How much fish oil should you take in a day

Decades of research studies converge on the findings that omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) provide important benefits for cellular and metabolic health throughout the lifespan.1,2

Upon learning of these benefits, one of the first things people want to know is, how much EPA and DHA should they take to meet their daily needs?

While this may seem like a simple question, because a number of factors contribute to an individual’s omega-3 status, the answer can actually be quite complicated.

To help address this question of dosage, several health organizations have released their own dosing recommendations based on available research and various other criteria.3,4

These organizations typically recommend that healthy adults consume a minimum of 500 mg of EPA and DHA each day, but recognize that higher amounts are often needed for individuals with metabolic risk factors and during specific periods of development, such as gestation and infancy.5

Many generalized dosage recommendations fail to account for certain variables

While these generalized recommendations are helpful, they fail to account for a number of known genetic and environmental variables that can affect omega-3 metabolism, and often lead to considerable variation between individuals.6

Coupled with the evidence that larger doses of EPA and DHA are safe, well-tolerated, and more effective for increasing omega-3 blood levels than modest doses, it stands to reason that many individuals would benefit from consuming a considerably higher dose than those historically recommended.7

Virtually all our cells depend on omega-3 fatty acids EPA and DHA

The average human body is composed of approximately 37 trillion cells and virtually all of them depend on omega-3 fatty acids EPA and DHA for maintaining foundational daily cellular activities.8,9

Although humans are able to synthesize EPA and DHA from alpha-linoleic acid (ALA)—a fatty acid precursor found in flaxseed, walnuts, and canola oil—because ALA’s conversion into EPA and DHA is very low, it is generally recommended that EPA and DHA be consumed directly through dietary sources including cold-water fatty fish and/or fish oil supplements.10,11

After EPA and DHA are ingested, they are placed within the phospholipids of cell membranes, where they directly and indirectly affect cellular function by promoting the fluidity, flexibility, and/or the permeability of cell membranes.8

These features are vital to numerous daily cell operations, including receiving, processing, and responding to information from nearby cells and messages coming from the surrounding environment.8,12

Importantly, because organs are made up of cells, obtaining sufficient omega-3s means that organs will also have the potential to function more optimally. And because normal organ functioning is associated with greater general health, adequate omega-3s can help optimize overall health. (For more information about omega-3 benefits, refer to “An Introduction to Omega-3 Fats”.)

In sum, the intake of fatty acids influences virtually all aspects of health and disease because of their diverse roles as structural lipids in every cell and as signaling precursors throughout the body.13

Evidence demonstrates larger doses of EPA and DHA are safe and potentially more effective

In spite of the body’s significant need for EPA and DHA (again, 37 trillion cells depend on these dietary fats for carrying out daily cellular activities!), most of the clinical trials evaluating the effects of EPA+DHA have historically tended to err on the side of caution by using smaller (and somewhat arbitrary) doses ranging between 250 mg per day to 1000 mg per day.

While modest dosing may have been a sound, precautionary tactic at an earlier point in the omega-3 literature, accumulating evidence demonstrating that larger doses are safe and potentially more effective suggests that research using smaller doses may not be speaking to the full potential of omega-3s for optimizing health.14–16

Moreover, smaller doses are less likely to provide sufficient support for all people, given that differences in diet and metabolism mean some individuals require much greater amounts of EPA and DHA than others.6

Omega-3 requirements vary from person to person

As discussed, a number of variables factor into the amount of omega-3 polyunsaturated fatty acids an individual’s body will require for maintaining normal cellular and metabolic activities.

More specifically, variables including age, sex, diet, body mass, genetics, medication use, health status, and exposure to pollutants and toxins all affect how well someone metabolizes dietary fatty acids, and thus, their omega-3 status.17,18

This variability in omega-3 status also helps explain why we tend to see mixed results at the outcome of omega-3 research trials.6

For example, giving a fixed dose of 1000 mg per day to someone who is wildly deficient in omega-3s may barely move the needle in terms of increasing omega-3 blood levels, whereas giving the same fixed dose to someone who eats a diet rich in fish and has no trouble metabolizing dietary fats may be perfectly sufficient for achieving a therapeutic EPA + DHA blood level. In light of this variability,

EPA+DHA recommendations should be based on individual omega-3 needs and requirements whenever possible.

Omega-3 blood testing: Important numbers to know

The fastest and most efficient way to determine your omega-3 requirements is by taking a blood test to evaluate your omega-3 index and working with your doctor to determine a dosing regimen that best suits your needs.

In recent years, a number of companies have started providing “at home” testing kits for determining your omega-3 index. While this may seem like a more convenient option than traditional testing, it is important to recognize that simply knowing your omega-3 levels is not enough information to determine the “optimal” amount of fish oil you should be taking.

Those truly interested in optimizing their health are encouraged to work directly with their primary care physician to obtain testing services, establish a supplementation regimen, and retest their omega-3 blood levels after 3-6 months to gauge how their omega-3 levels are reacting to supplementation.

The omega-3 index is a measure of the relative amount of EPA and DHA in red blood cells, expressed as the percentage of the total amount of fatty acids present.

