLDL). wo blood fats are more closely linked with atherosclerotic heart disease:

1.  low-density lipoprotein cholesterol (LDL "bad" cholesterol) 2.  high-density lipoprotein cholesterol (HDL "good" cholesterol)

In studies where people who ate more fish oil also ate less saturated fat, their LDL levels went down. But in studies where saturated fat intake remained constant while fish oil increased, LDL levels either didn't change or increased.

On glucose tolerance (in people with and without diabetes) aking fish oil capsules doesn't seem to impair glucose tolerance in nondiabetic coronary bypass patients. he effect of fish oil on diabetics is harder to determine. Early studies showed a deterioration in glucose tolerance in people taking fish oil. Later studies have suggested that fish oil may have some benefits for people with diabetes. More research is needed before anything definitive can be said.

On blood pressure Fish oil doesn't affect the blood pressure of people whose blood pressure is normal. It does appear to lower blood pressure in people who have high blood pressure and hypercholesterolemia . But the reduction isn't much, and the effect may not last.

On blood clots and bleeding

Fish oils interfere with the ability of blood to clot and to form protective barriers to hemorrhage (bleeding). While this effect can be useful in some cases, it may also be harmful. It's a potential risk when large amounts of fish oil are consumed.

On sudden cardiac death

Recent studies suggest that fish oil may help reduce risk for sudden cardiac death. More research on this topic is needed.

What are potential side effects of fish oil capsules? Fishy odor, upset stomach or intestines. Increased bleeding, nosebleeds, easy bruising. Can increase cholesterol in people with combined hyperlipidemia . Can increase calorie intake and weight gain. Some preparations have added cholesterol. Some lack vitamin E; concern for oxidation . Vitamin A and D toxicity in some preparations; pesticide in some fish oils (not highly refined). Expensive compared to eating fish in the diet. Nutrition Committee Advisory - Fish and Fish Oil November 1, 1996

Recommendation:

The American Heart Association encourages the consumption of fish as both an excellent source of omega-3 fatty acids and as a good protein source that is low in saturated fat. he basis of a heart- healthy diet, however, remains a diet low in saturated fat and cholesterol along with avoidance of extra calories to prevent obesity.

Fish oil capsules cannot be recommended at this time either to prevent disease of the coronary arteries, which carry blood to the heart tissue, or to prevent the re-closure of coronary arteries after they have been opened by balloon angioplasty. hese capsules can be recommended only for patients who have high levels of triglyceride (fat) in the blood that cannot be lowered by drug treatment and who are at increased risk for pancreatitis. However, people should not start taking fish oil capsules without checking with their doctor.

The AHA recommends continued research to answer the many questions surrounding omega-3 fatty acids.

Background:

Few can deny the benefits of substituting fish for dietary sources of protein that are loaded with saturated fat. But, in addition, fish and other marine life are rich sources of a special class of polyunsaturated fatty acids known as the omega-3 fatty acids. Early attention to omega-3 fatty acids focused on the lower heart attack death rates of Greenland Eskimos as compared to the Danish people. he Eskimos' diet, which included seal, walrus and mackerel, was rich in these fatty acids.

Clinical studies showed that fish oils could affect blood levels of cholesterol and triglycerides as well as prolong the time required for blood to clot. Prolonged bleeding time might explain the Eskimos' higher risk of hemorrhagic stroke compared to the Danes.

At first, scientists paid the most attention to the effects of fish oil on blood cholesterol levels, but research results were inconsistent. Saturated fat is a key dietary factor affecting the blood levels of total cholesterol and the harmful low-density lipoprotein (LDL)-cholesterol. Cholesterol carried by LDL helps create the plaque that obstructs blood flow in the arteries. When saturated fat intake is held constant, LDL-cholesterol levels do not decrease in response to fish oil consumption. In fact, in certain people with milder elevations of triglycerides and associated high cholesterol, the LDL cholesterol levels may actually increase. However, fish oil was found to be particularly useful in lowering greatly elevated levels of triglyceride.

Several lines of evidence suggest that fish in the diet is "heart healthy." Although several large-scale epidemiologic studies suggested that people with a higher fish intake had lower rates of coronary heart disease, studies of populations with relatively high fish intake did not confirm these results.

A British clinical trial of heart attack survivors did show that men who ate more fish experienced a 29 percent reduction in deaths from all causes despite no significant lowering of cholesterol. hese results showing beneficial effects with no cholesterol lowering may be due to omega-3 fatty acids' action on blood platelets; white blood cells, which are key to inflammation; and endothelial cells, which line the artery wall. Omega-3s make the platelets less likely to clump together to form a blood clot.

