The short answer: Omega-3 fatty acids are essential nutrients for cats, and the two that matter most are EPA and DHA, which come mainly from fish and other marine sources. Most complete-and-balanced cat foods already contain some. Extra omega-3s may help some cats, especially with itchy skin or stiff joints, but the research in cats is still thin, more isn’t always better, and the right amount depends on your cat. Talk to your vet before adding a fish oil supplement.
If you’ve spent any time in the cat aisle (or on cat-owner forums at 1 a.m.), you’ve seen “omega-3s” on everything from kibble bags to treat pouches. So what do they actually do, does your cat need more of them, and how do you choose a product without overthinking it?
We dug into the veterinary nutrition literature so you don’t have to. Here’s what we found, in plain English.
What are omega-3s, and why do cats need them?
Omega-3s are a family of polyunsaturated fats. Cats can’t make them on their own, so they have to come from food. That’s what makes them essential fatty acids.
Together with omega-6 fats, they help to:
- provide energy,
- build healthy cell membranes (including in the skin, eyes and brain),
- help the body absorb fat-soluble vitamins, and
- make signaling molecules involved in the body’s normal inflammatory response.
Veterinary nutritionist Dr. Catherine Lenox sums it up in Today’s Veterinary Practice: fats and fatty acids also “affect skin and coat health” and “promote healthy growth and development.” [1]
The three omega-3s you’ll see on labels
| Omega-3 | Full name | Where it comes from | How useful is it for cats? |
|---|---|---|---|
| ALA | Alpha-linolenic acid | Plants: flaxseed, canola, soy | Limited. Cats convert very little ALA into EPA or DHA. |
| EPA | Eicosapentaenoic acid | Fish oil, other marine sources | Used directly by the body. |
| DHA | Docosahexaenoic acid | Fish oil, algae, other marine sources | Used directly; especially important for kittens’ eyes and brain. |
This is the most important thing to know: cats are not good at turning plant omega-3s into EPA and DHA. Cats have very low activity of the enzyme needed for that conversion. [1] That’s why the National Research Council lists requirements for EPA and DHA themselves for cats, and why AAFCO nutrient profiles include EPA + DHA for growth and reproduction. [1]
So when a label says “rich in omega-3s,” it’s worth checking which omega-3s. A product whose omega-3s come from flaxseed alone isn’t doing the same job as one with fish oil.
Does my cat already get enough omega-3?
If your cat eats a commercial food labeled “complete and balanced” for its life stage, it’s getting the essential fatty acids it needs to avoid deficiency. Many foods add fish oil specifically. [1]
That said, amounts vary a lot from food to food, and “enough to avoid deficiency” isn’t the same as the higher amounts vets sometimes use for specific reasons. Which brings us to the big question.
Omega-3 benefits for cats: what does the research actually say?
Most of what you’ll read online is borrowed from human or dog research. Studies in cats are much rarer. Here’s an honest rundown.
Skin and coat
This is the best-known use. Cornell’s Feline Health Center explains that a combination of omega-3s from fish oil and omega-6s acts “like a low-level anti-inflammatory agent,” which can make some cats less itchy. In the words of Cornell dermatologist Dr. William Miller, “they act like a botanical aspirin.” [2]
Cornell is also careful to add that fatty acid supplements “are not 100 percent effective” and that too much can have an adverse effect, so the amount should come from your veterinarian. [2] Itchy or flaky skin has many possible causes (fleas, allergies, mites, infections), so get a diagnosis before reaching for a supplement.
Joints and mobility
Vets do use fish oil as part of the plan for some cats with joint problems. [1][3] A 2021 systematic review of omega-3 supplementation in dogs and cats found just three controlled studies in cats. The reviewers reported a benefit for feline osteoarthritis and a likely benefit for cats with allergic skin disease, while calling for better-designed studies. [4] With just three cat studies to go on, our translation is: promising, not proven, and something to plan with your vet.
Kittens, eyes and brain
DHA is a building block of the retina and brain, and growing kittens need more of it than adults. That’s one reason good kitten foods include it. [1]
Kidneys, heart and other conditions
You’ll see “omega 3 for cats with kidney disease” searched a lot. Fish oil is sometimes part of veterinary diets and treatment plans for specific conditions, but this is firmly vet territory. Cats with health conditions often need a whole-diet approach, and supplements can interact with medications. Please don’t self-prescribe here.
Is fish oil safe for cats? Side effects and cautions
Generally, fish oil is well tolerated at sensible amounts. But “natural” doesn’t mean “no limit.” Possible downsides include: [1][5]
- Tummy upset: vomiting, diarrhea or a fishy burp.
- Extra calories: fat is energy-dense, which matters for cats who are already a bit round.
- Slower blood clotting, which can matter before surgery or with certain medications.
- Changes in immune function and wound healing at high doses.
- Nutrient overload from cod liver oil–style products that also carry vitamins A and D.
One detail surprised us: while the NRC has published a safe upper limit of EPA + DHA for dogs, no safe upper limit has been published for cats. [1] That’s a big reason vets are cautious about “more is better” dosing for cats.
