In the Nua Series, the answers to all six questions are on the label and in the public report. Look, ask questions, then decide.
6 questions to ask when you pick up the box.
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Put two omega-3 boxes side by side and the numbers on the front may not mean the same thing. This guide goes through six questions to ask, in order, as you read the box and the independent test report. Under each question you will find what to look for on the label or in the report, and where the Nua Series shows that information. The guide does not rank products. The choice stays with you.
The number to look at is the amount of EPA or DHA per capsule. The number on the front of the box may be the total amount of fish oil.
An omega-3 label can show three different numbers: the total fish oil in the capsule, the total omega-3, and the amounts of EPA and DHA. The amount of fish oil alone does not tell you the amount of EPA and DHA. A capsule labelled 1000 mg fish oil may hold much less EPA and DHA in total. Some labels give the amount for a daily serving of more than one capsule rather than for a single capsule. If the label says “1000 mg in 2 capsules”, for example, one capsule holds 500 mg. In such cases the number on the label looks high. To find how much is in one capsule, divide that number by the number of capsules in the serving. The conditions of the authorised claims in the regulation are also set in mg, separately for EPA and DHA.
Concentrated omega-3 comes in two common forms: ethyl ester (EE) and re-esterified triglyceride (re-TG).
In natural fish oil, omega-3 fatty acids sit in a triglyceride structure, bound to a glycerol backbone. To concentrate the oil, this bond is broken and the fatty acids are bound to ethanol, which gives the ethyl ester form. Once purification is complete, and before the product goes on sale, the fatty acids are bound back onto a glycerol backbone. The oil is returned to the triglyceride structure of natural fish oil. This form is called re-esterified triglyceride, or re-TG for short. In some human studies, the re-TG form has been associated with higher omega-3 levels in the blood compared with the ethyl ester form.[1] In a six-month randomised, double-blind study in which the same amount of EPA and DHA was taken in re-TG form, the omega-3 index rose faster and further than in the ethyl ester group.[2] Results in this field can differ from study to study. Absorption also depends on taking the capsule with a meal and on the fat content of that meal.[3]
Purity is the percentage of the fish oil in a capsule that is omega-3. At 90% purity, 90 mg of every 100 mg of fish oil in the capsule is omega-3.
The rest is fatty acids other than omega-3. The higher the purity, the more active ingredient and the less of other fatty acids the same capsule carries. You can roughly work out purity from the label figures: divide the EPA and DHA total per capsule by the amount of fish oil in the capsule. This ratio shows the share of EPA and DHA in the fish oil. When other omega-3s are counted too, the total omega-3 share can be a little higher.
For liquid fish oils the calculation takes one more step. The label often gives the amount by volume, such as “500 mg omega-3 in 5 ml”. A millilitre is a unit of volume and a milligram is a unit of weight. So the two numbers cannot be divided directly. First you need to turn the volume into a weight. Fish oil is lighter than water, and 1 ml of fish oil weighs about 0.9 g, or 900 mg. Multiply the millilitre value by 0.9 and you get the weight of the fish oil in grams. 1 g is 1000 mg.
A certificate logo on the box is a starting point. The evidence is the report for your lot, published on the testing organisation’s own website.
International Fish Oil Standards (IFOS) is an independent programme that tests fish oil supplements lot by lot. The lot report has four test groups: amount and label accuracy, contaminants (PCB, dioxin, furan), freshness (oxidation) and heavy metals. The report shows no stars. Passing all four test groups corresponds to the IFOS 5-star rating. NSF Certified for Sport® is a separate programme developed for athletes. It screens the product for more than 280 banned substances, verifies the label contents and regularly audits the production site for good manufacturing practice (GMP).
Heavy metals are measured. The question to ask is whether they were measured and whether the result stays below the limit.
Independent tests measure mercury, lead, cadmium and arsenic, and contaminants such as PCB, dioxin and furan. Limits differ by substance. In IFOS they are 0.1 ppm for mercury and 0.05 ppm for lead. The laboratory writes a result below the lowest level it can measure with a “<” sign. This sign shows that the substance stayed below the level that method can measure. So instead of a flat statement such as “free from”, looking at the measured value and the limit in the report is the sounder approach.
Freshness is measured as oxidation. The IFOS report gives it as the TOTOX value.