Early trials employing X-rays of the coronary arteries suggested that fish oil prevented artery closure (restenosis) after an angioplasty procedure. Yet in spite of this promising beginning, newer studies have failed to confirm these impressions.

A recent Seattle study suggests that people who experienced sudden cardiac death had a lower intake of fish than comparable people. he authors speculate that fish intake may protect against a fatal arrhythmia, or irregular heartbeat. Also research suggests that omega-3 fatty acids have potentially beneficial effects in some diabetics, as well as those with inflammatory and allergic disease.

Omega-3 fatty acids are so named because the first of the several double bonds between carbon atoms occurs three carbon atoms away from the end of the carbon chain. hese fatty acids are also called "n-3 (n minus 3)" fatty acids where n stands for the number of carbon atoms in the chain.

The three omega-3 fatty acids are alpha linolenic acid (LNA), eicosapentenoic acid (EPA) and docosahexenoic acid (DHA). LNA is found in tofu, soybean and canola oils and nuts. EPA and DHA are found in seafood, especially cold-water seafood.

Omega-3 fatty acids affect the body differently from the polyunsaturated omega-6 fatty acids, which occur primarily in land plants and are the most common polyunsaturated fatty acids in the typical American diet.

American Heart Association Issues New Advice on Dietary Approaches to Prevent and reat Hypertension  February 2006 Weight loss. Approximately 65% of US adults are overweight or obese
(body mass index [BMI] ? 25 kg/m2) and  30% are clinically obese (BMI ? 30 kg/m2). Clinical trials show that weight loss lowers blood pressure even before desired body weight (BMI < 25 kg/m2) is reached. Greater weight loss leads to greater blood pressure reduction. Maintaining a high level of physical activity is a critical factor in sustaining weight loss. Reduced salt intake. Salt intake should be lowered as much as possible, ideally to about 65 mmol/day sodium (corresponding to 1.5 g/day sodium or 3.8 g/day of sodium chloride). Clinical studies have shown that reducing salt intake lowers blood pressure in people with and without hypertension. Reduced salt intake can blunt the rise in blood pressure that occurs with age and reduce the risk of atherosclerotic cardiovascular disease (CVD) events and congestive heart failure (CHF). he greatest effects of sodium reduction on blood pressure are in blacks, middle-aged and older people, and those already diagnosed with hypertension, diabetes, or chronic kidney disease. Because  75% of consumed salt comes from processed foods, the writing group calls on food manufacturers to reduce salts in food by 50% over the coming 10 years. Increased potassium intake. Often forgotten, potassium intake should be increased to 120 mmol/day (4.7 g/day). his can be achieved by consuming foods such as fruits and vegetables that have a high potassium content. High potassium intake is associated with reduced blood pressure levels in people with or without high blood pressure, more in blacks than in whites. It should be noted, however, that the recommended potassium intake may be too high for people with impaired urinary potassium excretion such as those with diabetes, chronic renal insufficiency, end-stage renal disease, and heart failure, as well as people taking some antihypertensive drugs. Moderation of alcohol intake. For those who consume alcohol, consumption should be limited to  2 alcoholic drinks/day (men) or  1 alcoholic drink/day (women). One drink is defined as 12 oz of regular beer, 5 oz of wine (12% alcohol), or 1.5 oz of 80-proof distilled spirits. Clinical trials have shown a dose-dependent relationship between alcohol and blood pressure, especially in people consuming  2 drinks/day. Although reduced alcohol consumption is associated with reduced blood pressure, evidence also suggests that a moderate alcohol intake is also effective in lowering blood pressure. DASH (Dietary Approaches to Stop Hypertension) dietary pattern. he DASH diet is rich in fruits and vegetables (8-10 servings/day), rich in low-fat dairy products (2-3 servings/day), and reduced in saturated fat and alcohol, and has been shown to help reduce blood pressure. he diet emphasizes fruits, vegetables, and low-fat dairy products; includes whole grains, poultry, fish and nuts; and is reduced in fats, red meat, sweets, and sugar-containing beverages. Other studies have shown that substituting some carbohydrates with protein, mostly from plant sources, or with monounsaturated fat, further lowers blood pressure. DASH-type diets that are relatively high in potassium, phosphorus, and protein are not recommended for people with chronic kidney disease.