Omega-3 fish oil is one of the most recognised supplement categories worldwide, and EPA and DHA are behind some of the largest clinical trials ever run on a dietary ingredient. Brands abroad ask for a Japan-made omega-3 product expecting that trial history to translate directly into label claims.
This guide is for brand owners planning a Japan-made EPA/DHA product. It covers what the largest trials actually tested and found, how Japan frames EPA and DHA in its own labelling system, the oxidation and odour problems that shape how fish oil is formulated, and what to fix before asking for a quotation.
Health supplements are foods, not medicines, and are not a substitute for medical treatment. Nothing here is a claim that any product prevents, treats or cures a disease.
💬 Planning an omega-3 product made in Japan? We check the full formula against Japanese food law first. See Japan-made supplement OEM.
What the research shows
The largest EPA/DHA trials were run in specific patient populations to test disease outcomes, not in the general population to test a supplement claim — and their results were mixed, not uniformly positive.
| Study | Design / population | Reported result |
|---|---|---|
| VITAL, New England Journal of Medicine 2019;380:23-32 (PMID 30415637) | Randomised, placebo-controlled, 2×2 factorial trial of 1 g/day marine n-3 fatty acids (460 mg EPA + 380 mg DHA) and vitamin D3, in around 25,000 initially healthy US adults (men ≥50, women ≥55), median follow-up 5.3 years | The primary composite endpoint (major cardiovascular events or cancer) was not significantly reduced. Secondary, non-primary analyses reported lower rates of myocardial infarction and total coronary heart disease events in the omega-3 group |
| REDUCE-IT, New England Journal of Medicine 2019;380:11-22 (PMID 30415628) | Randomised, double-blind, placebo-controlled trial of icosapent ethyl 4 g/day (a purified EPA drug, not a food supplement) in 8,179 statin-treated adults with established cardiovascular disease or diabetes plus risk factors, and elevated triglycerides (135-499 mg/dL) despite controlled LDL cholesterol; median follow-up 4.9 years | The icosapent ethyl group had a 25% relative reduction in the primary composite cardiovascular endpoint compared with placebo |
Caveats that matter for how you read these trials:
- Population. Both trials enrolled specific groups — VITAL enrolled generally healthy older adults with no prior cardiovascular disease, and REDUCE-IT enrolled statin-treated patients who already had cardiovascular disease or diabetes with elevated triglycerides. Neither trial tested a general-population supplement claim.
- Product type. REDUCE-IT tested icosapent ethyl, a prescription-only purified EPA drug at 4 g/day, not an over-the-counter fish oil supplement. Its dose and regulatory status differ from a typical supplement.
- Primary vs secondary results. VITAL’s primary composite endpoint was not statistically significant; the reported reductions in myocardial infarction were secondary, exploratory findings, not the trial’s pre-specified positive result.
- Placebo debate. REDUCE-IT’s placebo was a mineral oil, and some researchers have questioned whether the placebo itself affected the comparison. This is a genuine, published debate about the trial’s result, not a settled matter.
- General population evidence is weaker. A review by Japan’s Ministry of Health, Labour and Welfare’s eJIM service on integrative medicine cites a US government-commissioned review of 98 studies that found no evidence that omega-3 supplementation reduces the risk of heart attack or cardiovascular death.
None of this is a basis for a heart-health, cardiovascular-disease or blood-related claim on a product. VITAL and REDUCE-IT are disease-outcome trials in defined patient groups studied under medical supervision — not evidence for a general wellness claim on a food supplement.
Checked against the published abstracts on 25 September 2026.
What Japanese products say
Japan recognises EPA and DHA in two separate systems — Foods with Function Claims, and Foods with Nutrient Function Claims — and the approved wording in both cases describes everyday nutrition, not disease outcomes.
Under the Foods with Function Claims system, the notifying business is responsible for the scientific evidence and submits it to the Consumer Affairs Agency before sale; the content, including the safety and functionality evidence, is published on the Agency’s website. EPA and DHA are among the ingredients notified under this system, most commonly for functions related to maintaining blood triglyceride levels.
Separately, under Foods with Nutrient Function Claims, n-3 fatty acids (a category that includes EPA and DHA) are a listed nutrient. A food that contains between 0.6 g and 2.0 g of n-3 fatty acids per daily recommended serving may use the standard wording “n-3系脂肪酸は、皮膚の健康維持を助ける栄養素です” (“n-3 fatty acids are a nutrient that helps maintain the health of the skin”), without any pre-market notification, because the wording and the quantity range are fixed by the government.
Two points for a brand abroad:
- The Japanese wording is narrow and government-fixed. The Nutrient Function Claims wording is about skin health, not the heart or blood outcomes tested in VITAL and REDUCE-IT. It cannot be stretched to cover cardiovascular claims.
- A Japanese notification or nutrient function claim is not a global endorsement. Both are Japanese regulatory mechanisms for products sold in Japan. Your label abroad follows your own market’s rules.
💬 Need an evidence summary for your regulatory adviser that separates trial data from Japanese and other markets’ claim wording? We prepare it with the manufacturing documents. Tell us your market.