If an individual has an omega-3 index of 3.6%, this means that 3.6% of all fatty acids present in their red cell membranes is EPA+DHA. Importantly, this result would also suggest that the individual is omega-3 deficient, which is associated with a vast array of negative health implications.19

For example, research indicates that an omega-3 index less than 4% fulfills the criteria for a cardiovascular risk factor.20 Conversely, an index value larger than 8% is considered cardioprotective, and associated with reduced risks of cardiac events, cardiac death, and problems related to coronary health.21

As a point of reference, in studies with Americans not taking omega-3 supplements, the average omega-3 index values ranged from 4 to 5% (i.e., well below cardioprotective levels).

Given that experts typically recommend targeting an omega-3 index between 8% and 12%, these results suggest that the average American would benefit from increasing their omega-3 index through supplementation.22,23

But this begs a similar question—how much EPA and DHA does a person need to take to increase their omega-3 index?

Although this can only be definitively answered through testing, supplementing, and retesting, a number of observational and intervention studies find a dose-dependent relationship between omega-3 supplementation and the omega-3 index.6,21

In other words: the higher the dose of supplemental EPA+DHA, the greater the increase in omega-3 index.

Safety concerns: Is there such a thing as too much omega-3s?

Another frequently asked question concerning omega-3 dosage is the maximum amount of omega-3s a person can safely consume. According to the European Food Safety Authority (EFSA), a panel of scientific experts established by the European Union to assess risks associated with the food chain, the answer to this question is not yet known.

Based on their assessment of the available research, EFSA contends that the data on omega-3s is insufficient for establishing an upper intake level of EPA and DHA, but that supplemental intakes of up to 5000 mg per day are generally well-tolerated and do not increase the risks of adverse health complications, such as prolonged bleeding or cardiovascular disease (CVD).7

With respect to the safety of omega-3 fish oil, a more important consideration than dosage is the oxidative stability of the product. Oxidative rancidity occurs when the double bonds of a fatty acid molecule react with oxygen and break down, forming a free radical and a chemical group that contribute to the ‘fishy smell’ often associated with less fresh fish oil.

Because of their multiple double bonds, the fatty acids in fish oils are more susceptible to oxidative rancidity than other dietary fats. Moreover, since the consumption of oxidized fatty acids has been shown to contribute to negative health outcomes—such as free radical formation and increased susceptibility to oxidative damage to tissues—individuals should take great care in selecting high-quality, third party tested fish oil to help ensure the freshness and safety of their fish oil.25

Omega-3 intake recommendations

All individuals, regardless of age or health status, are encouraged to undergo blood testing and work with a physician who can make personalized recommendations based on their unique dietary needs. However, in the absence of testing, we have provided general daily recommendations, based on life stage and general health status.

These recommendations are informed by:

1. extensive review of the omega-3 and human physiology literatures
2. consideration of the many factors impeding omega-3 synthesis and absorption
3. clinical evidence demonstrating that higher doses of omega-3s result in higher omega-3 levels,6,21 and
4. research indicating that doses as large as 5000 mg per day are safe for daily consumption by adults.7

Importantly, these dosage recommendations should be combined with efforts to consume: 1) oily, wild-caught fish at least twice a week, and 2) a low intake of omega-6 fats (commonly found in vegetable oils, nuts, processed foods, etc.).

This is because omega-6 fats compete with omega-3s for the enzymes needed to synthesize their fatty acid derivatives, and thus, excessive consumption of omega-6 fatty acids may effectively replace omega-3s within cell membranes.

(For a comprehensive summary of omega-3 benefits and the risks associated with a high omega-6 to omega-3 ratio, see “An Introduction to Omega-3 Fats”.)

• Healthy Children (ages 4-12): 2000 mg EPA+DHA per day
• Healthy Adolescents (ages 13-18): 2000-3000 mg EPA+DHA per day
• Healthy Adults (ages 18+): 3000-4000 mg EPA+DHA per day

As you likely noted, these intake recommendations are substantially higher than those provided by other health organizations, who generally recommend healthy adults take a minimum of 500 mg of EPA+DHA daily.5

It is important to recognize that these more modest intake recommendations are suggested minimums, rather than recommendations for optimal cellular health and functioning.

Moreover, these modest intake recommendations are informed by research which has historically tended to err on the side of caution by using smaller doses, when we now have sufficient evidence that doses as large as 5000 mg per day are safe for daily consumption and more effective for raising the omega-3 index towards cardioprotective levels.6,21

3000-4000 mg of EPA and DHA per day is supportive for most healthy adults

In summary, a number of factors contribute to an individual’s omega-3 status, and the amount of EPA and DHA they require for optimal cellular health.

Although the only conclusive way to ensure you are meeting your daily needs is through blood testing, supplementing with 3000 to 4000 mg of EPA+DHA daily should provide sufficient support for most healthy adults, and importantly, buffer against the competitive effects of factors impeding omega-3 metabolism.

About the author

Gina Jaeger, PhD is a Developmental Specialist and Lead Research Writer for Nordic Naturals. She holds a doctorate in Human Development, and has published several research articles on children's cognitive development. Gina enjoys studying and educating others on strategies for optimizing health and wellness throughout the lifespan.

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