Check with your vet before starting fish oil if your cat:
- is scheduled for surgery or has a bleeding or clotting problem,
- has pancreatitis, a history of digestive trouble, or needs a low-fat diet,
- is overweight,
- takes any medication, or
- is a kitten, pregnant or nursing.
How much omega-3 does a cat need?
There isn’t one magic number, and there’s no consensus on the best way to dose. [1] Your vet will consider your cat’s weight, diet (many foods already contain EPA and DHA), health and goals.
Two practical tips:
- Count everything. Add up omega-3s from food, treats and supplements so you don’t accidentally double up. [1]
- Start low, go slow. Introducing anything new gradually is easier on your cat’s stomach and makes it easier to spot a reaction.
How to choose an omega-3 supplement for your cat
Whether it’s an oil, a capsule or a treat, here’s a quick checklist:
- Look for EPA and DHA in milligrams. “Omega-3s” alone doesn’t tell you much. If the label doesn’t list EPA and DHA, ask the company.
- Prefer marine sources (fish, krill, algae) over flaxseed-based products for cats.
- Check the serving size and how it’s based. Is it per pump, per chew, per pound of body weight?
- Watch for extra vitamins A and D, especially if you’re also feeding a fortified food.
- Ask about quality control. Dr. Lenox recommends choosing a reputable company with good quality-control practices, calling the manufacturer about testing, and looking for third-party evaluation. [1]
- Make sure your cat will actually eat it. The best supplement in the world doesn’t help if it ends up under the couch. Many cats refuse oily liquids on their food; others happily take a treat-style supplement.
- Make it cat-specific. Skip human fish oil capsules unless your vet gives you a product and a dose.
Where omega-3s fit in Maxi’s Multi (full disclosure)
We make Maxi’s Multi, so here’s exactly what’s in it on this topic: our human-grade crispy cat bites (chicken flavor) list fish oil among the ingredients, and the pouch lists 12 mg EPA and 8 mg DHA per 10 bites (3 grams), which is the suggested daily amount for a 10-lb cat (1 bite per pound of body weight). You can see the full ingredient panel in What’s inside Maxi’s Multi. That’s a small, everyday amount in a treat your cat (hopefully) begs for. It isn’t a therapeutic dose, and it isn’t meant to replace anything your vet prescribes. If your vet recommends a specific fish oil plan, follow it, and let them know about any treats or supplements your cat already gets.
Our own cat Maxi had a rough start in life, so we’re big believers in checking in with the vet before trying anything new. That’s how we’d want any cat parent to approach supplements.
Quick FAQ
Is fish oil good for cats?
Fish oil is the main source of EPA and DHA, the omega-3s cats can use directly. It can be useful for some cats, especially under a vet’s guidance, but it isn’t automatically necessary if your cat eats a complete-and-balanced diet. [1][2]
Can I give my cat human fish oil?
It’s not recommended without your vet’s input. Human products can be dosed for people, may contain flavorings or extra vitamins, and are hard to portion for a 10-lb cat.
How long do omega-3s take to work for dry skin?
It varies. Cornell notes that diet changes for itchy skin can take roughly 7 to 30 days to show a response, and if there’s no improvement within about 30 days, it’s time to see your vet. [2]
Is flaxseed oil a good omega-3 for cats?
Not really on its own. Cats convert very little ALA (the omega-3 in flax) into EPA and DHA. [1]
Do indoor cats need omega-3 supplements?
Not automatically. Plenty of indoor cats here in the Bay Area (and everywhere else) do great on a complete-and-balanced diet. If your cat has dry skin, a dull coat or stiff joints, start with a vet visit rather than a supplement.
Sources
- Lenox, C. “Role of Dietary Fatty Acids in Dogs & Cats.” Today’s Veterinary Practice, Sept/Oct 2016 (ACVN Nutrition Notes). https://todaysveterinarypractice.com/nutrition/role-of-dietary-fatty-acids-in-dogs-cats/
- Cornell Feline Health Center. “The Challenge of Skin Disorders.” Cornell University College of Veterinary Medicine. https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/challenge-skin-disorders
- Bauer, J.E. “Therapeutic use of fish oils in companion animals.” JAVMA 2011; 239(11):1441-1451. https://doi.org/10.2460/javma.239.11.1441 (PubMed: https://pubmed.ncbi.nlm.nih.gov/22087720/)
- Magalhães, T.R., et al. “Therapeutic Effect of EPA/DHA Supplementation in Neoplastic and Non-neoplastic Companion Animal Diseases: A Systematic Review.” In Vivo 2021; 35(3):1419-1436. https://pmc.ncbi.nlm.nih.gov/articles/PMC8193331/
- Lenox, C.E., Bauer, J.E. “Potential adverse effects of omega-3 fatty acids in dogs and cats.” J Vet Intern Med 2013; 27(2):217-226. https://doi.org/10.1111/jvim.12033 (PubMed: https://pubmed.ncbi.nlm.nih.gov/23323770/)