Fish oils are gaining popularity as a dietary supplement. But is there a link between high consumption of fish and a lower risk of heart disease, and if so, who may benefit?
Certain “fatty” fish have been found to be rich in omega-3 fatty acids. It is these substances that are thought to confer a benefit to the heart. Normally, we think of fat being bad, in and of itself. But, in studying cultures that eat large amounts of fish in their diets, such as the Inuit people living in northern climates, we see that they have a lower relative risk of heart disease.
This has led researchers to examine the properties of these substances and their possible benefits for the general population. The main omega-3 fatty acids are eicosapentanoic acid (EPA) and docosahexanoic acid (DHA). These fatty acids are found naturally in high amounts in fish such as salmon, mackerel, herring and sardines. They can also be found in smaller amounts in tuna, trout and shellfish. Omega-3 fats are also contained in flaxseed, soybean, canola and walnut oil. These vegetable oils are also referred to as polyunsaturated fats.
The terms “saturated,” “unsaturated,” “polyunsaturated,” “trans-fat” and “omega-3” can all be very confusing to the average health-conscious citizen who is just trying to make prudent dietary choices. Often the food manufacturers will include these terms in their packaging merely to entice individuals to buy their products.
These terms actually refer to the chemical structure of the fats. If fats have chemical bonds that are very stable, they are not as easily broken down by our bodies. Such is the case in saturated fats and “trans” fats. The saturated fats are found mostly in animal foods such as beef, pork, poultry and dairy. These fats are thought to aid in the development of hardening of the arteries.
On the other hand, unsaturated fats, polyunsaturated fats, and omega-3 fats have weaker chemical bonds and are more easily metabolized in the body. Therefore, it is thought that they don’t easily collect in the vascular system to promote heart or blood vessel disease. Polyunsaturated fats are more liquid (like vegetable oil) than their counterpart, the saturated fats (like butter or lard).
Most studies that have examined the consumption of omega-3 fats have focused mainly on individuals who already have heart disease. That is, in people who have had a heart attack, increasing the amount of omega-3 fatty acids in the diet seems to lower their risk of another heart event. Generalizing these findings for all individuals cannot be done with 100 percent certainty.
If you decide to increase your intake of omega-3s, the easiest way is to eat more fish. Eating a variety of fish at least twice a week will naturally increase your EPA and DHA intake. One exception to keep in mind is tuna. Eating more than two servings (12 ounces) a week has been associated with elevated mercury content.
Fish oil supplements are also available over the counter and by prescription. When choosing a supplement, look for the DHA/EPA content; more is better. The maximum intake per day should be 4,000 mg or 4 grams per day. Look for a product that is “standardized” so you know you’re getting exact amounts. Finally, always check with your physician before starting any supplement.
The content in this column is for informational purposes only. Consult your physician for appropriate individual treatment. Dr. Reynolds practices Family Medicine in Chesterfield.