Tune Into The Nutrition Science Podcast

The Nutrition Science Blog

Practical, science-based articles to help you better understand how to eat in a way that is going to support your health. 

Omega 3 Fats: Why They're Important, How to Get Them, and More

nutreints nutrition omega-3 podcast Feb 20, 2023



Introduction to Omega-3 Fats

Omega-3 fats are a class of essential polyunsaturated fatty acids (PUFAs) that are an important part of our cell membranes and are involved in the formation of eicosanoids which are signaling molecules that regulate inflammatory responses and have a range of functions throughout the body. (Essential, means that we cannot create these fats within our body, and we have to get them through food or supplementation.)

There are over 11 different types of omega-3 fats, however, most of them are found in very small quantities in our diet and aren’t as well studied as the 3 that we will focus on during this discussion which are ALA, EPA, and DHA.

Of these 3 ALA is the only one that is technically considered essential, since the human body can convert ALA to both EPA and DHA. However, as we will discuss later conversion happens at a very low rate and may not be sufficient for taking advantage of some of the important health effects of these fatty acids.


Sources of Omega-3 Fats  

ALA is found in plant foods such as flaxseeds, chia seeds, soybean, and canola oils. EPA and DHA are found only in marine foods including fish, krill, and to a lesser extent algae. The omega-3 fats from marine sources originate in microalgae and they accumulate in fish that consume phytoplankton which consume the microalgae.

Top sources of ALA include flaxseed oil which provides 7.26 grams per TBSP, chia seeds, which provide about 5 grams per ounce, English walnuts which provide 2.5 grams per 1 ounce, flaxseed which provides 2.35 grams per TBSP, and canola oil which provides 1.28 grams per TBSP.


For EPA and DHA, the top source is salmon which provides about 1.25 grams of EPA per 3-ounce serving and .5 grams of DHA per 1-ounce serving, herring which provides about 1 gram of EPA and .75 grams of DHA per serving, sardines which provide about .75 and .5 grams of EPA and DHA per serving, and mackerel which provides about .6 of EPA and .4 grams of DHA per serving (1).


Omega-3 Needs and Current Intakes

According to the National Academy of Medicine, the recommend daily adequate intake for omega-3 fatty acids is 500 mg from birth to 12 months, 700 mg for children 1-3 years old, 900 mg for children 4-8 years old, 1.2 grams for males and 1 gram for females 9-13 years old, and 1.6 grams for men over 14 and 1.1 grams for women over 14. Nutritional needs go up during pregnancy and lactation to 1.4 grams and 1.3 grams respectively.


All these values refer to ALA, not EPA and DHA which are not considered essential because we are able to convert them from ALA. However, the conversion of ALA to EPA and DHA is quite low and it is estimated that about 5% of ALA is converted to EPA and only .5% of ALA is converted into DHA (2).

This means that 1 gram of ALA would provide approximately 50 mg of EPA and 5 mg of DHA (3), which is well below the amounts recommended by most major organizations.  For example, the USDA recommends consuming 8 ounces of seafood a week which would provide approximately 250 mg of EPA/DHA daily.

In the US, adults on average are consuming enough total omega-3s, however, consumption of EPA and DHA is generally insufficient. According to a study published in the British Medical Journal in 2021, 95% of children and 68% of adults in the US had blood omega-3 concentrations below what would be expected if they were meeting the recommended 250 mg/day (3).

So why is this important? Let’s dive into some of the research on omega-3 consumption, omega-3 status, and health outcomes, and then we will discuss data on omega-3 supplementation for various health conditions as well.


Health Benefits of Omega-3 – Population Research 

First, let’s cover some of the evidence on omega-3 fat consumption on human health from population studies. The largest study to date on this topic is a study published in the Asian Pacific Journal of Clinical Nutrition that was published in 2017 (4). This study included 23 prospective cohort studies with over 1 million participants and found that fish intake was associated with a 6% reduction in death from any cause in the highest vs. lowest intake groups. In addition, higher consumption of EPA and DHA was associated with a 14% reduction in death from any cause, and that for each 200 mg per day of long-chain omega-3 fats was associated with a 7% reduction in death from any cause.

