Can You Calculate How Much Omega-3 You Need?
Until now, there has been very little guidance about what dose of EPA and DHA should be tested in a study. And with the wide differences in study results in recent years, it is likely that dose played a central role in the relative success or failure of omega-3 studies. In other words, if the dose of EPA and DHA in a study wasn’t high enough to make an impact on blood levels (i.e. Omega-3 Index), there would most likely be no effect on the desired endpoint, leading to a neutral or negative result.
When it comes to cardiovascular disease (CVD) in particular, the literature supporting the benefits of omega-3s EPA and DHA has been mixed. On one hand, a 2018 meta-analysis concluded that current evidence does not support a role for omega-3s in CVD risk reduction.
On the other hand, three major randomized trials reported in late 2018 showed that omega-3s significantly reduced risk for vascular death, myocardial infarction, and major adverse cardiovascular events. The latter study was particularly compelling because it used 4 grams of EPA (as opposed to the usual 0.84 grams of EPA and DHA) in statin-treated patients and found a 25% risk reduction in CVD events.
According to Kristina Harris Jackson, PhD, RD, who is an author on this latest paper, “A low dose could make a study show no effect of EPA and DHA, which makes the literature more indecisive and the consumer more confused,” she said. “Hopefully, ensuring the dose of EPA and DHA is high enough to reach a target Omega-3 Index level will clarify whether or not EPA and DHA are effective.”
Earlier this year, a study published in Prostaglandins, Leukotrienes, and Essential Fatty Acids, showed that people likely need to eat more fish and take an omega-3 supplement to reach a cardioprotective Omega-3 Index level of 8% or higher.
Dr. Jackson was the lead author on this study, the goal of which was to answer the question: “What combination of non-fried fish intake and omega-3 supplement use is associated with a cardioprotective Omega-3 Index level (i.e., 8% or above)?”
In 2018, the American Heart Association (AHA) updated its 2002 recommendations regarding fish and seafood consumption from “…a variety of (preferably oily) fish at least twice a week” to “…1 to 2 seafood meals per week.”
“This apparent downgrade in the recommendation (i.e., removal of ‘preferably oily’ and ‘at least’) was made despite evidence that consuming fish more frequently (such as daily or multiple times per day) may impart even greater cardioprotection,” Dr. Jackson and her colleagues pointed out this paper.
An online commentary by Louis Kuller, MD that accompanied the publication of the new AHA guidelines questioned whether the new fish intake recommendations would produce cardioprotective blood omega-3 levels. He argued that intake recommendations should be based on those that achieve a target blood level.
In this study, Dr. Jackson and her team evaluated blood levels of omega-3s EPA and DHA from almost 3500 people, alongside questions about their fish and supplement intake. Individuals reporting no fish intake and taking no omega-3 supplements had an average Omega-3 Index of about 4.1%, which reflects the average for most Americans and is considered “deficient.”
At the other extreme, the average Omega-3 Index of people reporting taking a supplement AND eating three fish meals a week was 8.1%, which is the level defined in the research as being “cardioprotective.”
Thus, in a free living setting, Dr. Jackson and her colleagues believe an 8% Omega-3 Index is most likely to be found in people eating at least three “non-fried’” fish meals per week and taking an omega-3 EPA/DHA supplement.
“The AHA currently recommends two fish meals per week and it does not recommend supplementation. In light of our findings, this regimen is unlikely to produce a cardioprotective Omega-3 Index of 8%,” Dr. Jackson explained. “Having dietary recommendations that aim to achieve a target blood level would likely be more effective at reducing the risk for heart disease.”
How to Use the Omega-3 Index Calculator
The model equation developed in the most recent AJCN paper can be used to estimate the final Omega-3 Index (and 95% CI) of a population given the omega-3 EPA and DHA dose and baseline Omega-3 Index. As an example, a population with a baseline Omega-3 Index of 4.9% that is given 840 mg EPA and DHA per day (as a 1-gram ethyl ester capsule) would achieve a mean Omega-3 Index of ∼6.5% (95% CI: 6.3%, 6.7%).
Rearranging the equation, one can calculate the approximate EPA/DHA doses (of triglyceride forms) to achieve a mean Omega-3 Index of 8% in 13 weeks. This would require 2200 mg of EPA and DHA for a baseline Omega-3 of 2%, 1500 mg for an Omega-3 Index of 4% at baseline, and 750 mg of EPA and DHA for a 6% baseline.
Using this example, the researchers in this paper predict that the minimum dose of EPA and DHA necessary to be 95% certain that the mean baseline Omega-3 Index of 4% will increase to 8% (in 13 weeks) is ∼1750 mg per day of a triglyceride formulation or 2500 mg per day of an ethyl ester formulation. Both of these forms are most prominent in fish oil preparations.
So in order for 95% of subjects (not just 50%) to achieve a desirable Omega-3 Index from a baseline of ∼4%, roughly 2000 mg per day of EPA and DHA (depending on the chemical form) would likely be required.