Over time fish oil oxidises, in other words it goes stale. TOTOX is a total value that shows how oxidised the oil is. The lower the value, the fresher the oil. The IFOS limit is 19.5. As oxidation goes on, volatile compounds form in the oil, most of them aldehydes and ketones. In one study these compounds were linked to the perceived change in the oil’s smell and taste. According to the same study, common chemical oxidation measures do not always match smell and taste.[4]
Two more facts appear on the label or in the manufacturer’s product information: which fish the oil comes from and what the capsule shell is made of. They do not replace the six questions. They complete them. If you have a dietary preference or an allergy, check the capsule shell and the source fish in particular. If you have a fish allergy, consult your physician before use.
The raw material of NuaDHA® and NuaEPA® is wild anchovy (anchoveta) caught by sustainable fisheries. Anchovy is a small, short-lived fish low in the food chain.
The soft capsules of the Nua Series are made from bovine gelatine. The gelatine comes from a halal-certified producer. The products are made in Spain. The full ingredient list is on the box label.
This list is the short version of the six questions above. Look at the box in your hand and the test report for its lot, and tick each item you found an answer to. When all six are ticked, you can see that the box gives information on every one of these points. You can ask the manufacturer for anything you could not find. The list does not score a product. It only checks whether the information is on the box or in the report.
This list does not recommend a product and is not a health assessment. Your ticks are not saved. They are cleared when you close the page.
Test reports do not say “free from”. Heavy metals are measured and the result is checked against a limit. In the independent test report, look at the lines for mercury, lead, cadmium and arsenic. A result below the lowest level the laboratory can measure is written with a “<” sign. IFOS limits differ by metal (mercury 0.1 ppm, lead 0.05 ppm).
Look for an independent testing programme that publishes its results openly. IFOS tests fish oils lot by lot, and the lot report has four test groups: amount and label accuracy, contaminants (PCB, dioxin, furan), freshness (oxidation) and heavy metals. The NSF Certified for Sport® programme screens the product for more than 280 banned substances. Besides the logo on the box, check the listing on the organisation’s own website and the report for your lot.
Find the EPA and DHA lines in the nutrition table and check whether the value is given per capsule or per daily serving of more than one capsule. If it is given per serving, divide by the number of capsules in the serving to get the amount in one capsule. For example, 1000 mg in 2 capsules means 500 mg per capsule. The total amount of fish oil alone does not tell you the amount of EPA and DHA.
Ethyl ester (EE) is the intermediate form created while fish oil is being concentrated, with each fatty acid bound to ethanol. In the re-esterified triglyceride (re-TG) form, once purification is complete, the fatty acids are bound back onto a glycerol backbone and the oil is returned to the triglyceride structure of natural fish oil. The form is stated on the label or in the manufacturer’s product information.
Freshness is measured through oxidation. In the independent test report, look at the TOTOX value. The lower the value, the fresher the oil. The IFOS limit is 19.5. Also check the expiry date and the storage conditions on the label.
Purity is the percentage of the fish oil in a capsule that is omega-3. You can roughly work out the share of EPA and DHA by dividing the EPA and DHA total per capsule by the amount of fish oil in the capsule. 90% purity means 90% of the fish oil is omega-3. For liquid fish oil, first multiply the ml value by 0.9 to get the weight of the fish oil. For example, 5 ml is about 4500 mg of fish oil. If it contains 500 mg omega-3, the purity is about 11%.
As fish oil oxidises, volatile compounds form, most of them aldehydes and ketones. In one study these compounds were linked to the perceived change in the oil’s smell and taste. According to the same study, common chemical oxidation measures do not always match smell and taste. Personal experience can vary.
The six questions help you read what an omega-3 box is telling you. The difference between EPA and DHA, and the claims the regulation allows for each, are covered in a separate guide. On the Science page you will find the sources on form, purity and certifications. On the Nua Series page you will find what is in each box and the ways to buy.
The studies reflect the general scientific literature on omega-3 forms and fish oil oxidation. They make no claim about clinical results specific to our products. Lot data are taken from the reports on the public IFOS results page.
To read more on the topic, our other guides are on the Longevity Analyses page.
This page is for information. It is not a product recommendation or a health assessment. Food supplements are not medicines and should not be used as a substitute for a varied, balanced diet. If you are pregnant or breastfeeding, take medication or have a chronic condition, consult your physician. Do not exceed the recommended daily serving.
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