Fish oil - Health Benefits

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

Further research is needed to better understand the benefits and risks of consuming fish oil. Currently, the American Heart Association does not recommend the general use of fish oil supplements (capsules) for overall cardiovascular health until compelling evidence is available. Their use for lowering high blood cholesterol levels is also not recommended.

Fish oil capsules are only recommended for a specific group of patients with severely high triglyceride levels, who have not responded well to other treatments and are at an increased risk of pancreatitis (inflammation of the pancreas).

Recently, there has been public interest in the role of fish and fish oils in the diet. Some studies have suggested that individuals who regularly consume fish have lower rates of heart disease. However, more research is needed to fully understand the relationship between fish consumption and heart health.

Recent research indicates that the fat content of fish contributes to its health benefits. Fish is known to be a valuable source of omega-3 fatty acids, which are a type of polyunsaturated fat. It's important to note that omega-3 fatty acids differ chemically from the omega-6 fatty acids predominantly found in vegetable oils.

What are the effects of omega-3 fatty acids?

Omega-3 fatty acids have been found to have specific effects on blood fats, glucose tolerance, and blood pressure. Here are the key findings:

Blood fats: Omega-3 fatty acids, found in fish oil, can decrease levels of triglycerides and very low-density lipoproteins (VLDL) in the blood. However, the two blood fats most strongly associated with atherosclerotic heart disease are low-density lipoprotein cholesterol (LDL, "bad" cholesterol) and high-density lipoprotein cholesterol (HDL, "good" cholesterol). Studies have shown that when people consume more fish oil and reduce their saturated fat intake, LDL levels tend to decrease. However, if saturated fat intake remains constant while fish oil supplementation increases, LDL levels may not change or even increase.

Glucose tolerance: Fish oil capsules do not appear to impair glucose tolerance in non-diabetic individuals who have undergone coronary bypass surgery. The effects of fish oil on individuals with diabetes are less clear. Early studies suggested a potential deterioration in glucose tolerance in people taking fish oil, but later studies have indicated some benefits for individuals with diabetes. Further research is needed to establish definitive conclusions in this regard.

Blood pressure: Fish oil does not significantly impact blood pressure in individuals with normal blood pressure. However, it may have a modest lowering effect on blood pressure in individuals with high blood pressure and hypercholesterolemia (high cholesterol levels). It's important to note that the reduction in blood pressure may not be substantial, and the effects might not be sustained over time.

In summary, omega-3 fatty acids from fish oil can influence blood fats, with a potential reduction in triglycerides and VLDL. The effects on LDL and HDL cholesterol are influenced by the overall dietary pattern, including saturated fat intake. The impact of fish oil on glucose tolerance is still under investigation, particularly in individuals with diabetes. While fish oil may have a minor lowering effect on blood pressure in certain populations, its long-term efficacy in this regard requires further study.

On blood clots and bleeding

Fish oils have anticoagulant properties, meaning they can interfere with blood clotting and the formation of protective barriers against bleeding. While this effect can be beneficial in certain situations, it can also pose risks. Consuming large amounts of fish oil carries the potential risk of excessive bleeding.

On sudden cardiac death

Recent studies suggest that fish oil may have potential benefits in reducing the risk of sudden cardiac death. However, it is important to note that further research is needed to fully understand this topic and confirm these findings.

When it comes to potential side effects of fish oil capsules, some commonly reported issues include a fishy odor, upset stomach, and digestive discomfort. There is also a concern that fish oil can increase the risk of bleeding, leading to nosebleeds and easy bruising. In individuals with combined hyperlipidemia, fish oil may increase cholesterol levels. Additionally, fish oil capsules can contribute to increased calorie intake and weight gain. Some preparations may contain added cholesterol, while others may lack vitamin E, which raises concerns about oxidation. Certain preparations of fish oil have the potential for vitamin A and D toxicity, and some may contain traces of pesticides if they are not highly refined. It is worth noting that fish oil capsules can be more expensive compared to obtaining fish through dietary sources.

It is important to consult with a healthcare professional before starting any new supplement, including fish oil capsules, to discuss potential side effects and determine the most appropriate approach for individual health needs. The information provided regarding side effects is based on an advisory from the Nutrition Committee dated November 1, 1996, and more recent studies and guidelines may provide additional insights.

Recommendation

The American Heart Association promotes the consumption of fish as it is an excellent source of omega-3 fatty acids and a good protein source with low saturated fat content. However, it is crucial to maintain a heart-healthy diet that is low in saturated fat, cholesterol, and excess calories to prevent obesity.

At present, fish oil capsules are not recommended for the prevention of coronary artery disease, which involves the blockage of blood flow to the heart tissue, or for preventing the reocclusion of coronary arteries after balloon angioplasty. These capsules are only recommended for patients with elevated levels of blood triglycerides that cannot be effectively lowered through medication, and who are at a higher risk of pancreatitis. It is important for individuals to consult their doctor before starting fish oil capsules.

The American Heart Association emphasizes the need for further research to address the numerous questions surrounding omega-3 fatty acids.

Background

The benefits of replacing protein sources high in saturated fat with fish are widely acknowledged. Furthermore, fish and other marine organisms are abundant in a unique type of polyunsaturated fatty acids called omega-3 fatty acids. Initial research on omega-3 fatty acids centered around the lower rates of heart attack deaths among Greenland Eskimos compared to the Danish population. The Eskimos' diet, which consisted of seal, walrus, and mackerel, was particularly rich in these fatty acids.

