Guide to Omega-3 Supplements: Uses, Health Benefits & Side Effects

As of 2012, nearly eight percent of the U.S. adult population—about 18.8 million individuals—used an omega-3 dietary supplement (specifically, fish oil), which represented an increase of more than eight million people compared to just five years before.

Is it a foregone conclusion, though, that all of these consumers are getting meaningful value for their money? In other words, is there clinical support that omega-3 supplementation can help you achieve real-world health benefits? 

With the assistance of professionals, we’ll help you answer this nuanced question by walking you through the basics, step-by-step.

Your Quick Reference Guide to Omega-3 Fatty Acids

Q: What are omega-3s and how do they work?

A: Omega-3s are a type of polyunsaturated (healthy) fatty acid that’s essential for human health.

Specifically, the University of Maryland Medical Center indicates they play an important role in brain function and normal growth and development, while Harvard’s T.H. Chan School of Public Health reports they’re “an integral part of cell membranes throughout the body,” help make hormones that regulate blood clotting, artery wall contraction and relaxation, inflammation, and even genetic function regulation.

Q: Are there different types of omega-3 fatty acids?

A: There isn’t just one type of omega-3 fatty acid. In fact, Healthline reports that there are a total of 11 found in nature, although only three of these are important in human physiology:

  • Eicosapentaenoic Acid (EPA) – Fatty acids associated with helping the blood clot, as well as reducing pain and swelling.
  • Docosahexaenoic Acid (DHA) – Helps promote the development of eye and nerve tissues, as well as retina, brain, and sperm cells; decrease blood thickness, and lower blood triglyceride levels.
  • Alpha-Linolenic Acid (ALA) – May play a role in helping the heart maintain pumping rhythm, as well as in reducing blood clots.

Is any one of these better, or more beneficial, than the other when it comes to supplementation?

In general, no, although Marc S. Schneider, MD, Director of the Schneider Centre for Plastic Surgery and Neogenics age management in Ft. Myers, FL, tells us “that athletes should consume an omega-3 supplement with higher quantities of EPA, as it is very beneficial in decreasing inflammation associated with intense exercise and neuromuscular recovery.

Also, “higher DHA dosing is preferred for those concerned with neurocognitive issues such as depression, anxiety, and loss of motivation,” he says. We’ll come back to many of these benefits shortly.

Q: Where can you get omega-3 fatty acids, and how much does your body need?

A: Although omega-3s are essential fatty acids, our body can’t produce them. As such, there are a wide variety of food sources, including popular ones like:

  • Seafood – Halibut, herring, mackerel, oysters, salmon, sardines, trout, fresh tuna
  • Dairy – Eggs, margarine, milk, yogurt
  • Grain & Nuts – Bread, cereal, flaxseed, flour, peanut butter, oatmeal, pumpkin seeds, walnuts
  • Fresh Produce – Brussels sprouts, kale, spinach, broccoli, cauliflower
  • Oils – Canola, cod liver, flaxseed, mustard, soybean, walnut

While there’s no official Recommended Daily Allowance (RDA) for omega-3, according to the NIH Office of Dietary Supplements, adult men and women require between 1.1 and 1.6 g of the ingredient per day, although they report that recommended amounts of EPA and DHA haven’t been established.

With this said, organizations and offices like the World Health Organization, the International Society for the Study of Fatty Acids and Lipids, the U.S. Department of Agriculture, and the U.S. Department of Health and Human Services recommend that healthy adults consume a minimum of 250-500 mg combined EPA and DHA each day.

To obtain this from food, Jessica Crandall, Registered Dietitian Nutritionist, personal trainer, and director of Denver Wellness and Nutrition in Englewood, CO, tells us that one of the best methods is eating oily fish, whose EPA and DHA do not need to be converted in the body,” she says.

As a helpful tip, she points out that the fish—and other seafood—below provide the specified amount of omega-3 fatty acids (EPA and DHA combined):

Herring, Atlantic 1.5 g
Salmon, Atlantic 2.5 g
Trout 3.5 g
Sardines 2.5 g
Oysters 2.5 g
White Tuna, Canned 4.0 g
Crab, Dungeness 9.0 g

If our body doesn’t obtain sufficient omega-3s from these sources, the ODS tells us that a deficiency can lead to a “rough, scaly skin and a red, swollen, itchy rash.” Let’s see how common this is.

Q: Are most of us deficient in omega-3s?

A: In Do You Need to Take Vitamins or Dietary Supplements, we discuss that, according to organizations like the National Institutes of Health and Nutrition.gov, supplementation isn’t recommended for those not deficient in an essential ingredient.

Naturally, this raises the question: Are most of us deficient in omega-3 fatty acids? Here’s where some additional nuance enters the picture, as the answer we received during our research largely depended on who we asked, as well as the population being referenced. For example:

The Office of Dietary Supplements qualifies their earlier warnings by emphasizing that omega-3 deficiency is very rare in the United States. In other words, as a whole, they tell us the vast majority of Americans get enough omega-3s from the foods they eat.

