Omega-3 fatty acids are essential fatty acids: They are necessary for human health but the body can't make them -- you have to get them through food. Omega-3 and Omega-6’s are important structural components of cell membranes. They affect cell membrane properties such as flexibility, permeability and the activity of membrane bound enzymes. Omega-3’s are required for the normal development and function of the retina and brain and play a crucial role in brain function.
It is estimated that the ratio of Omega-6 to Omega-3 fatty acids in the diet of early humans was 1:1, but the ratio in the typical Western diet is now almost 10:1 due to increased use of vegetable oils and reduced fish consumption.
A large body of scientific research suggests that increasing the relative abundance of dietary Omega-3 fatty acids may have a number of health benefits, including lower risk of heart disease, cancer, asthma and arthritis. The American Heart Association recommends eating fish at least 2 times a week.
The lipid composition of farmed fish is generally more constant and less affected by seasonal variations than that of wild fish because it is largely dependent on the fatty acid composition of their feed, which can be tailored to achieve specific targets, depeding on the species and environment.
Promising news about Omega-3 fatty acids just keeps rolling in. The following provides an overview of research on how Omega-3 fatty acids may affect disease and aging.
A large body of scientific research suggests that higher dietary Omega-3 fatty acid intake is associated with reductions in cardiovascular disease risk. In one large study that followed more than 20,000 men for 11 years, those who ate fish at least once a week had a risk of sudden cardiac death that was 52% lower than those who ate fish less than once a month.
Scientists investigated the effect of Omega-3s on telomere length. Telomeres are the strings of DNA at the ends of chromosomes that are thought to keep them from fraying during cell division. Telomeres are thought to be a major determinant of aging. After five years, participants who started the study with higher levels of Omega-3’s in their blood experienced substantially less telomere shortening than those with lower Omega-3 levels. The investigators believe that these findings may explains the potentially protective effects of Omega-3 fatty acids on aging related disease.
Observational studies have found that lower DHA status is associated with increased risk of Alzheimer's disease as well as other types of dementia, but it is not yet known whether DHA supplementation can help prevent or treat such cognitive disorders.
People who follow a Mediterranean-style diet tend to have higher HDL or “good” cholesterol levels, which help promote heart health. Inuit Eskimos, who get high amounts of Omega-3 fatty acids from eating fatty fish, also tend to have increased HDL cholesterol and decreased triglycerides (fats in the blood). Several studies have shown that fish oil supplements reduce triglyceride levels.
Several clinical studies suggest that diets rich in Omega-3 fatty acids lower blood pressure in people with hypertension. An analysis of 17 clinical studies using fish oil supplements found that taking 3 or more grams of fish oil daily may reduce blood pressure in people with untreated hypertension.
Increasing EPA and DHA intake may be beneficial in individuals with type 2 diabetes, especially those with elevated serum triglycerides. Omega-3 fatty acids can help lower triglycerides and apoproteins (markers of diabetes), and raise HDL, so eating foods or taking fish oil supplements may help people with diabetes.
Three meta-analyses of randomized controlled trials in rheumatoid arthritis patients found that fish oil supplementation significantly decreased the number of painful and/or tender joints on physical examination.
Some studies suggest that consumption of Omega-3 fatty acids may help increase levels of calcium in the body and improve bone strength, although not all results were positive. Some studies also suggest that people who don' t get enough of some essential fatty acids (particularly EPA and gamma-linolenic acid [GLA], an Omega-6 fatty acid) are more likely to have bone loss than those with normal levels of these fatty acids. In a study of women over 65 with osteoporosis, those who took EPA and GLA supplements had less bone loss over 3 years than those who took placebo and some of the women experienced an increase in bone density.
Joseph Hibbeln, a psychiatrist from the National Institutes of Health, has found a correlation between the amount of fish a country eats and the rate of depression. Studies have found mixed results as to whether taking Omega-3 fatty acids can help alleviate the symptoms on depression. Several studies have found that people who took Omega-3 fatty acids in addition to prescription antidepressants had a greater improvement than those who took antidepressants alone. Other studies were mixed on whether Omega-3 fatty acids alone have an effect on depression. Depression is a serious illness and you should not try to treat it on your own. See a doctor for help.
In a clinical study of 30 people with bipolar disorder, those who took fish oil in addition to standard prescription treatments for bipolar disorder for 4 months experienced fewer mood swings and relapse than those who received placebo. But another 4-month long clinical study treating people with bipolar depression and rapid cycling bipolar disorder did not find that EPA helped reduce symptoms.
Children with attention deficit/hyperactivity disorder (ADHD) may have low levels of certain essential fatty acids (including EPA and DHA). In a clinical study of nearly 100 boys, those with lower levels of Omega-3 fatty acids had more learning and behavioral problems (such as temper tantrums and sleep disturbances) than boys with normal Omega-3 fatty acid levels. Studies examining whether Omega-3 fatty acids help improve symptoms of ADHD have found mixed results. A few studies have found that Omega-3 fatty acids helped improve behavioral symptoms. More research is needed, but eating foods that are high in Omega-3 fatty acids is a reasonable approach for someone with ADHD.
Studies examining Omega-3 fatty acids for asthma are mixed. In one small, well-designed clinical study of 29 children with asthma, those who took fish oil supplements rich in EPA and DHA for 10 months reduced their symptoms compared to children who took placebo. However, other studies have shown no effect.
A questionnaire given to more than 3,000 people over the age of 49 found that those who ate more fish were less likely to have macular degeneration (a serious age-related eye condition that can progress to blindness) than those who ate less fish. Similarly, a clinical study comparing 350 people with macular degeneration to 500 without the eye disease found that those with a healthy dietary balance of Omega-3 and Omega-6 fatty acids and more fish in their diets were less likely to have macular degeneration.
In one study of 42 women, they had less menstrual pain when they took fish oil supplements than when they took placebo.
Eating foods rich in Omega-3 fatty acids seems to reduce the risk of colorectal cancer. For example, Eskimos, who tend to have a high-fat diet but eat significant amounts of fish rich in Omega-3 fatty acids, have a low rate of colorectal cancer. Animal studies and laboratory studies have found that Omega-3 fatty acids prevent worsening of colon cancer. Preliminary studies suggest that taking fish oil daily may help slow the progression of colon cancer in people with early stages of the disease. If you have colorectal cancer, ask your doctor before taking any supplements.
Although not all experts agree, women who eat foods rich in Omega-3 fatty acids over many years may be less likely to develop breast cancer. More research is needed to understand the effect that Omega-3 fatty acids may have on the prevention of breast cancer.
Population based studies of groups of men suggest that a low-fat diet including Omega-3 fatty acids from fish or fish oil help prevent the development of prostate cancer.
*The information provided here, is at best, of a general nature and cannot substitute for the advice of a medical professional. Please consult your physician if you feel you have any of the above conditions.