Clinical studies have demonstrated that fish oils have an impact on blood cholesterol and triglyceride levels, as well as the clotting time of blood. The longer bleeding time observed in Eskimos may contribute to their increased risk of hemorrhagic stroke when compared to the Danes.

Initially, researchers primarily focused on studying the impact of fish oil on blood cholesterol levels, but the findings were inconsistent. Dietary saturated fat plays a crucial role in influencing total cholesterol levels and the harmful low-density lipoprotein (LDL)-cholesterol. LDL cholesterol, when present in high amounts, contributes to the formation of arterial plaque that hinders blood flow. Interestingly, when saturated fat intake remains constant, fish oil consumption does not lead to a decrease in LDL-cholesterol levels. In some individuals with mild elevations in triglycerides and high cholesterol, fish oil may even cause an increase in LDL cholesterol levels. However, fish oil has been found to be particularly effective in reducing significantly elevated triglyceride levels.

Numerous pieces of evidence indicate that including fish in one's diet promotes heart health. Although several large-scale epidemiological studies have suggested a correlation between higher fish consumption and lower rates of coronary heart disease, studies conducted on populations with already high fish intake failed to confirm these findings.

However, a clinical trial conducted in Britain on individuals who had experienced heart attacks revealed that men who consumed more fish had a 29 percent reduction in deaths from all causes, despite no significant reduction in cholesterol levels. This suggests that the beneficial effects of fish consumption, independent of cholesterol lowering, could be attributed to the action of omega-3 fatty acids on various components of the cardiovascular system. Omega-3s are believed to influence blood platelets, white blood cells involved in inflammation, and endothelial cells that line the walls of arteries. By reducing platelet aggregation, omega-3s help prevent the formation of blood clots.

Initial trials utilizing X-rays of the coronary arteries indicated that fish oil could prevent the closure of arteries (restenosis) following an angioplasty procedure. However, despite this promising start, more recent studies have failed to validate these findings.

A recent study conducted in Seattle suggests that individuals who experienced sudden cardiac death had a lower intake of fish compared to similar individuals. The authors speculate that fish consumption may offer protection against fatal arrhythmias, or irregular heartbeats. Furthermore, research indicates that omega-3 fatty acids may have potential benefits for certain individuals with diabetes, as well as those with inflammatory and allergic conditions.

Omega-3 fatty acids derive their name from the fact that the first of the multiple double bonds between carbon atoms occurs three carbon atoms away from the end of the carbon chain. They are also referred to as "n-3 (n minus 3)" fatty acids, with "n" representing the number of carbon atoms in the chain.

There are three main types of omega-3 fatty acids: alpha-linolenic acid (LNA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). LNA can be found in sources such as tofu, soybean and canola oils, as well as nuts. EPA and DHA, on the other hand, are primarily found in seafood, particularly cold-water varieties.

It's worth noting that omega-3 fatty acids have distinct effects on the body compared to omega-6 fatty acids, which are another type of polyunsaturated fatty acids. Omega-6 fatty acids are predominantly found in land plants and are commonly consumed in the typical American diet.

The American Heart Association (AHA) released new recommendations in February 2006 regarding dietary approaches to prevent and treat hypertension. These recommendations include the following:

Weight loss: Clinical trials have shown that weight loss leads to a reduction in blood pressure, even before reaching the desired body weight. The greater the weight loss, the greater the blood pressure reduction. Maintaining a high level of physical activity is crucial to sustaining weight loss.

Reduced salt intake: It is advised to lower salt intake as much as possible, ideally to around 65 mmol/day sodium (equivalent to 1.5 g/day sodium or 3.8 g/day of sodium chloride). Studies have demonstrated that reducing salt intake lowers blood pressure in individuals with and without hypertension. Decreasing salt intake can also help prevent age-related rise in blood pressure and reduce the risk of cardiovascular diseases and congestive heart failure. The most significant effects of sodium reduction on blood pressure are observed in blacks, middle-aged and older individuals, and those already diagnosed with hypertension, diabetes, or chronic kidney disease. The AHA calls on food manufacturers to gradually reduce salt in processed foods by 50% over the next decade, as 75% of consumed salt comes from processed foods.

Increased potassium intake: Increasing potassium intake to 120 mmol/day (equivalent to 4.7 g/day) is recommended. This can be achieved by consuming potassium-rich foods such as fruits and vegetables. High potassium intake is associated with reduced blood pressure levels, particularly in blacks. However, individuals with impaired urinary potassium excretion (such as those with diabetes, chronic renal insufficiency, end-stage renal disease, heart failure, or those taking certain antihypertensive drugs) may need to adjust their potassium intake.

Moderation of alcohol intake: For individuals who consume alcohol, it is advised to limit consumption to no more than 2 alcoholic drinks per day for men, and 1 alcoholic drink per day for 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 relationship between alcohol and blood pressure, especially in individuals consuming more than 2 drinks per day. While reduced alcohol consumption is associated with lower blood pressure, moderate alcohol intake has also been found to be effective in lowering blood pressure.

DASH dietary pattern: The DASH diet, known as Dietary Approaches to Stop Hypertension, is recommended. It emphasizes consuming fruits and vegetables (8-10 servings per day), low-fat dairy products (2-3 servings per day), and reducing saturated fat and alcohol intake. The diet includes whole grains, poultry, fish, and nuts while limiting fats, red meat, sweets, and sugary beverages. Other studies have shown that substituting some carbohydrates with protein (preferably from plant sources) or monounsaturated fat can further lower blood pressure. However, DASH-type diets that are relatively high in potassium, phosphorus, and protein are not recommended for individuals with chronic kidney disease.

Fish oil - Health Benefits