Everything You Wanted To Know About Omega-3

Fat hasn't always had the best reputation. In a paper published in the Journal of the History of Medicine and Allied Sciences in 2008, Dr. Ann F. La Berge traced the convoluted history of dietary fat and how the United States became swept up in an "ideology of low fat" beginning in the 1960s. For decades, Americans shunned fat, "even though there was no clear evidence that it prevented heart disease or promoted weight loss." But beginning in the early 2000s, views on fat changed, and most health professionals now believe fat is a critical part of the diet.

However, one type of fat — omega-3 fatty acids — never experienced the popularity rollercoaster that other fats endured. This group of fats has been universally praised for decades. They make up a large portion of the dietary fat in the Mediterranean diet, which is widely considered as one of the healthiest and most sustainable eating patterns (via the Mayo Clinic). Omega-3s are also the most popular supplement in the United States, with about 8% of Americans taking some form of it (via Time). But what exactly do omega-3s do for your body, and is all the hype really warranted?

Omega-3s are a type of polyunsaturated fat

Fat isn't just a single nutrient. According to WebMD, dietary fat can be divided into four broad categories: saturated, monounsaturated, polyunsaturated, and trans fats. There are many different individual fatty acids within each category. All fats are chains of carbon molecules bonded to hydrogen molecules. It's the length and shape of these carbon chains and how the hydrogen molecules are attached that give fats their different properties. As WebMD explained: "In saturated fats, the carbon atoms are totally covered, or 'saturated,' with hydrogen atoms. This makes them solid at room temperature." The two types of unsaturated fat (monounsaturated and polyunsaturated) have fewer hydrogen atoms bonded to the carbon chain, which makes them liquid at room temperature.

Harvard Medical School identified polyunsaturated fats (along with monounsaturated fats) as the healthiest class of fats to consume. There are two broad types of polyunsaturated fats: omega-3s and omega-6s. Both types have two or more double bonds in their carbon chain, and the number refers to the distance between the beginning of the carbon chain and the first double bond. Harvard Medical School and many other experts recommend replacing saturated fat (found largely in meat) with more polyunsaturated fats, particularly omega-3s.

Types of omega-3 fats and what they do in the body

Although often treated as a single entity, omega-3s are actually a group of many fatty acids. The three most common are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), per the National Institutes of Health. While ALA is the most naturally abundant and the omega-3 most consumed by Americans, research tends to focus on EPA and DHA, since they're considered more important biologically. According to the Linus Pauling Institute, however, there are other types of omega-3s, including stearidonic acid (SDA), eicosatetraenoic acid (ETA), and docosapentaenoic acid (DPA).

The three main types of omega-3s serve different functions. ALA is used as an energy source — it's either burned for fuel now or stored in fat cells for later. The body also uses ALA to make EPA and DHA (more on that below). EPA and DHA, on the other hand, play a wide variety of very important roles. They're considered structural fats, because they're a key component of the membrane that surrounds every cell. They also impact how these cell membranes function. EPA and DHA are needed to create hormones and to regulate contraction and relaxation of artery walls and the process of blood clotting. They have an anti-inflammatory effect and appear to even influence expression of certain genes (via the Harvard School of Public Health).

How much omega-3s should you be getting?

Among the omega-3s, ALA is the only essential fatty acid, meaning that while it's essential for health, your body can't make it on its own from other substances (via the National Institutes of Health). Because of this, the Food and Nutrition Board of the Institute of Medicine (IOM) has established dietary guidelines only for ALA. These guidelines come in the form of an adequate intake (AI) level. 

The AI for ALA varies based on age and gender. Infants one year and younger should get 0.5 grams daily, while children age one to three need 0.7 grams. Between the ages of four and eight, children need 0.9 grams of ALA daily. At puberty, needs change based on sex. Boys age 9–13 should aim for 1.2 grams, while girls in this age range need only 1.0 gram. Males 14 and older should get 1.6 grams, while the AI for females 14 and older is 1.1 grams.

Although no official dietary reference intake (DRI) has been established for EPA and DHA, this hasn't stopped health experts and organizations from weighing in on how much Americans should be aiming for. A widely accepted recommendation is that healthy adults should aim to get at least 500 mg of EPA and DHA combined daily, but those with diagnosed heart disease or heart failure should get at least 800 to 1,000 mg each day (via WebMD).

