Omega-3 on keto: do you need it and where to get it
You can take omega 3 on keto from oily fish, fish oil or algae oil, though our searches found no human trials testing omega-3 supplements in adults on keto. Whether you need one depends on what you eat: the NHS benchmark is two portions of fish a week, one of them oily. If you rarely eat oily fish, a teaspoon of algae oil fits keto macros.
Passionate about writing and a graduate in clinical dietetics. She is particularly interested in phytotherapy and the effects of ketogenic nutrition on cognitive brain function.
Can you take omega-3 on keto? You can take omega-3 on keto: fish oil and algae oil are fats without carbohydrate. The omega-3 fatty acids EPA and DHA do not raise blood sugar, and meta-analyses show no effect or a small improvement in fasting glucose, with no change in HbA1c [9].
What nobody can say yet is how supplements work on keto specifically. Two PubMed searches found no human trials of omega-3 supplementation in adults on a ketogenic diet [3].
That means the honest answer is simple: omega-3 is compatible with keto, but it is not a keto-specific shortcut. If it fits your food pattern, it sits among other keto supplements.
Do you need omega-3 on keto?
Do you need omega-3 on keto? Whether you need omega-3 on keto depends on what you eat. The amount of EPA and DHA in a keto diet depends on food choices: oily fish versus meat, dairy, nuts and plant oils, including the plant sources covered in our guide to omega-3 foods [3].
The NHS benchmark is two portions of fish a week, one of which is oily fish, about 140 g each [12]. SACN’s UK guideline is 450 mg of long-chain omega-3 a day, and UK adults aged 19 to 64 eat about 56 g of oily fish a week [13]. If you are choosing oily fish, our guide to what fish to eat on keto is a useful next read. For context on mercury, salmon and trout average 0.03 mg/kg, mackerel 0.11 mg/kg, compared with swordfish at 1.21 mg/kg in European fish flesh, from more than 12,000 measurements in 20 countries [11]. The omega-6 to omega-3 ratio of Western diets is estimated at 15:1 to 16.7:1 (mainly US diets, not a UK measurement), but EFSA has set no ideal ratio [4].
Fish
Mean total mercury [mg/kg]
Counts as oily fish (NHS)
Salmon
0.03
yes
Trout
0.03
yes
Herring
0.04
yes
Mackerel
0.11
yes
Tuna
0.29
no
Shark
0.69
no
Swordfish
1.21
no
Data for European fish flesh from more than 12,000 measurements in 20 countries, EFSA 2012 [11]. NHS: shark, swordfish and marlin are not for anyone pregnant, trying to get pregnant or under 16; other adults should have at most 1 portion a week of these fish [12].
Oily fish on keto, without the usual bread?
Keto bagels, tortillas and mini rolls give smoked salmon or sardines a base. See keto breads in the BeKeto shop.
Is fish oil keto-friendly? Fish oil is keto-friendly as a fat. What can make a product less keto-friendly is the format: gummies and flavoured syrups may contain sugar, so check the carbohydrate on the label.
Capsules and liquids are both common forms of omega-3 fish oil, but in one storage study, liquids oxidised faster than capsules after opening: peroxide value reached up to 44.6 meq/kg in bottled oils compared with 7.6 meq/kg in capsules [6]. The GOED voluntary industry monograph sets PV 5 meq/kg, p-AV 20 and TOTOX 26 together [5].
Take omega-3 with a meal containing fat for better absorption; in a short-term absorption study, 72 volunteers took omega-3 for 2 weeks [7]. On keto, that is almost any meal.
Did you know? GOED treats p-anisidine value and TOTOX as not applicable to flavoured oils, because flavour components distort the test.
Does an omega-3 supplement break a fast?
Does an omega-3 supplement break a fast? Whether an omega-3 supplement breaks a fast depends on your fasting rule. It contains fat and therefore calories, but no carbohydrate, and omega-3 does not raise blood sugar [9].
If your rule is zero calories, take it with your first meal. That also fits the absorption advice to take omega-3 with a meal containing fat, based on a 2-week study in 72 volunteers [7].
