The most effective way to increase your omega-3 intake is to eat fatty fish two to three times per week, which provides the forms of omega-3 your body uses most readily: EPA and DHA. A single 100-gram serving of Atlantic mackerel delivers about 2,500 mg of combined EPA and DHA, while farmed Atlantic salmon provides around 1,800 mg. If you don’t eat fish, plant sources, algal oil supplements, and fortified foods can fill the gap, though each comes with trade-offs worth understanding.
Why the Type of Omega-3 Matters
There are three main omega-3 fatty acids: ALA, EPA, and DHA. ALA comes from plants. EPA and DHA come primarily from seafood and algae. Your body can technically convert ALA into EPA and DHA, but the conversion rate is poor. Estimates suggest only 5 to 10% of ALA converts to EPA, and as little as 1% or less converts to DHA in adults. This means that eating flaxseeds alone won’t reliably raise your DHA levels the way eating salmon will.
EPA and DHA are the forms that do the heavy lifting for heart health, brain function, and controlling inflammation. ALA is still classified as an essential fat (your body can’t make it at all), but for practical purposes, getting EPA and DHA directly from food or supplements is far more efficient than relying on your body’s conversion machinery.
Best Fish and Seafood Sources
Fatty, cold-water fish are the richest natural sources of EPA and DHA. Here’s what a 100-gram serving (roughly the size of a deck of cards) provides in combined EPA and DHA:
- Atlantic mackerel: about 2,500 mg
- Farmed Atlantic salmon: about 1,800 mg
- Chinook salmon: about 1,400 mg
- European anchovies: about 1,400 mg
- Sockeye salmon: about 1,200 mg
- Canned sardines: about 1,000 mg
Two servings of salmon per week would give you roughly 3,600 mg of EPA and DHA, well above what most health organizations consider adequate for general health. The European Food Safety Authority recommends 250 mg per day of combined EPA and DHA for adults, which works out to about 1,750 mg per week. For people with existing heart disease, the American Heart Association suggests approximately 1,000 mg per day.
Canned sardines and anchovies are especially practical. They’re inexpensive, shelf-stable, and require no cooking. Toss sardines on toast with lemon and a pinch of salt, or stir anchovies into pasta sauce where they dissolve and add savory depth without a fishy taste.
Mercury: Which Fish to Favor
Mercury is a legitimate concern, but it shouldn’t keep you from eating fish altogether. The species highest in omega-3s tend to be low in mercury. According to FDA testing data, salmon (fresh or frozen) averages just 0.022 parts per million of mercury, sardines average 0.013, and anchovies average 0.016. These are among the cleanest options available.
The fish to limit or avoid are king mackerel (0.73 ppm), shark (0.979 ppm), swordfish (0.995 ppm), and Gulf of Mexico tilefish (1.123 ppm). Note that king mackerel is very different from Atlantic mackerel. Atlantic mackerel is a small, oily fish with low mercury, while king mackerel is a large predator that accumulates far more.
Plant-Based Sources of Omega-3
If you eat a mostly plant-based diet, you can still get plenty of ALA. Three tablespoons of ground flaxseed provide about 4,800 mg of ALA, and two tablespoons of chia seeds deliver roughly 3,700 mg. Walnuts, hemp seeds, and canola oil are other solid sources. The adequate intake for ALA is 1,100 mg per day for women and 1,600 mg per day for men, so even a single tablespoon of ground flaxseed in your morning oatmeal gets you there.
The catch, again, is conversion. Even a generous ALA intake won’t substantially raise your DHA levels. If you’re vegetarian or vegan and want the benefits of DHA specifically, you’ll need a supplement made from algae rather than fish.
Algal Oil for Vegans and Vegetarians
Algal oil is extracted from microalgae, the original source of DHA and EPA in the marine food chain (fish accumulate omega-3s by eating algae, or by eating smaller fish that ate algae). A 2025 randomized controlled trial comparing microalgal oil to fish oil supplements found that the bioavailability of DHA and EPA from algal oil was statistically equivalent to fish oil in plasma levels after 14 weeks. This makes algal oil a reliable option if you avoid seafood entirely.
Most algal oil supplements emphasize DHA over EPA. If you want both, check the label and choose a product that lists amounts of each. A dose providing at least 250 mg of combined DHA and EPA daily matches the baseline recommendation for adults.
Choosing a Quality Supplement
Whether you choose fish oil or algal oil, freshness matters more than most people realize. Researchers at George Washington University tested 72 of the most popular omega-3 supplement brands over six years and found that many exceeded recommended limits for oxidation, meaning the oil had gone rancid. Rancid omega-3 supplements may not provide the same benefits, and could introduce harmful oxidation byproducts.
A simple test: if your fish oil capsule has a strong fishy smell or taste, it’s likely oxidized. Fresh fish oil is nearly odorless. Be cautious with flavored supplements, since added flavoring can mask signs of rancidity. Store your supplements in a cool, dark place (the refrigerator works well), and pay attention to expiration dates. Buying from brands that list third-party testing on the label is a reasonable way to improve your odds of getting a fresh product.
Reducing Omega-6 Is Part of the Equation
Increasing omega-3 is only half the picture. Your body uses omega-6 and omega-3 fatty acids in competing pathways. Omega-6 fats, found abundantly in soybean oil, corn oil, sunflower oil, and most processed snack foods, promote inflammation when consumed in excess relative to omega-3. Historically, humans ate omega-6 and omega-3 in roughly a 4:1 ratio. In modern Western diets, that ratio has ballooned to around 20:1.
You don’t need to obsessively track this ratio, but a few practical shifts help. Cook with olive oil or avocado oil instead of soybean or corn oil. Check ingredient labels on packaged foods, where “soybean oil” and “vegetable oil” appear far more often than most people expect. Cut back on fried fast food, which is almost always cooked in high-omega-6 oils. These changes reduce the omega-6 side of the ratio while you build up the omega-3 side with fish, seeds, and supplements.
Signs Your Intake May Be Low
Omega-3 deficiency doesn’t announce itself with a single dramatic symptom. Instead, it tends to show up as a cluster of low-grade issues: persistently dry or irritated skin, an uptick in acne, dry eyes, joint stiffness, or hair that’s thinning or changing in texture. Some research also links low omega-3 status to a higher incidence of depression, though depression has many contributing factors.
None of these symptoms are specific to omega-3 deficiency on their own. But if you recognize several of them and you rarely eat fish, it’s worth increasing your intake and seeing if things improve over a few weeks. A blood test can confirm your omega-3 status by measuring the fatty acid composition of your red blood cells, which reflects your intake over the previous several months.
Simple Weekly Targets
For most people, the goal doesn’t need to be complicated. Eat fatty fish twice a week, choosing low-mercury species like salmon, sardines, mackerel (Atlantic, not king), or anchovies. Add a tablespoon of ground flaxseed or chia seeds to meals most days for ALA. If you’re plant-based, take a daily algal oil supplement providing at least 250 mg of combined DHA and EPA. And swap out high-omega-6 cooking oils for olive oil when you can. Those four moves, applied consistently, will shift your omega-3 status meaningfully within a couple of months.