Verified by 
Fish oil supplements are on track to become a $4 billion dollar industry by 2022, but alas, it’s not clear that supplements make a difference in your mood. It is clear that our omega-3 fatty acid levels affect our overall health. Our bodies can’t synthesize omega-3 fats, so we must get them either from supplements or food, particularly nuts and seeds and fish. We also know that people vary in how well they can absorb and metabolize omega-3 fats.
Many people take fish oil supplements to manage their mental health. It’s true that omega-3 fatty acids may reduce inflammation, which is linked to depression, and, research suggests, deficiencies are associated with any number of mental health problems, including dementia, bipolar disorder, ADHD, schizophrenia, and autism.
Why might that be? Besides dysregulating our immune-inflammatory system, a lack of omega-3 fatty acids could interfere with our endocrine system governing hormones and the nervous system. Your symptoms might arise from your diet or because your body doesn’t absorb these essential fats well. That’s the case for supplements.
But there’s a catch: in a 2019 overview of 31 trials analyzing the effects of omega-3 supplements, typically over six or twelve months, researchers concluded that they had “little or no effect in preventing depression or anxiety symptoms.” Ditto for hope that the pills could help children with autism or attention deficit disorder.
While there’s very strong evidence that those suffering from depression often have low omega-3 levels, the deficiency may be a marker rather than a cause. In a six-year study published this year, researchers tested omega-3 levels in nearly 3,000 participants and asked about their mental health. People with signs of depression at the beginning of the study and six years later had lower omega-3 levels than people who were never depressed. But in people whose symptoms or omega-3 levels changed, the link didn’t hold. For example, some volunteers had lower omega 3 levels and no increase in depression.
How can you use this? If you’re concerned about your mood but are not in a depression, your best bet is a variety of strategies, including exercise, time with friends and family, getting a pet, a good overall diet, community and religion, and stress relievers like yoga and meditation or music.
You may be in a depression if you experience at least two weeks of the following symptoms:
- Feeling sad or having a depressed mood.
- Loss of interest or pleasure in activities once enjoyed.
- Changes in appetite — weight loss or gain unrelated to dieting.
- Trouble sleeping or sleeping too much.
- Loss of energy or increased fatigue.
- Increase in purposeless physical activity (e.g., hand-wringing or pacing) or slowed movements and speech (actions observable by others).
- Feeling worthless or guilty.
- Difficulty thinking, concentrating or making decisions.
- Thoughts of death or suicide.
Talk to your primary care doctor, a therapist, or a psychiatrist. They can help you decide if you need to try anti-depressants, and if you do, there is evidence that adding fish oil supplements can help.
Increasing the omega-3 fats in your diet is a good bet for anyone’s overall health. The American Heart Association recommends eating fatty fish at least twice a week. A serving comes to 3.5 ounces cooked, or about a three-quarter cup of flaked fish. The best sources of omega-3 fats are wild and Alaskan salmon (canned is okay), lake trout, sardines, oysters, herring, and Atlantic mackerel. Next best are canned light tuna, catfish, crab, founder and sole, haddock, lobster, mullet, Pollock, wild and some farmed shrimp, tilapia, scallops, and squid.
Some fish contain high levels of mercury and other pollutants—a good reason to stay away. These show up in bigger predatory fish and marine mammals. The ones you are most likely to see on a menu are swordfish, shark, gulf tilefish, orange roughy, and King mackerel.
If you‘re a vegetarian or hate fish, focus on foods high in vegan sources of omega-3. Flax and chia seeds, walnut oil and walnuts, and hemp seed oil and beverages will help you get alpha-linolenic acid (ALA), one of the three omega-3 fatty acids. Docosahexaenoic acid (DHA) is the kind found in fish. The fish get it from algae, so you could eat the algae or try an algae supplement.
If you have heart disease especially, check with your doctor. Fish oil may have a thinning effect on your blood and may affect the correct dose of a blood thinner. (Warfarin is the most common.)
A version of this story appears at Your Care Everywhere.
