The One Type Of Fat That's Best For Beating Winter SAD & Fighting Inflammation

Registered Dietitian By Jessica Cording, M.S., R.D., CDN
Registered Dietitian
Jessica Cording, M.S., R.D., CDN, INHC is a registered dietitian, health coach, and writer with a passion for helping people streamline their wellness routine and establish a balanced relationship with food and exercise.
The One Type Of Fat That's Best For Beating Winter SAD & Fighting Inflammation

Image by Cameron Whitman

I get a lot of questions from clients about fish oil. What is it, exactly? What is it good for? Can we get enough from food? Is it possible to get too much? How should we use fish oil supplements? I know it can be overwhelming to try to sift through all that information out there (I kid you not: Google "fish oil" and you'll get well over 500 million search results in a matter of seconds). To save you all that pointing and clicking, here are the basics of what you need to know.

What is fish oil?

Fish oil is basically what it sounds like: oil derived from the tissues of fatty fish. You can get it from consuming fish as part of your regular diet or from taking a fish oil supplement. Some of the fish most commonly consumed as sources of fish oil include mackerel, herring, tuna, and salmon. Cod liver is commonly used for supplement forms. 

Fish oil is primarily consumed as a source of omega-3 fatty acids, polyunsaturated fatty acids. Of the three types of omega-3s, fish oil provides eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA is a 20-carbon fatty acid that's responsible for producing chemicals called eicosanoids, which work to reduce inflammation. EPA has also been noted for its association with decreased symptoms of depression. DHA is a 22-carbon fatty acid that is extremely important for normal brain development and proper brain function.

There is a third source of omega-3 fatty acids, alpha-linolenic acid (ALA), which is plant-based and a precursor to EPA and DHA. This means that ALA we consume in foods like chia seeds, flaxseeds, pumpkin seeds, walnuts, and certain oils can be converted into EPA and DHA in the body, though the process is not incredibly efficient. ALA is considered an essential fatty acid since our body is unable to synthesize it on its own, meaning we need to consume it from food. In this article, however, we'll focus primarily on EPA and DHA when we talk about omega-3s.

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What are omega-3s helpful for?

Omega-3 fatty acids, both in food and supplement forms, are key to numerous body processes and have been studied for a range of potential health benefits. They're famous for helping the brain and aiding in mood disorders. They make up part of the cell membrane and are also involved in the functioning of cell receptors in those membranes. Omega-3s have also been shown to play a role in genetic function. Additionally, they are also involved in the production of hormones that help regulate contraction of arterial walls, blood clotting, and inflammation. They also help beat inflammation by supporting the endocannabinoid system, the "master regulatory" system in the body.

Because inflammation is the root cause of so many ailments, omega-3s have been researched as potential factors in the prevention and treatment of conditions such as:



Cognitive decline

Depression and other psychiatric conditions


Heart disease

High blood pressure

High cholesterol and overall dyslipidemia

High triglycerides


Rheumatoid arthritis


How much fish oil do you need per day?

It is recommended that healthy adults consume about 1.1 to 1.6 grams per day of omega-3 fatty acids. This number reflects what is considered an adequate amount of ALA, since that's technically the only omega-3 fatty acid that is essential. If you're regularly consuming fish or fish oil, you will reach that amount more quickly.

There is currently no established recommended amount of DHA and EPA that should be consumed; however, many health care professionals and organizations recommend that healthy adults consume 250 to 500 milligrams of combined EPA and DHA each day. While there is no established guideline for pregnancy, health professionals typically recommend that pregnant women aim for 650 milligrams of total omega-3s per day, with 300 milligrams coming from DHA. This is to account for the needs of the developing baby's brain, nervous system, and eyes.

Health care professionals may recommend different amounts for specific conditions. For example, research has looked at higher intake of omega-3s as a potential aid in depression treatment. Higher amounts may also be recommended for certain heart conditions, especially high triglycerides. Higher intake of omega-3s has also been associated with decreased risk of certain cancers such as breast, prostate, renal, and colorectal, with more research being done on other types of cancer.