Wording that stays on safe ground
Describe what was studied, in whom, and under what conditions — not the disease outcomes of VITAL or REDUCE-IT.
| Safer wording | Wording to avoid |
|---|---|
| ”Contains EPA and DHA” with the amount per serving | ”Reduces heart attack risk”, “lowers cholesterol”, “for cardiovascular disease" |
| "Source of omega-3 fatty acids” | Referencing VITAL or REDUCE-IT as proof your product prevents or treats a condition |
| An EU-authorised claim, quoted exactly and only where it is authorised for your product and the stated intake condition is met (for example, the EU’s “EPA and DHA contribute to the normal function of the heart” claim requires 250 mg EPA+DHA per day; its blood-triglycerides claim requires 2 g per day) | Using EU claim wording in a market where it has no legal standing, or without meeting its exact intake condition |
How omega-3 is formulated
EPA and DHA oxidise easily, which is why the format, the antioxidant system and the packaging matter as much as the source material.
| Dosage form | Why brands choose it | What to weigh up |
|---|---|---|
| Soft capsule | The standard format for oil-based EPA/DHA; the gelatin (or plant-based) shell limits oxygen contact and masks taste | Shell material for dietary suitability; enteric or odour-controlled coating for sensitive users |
| Liquid oil | Higher daily doses without multiple capsules | Fastest to oxidise once opened; needs refrigeration guidance and a short use-by period |
| Powder (microencapsulated) | Mixes into drinks or other formats | Encapsulation quality determines both oxidation resistance and odour control |
Decisions that shape the specification:
- Oxidation risk and stabilisation. Long-chain n-3 fatty acids are highly unsaturated and prone to oxidation, which produces the rancid, fishy odour associated with poor-quality fish oil. Antioxidants such as tocopherol (vitamin E) are commonly added to slow this, and oxygen-impermeable packaging and appropriate storage conditions matter as much as the antioxidant itself.
- Fish odour and enteric coating. Consumer complaints about fish oil supplements are usually about fishy aftertaste or reflux rather than efficacy. Odour-controlled and enteric-coated soft capsules, which delay the capsule opening until after the stomach, are a standard response; ask the supplier what coating and flavouring options are available.
- Source and material specification. EPA and DHA for supplements come from fish body oil (commonly sardine, anchovy, mackerel or tuna) or, for a fish-free formula, algal oil. Confirm the EPA and DHA content per gram of oil, the source species, and whether the material is fish-derived or algal.
- Fish allergen labelling. Fish is a recognised food allergen requiring declaration in major markets, including the EU’s 14 mandatory allergens and the United States’ major food allergen list. Confirm your own market’s allergen labelling rule for fish-derived oil, and note that an algal-oil source avoids the fish allergen question entirely.
- Companion ingredients. EPA/DHA is often combined with astaxanthin or other oil-soluble ingredients in a single soft capsule. Every companion ingredient needs its own check against Japanese food law.
The check that comes first
Every ingredient must be permitted in foods in Japan, or a Japanese factory cannot make the product.
EPA and DHA themselves are widely used in Japanese foods, in both fish-oil and algal-oil form. The more common obstacle is a companion ingredient or a claim that goes beyond what either Japanese notifications or the underlying trials support. See the Japan-made supplement OEM page, and compare with our astaxanthin and collagen peptide guides if you are planning a combined healthy-ageing formula.
Before you ask for a quotation
A factory can quote accurately once the source, the amount, the form and the packaging are fixed.
- EPA and DHA source (fish body oil species, or algal oil) and content per gram
- EPA and DHA amount per serving and servings per pack
- Dosage form, and any coating or flavouring requirements
- Companion ingredients and their amounts
- Packaging and storage requirements
- Countries you will sell in, and fish allergen labelling requirements there
💬 Ready to design a Japan-made omega-3 product? Send us the concept — source, amount, form and the countries you will sell in.
Frequently asked questions
1. Do VITAL and REDUCE-IT prove that omega-3 supplements prevent heart disease?
No. VITAL’s primary cardiovascular and cancer endpoint was not significantly reduced in generally healthy adults; the myocardial infarction result was a secondary finding. REDUCE-IT tested a prescription-only purified EPA drug at 4 g/day in patients who already had cardiovascular disease or diabetes with elevated triglycerides, not a general-population supplement. Neither trial supports a disease-prevention claim on a food product.
2. What does Japan allow EPA and DHA to say on a label?
Two separate mechanisms: Foods with Function Claims, where the notifying business submits its own evidence to the Consumer Affairs Agency (often for blood triglyceride maintenance), and Foods with Nutrient Function Claims, where a fixed government wording about skin health applies automatically to products with 0.6-2.0 g of n-3 fatty acids per daily serving.
3. Why does fish oil smell fishy, and how is that controlled?
EPA and DHA are highly unsaturated and oxidise easily, producing compounds that cause a rancid odour. Manufacturers control this with antioxidants such as tocopherol, oxygen-impermeable packaging, and odour-controlled or enteric-coated soft capsules.
4. Is fish oil an allergen I need to declare?
Fish is a mandatory allergen in major markets, including the EU’s 14-allergen list and the US major food allergen list. Confirm your market’s specific requirement, or consider an algal-oil source if you want to avoid the fish allergen question.
5. Can I use the EU’s heart or triglyceride health claims on my product?
Only where that claim is legally authorised for your product and market, and only if you meet its exact daily intake condition (for example 250 mg EPA+DHA/day for the heart-function claim, or 2 g/day for the blood-triglycerides claim). It is not a claim you can use elsewhere just because it is EU-authorised.
Sources: “Marine n-3 Fatty Acids and Prevention of Cardiovascular Disease and Cancer” (VITAL trial), New England Journal of Medicine 2019;380:23-32 (PMID 30415637); “Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia” (REDUCE-IT trial), New England Journal of Medicine 2019;380:11-22 (PMID 30415628); Ministry of Health, Labour and Welfare eJIM, overview of omega-3 fatty acid evidence; Consumer Affairs Agency notifications for Foods with Function Claims and standards for Foods with Nutrient Function Claims; EU Register on nutrition and health claims / Commission Regulation (EU) No 432/2012, authorised claims for EPA and DHA. Checked on 25 September 2026.