The ratio of omega-3s to omega-6s also matters

It's not just a matter of getting a certain amount of omega-3s, though. The ratio of omega-6s to omega-3s in the diet is also important. This is because omega-6s, while essential for good health, also have pro-inflammatory qualities (via Medichecks). Omega-3s, on the other hand, are anti-inflammatory. Consuming these two types of fats in a balanced ratio ensures that you get the health benefits of each without exposing the body to too much potentially harmful inflammation.

The problem is that Americans' omega-6 to omega-3 ratio is way out of whack. According to a 2002 paper published in Biomedicine & Pharmacotherapy, the standard Western diet features an omega-6 to omega-3 ratio of between 15:1 and 16.7:1. By contrast, humans evolved on a diet that provided a roughly 1:1 ratio. The paper's authors noted that a ratio of 4:1 offered a 70% decrease in the risk of death from cardiovascular disease, while a ratio of 2.5:1 offered benefits for those with colorectal cancer. A ratio between 2:1 and 3:1 suppressed inflammation in people with rheumatoid arthritis (a type of autoimmune disease). For those with asthma, a ratio of 5:1 had a beneficial effect. The authors concluded that "the optimal ratio may vary with the disease under consideration ... A lower ratio of omega-6/omega-3 fatty acids is more desirable in reducing the risk of many of the chronic diseases of high prevalence in Western societies."

Your body can make certain omega-3s

ALA is the only essential omega-3 fat (via the Linus Pauling Institute). In nutrition terms, an essential nutrient is one that our bodies need but can't make, so we have to get it from our diet. EPA and DHA are just as (if not more) "essential" than ALA in the sense that they play critical roles in the body. However, they aren't considered essential nutrients because our bodies can convert ALA into EPA and DHA. Technically, we don't need to get them from our diet.

That said, the conversion rate is pretty lousy and heavily influenced by gender and genetics, per the Linus Pauling Institute. In healthy young men, only about 8% of dietary ALA can be converted to EPA and a measly 0%–4% can be converted to DHA. Premenopausal women fare a bit better: they can convert about 21% of dietary ALA to EPA and 9% to DHA. Estrogen is at the root of women's more efficient conversion, but this means that when menopause hits, their ability to convert ALA to EPA and DHA drastically diminishes. 

The genes controlling production of two enzymes used in the conversion process also play a significant role in how well an individual is able to turn ALA into EPA and DHA. Some genotypes lead to higher enzyme production, which means more efficient conversion. This lackluster conversion rate has led experts to strongly recommend that individuals get EPA and DHA directly from either food or supplements.

Food sources of omega-3 fats

ALA is found predominantly in plant foods, while EPA and DHA are found largely in seafood (via the National Institutes of Health). Flaxseed, canola, and soybean oil contain ALA, as do chia seeds and walnuts. A single tablespoon of flaxseed oil, for instance, contains 7.26 grams of ALA, wile the same amount of canola oil contains 1.28 grams. An ounce of chia seeds packs 5.06 grams of ALA and the same serving size of English walnuts contains 2.57 grams. Beans, milk, and beef also contain small amounts of ALA. (ALA content in grass-fed beef is higher, but still not on par with richer plant sources.)

Meanwhile, the fattier the fish, the more EPA and DHA it contains. Three ounces of wild Atlantic salmon, for instance, contains 1.22 grams of EPA and 0.35 grams of DHA, while the same serving size of cod (a much leaner fish) offers only 0.10 grams of EPA and 0.04 grams of DHA. Other good seafood sources include oysters, shrimp, and scallops. One cooked egg contains 0.03 grams of EPA but no DHA, while three ounces of chicken breast contains 0.02 grams EPA and 0.01 grams DHA. Some brands of eggs, yogurt, juices, milk, soy beverages, and infant formula are fortified with omega-3s, particularly DHA. For vegans or those allergic to fish and other seafood, seaweed and kelp are other good options, providing between 0.04 and 0.13 grams (combined) in just one ounce (via Eating Well).

Omega-3 supplements

Most Americans get plenty of ALA, thanks to its abundance in commonly used cooking oils. In fact, adult American women get an average of 1.59 grams daily, while men get 2.06 grams (via the National Institutes of Health). Average consumption of EPA and DHA from food, however, is minimal: Adults get an average of just 90 milligrams daily. So unless you're a real fish fanatic, you may want to consider an omega-3 supplement.

Most omega-3 supplements come in the form of EPA- and DHA-rich fish oil (via Forbes). You can get these in softgels or, for the brave, in liquid form. Manufacturers often deodorize the supplements to remove as much of the fishy smell as possible. High-dose prescription fish oil supplements are also available for some individuals with high triglycerides or cardiovascular disease.