You don't have to freak out about counting milligrams, though. Translated to how much fish you need to eat to reach that amount, even just a few 3-ounce servings per week give you a big leg up. That said, it's not uncommon that restaurants serve larger amounts or that we may serve ourselves more in one sitting than that 3-ounce amount. The World Health Organization (WHO) recommends eating at least two 6-ounce portions of fish each week, and the 2015 to 2020 Dietary Guidelines for Americans recommends eating at least two servings of fish per week (about 8 ounces per week) to provide an average of 250 milligrams (0.25 grams) of EPA and DHA.

Just to give you a few examples, a 3-ounce serving of wild Atlantic salmon provides 1.22 grams of DHA and 0.35 grams of EPA. Atlantic herring provides 0.94 grams of DHA and 0.77 grams of EPA. Wild rainbow trout provides 0.44 grams of DHA and 0.40 grams of EPA.

Something I see a lot with clients is that they eat a lot of one type of fish and completely skip others. Having more variety can help you cover your bases without getting bored or accidentally consuming high levels of mercury or other contaminants that, unfortunately, may be present in fish. It's worth doing a little research to identify some high-quality, sustainable, and safe options you'll enjoy. Sound overwhelming? The good news is that there are some great resources to help you out. I always send my clients to Monterey Bay Aquarium's Seafood Watch website and app. Also, don't be afraid to try new-to-you stuff—I promise it's never too late to expand your palate. To give you a personal example, I didn't find out about how much I loved sardines until I was 31, and they've since become a pantry sample.   

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What other nutrients are in fish oil?

While omega-3s get the most airtime, fish oil also provides some other key nutrients. A few important ones are vitamin A and vitamin D, both of which are fat-soluble.

Vitamin A is important for immune system function, eye health, and reproduction as well as in the formation and general function of organs like the heart, kidneys, and lungs. Vitamin D plays a role in our health by enhancing the absorption of calcium to help support strong bones and protect against issues like fractures and osteoporosis. It also plays a role in immune system and neuromuscular function, modulation of cell growth, and genetic function. It has also been studied for its potential role in protecting against diabetes, hypertension, and other medical conditions.

When should you supplement with fish oil?

If fish is a regular part of your diet, you may not need to supplement with fish oil. However, if you don't eat much fish or have a health condition that increases your needs or where you want to make sure you're consistently covering your bases, consider a supplement. Talk to your doctor about the appropriate form and dosage. Despite what it says on a supplement label, you may need a different amount. For example, you may not actually need to take a fish oil supplement every day to meet your needs. Additionally, your health care provider can also provide you with tips to help you fit that supplement into your routine.

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When DOESN'T it make sense to take fish oil?

Fish oil supplementation is not appropriate for everyone. A big one is that if you're allergic to fish, you should talk to your doctor about whether fish oil supplements are safe for you, based on which specific types of fish you're allergic to. As a general rule of thumb, I encourage my clients with fish allergies to skip supplements and instead get those omega-3 fatty acids from other sources such as chia and flaxseeds, walnuts, grass-fed beef, and eggs.

Fish oil supplements can interfere with certain medications, so check in with your health care provider or pharmacist. Some common interactions include blood-thinning and blood pressure medications as well as diabetes medications. If you have a surgically implanted device used to treat an irregular heartbeat, the blood-thinning impact of fish oil could also be a concern. 

If you're taking fish oil to treat depression, be open with your doctor about how you're feeling. If you're feeling severely depressed, having manic or depressive episodes, or are struggling with feelings of hopelessness or thoughts of suicide, please get help. While fish oil can be a part of an effective treatment plan, you may require additional approaches to stabilize and support your mental well-being.

Lastly, if you are taking other supplements, check what's in them to make sure you're not unintentionally taking more fish oil than you need.

Are there any side effects of fish oil?