With omega-3 consumption, most of the strongest available research comes from biomarker studies and randomized controlled trials. The omega-3 index is a measure of the % of EPA and DHA in red blood cells and this has been used in many trials to get a more accurate picture of the relationship between omega-3 fats and health outcomes. 

A 2017 study published in the journal Atherosclerosis looked at the relationship between omega-3 status and cardiovascular disease outcomes. This study included ~26,000 participants from 10 cohort studies. In this study, the average omega-3 index value was 6% and those with an omega-3 index of 8% or higher had a 15% lower risk of death from coronary heart disease, while those with a value of lower than 4% had a 15% increased risk of death from coronary heart disease (5).  The authors of this study estimate that it would take about 1.5 g of EPA/DHA daily to bring blood levels from 4% to 8%, which could theoretically reduce the risk of coronary heart disease by up to 30%.


Another study published in 2022 in the Journal of Clinical Nutrition looked at EPA and DHA separately and their relationship with various health outcomes (6). They compiled the results from 67 prospective cohort studies that included 310,000 participants and reported that higher ALA levels were associated with an 11% lower risk of type 2 diabetes, while EPA was associated with a 15% reduced risk.

They also reported that EPA and DHA were associated with lower risks of heart disease and death from any cause with risk reductions ranging from 15-30% and that high DHA was associated with 26% lower risks of colorectal cancer.


Health Benefits of Omega-3 Supplement Trials

Omega-3 Supplementation and Heart Disease

Most of the strongest research in this field comes from supplement studies as omega-3 fats are among the most well-studied supplements on the market. A recent meta-analysis published in 2021 that included 38 randomized controlled trials including ~150,000 participants in total showed that long-chain omega-3 supplementation (EPA/DHA) was associated with a 7% reduced risk of death from heart disease and a 13% lower risk of heart attack (7). However, supplementation was also associated with an increased risk of bleeding atrial fibrillation so those on blood thinning medications or with a history of atrial fibrillation should supplement with caution.


Omega-3 Supplementation and Cancer

It is quite clear that long-chain omega-3 fats have some benefits to cardiovascular health, but what about cancer?

A 2020 study that included 47 randomized trials and 108,000 participants showed that supplementation with omega-3 fats had no impact on the risk for cancers (8). There has been some evidence demonstrating a positive association between omega-3 fats and prostate cancer, however, results from studies are mixed and no conclusive link has been established (9).


Omega-3 and Cognitive Decline

Another important area of research where omega-3 fatty acids are thought to have some benefit is in preventing cognitive decline. A meta-analysis of 21 cohort studies that included ~181,000 participants published in the American Journal of Clinical Nutrition demonstrated that fish intake was associated with a slightly lower risk of Alzheimer’s and Dementia (10). This study also showed that an increase in 100 mg of DHA per day was associated with a 14% reduction in risk for dementia and a 37% lower risk of Alzheimer’s disease.


However, supplement studies have not shown to be very effective. A 2020 study that included 25 randomized controlled trials in participants without dementia demonstrated only a slight benefit in memory, but in no other cognitive outcomes (11). These findings are supported by another meta-analysis that included 38 randomized controlled trials and almost 50,000 participants showed no benefits of omega-3 supplementation on cognitive decline (12).


Omega-3 and Other Health Outcomes  

Omega-3 supplementation has also been a possible treatment for age-related macular degeneration, dry eye disease, rheumatoid arthritis, depression, inflammatory bowel disease, ADHD, childhood allergies, hypertriglyceridemia, and for reducing inflammatory biomarkers.


They don’t appear to be helpful for improving age-related macular degeneration (13), the evidence is mixed for mild improvements in dry eye disease (14), and there is evidence for slight benefit, although not extremely consistent for improvement of some symptoms of rheumatoid arthritis (15), depression (16), anxiety (17), inflammatory bowel disease (18), ADHD (19), and childhood allergies (20). The evidence for reducing triglycerides (21) and improving markers of inflammation (22) shows a consistent benefit.


