Omega -3 Fats – What they Can and Can’t Do For Health
Omega-3 fats: What they can do for health
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.
Anti-inflammatory properties
Chronic inflammation — also called low-grade inflammation — is linked to the development of obesityT, heart disease, and cancers.
Omega-3 fatty acids have been shown to exert anti-inflammatory effects in the human body and may aid in lowering markers of inflammation, such as C-reactive protein and interleukin-6.
In fact, omega-3 fatty acids are regarded as one of the most potent lipids capable of reducing oxidative stress and inflammation. It also potentially guards against the development of chronic diseases.
Lower cholesterol
In a 6-week study, daily supplementation with at least 1.2 g of DHA significantly reduced triglyceride levels and increased “good” cholesterol, or high-density lipoprotein.
In addition, omega-3 fatty acids lowered the “bad” cholesterol, low-density lipoproteins (LDL), when dietary saturated fats were replaced with polyunsaturated and monounsaturated fatty acids found in plants foods such as nuts and avocados.
Elevated triglycerides and LDL cholesterol are linked to an increased risk for metabolic syndrome and heart disease.
However, a recent evidence-based practice summary has shown no impact on a range of cardiovascular disease (CVD) outcomes from the use of omega-3 fatty acid supplements in patients with established CVD or raised risk factors for CVD.
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.
In a phase 2 scientific study, nitric oxide induced dilation (relaxation) of the blood vessels and led to a significant reduction in blood pressure.
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 review analyzing existing studies.
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.
In their 2018 review, Prof. Fereidoon Shahidi, professor of biochemistry at Memorial University, Canada, and Prof. Priyatharini Ambigaipalan, currently at the School of Science and Engineering Technology at Durham College, also in Canada, identified evidence of health benefits from omega-3 in noncardiovascular health conditions.
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.
More specifically, daily supplementation with EPA and DHA helped patients with head and neck cancers and breast cancer to maintain body weight and reduce cancer-related muscle loss.
Improves depression
A 2019 review study of over 2,000 participants showed a beneficial impact of EPA omega-3 fatty acids on depression, with DHA showing little benefits.
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 fats: What they cannot do for health
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 neither prevented death from all causes nor heart disease.
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 weak — typical doses of omega-3 fats from foods and supplements have a mild effect.
Prevent or treat diabetes
Evidence suggests that increasing omega-3 intake does not prevent or treat diabetes.
It does not affect fasting blood sugar, insulin resistance, or glycosylated hemoglobin in those with type 2 diabetes and metabolic syndrome.
Prevent cancer
Omega-3 fatty acids have been reported to reduce the complications of some cancer patients, and early findings look promising. However, there is no evidence of any action of omega-3s preventing the development of cancers.
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, increased the risk of developing lung cancer.
Therefore, too low or too high omega-3 intake may be harmful.
The bottom line
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.