Fish oil vs omega-3: what 1000 mg really means

On a pharmacy shelf, "fish oil" and "omega-3" boxes sit side by side, and many people assume they are the same thing. In fact, the benefit of fish oil depends on how much omega-3 it contains — EPA and DHA — while the total weight of the capsule tells you very little. "Omega 3 1000 mg" on the front of a box does not always mean 1000 mg of omega-3. In this article we explain in plain words how fish oil differs from an omega-3 concentrate, how to read the label and how to choose a quality product.

Fish oil and omega-3: the same thing or not?

Fish oil is a natural oil obtained from fish. It contains omega-3 fatty acids, but they make up only part of the oil. The rest is other fatty acids: saturated and monounsaturated fats.

Omega-3 is a group of fatty acids. Three of them are the best studied in humans:

ALA (alpha-linolenic acid) — in plants: walnuts, flaxseed, rapeseed and soybean oil;
EPA (eicosapentaenoic acid) — mainly in fish and seafood;
DHA (docosahexaenoic acid) — in fish and also in some algae.

So fish oil is a source of omega-3, while an omega-3 concentrate is made from fish oil by increasing the share of EPA and DHA. We explain what each type of fatty acid is for in our article on the difference between omega-3, 6 and 9.

Why "omega 3 1000 mg" is not always 1000 mg of omega-3

Many boxes show "1000 mg" in large print. Most often this is the total weight of fish oil in the capsule, not the EPA and DHA in it. In ordinary fish oil the share of omega-3 varies with the type of fish and processing, and it usually makes up the smaller part of the oil.

That is why, when comparing two products, you should look not at the capsule weight but at the exact amount of EPA and DHA. Two capsules can weigh the same, yet one may contain several times more EPA+DHA than the other.

How to read the label: count the EPA and DHA

A quality product lists EPA and DHA separately, in milligrams and per capsule (or per serving). Check step by step:

Find the "Ingredients" or "Supplement facts" table — look at the table, not the marketing text.
Add EPA and DHA together — this sum is what matters.
Check how many capsules make one serving: some labels give amounts per 2 or 3 capsules.
Look at the form of omega-3 (TG, rTG or EE).
Check whether an antioxidant (for example, tocopherols — vitamin E) is added.

A hypothetical example: if the label says "fish oil 1000 mg" and below it "EPA 180 mg, DHA 120 mg", one capsule provides 300 mg of the main forms of omega-3, not 1000 mg. Timing and taking omega-3 with food are covered in our guide how to take omega-3.

Feature	Ordinary fish oil	Omega-3 concentrate
What it is	Natural oil from fish	Oil with an increased share of EPA and DHA
Big number on the box	Often the total weight of oil	EPA and DHA often listed separately
EPA+DHA per capsule	Relatively low	Relatively high
Capsules for a given amount	May need more	May need fewer
What to check	EPA+DHA, freshness	EPA+DHA, form, antioxidants

What are the TG, rTG and EE forms?

In fish itself, omega-3 is mostly in triglyceride (TG) form — the same form as ordinary dietary fats. To make a concentrate, the fatty acids are often converted into ethyl esters (EE): this makes it possible to separate EPA and DHA from other fats and raise their share.

Some manufacturers then convert the ethyl esters back into triglyceride form. This is called rTG (re-esterified triglyceride). The result is a high share of omega-3 in a form close to dietary fats.

There are various studies on differences in absorption between forms, but their results are not consistent. So be cautious about precise claims such as "this form is absorbed so many percent better". Whatever the form, omega-3 is usually best taken with a meal that contains some fat.

Fish liver oil vs fish body oil: the vitamin A question

The "fish oil" many of us remember from childhood was often cod liver oil. Besides omega-3, liver oil contains vitamins A and D, in amounts that vary between products. In excess, these vitamins can be harmful.

According to the NHS, fish liver oils are high in vitamin A (retinol), which can harm an unborn baby, so they should be avoided during pregnancy and when trying for a baby unless a doctor advises otherwise.
The NHS notes that adults' total vitamin A from food and supplements should not exceed 1.5 mg a day.
If you already take a multivitamin or other products with vitamins A and D, adding liver oil may push the total too high.

Oil from the body of the fish, and concentrates made from it, usually contain little vitamin A. So check whether the label says "liver oil" or "fish oil".

Freshness and oxidation: how to judge quality

Omega-3 fatty acids oxidise easily when exposed to air, heat and light. Oxidised oil smells and tastes rancid, is unpleasant to take and its benefit is doubtful. To choose and keep a good product:

pierce a capsule and smell it: a strong rancid "old fish" smell is a bad sign;
check the expiry date and do not take an expired product;
see whether antioxidants (tocopherols, ascorbyl palmitate) are listed;
store the pack in a cool, dry place away from sunlight; do not leave it in a car or on a windowsill in the summer heat;
close the pack tightly after use.