It is my opinion that supplement trials show mixed effects because 1) they don’t screen for baseline omega-3 status and 2) doses of EPA and DHA and duration of supplementation range dramatically from study to study. However, given the totality of the evidence, I think that it is quite clear that omega-3 fats are an essential nutrient for health and for reducing the risk of various chronic diseases.


So how do we make sense of this information?

Eating ALA from plant sources is a wise strategy to help meet those needs, especially considering that foods like flax and walnuts have several additional nutrients and potential health benefits associated with their consumption (23-24). 

However, it is likely that many people will not be able to achieve optimal blood levels of EPA + DHA simply from consuming ALA due to the low conversion rates that we discussed above. Therefore, it would be ideal to try to consume a few servings per week of fatty fish to help meet those needs.

If this is not doable for whatever reason (cost, don’t enjoy the taste, being a vegetarian) it may be worth considering supplementing with long-chain omega-3 fats to achieve adequate levels. 

For those who are not vegetarian a high-quality fish oil supplement providing ~1 gram of EPA-DHA should be sufficient to support omega-3 needs. For those who choose to avoid products made from animals, microalgae oil is an option as well. However, the levels of EPA in these supplements tend to be lower and they come at a higher cost for the same doses of EPA/DHA compared to a fish oil supplement. 

In this case, it might be best to prioritize higher consumption of ALA to support total long-chain omega-3 synthesis and complement that intake with a dietary supplement that provides additional EPA + DHA. If you would like to see some of my personal supplement recommendations, you can find them under my favorites and receive a discount if you would like to purchase through this site here. (link)


Testing Omega-3 Status

Another option that I recommend is testing your omega-3 status via a lab test (like the one linked here) and making decisions about consumption and supplementation based on your current levels. Our omega-3 status seems to be the most important factor, so if your levels are in optimal ranges with your current dietary and supplementation habits then there is no need to make changes. But if you are currently in the high cardiovascular risk ranges based on omega-3 blood levels it might be wise to increase your consumption or consider a supplement.


As always, make sure to speak with your personal healthcare provider before making any drastic dietary changes or starting a new supplement to ensure that there will be no interactions with your current medications or risks given your underlying health status.


If you would like to support the work that I do you can do so here: 

Paypal One-Time Donation Page 



  1. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/

  2. https://pubmed.ncbi.nlm.nih.gov/17622276/ 

  3. https://pubmed.ncbi.nlm.nih.gov/33972333/ 

  4. https://pubmed.ncbi.nlm.nih.gov/28802305/ 

  5. https://pubmed.ncbi.nlm.nih.gov/28511049/

  6. https://pubmed.ncbi.nlm.nih.gov/35830775/

  7. https://pubmed.ncbi.nlm.nih.gov/34505026/

  8. https://pubmed.ncbi.nlm.nih.gov/32114592/

  9. https://pubmed.ncbi.nlm.nih.gov/33530576/

  10. https://pubmed.ncbi.nlm.nih.gov/26718417/

  11. https://pubmed.ncbi.nlm.nih.gov/31841161/

  12. https://pubmed.ncbi.nlm.nih.gov/32305302/

  13. https://pubmed.ncbi.nlm.nih.gov/33119047/

  14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6234923/

  15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7362115/

  16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683166/

  17. https://pubmed.ncbi.nlm.nih.gov/30646157/

  18. https://pubmed.ncbi.nlm.nih.gov/33084958/

  19. https://pubmed.ncbi.nlm.nih.gov/28741625/

  20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8746967/

  21. https://pubmed.ncbi.nlm.nih.gov/31530008/

  22. https://pubmed.ncbi.nlm.nih.gov/35914448/

  23. https://pubmed.ncbi.nlm.nih.gov/34635132/

  24. https://pubmed.ncbi.nlm.nih.gov/29931130/




Dr. Adrian Chavez Newsletter

Want Actionable Nutrition and Health Advice Delivered to Your Inbox?

Stay up to date with our latest content, new programs and courses, special discounts and more!

You're safe with me. I'll never spam you or sell your contact info.