While fish oil is the most common form of omega-3 supplement, there are others (per the National Center for Complementary and Integrative Health). Cod liver oil contains EPA and DHA, as well as large amounts of vitamins A and D. Krill oil, made from tiny shrimp, is also an excellent source of EPA and DHA. For vegetarians, algae oil supplements are available, although not all contain EPA. Flaxseed oil is another widely available omega-3 supplement, but since it provides only ALA (which most people already get enough of), it isn't in the same league as the others.

Risks with omega-3 supplements

Just because a supplement's label clearly lists the amounts of EPA and DHA it contains, that doesn't mean that's actually what's in the bottle. That's because omega-3 supplements, along with all dietary supplements, fall into a regulatory gray area. The Food and Drug Administration (FDA) doesn't have the authority to review the safety or effectiveness of dietary supplements before they're put on the market. It's up to manufacturers to ensure that their products are safe and contain the quantity and quality of ingredients they claim to have. 

If you want to ensure the supplement you're taking is on the up-and-up, look for bottles with the USP Verified label. The United States Pharmacopeia (USP) program is an independent and unbiased certification program that evaluates the quality of dietary supplements. If you see the label on a bottle, you can be assured that the product contains the amount of EPA and DHA it claims to have.

Omega-3 supplements are generally considered safe. They may cause mild side effects, such as an unpleasant aftertaste, bad breath, "fish burps," and nausea (via the Mayo Clinic). If taken in high doses, fish oil supplements may increase the risk of bleeding or having a stroke. They should be used with caution if you're also taking blood thinners or blood pressure medication, since fish oil can heighten the effects of these drugs.

Omega-3s and cardiovascular health

Heart disease is a big problem in the United States. According to the Centers for Disease Control and Prevention (CDC), it's the leading cause of death, claiming the lives of almost 700,000 people annually. More than 18 million Americans have coronary artery disease, the most common (and largely preventable) type of heart disease. High cholesterol is a key risk factor for heart disease, and omega-3s may be able to help.

Because omega-3 fats are anti-inflammatory, they can combat the inflammation that damages blood vessels and increases risk for heart disease (via the Mayo Clinic). They also decrease triglycerides (a type of cholesterol), slightly lower blood pressure, and reduce the frequency of irregular heartbeats. Those who get the most omega-3s have a lower risk for both heart failure and sudden cardiac death. In fact, prescription-strength omega-3 supplements are often given to those with high cholesterol and at high risk for heart attack. Epanova, for instance, contains 550 mg of EPA and 200 mg of DHA per capsule, while Vascepa only contains 1,000 mg of EPA (via Straight Healthcare). 

Results have been mixed, however, with some studies showing a benefit to using supplements and others showing no difference between those taking omega-3s and those taking placebo. The size of the dosage and the length of time taken likely influence the supplements' effectiveness.

Omega-3s and a healthy pregnancy

Omega-3 needs increase during pregnancy and breastfeeding. According to the National Institutes of Health (NIH), pregnant women need 1.4 grams of ALA daily, while lactating women should get 1.3 grams. It's also advised that mothers-to-be and new mamas increase their intake of EPA and DHA, either through seafood or supplements. 

But why are omega-3s so important during pregnancy? As the American Pregnancy Association (APA) explained, omega-3s are essential for the development of a fetus's vision and nervous system. The APA also noted that "increased intake of EPA and DHA has been shown to prevent pre-term labor and delivery, lower the risk of preeclampsia, and may increase birth weight." During pregnancy, women's omega-3 levels may become depleted as the developing baby takes what it needs at the expense of the mother. Low levels of omega-3s may also increase a woman's risk for postpartum depression.

The APA recommends women begin upping their omega-3 intake before they begin trying to conceive and continue throughout pregnancy and breastfeeding. Supplements or certified Safe Catch fish are preferable, since some fatty fish may contain high levels of mercury. As with pregnancy, breastfeeding depletes a woman's omega-3 levels (as her stores go to the baby, whose brain will continue to develop until age two). Getting enough omega-3s in utero and during the first two years of life can set the stage for improved attention, focus, learning, and immune function well into childhood.

Omega-3s and brain health

If you want to improve your cognitive abilities and stay sharp into old age, getting enough omega-3s may be important. As a 2015 paper published in Frontiers in Aging Neuroscience explained, our brains contain a much higher concentration of DHA compared to EPA. In fact, DHA levels in the brain are 250–300 times higher than EPA levels. 

