There is well-established evidence that regular intake of the omega-3 fats EPA and DHA can actually lower triglycerides, may help lower risk of rheumatoid arthritis and cardiovascular disease and may boost immunity by supporting B cell function, among other potential benefits.

Omega-3 fats are essential fatty acids. This means that your body needs them to work normally, but it doesn't make them so they must instead be eaten. (Most nutrition surveys show most Americans aren't getting enough omega-3 fats in their diets.)

The omega-3 fats include eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and alpha-linolenic acid (ALA). The best food sources of EPA and DHA are wild, cold-water, oily fish: salmon, sardines, anchovies, tuna and trout. ALA comes primarily from plant foods, such as flax, hemp, chia, nuts and green leafy veggies. And, a just-published study found high levels of all three types in organic whole milk.

After more than 25,000 research studies, there are ample data showing omega-3 fats are more than just necessary and have a number of added benefits to your health. The two that have the most research support for improving health are EPA and DHA, though ALA is important as well. There is well-established evidence that regular intake of the omega-3 fats EPA and DHA can actually lower triglycerides, may help lower risk of rheumatoid arthritis and cardiovascular disease and may boost immunity by supporting B cell function, among other potential benefits.

Understandably, as with many hot-button nutrients, omega-3s' super potential has led to much interest in supplementation and fortification: the omega-3 supplement industry is booming and supermarket shoppers can now find many foods fortified with these fats, including eggs, milk, peanut butter, margarine and yogurt. The authors of this new review study call for establishment of a dietary reference intake (DRI) for omega-3s, due to concern that overzealous consumption may result in adverse health effects. They propose setting a daily value (DV) and specifying a maximum amount beyond which consumption might not be safe. No specific values were proposed in this paper. And the takeaway seems to be that we should keep seeking out healthy sources of omega-3s, especially from whole food (natural) sources such as oily fish, but should be cautious and moderate with supplements and fortified foods until clearer parameters are advised.

The review's conclusions have certainly sparked much debate. "If diets rich in omega-3s were bad for humans, we would expect to see poor health in populations like the Japanese, Norwegians or especially people like the Greenland Eskimos-who routinely eat 9 to 14 grams of omega-3s each day-yet we see quite the opposite," says Doug Bibus, Ph.D., renowned omega-3 expert and faculty member at the Center for Spirituality and Healing at the University of Minnesota. Nine to 14 grams a day of omega-3 fats is equivalent to eating about 1.5 to 2.5 pounds of wild salmon. Daily. The Greenland Eskimo population has the lowest cardiovascular mortality in the world.

So How Much is Safe?

The U.S. Food and Drug Administration says a safe intake of EPA and DHA (combined total) is up to 3 grams daily. European guidelines state that a combined intake of up to 5 grams per day of EPA and DHA is safe. Since the average American consumes only around a quarter of a gram per day, there's no need for most of us to be alarmed by scary headlines like "Hold the Salmon."

What Do We Do From Here?

Look at the big picture: the majority of data suggests you should regularly get omega-3s in your diet. From food, this means eating cold-water, oily fish-like those listed above-at least twice per week. This is in line with the American Heart Association's recommendations. Further, include plant sources of omega-3s, such as walnuts, almonds, chia, hemp and flax seed, in your diet. And, be sure to talk with your doctor before adding a supplement to your diet or piling on the fortified foods.

Many omega-3 supplements contain vitamin A, which, if taken in high doses, can lead to vitamin A overdose and toxicity. Some symptoms include joint pain, nausea, and rash or skin irritation. It could even lead to liver damage over time.

What happens when you're told to go fish, but you don't have access to a fresh piece of salmon? Or if you simply don't like fish? Or if you don't have it in your budget to dine on halibut a few times a week?

You're not alone. Despite Dietary Guidelines recommending seafood as part of a healthy diet, "[seafood is] under-consumed in a typical American diet or eliminated from certain diets such as vegetarian or vegan diets.

"Most people do not consume enough fish on a daily basis to meet their requirements for essential omega 3 fatty acids, and many would prefer to take a supplement than eat fish daily or 3-4 times a week," says Alicia Galvin, RD, a registered dietitian for Sovereign Laboratories.

So when you can't go fish, supplements are your next best option—and a popular one, at that.

Fish oil supplements are the most commonly taken nonvitamin/nonmineral supplement in America, according to a National Health Interview Survey.

"Fish oil is known for its high content of omega-3 fatty acids. The body can't make omega-3s, so we must get them through the food we eat. For those who do not get optimal amounts of omega-3s from their diet, supplements can be useful and effective," says Danielle Gaffen, MS, RDN, a registered dietitian who specializes in autoimmune diseases.

Gaffen tells us that fish oil supplements contain two types of omega-3 fatty acids that occur naturally in fish and seafood: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). "Both are types of essential omega-3s that make unique and irreplaceable contributions to our body's function, like overall brain and nervous system functioning as well as lower inflammation," explains Gaffen.

There are many benefits of taking a fish oil supplement every day, but there are also some lesser-known negative side effects you should be aware of. So we asked experts about the side effects you can expect to experience when taking a fish oil supplement. Read on, and for more on healthy eating, don't miss Healthiest Foods to Eat Right Now.

You may protect your brain

When it comes to making a list of foods that boost brain power, omega-3 containing foods [like fish oil] are generally at the top. This is because roughly 60% of the brain is made of fat, and half that amount is omega-3 type fats," says Trista Best, MPH, RD, LD, a Registered Dietitian at Balance One Supplements. "It has been found that omega-3 rich foods can help prevent cognitive diseases like Alzheimer's and slow mental decline. The brain requires omega-3 fat to make nerve cells, which are vital to memory and one's ability to learn."

You may notice lower levels of inflammation

Fish oil also may help decrease inflammation. This is due to fish oils' anti-inflammatory properties. This results in reduced joint pain and stiffness," says Allison Gregg, RDN, LD/N, a registered dietitian and Nutritional Consultant at Mom Loves Best. The National Institutes of Health (NIH) notes that omega-3 fatty acids may help relieve symptoms of rheumatoid arthritis—an autoimmune disease characterized by chronic inflammation of the joints—but more research is still needed to confirm this.

You may start to see healthier hair and skin

"Having enough omega 3s is also important for skin and hair health, which can suffer if one is deficient in omega 3s," says Galvin.

You may experience some bad breath

"When you take fish oil every day, you may experience some fishy breath for a couple of hours after taking it. This is unpleasant for many people, but can be avoided if you switch to a flaxseed oil supplement," says Megan Byrd, RD, a registered dietitian with a food blog called The Oregon Dietitian.

Galvin explains that this aftertaste may be more prevalent if you have a poorly functioning gallbladder, as "having a 'fishy aftertaste can be a side effect due to a reduced ability to properly digest fats."

Men may experience improved fertility

"Men who take fish oil supplements every day may experience improved fertility. In a recent study published in JAMA Network Open, researchers found that fish oil supplements resulted in improved sperm count and fertility hormone levels," says Lauren Manaker MS, RDN, LD, registered dietitian and author of Fueling Male Fertility.