Fishy burps after taking it are common. According to NCCIH, side effects of omega-3 supplements are usually mild: an unpleasant taste, bad breath, bad-smelling sweat, headache, heartburn, nausea and diarrhoea.

Fish oil benefits: what does research show?

EPA and DHA are considered important fatty acids for the heart and blood vessels, the brain, the retina and cell membranes. EFSA has set 250 mg of EPA+DHA a day as an adequate intake for maintaining cardiovascular health in healthy adults. EFSA has also noted that supplemental intakes of up to 5 g of EPA+DHA a day do not raise safety concerns for adults.

Research on fish oil and the risk of heart disease has produced mixed results. So it cannot be seen as something that prevents heart disease or replaces its care. Heart and vessel health depends mainly on diet, activity, not smoking and blood pressure control — see our article on foods that are good for the heart. Other areas are covered in detail in our guide to omega-3 benefits.

You can also get omega-3 from food. The NHS recommends at least 2 portions of fish a week, including 1 portion of oily fish (salmon, mackerel, herring, sardines, trout); a portion is about 140 g. In Uzbekistan sea fish is not always cheap, but frozen mackerel, herring and tinned sardines are available in many shops.

What about vegetarians and people who do not eat fish?

There are two options. The first is algal oil. According to NCCIH, algal oils are a vegetarian source of DHA, and some also contain EPA. In fact, fish themselves get their omega-3 from algae through the food chain.

The second is plant foods rich in ALA: walnuts, flaxseed and flaxseed oil, chia seeds, rapeseed oil. The body converts only a small part of ALA into EPA and DHA, so plant omega-3 does not fully replace the EPA and DHA from fish. Even so, these foods remain a good part of a healthy diet.

When to see a doctor

Talk to a doctor before starting fish oil or omega-3 if:

you take blood thinners (anticoagulants or antiplatelet medicines);
you have surgery or a tooth extraction planned;
you have a bleeding disorder, frequent nosebleeds or bruise easily;
you are pregnant, planning a pregnancy or breastfeeding;
you are allergic to fish or seafood;
you have a heart rhythm disorder, heart disease or very high triglycerides — only a doctor decides whether you need it and in what amount;
after taking it you notice black stools, blood in urine, severe abdominal pain or an allergic rash — stop taking it and see a doctor urgently.

Do not swap medicines your doctor prescribed for omega-3 and do not stop them on your own. Read about the state of the arteries in our atherosclerosis guide.

How Nutva Omega-3 can help

Nutva Omega-3 is a dietary supplement (BAA) made by NUTVA PHARM MChJ (Uzbekistan). It is not ordinary fish oil but a concentrate: one capsule contains 992 mg of omega-3 fatty acid concentrate in rTG (re-esterified triglyceride) form, including EPA 450 mg and DHA 300 mg. Antioxidants are added to protect it from oxidation: mixed tocopherols 10 mg and ascorbyl palmitate 4 mg. The pack holds 60 capsules.

As a source of omega-3, the product supports the normal function of the heart and blood vessels, the brain and nervous system, vision and cell membranes.

Permit number: №1578936 (Ministry of Health of Uzbekistan).
The product is not a medicine.
If you take blood thinners or have surgery planned — consult a doctor first. It does not replace prescribed medicines.
How to take it — follow the instructions on the pack and your doctor's advice.

No supplement replaces a balanced diet, enough sleep, physical activity or medicines prescribed by your doctor.

Frequently asked questions

Which is better — fish oil or omega-3?

The main difference is the amount of EPA and DHA per capsule. A concentrate contains more, so you reach the same amount with fewer capsules. When choosing, look at the EPA+DHA total, the form and the freshness.

Is "omega 3 1000 mg" enough per day?

First find out what the 1000 mg refers to: the weight of fish oil or the amount of EPA+DHA. EFSA considers 250 mg of EPA+DHA a day adequate for healthy adults, but how much you need depends on your health, so it is best to discuss this with a doctor.

Can I take cod liver oil?

You can, but remember that it contains vitamins A and D, and count the total together with other vitamins. During pregnancy and when trying for a baby, the NHS advises avoiding such supplements unless a doctor recommends them.

How can I tell if fish oil has gone rancid?

Pierce a capsule and smell it: a sharp, rancid smell may be a sign of oxidation. Check the expiry date and keep the pack in a cool, dark place.

If I do not eat fish, can flaxseed oil replace omega-3?

Not fully. Flaxseed oil contains ALA, from which the body makes only small amounts of EPA and DHA. For people who do not eat fish, algal oil can be a source of DHA; discuss the choice with a doctor.

What should I do about fishy burps after fish oil?

Try taking the capsule with a meal and check the freshness of the product. If the discomfort persists or your stomach hurts, discuss it with a doctor.