For fasting blood tests, follow the laboratory’s instructions. For autophagy, our sources contain no human data on omega-3 and autophagy, so we make no claim either way.
Did you know? EPA and DHA are made at the base of the marine food chain by microalgae and other marine microorganisms; fish obtain them mainly from their diet.
Which omega-3 supplement suits keto best?
Which omega-3 supplement suits keto best? The omega-3 supplement that suits keto best lists EPA and DHA per serving, contains no carbohydrate and stays fresh. Verdict: MEGA Omega 3 Vegan Algae Oil comes out best on keto, because a 5 ml teaspoon gives 570 mg DHA and 185 mg EPA, above SACN’s population intake goal of 450 mg of long-chain omega-3, not a formal DRV [14] [13].
The oil is from Schizochytrium sp. microalgae, and the product is fish free, free from allergens requiring declaration and vegan [14]. The algae oil used in production has a typical TOTOX value below 8, against the GOED industry monograph limit of 26; this refers to the algae oil ingredient, not the finished lemon product [14] [5]. As a lemon-flavoured liquid, take it from a spoon or in cold dishes, not for frying [14].
In a 6- and 14-week randomised double-blind trial involving 74 adults, microalgal oil raised blood EPA and DHA as effectively as fish oil; it was run by algal oil producer dsm-firmenich, with five authors employed there and the sixth a contracted statistician [2].
“This product is intended for adults. Not for use by children or by women who are pregnant or breastfeeding. If you take anticoagulant medication or are due to have surgery, consult your doctor before use.” [14]
Need a fish-free omega-3 for keto?
MEGA Omega 3 Vegan is a liquid algae oil you can add to cold keto dishes such as salads or yoghurt. One 5 ml teaspoon provides 570 mg DHA and 185 mg EPA.
This product is intended for adults. Not for use by children or by women who are pregnant or breastfeeding. If you take anticoagulant medication or are due to have surgery, consult your doctor before use.
How much omega-3 per day?
How much omega-3 per day? SACN’s UK guideline is 450 mg of long-chain omega-3 a day [13]. Take omega-3 with a meal containing fat, based on a 2-week study in 72 volunteers [7].
For practical details on portions, labels and daily amounts, read our guide to how much omega-3 per day.
Is there vegan omega-3 for plant-based keto?
Is there vegan omega-3 for plant-based keto? Algae oil gives EPA and DHA without fish. Plant ALA converts poorly to DHA: in young women given 700 mg labelled ALA, estimated net conversion to DHA was 9% over 21 days, while labelled DHA was not detected in 6 young men [1].
For the plant-based options, see our guide to vegan omega-3.
Frequently asked questions (FAQ)
Are two eggs enough omega-3?
Are two eggs enough omega-3? Two eggs are not a main omega-3 source. The NHS benchmark counts oily fish, such as salmon, mackerel, sardines, herring and trout [12].
What other supplements do people take on keto?
What other supplements do people take on keto? Other supplements people take on keto are mainly electrolytes, including sodium, potassium and magnesium, and vitamin D. “Vitamin D contributes to the maintenance of normal bones”, for products that are at least a source of vitamin D.
Does omega-3 help with weight loss on keto?
Does omega-3 help with weight loss on keto? Omega-3 does not help with weight loss on keto or any diet. In 11 RCTs involving 617 people, the difference in body weight was 0.00 kg [10].
What is the downside of omega-3?
What is the downside of omega-3? The downside of omega-3 shows at higher doses. In 8 trials with 83,112 people, mostly in people with heart disease or at high risk, atrial fibrillation increased with dose: RR 1.12 up to 1 g/day and RR 1.51 above 1 g/day [8]. If you take anticoagulant medication or are due to have surgery, consult your doctor before use.
Discover more in the BeKeto keto shop
Besides supplements, the shop has keto vitamins, snacks and bread.
A graduate in clinical dietetics whose interests begin, not end, with the word diet. She has written specialist content on nutrition. She is fascinated by contemporary food culture, phytotherapy and the effects of the ketogenic diet on cognitive brain function. She promotes diet therapy and the nutritional treatment of disease.
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