On the other hand, Marc S. Schneider, MD, tells us it’s “been documented that 45 percent of the population worldwide has an omega-3 essential fatty acid deficiency,” and it’s “estimated to be much higher in North America.”  

We found a 2014 observational study supporting this assertion on the National Institutes of Health’s PubMed, along with a 2008 study conducted by the Child & Family Research Institute at the British Columbia Women’s Hospital.

5 Potential Health Benefits of Omega-3 Dietary Supplement

Outside of maintaining some of the essential bodily functions we discussed earlier, what are the health benefits provided by omega-3 supplementation? First, let’s define what we mean by the term ‘supplement.’

Omega-3 From Whole Foods vs. Supplements

When it comes to whole fish, Healthline tells us that omega-3s are present as free fatty acids, phospholipids, and triglycerides. On the other hand, in unprocessed fish, krill, cod liver, or algal oils (the most popular types of omega-3 supplements), these fatty acids are mostly present as triglycerides. When processed, these then become ethyl esters.

And according to some research, “the absorption of omega-3s in the form of free fatty acids (mostly found in food) is 50% greater than triglycerides, and the absorption of triglycerides is 50% greater than ethyl esters.”

In layman’s terms, according to Arielle Levitan M.D., author of “The Vitamin Solution: Two Doctors Clear the Confusion About Vitamins and Your Health,” the preferred way to obtain omega-3s is from whole foods.

But she says that if you’re not getting enough via your diet or your doctor diagnoses you with “high triglyceride, low HDL, … [poor] memory, ADD, depression, or arthritis” symptoms, getting high doses via supplementation could be a viable option.

With these details in mind, the vast majority of clinical evidence related to omega-3’s real-world benefits—many of which Dr. Levitan mentions—revolves around fish oil. So, this is what we’ll discuss next, in order of strongest evidence.

Potential Fish Oil Omega-3 Benefit #1: Triglycerides & Cholesterol

According to the summarizations of clinical evidence provided by sites like the Natural Medicines Database and WebMD, fish oil is classified as ‘highly effective’ for reducing triglyceride (‘bad’ fat) levels by anywhere between 20 and 50 percent.

However, they emphasize existing clinical evidence indicates that a) this effect varies between type (e.g., supplemental fish oil or prescription medications like Lovaza), as well as dose (anywhere between one and six grams), and b) it seems to be most effective for those with severe hypertriglyceridemia, or high triglyceride levels.

And while the Mayo Clinic tells us that there “also appears to be a slight improvement in high-density lipoprotein (HDL, or ‘good’) cholesterol, an increase in levels of low-density lipoprotein (LDL, or ‘bad’) cholesterol also was observed.”

WebMD is more straightforward when stating that existing omega-3 research “does not show it has a significant effect on cholesterol levels.”

According to the University of Maryland Medical Center, though, this could lead to trickle down effects, such as a beneficial impact on diabetes.

Potential Fish Oil Omega-3 Benefit #2: Heart/Cardiovascular Disease

Along these same lines, the Harvard School of Public Health article cited earlier reports that “the strongest evidence for a beneficial effect of omega-3 fats has to do with heart disease,” although this seems to relate to those who aren’t already taking statins and those who already consume fish regularly.

Specifically, several clinical studies have indicated that they can help maintain a steady heartbeat, instead of an erratic rhythm, which “causes most of the 500,000-plus cardiac deaths that occur each year in the United States.”

We’re told there’s also evidence that omega-3s can impact factors that play a role in the development of atherosclerosis, including lowering blood pressure and heart rate, improving blood vessel function, and reducing inflammation.

However, the Food and Drug Administration emphasizes that, overall, the clinical support for omega-3’s beneficial impact on heart disease is classified as “supportive but not conclusive.”

Writing for the New York Times Wellness blog, Anahad O’Connor also reports:

“From 2005 to 2012, at least two dozen rigorous studies of fish oil were published in leading medical journals, most of which looked at whether fish oil could prevent cardiovascular events in high-risk populations. These were people who had a history of heart disease or strong risk factors for it, like high cholesterol, hypertension or Type 2 diabetes.

“All but two of these studies found that compared with a placebo, fish oil showed no benefit.”

Potential Fish Oil Omega-3 Benefit #3: Rheumatoid Arthritis

These same sites report mounting evidence that oral omega-3 supplementation, when taken alone or in combination with naproxen, may help moderately relieve morning stiffness and joint tenderness in those with rheumatoid arthritis.

While generally modest, in some instances, this relief was great enough that trial participants were able to stop taking over the counter NSAIDS (nonsteroidal anti-inflammatory drugs).

