They are one of the key building blocks for cell membranes and remain a subject of interest in the scientific community.
The family of omega-3 fatty acids includes:
- alpha-linolenic acid (ALA)
- stearidonic acid (SDA)
- eicosapentaenoic acid (EPA)
- docosapentaenoic acid (DPA)
- docosahexaenoic acid (DHA)
DHA and EPA are the primary polyunsaturated fats in brain cell membranes and have been popularized and successfully
Omega-3 fatty acids are essential, meaning the human body is incapable of creating them on its own — the fatty acids or their precursors must be obtained from the diet.
For instance, ALA from plant seeds can be converted in the body to all the other types of omega-3 fats: EPA, SDA, DHA, DPA.
However, this conversion is quite
DHA, EPA, and DPA omega-3 fatty acids are synthesized by marine organisms such as algae and phytoplankton.
When consumed by fish, aquatic mammals, and crustaceans, the fatty acids enter the food chain and are stored in body fat, liver, and blubber. They are then later consumed by humans.
Food sources of DHA, EPA, and DPA include:
fatty fish, such as salmon, sardines, mackerel, menhaden, or herring
- the liver of lean, white fish, such as halibut or cod
- blubber from seals or whales
fish oilsfrom cod flesh, tuna, haddock, flounder, or krill oil
ALA, on the other hand, is concentrated in plant sources and is the most frequent omega-3 fatty acid used by the body to create all other types of omega-3 fatty acids.
Sources of ALA include nuts and seeds, such as flaxseed, chia seeds, and walnuts as well as oils, such as echium seed oil, canola, and soybean oils.
According to the
Furthermore, a myriad of DHA and EPA omega-3 supplements are available and contribute significantly to daily omega-3 intake. Fish oil is the most
Decades of research on the health impacts of omega-3 fatty acids have provided controversial findings. Here are some evidence-backed benefits of consuming omega-3 fatty acids.
Omega-3 fatty acids have been shown to exert
In fact, omega-3 fatty acids are regarded as one of the most
In a 6-week
In addition, omega-3 fatty acids lowered the “bad” cholesterol, low-density lipoproteins (LDL), when dietary saturated fats were replaced with
However, a recent
Lower blood pressure
On the other hand, omega-3 fatty acids have been shown to improve vascular health — the health of the blood vessels — by increasing the bioavailability of nitric oxide.
May reduce the risk of heart disease
By reducing markers associated with an increased risk of developing heart disease — high triglycerides, cholesterol, and blood pressure — omega-3 fatty acids may reduce the risk of heart disease, according to a
The same review concluded that high-dose daily supplementation with 4 g of purified EPA in people with elevated triglycerides levels led to a 25% reduction in cardiovascular events.
Improve tolerance to cancer treatment
Omega-3 fatty acids may improve the efficacy and tolerance of chemotherapy and is a potential supportive treatment to people undergoing cancer treatment.
This finding is supported by other studies included in Prof. Shahidi’s and Prof. Ambigaipalan’s review, indicating that fish oil supplementation helps protect against major depressive disorder in people between the ages of 15 and 25 years.
Furthermore, moderate intakes of fatty fish and seafood were associated with fewer occurrences of depression.
Omega-3 fatty acids have been successfully marketed as heart-friendly and reported to reduce the risk of adverse heart disease-related outcomes.
However, its role and health benefits for some conditions have been challenged and discredited. This Cochrane report review found no evidence of the benefit of omega-3 supplements on heart disease, stroke, or death.
Here are some conditions that omega-3 fatty acids may not prevent or improve, based on the latest scientific evidence.
Reduce risk of death by heart disease
Prof. Shahidi and Prof. Ambigaipalan also found that the consumption of omega-3 fatty acids does not reduce the risk of adverse heart disease-related outcomes, such as sudden cardiac death, heart attack, or stroke, even in individuals without a history of disease.
Although omega-3 fats lower the risk of developing heart disease by lowering triglyceride, the “bad” cholesterol LDL, and blood pressure, a meta-analysis of over 80,000 individuals found that their supplementation
Prevent blood clots
Anti-clotting effects of omega-3 fatty acids have been proposed by reducing platelet aggregation. However, this finding has been controversial, and the evidence in this regard is
Prevent or treat diabetes
Omega-3 fatty acids have been reported to
In a meta-analysis of over one million people, a particularly high intake of omega-3 fats — 5–15 g per day — did not significantly reduce lung cancer risk, and in some cases,
Therefore, too low or too high omega-3 intake may be harmful.
Omega-3 polyunsaturated fatty acids are essential compounds that are key building blocks for cell membranes, particularly in the brain.
For decades, they have been the subject of scientific interest, but findings have been controversial and inconsistent.
The evidence shows that omega-3 fatty acids have anti-inflammatory properties and may lower cholesterol, blood pressure, depressive episodes, weight loss during cancer treatment, and the risk for heart disease.
However, omega-3 intake does not reduce the risk of adverse and severe heart disease-related outcomes, including sudden death and stroke. Additionally, it cannot prevent or treat diabetes or prevent blood clots.
This is an emerging area of evidence, and further results will continue to inform health recommendations.