Both EPA and DHA are important for proper brain structure and functioning, though. They combat neuroinflammation and are needed for the creation of new neurons. These omega-3s become increasingly important as we get older and our brains begin to show signs of aging, including shrinking. Higher blood levels of EPA and/or DHA have been associated with lower rates of gray matter atrophy in certain parts of the brain, as well as slower rates of cognitive decline and decreased risk for Alzheimer's disease and other forms of dementia.

That said, the research is mixed. For example, a 2016 meta-analysis published in The American Journal of Clinical Nutrition found that consuming either one serving of fish per week or 100 milligrams of DHA per day decreased individuals' risk for dementia generally and Alzheimer's disease specifically. But a 2012 review published in The Cochrane Database of Systematic Reviews found no link between omega-3s, cognitive function, and dementia risk.

Omega-3s and mood

In addition to possibly improving the thinking side of your brain, omega-3s may also give the feeling part of your brain a boost. When it comes to tackling depression, the Harvard Medical School explained that "meta-analyses ... generally suggest that the omega-3s are effective, but the findings are not unanimous because of variability between doses, ratios of EPA to DHA, and other study design issues." They noted, however, that the omega-3 regimen with the greatest depression-fighting activity appears to have at least 60% EPA relative to DHA. It's unclear, though, exactly how EPA and DHA work as antidepressants. Because they can easily pass through the blood-brain barrier and cross the membranes of individual brain cells, it's possible they interact directly with mood-regulating molecules like serotonin.

The Harvard Medical School also pointed out that omega-3s may help ease anxiety symptoms in those coping with other physical or mental conditions. But, as with the connection between omega-3s and depression, more research is needed to better understand the possible link between omega-3s and reductions in anxiety.

If you or someone you know is struggling with mental health, please contact the Crisis Text Line by texting HOME to 741741, call the National Alliance on Mental Illness helpline at 1-800-950-NAMI (6264), or visit the National Institute of Mental Health website.

Omega-3s and cancer

Research suggests that getting plenty of omega-3s may help prevent certain types of cancer. In an interview with WebMD, registered dietitian Sarah Rafat explained: "Omega-3 fatty acids are thought to reduce inflammation in the body. And a variety of cancers have been linked to chronic inflammation." These cancers include colorectal, liver, lung, and prostate. Omega-3s may also slow the growth of tumors and encourage apoptosis, the programmed self-destruction of diseased or damaged cells. WebMD notes, however, that study results have been mixed, with some showing a positive link between dietary omega-3s and cancer risk and others showing no connection between the two.

For those who've received a cancer diagnosis and are undergoing treatment, omega-3s may help reduce cancer-related complications. According to a 2019 paper published in Nutrients, 20%–80% of cancer patients use dietary supplements after their diagnosis to help manage symptoms caused by the cancer itself or treatments like chemo and radiation. The authors noted that omega-3s are often included as part of nutritional therapy for cancer patients because of the fats' many benefits. They may be able to address issues such as lack of appetite, cachexia (extreme weakness and body wasting), pain, depression, and paraneoplastic syndrome (a condition in which the body's immune cells begin attacking healthy tissue while trying to combat cancerous cells).

Omega 3s and eye health

Omega-3s, particularly DHA, play important roles in eye development, function, and health. In utero, DHA is needed for proper development of the retina, the light-sensitive part of the eye (via the Linus Pauling Institute). If a fetus doesn't get enough DHA when the retina is forming, it can lead to permanent abnormalities. DHA is found in high concentrations in the membranes of retina cells, and it's also needed for the regeneration of rhodopsin, the pigment in retina cells that allows them to transmit light signals to the brain.

Getting adequate amounts of DHA has also been shown to reduce the risk of several eye conditions, including dry eye, macular degeneration, and glaucoma (per All About Vision). Research suggests that those with an omega-6 to omega-3 ratio of 4:1 were far less likely to get dry eye than those with the more prevalent ratio of 15:1. Animal studies suggest that directly applying omega-3s to the eye may also reduce inflammation for those who already have dry eye. Macular degeneration is a condition in which individuals gradually lose central vision, but those who consume the most omega-3s are 30% less likely to get the condition. Other research looking specifically at supplements didn't find a link between omega-3s and decreased risk for macular degeneration, so it's possible that supplements don't carry the same benefits as fish. Omega-3s may also prevent glaucoma (damage caused by high pressure inside the eye) by helping the fluid inside the eye drain properly.