Potential Fish Oil Omega-3 Benefit #4: High Blood Pressure 

Medically, the Natural Medicines Database tells us that omega-3s are possibly effective for “modest but significant reductions in systolic and diastolic blood pressure in patients with hypertension with or without type 2 diabetes.” In other words, for decreasing high blood pressure.

However, existing evidence indicates this effect might be more pronounced in those with moderate to severe hypertension, and not necessarily those diagnosed with a mild form.

With all of this said, they report there are some discrepancies related to the best type of fish oil to use, as well as the most appropriate dose.

Potential Fish Oil Omega-3 Benefit #5: Cancer  

The University of Maryland Medical Center also indicates there is mounting evidence that consuming high levels of omega-3 fatty acids from omega-3-rich foods could decrease rates of colorectal cancer, as well as “slow the progression of colon cancer in people with early stages of the disease.”

They also report that, although more research is needed, “women who eat foods rich in omega-3 fatty acids over many years may be less likely to develop breast cancer” and consuming a “low-fat diet including omega-3 fatty acids (from fish or fish oil) may help prevent the development of prostate cancer.”

» SEE ALSO: Cancer Prevention Diet: 7 Foods That Can Lower the Risk of Cancer

Other Potential Benefits of Fish Oil Omega-3 Fatty Acid Supplementation

In addition to the above, WebMD and the Natural Medicines Database point out that fish oil is classified as ‘possibly effective’ for a variety of ultra-specific instances. These include:

  • Preventing re-blockage of blood vessels after angioplasty: 6 g daily
  • Improving symptoms of depression, but not mania, in those with bipolar disorder: 6.2 g EPA, 3.4 g DHA daily
  • Keeping veins open following coronary artery bypass surgery: 4 g per day
  • Preventing kidney damage in people taking cyclosporine: 12 g daily
  • Improving cold tolerance in some people with the usual form of Raynaud’s syndrome: 3.96 g EPA, 2.64 g DHA daily for 12 weeks

Along these same lines, these sites indicate that the ALA, EPA, and DHA found in fish oil may help treat depression (when used alongside traditional antidepressants), psoriasis, symptoms of menopause (mainly, hot flashes), and age-related macular degeneration, as well as reduce the risk of pneumonia.

Omega-3’s Potential Side Effects, Interactions, & Other Hazards

The Natural Medicines Database indicates that when used in oral doses of 3 g or less, fish oil is considered safe for most individuals, and emphasizes that it’s classified as Generally Recognized As Safe (GRAS) by the Food and Drug Administration.

However, they qualify this by pointing out that fish oil is considered possibly unsafe when consumed in large amounts from dietary sources, since “fatty fish can contain significant amounts of toxins such as mercury, polychlorinated biphenyls (PCBs), dioxin, and dioxin-related compounds.”

According to the University of Maryland Medical Center, though, fish oil can sometimes lead to gas, bloating, belching, and diarrhea, although this could be reduced by taking a time release supplement.

» SEE ALSO: Can Dietary Supplements & Vitamins Cause Dangerous Side Effects?

They also note that an omega-3 supplement can interact with blood thinning, diabetes, and cholesterol-lowering medications, as well as NSAIDs, some topical steroids, and cyclosporine.

Jessica Crandall adds, “although small, there is a risk of increased bleeding possible when people who take anti-platelet agents or anticoagulants also take 3 to 4 grams of EPA and DHA.”

The Bottom Line About the Benefits & Side Effects of Omega-3 Dietary Supplements

In the end, here’s the takeaway: According to medical professionals, there is mounting clinical evidence that omega-3 supplementation can provide some real-world health benefits.

However, as with just about any health topic, the answer regarding whether or not you—specifically—will benefit from the ingredient is much more nuanced and depends on factors like any conditions diagnosed by your doctor, as well as if you’re getting sufficient levels from the foods you eat.

To this last point, the NIH’s National Center for Complementary and Integrative Health tells us “moderate evidence has emerged about the health benefits of eating seafood.” However, “the health benefits of omega-3 dietary supplements are unclear.”

Why is this? Continuing our emphasis on nuance, we’ll wrap up with the following explanation from the Harvard Health link cited earlier:

“How food, and its component molecules, affect the body is largely a mystery. That makes the use of supplements for anything other than treating a deficiency questionable.”

Still, you should “consider eating fish and other seafood as a healthy strategy. If we could absolutely, positively say that the benefits of eating seafood come entirely from omega-3 fats, then downing fish oil pills would be an alternative to eating fish. But it’s more than likely that you need the entire orchestra of fish fats, vitamins, minerals, and supporting molecules, rather than the lone notes of EPA and DHA.”

» SEE ALSO: Best Omega-3 Supplements Buying Guide


Derek Lakin

Senior Editor at HighYa. With more than a decade of experience as a copywriter, Derek takes a detail-oriented, step-by-step approach to helping you shop smarter. Whether it’s nutritional supplements or new scams, he believes an informed consumer is a happy customer. Connect with him on Twitter: @DALwrites


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