While fish oil supplementation is considered likely safe in low doses (less than 3 grams per day) for most people, there are some potential side effects to be aware of, especially with high doses. For example, high doses may interfere with blood clotting and cause you to bruise or bleed more easily. High doses should only be used with a doctor's supervision, especially if you have a health condition, recently had surgery, are the recipient of an organ transplant, or are on other medications. 

Some common but less serious side effects that may be experienced with lower doses are bad or "fishy" breath, belching, heartburn, nausea, loose stools, nosebleeds, and rashes. Freezing or refrigerating supplements may help reduce these side effects.

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What type of supplement should you buy?

Fish oil supplements are generally sold as a liquid or capsule. Many people prefer the convenience of capsules, so the bulk of fish oil supplements are sold this way. Because the omega-3s are susceptible to degradation caused by exposure to oxygen, light, and heat, supplements should be sold in dark or opaque bottles and stored in a cool, dry place. The refrigerator or even freezer is a good place to store fish oil capsules, especially after opening the bottle. If it starts to smell rancid, toss it.

I know there are lots of options on the market like gummies and flavored varieties, but generally, I'd encourage sticking with a supplement without these added flavors or colors. Aside from the fact that the gummies tend to have lower levels of omega-3s than capsules, that little bit of added sugar can add up over time. At the end of the day, it's fish oil—it should taste like fish. 

Quality is something my clients ask about a lot—how do you know if it's a good option? Because supplements are not regulated as tightly as prescription medications, look for a fish oil supplement that is tested by a third party.

Sustainability is another issue that frequently comes up when talking about fish oil supplements, and for good reason. I mean, fish oil is made from real fish in the ocean—those fish are a key part of that delicate ecosystem. Overfishing is absolutely a concern when it comes to supplements as it does with fish that we eat. If you need some guidance, the Marine Stewardship Council (MSC) is an organization that evaluates fisheries for their sustainability practices. If you see fish and fish oil with the MSC "blue label," that means that that fishery takes only an established sustainable amount of fish from the water, complies with relevant laws, and ensures that its operations have a low environmental impact.

When should you take fish oil?

There are no hard-and-fast rules about when you should take fish oil, but if you're taking more than one capsule per day, many health care professionals recommend splitting it up into two doses: one in the morning, and one at night. In general, I recommend my clients take supplements at a time of day they'll remember to take them, when it's easy to make it a part of their regular routine.

To help with tolerance (and to mask the fishy taste if you're sensitive), try taking your fish oil supplement with a meal. You may not need it with a fish meal, though!

Depending on how much fish oil someone needs based on what is going on with them, it may not need to be a daily supplement. For example, for someone who eats fish only once or twice a week and it's not generally the fatty type, taking a supplement on days they don't eat fish can be a good way to work it in.

One thing I learned the hard way, though: Maybe don't add your fish oil supplement to your smoothie. Even when you've got tons of other stuff in there, the flavor profile is a little on the "tuna noodle casserole" side. That's definitely one I filed in the "S*** I tried so you don't have to" category. That said, if you add your supplement to your smoothie and you love it, go for it—it's really whatever works for you!

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What if you're vegan?

This might sound obvious, but if you're on a vegan diet, then fish oil supplements are not going to be a good fit. However, there are lots of marine-algae-based supplements available. You can also incorporate sea vegetables into your regular diet as well as food sources of ALA. If you need a boost and know that sea vegetables and sea vegetable supplements aren't your thing, try flax oil.

The bottom line?

Fish oil, whether it comes from food sources or a supplement, can help support overall health by providing us with omega-3 fatty acids EPA and DHA along with other key nutrients. Consuming fatty fish at least twice a week can help you cover your nutritional bases, but if it's not a regular part of your diet, you can fill the gap with supplements. To help you choose high-quality, safe, and sustainable products, take advantage of available resources to help you make an educated decision.

Just be sure to check in with a trusted health care provider, especially if you're pregnant, have a medical condition, or are taking any medications. The goal is to feel great, stay well for the long haul, and to establish a routine that works for your real life.

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