Nutrition & Diet
The Benefits of Eating Fish
AUTHOR: Gary Italia, DC, DABCN, PhD
Does eating fish help my cholesterol levels?
The omega-3 fatty acids found in marine sources can inhibit cholesterol by improving its breakdown and preventing it from being made. Studies have shown that if people have high cholesterol levels and eat fish (or fish oils) their cholesterol levels can be decreased.
The omega-3 polyunsaturated fatty acids inhibit VLDL and triglyceride synthesis, decrease apoprotein B synthesis, improve the catabolic rate of VLDL, and suppress LDL synthesis. Marine sources only (not vegetable sources) of omega-3 fatty acids lower triglyceride levels. Animal studies have shown that when animals are fed high cholesterol diets with cod liver oil, there is less coronary atherosclerosis and lower thromboxane levels in these animals. Most studies demonstrate that when people substitute their saturated fat intake with fish oil intakes, LDL cholesterol decreases. However, if the level of saturated fats remains and fish oils are added, LDL cholesterol levels do not change and may even increase. HDL cholesterol has been shown to increase 5% to 10% with taking fish oils.
What this means is that if you are going to buy and take fish oil supplements or eat the fatty fish, you must reduce the amount of saturated fats if any benefit is to be expected. Simply stated, reduce your amount of meat intake and substitute it with fish.
Can eating fish help me live longer?
If consuming the right types of fish, you may very well live longer than if you did not eat fish. People who ate 200–400 grams of oily fish per day were found to have an overall decrease in mortality. In a review of five studies, it was demonstrated that people who consumed fish but not meat, had a 34% lower mortality rate.
The United States Physicians Health Study evaluated the effect of dietary fish on sudden cardiac death in 20,551 United States male physicians who were free of cardiovascular disease at baseline and then followed for up to 11 years. Eating fish greater than one meal per week was associated with a 52% reduction in sudden death from cardiovascular disease. Eating fish at least once per week was associated with a 30% decrease in total mortality. However, eating fish more often than once a week did not appear to offer any further health benefit.
A large trial called the Diet and Reinfarction Trial (DART) demonstrated that men who ate fish after a myocardial infarction had a 29% decline in all-cause mortality compared to a placebo group after two years. This means that after the heart attack those who ate fish were less likely to die from any cause. However, fish intake above 1–2 servings per week does not appear to cause any further benefit, and in fact, epidemiological studies support this concept. The fish consumed was mackerel, herring, kipper, pilchard, sardine, salmon, and trout.
In addition, the chance of dying from sudden death is less likely in those people who eat fish. The number of heart attacks appears to be the same between those who do and do not have high intakes of omega-3 fatty acids. However, if a heart attack does occur, it is less fatal among those with high levels of omega-3 fatty acids. In addition, The Lyon Trial compared a Mediterranean-type diet (high in alpha-linolenic acid) with the AHA Step I diet in patients who had myocardial infarctions. There were eight sudden deaths in the control group and none in the alpha-linolenic group.
A population-based, case-control study of 334 patients with primary cardiac arrest and 493 population-based controls from Washington was performed. The study demonstrated that an intake of 5.5 grams of n-3 polyunsaturated fatty acids per month (equivalent to one fatty meal of fish per week) was associated with a 50% reduction in the risk of myocardial infarction. The U.S. Physician’s Health Study previously mentioned found that eating fish resulted in a 52% decrease in sudden death in a group of more than 20,000 men.
Can fish help reduce my risk of having a stroke?
Probably, yes. As a result of its ability to help lower cholesterol levels and blood pressure, as well as its ability to decrease platelet clumping and inflammation activity, the risk of stroke should be decreased by eating fish. In fact, in a recent study in The Journal of the American Medical Association, of more than 43,671 men between the ages of 40 and 75 years demonstrated that men who ate fish 1 to 3 times per month, compared to those who ate it less than once a month, had a lower risk of ischemic stroke. Unfortunately, higher intakes of fish did not appear to reduce the risk any further.
Are all fish created equal? Which fish should I eat?
The omega-3 fatty acids are found in many fish, but greater amounts are found in oily fish. These would include tuna, herring, mackerel, salmon, kipper, pilchard, sardine, and trout. Keep in mind that many fish contain omega-3 fatty acids, but some have significantly more amounts than others. A leaner type of fish, such as cod, would be beneficial, but not as beneficial as a more fatty, oily fish like salmon. Therefore, the greater fat content of the fish, the greater likelihood of cardiovascular and overall health benefit. In fact, fatty fish consumption compared to nonfatty fish consumption has been associated with lower heart disease mortality. It appears that the oily fish provide the most heart protection and overall health benefits. I would begin the anti-aging program by consuming the types of fish mentioned above most frequently and then adding additional fish (such as cod, sole, etc.) for variety.
Are there any risks involved in eating fish?
There may be some risk in eating fish in certain people in high-risk groups. These include pregnant women, nursing mothers, and children. Some large fish can have high levels of methyl mercury. Mercury is a toxic element often found in contaminated fish and is toxic to the body in high amounts. Fish become contaminated from eating food in areas that have been exposed to pollution. The larger the fish, the higher the mercury content. Therefore, larger fish such as shark, swordfish, and mackerel need to be eaten on a restricted basis by those in a high-risk group. If you are in one of the high-risk groups, you need to limit your large fish intake to 6–12 oz per week. An alternative to these fish could be smaller fish or farm-raised fish.
How much fish should I eat?
Many Americans are eating too little of the beneficial fatty acids mentioned above. It is estimated that to reach the recommended eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intake of 0.65 grams per day, an increase in fish intake four times that of the current intake would need to occur. Therefore, one of the strategies in the anti-aging plan is to increase consumption of oily fish.
Studies suggest that a significant health benefit from fish occurs at an intake of 1–2 fish meals per week, with no additional benefit from greater intakes. The oily fish mentioned in this course should be eaten at a greater frequency than ones containing less oil. You can also purchase fish oils in liquid or capsule form if you do not want to eat the fish.