Not All Fish Oil Is Equal: Quality, Form and Certifications
Not All Fish Oil Is Equal: How Source, Processing and Testing Change What You Get
Walk down any pharmacy aisle and the fish oils look almost identical: a gold capsule, a big number on the front, a picture of the sea. Yet what actually reaches your bloodstream can differ enormously between them. For people focused on the two organs omega-3s matter most to, the heart and the brain, that difference is the whole point of buying one.
Here is the short answer. Two fish oils with similar labels can deliver very different amounts of usable EPA and DHA. Freshness varies, and some products have tested well below their label claims; the triglyceride form was absorbed better than the ethyl ester form in one comparison; and purity depends on sourcing and refining. Look for a Canadian NPN, third-party testing such as IFOS, USP or NSF, the actual EPA plus DHA per serving, and compare cost per gram of EPA plus DHA.
First, an honest note on the evidence: over-the-counter fish oil hasn't been shown in large trials to prevent heart attacks or strokes in most people (see what the evidence supports). If you and your doctor decide it's worth taking, quality determines whether you get what you're paying for.
简短的答案： 走进任何一家药房，鱼油看起来都差不多：金色胶囊、正面一个大数字、一张大海的图片。但真正进入血液的量，可能天差地别。对于关注 Omega-3 最重要的两个器官——心脏和大脑——的人来说，这种差别正是购买的意义所在。标签相似的两款鱼油，可利用的 EPA 和 DHA 可能差别很大：新鲜度不同，有些产品检测含量远低于标签；一项比较中甘油三酯型比乙酯型吸收更好；纯度取决于原料和精炼。请看加拿大 NPN、IFOS、USP 或 NSF 等第三方检测、每份实际的 EPA＋DHA，并按每克 EPA＋DHA 的价格比较。
先如实说明证据：柜台鱼油在大型试验中并未被证明能预防大多数人的心梗或卒中；如果你和医生认为值得吃，质量决定你是否得到了所付钱的价值。
Why the heart and brain care about EPA and DHA
EPA and DHA are long-chain omega-3 fats built into cell membranes throughout the body. DHA is the main omega-3 in the brain and retina; both are part of heart muscle cell membranes. That's why people recovering from a heart attack or stroke are often interested in them.
Their best-established effect is on triglycerides: at 4 g a day, prescription omega-3 medicines lower triglycerides by about 20% to 30% in people with raised levels (Skulas-Ray et al., AHA Science Advisory, Circulation, 2019). A high-dose prescription EPA medicine also reduced cardiovascular events in selected patients already on statins, but ordinary supplements haven't shown the same in large trials. And dose matters for safety: omega-3 doses above 1 g a day were associated with about 49% higher risk of atrial fibrillation in a meta-analysis (Gencer et al., Circulation, 2021), and high doses can add bleeding risk with antiplatelets or anticoagulants. So the goal isn't "as much as possible"; it's the right amount, of good quality, agreed with your doctor.
为什么心脏和大脑在意 EPA 和 DHA： EPA 和 DHA 是长链 Omega-3 脂肪，构建在全身细胞膜中；DHA 是大脑和视网膜中最主要的 Omega-3，两者也是心肌细胞膜的组成部分，这也是心梗或卒中后康复的人常关注它们的原因。
证据最确定的作用是降低甘油三酯：每天 4 克的处方 Omega-3 药物，可使甘油三酯偏高者的甘油三酯降低约 20%–30%（AHA 科学建议，Circulation 2019）；高剂量处方 EPA 药物也在已服他汀的特定患者中减少了心血管事件，但普通补充剂在大型试验中没有显示同样的效果。剂量也关乎安全：荟萃分析中，每天超过 1 克的 Omega-3 与房颤风险约高 49% 相关（Circulation 2021），高剂量与抗血小板或抗凝药同用还会增加出血风险。所以目标不是「越多越好」，而是与医生商定、质量好的适当剂量。
What makes one fish oil different from another
1. How much EPA and DHA is really in it. The big number on the front is often total fish oil, not EPA plus DHA. Check the back: a 1,000 mg capsule may contain only 300 mg of EPA plus DHA. Some products also test below their claims: a 2015 New Zealand study of 32 supplements found they contained on average 68% of their labelled EPA plus DHA (Albert et al., Scientific Reports, 2015).
2. Freshness (oxidation). Omega-3s are fragile and oxidise with heat, light and time, which can produce a fishy smell and taste. The same 2015 study reported that most products exceeded recommended oxidation limits. An industry-led follow-up of 47 products found better results, with 91% meeting label claims and 72% meeting the stricter GOED limit for primary oxidation (Bannenberg et al., Scientific Reports, 2017). The disagreement itself is the lesson: quality varies by product, and independent testing is what tells them apart.
3. Molecular form. Fish oil comes as natural triglycerides, concentrated ethyl esters or re-esterified triglycerides. In a controlled comparison, EPA plus DHA from re-esterified triglycerides showed 124% relative bioavailability versus natural fish oil, compared with 73% for ethyl esters (Dyerberg et al., Prostaglandins, Leukotrienes and Essential Fatty Acids, 2010). Taking any form with a meal containing fat helps absorption.
4. Purity and sourcing. Small, short-lived fish such as anchovies and sardines, plus molecular distillation, help keep mercury, PCBs and dioxins low. Sustainability certification shows how the fish were caught.
是什么让一款鱼油和另一款不同：
1. 实际含有多少 EPA 和 DHA：正面的大数字常是鱼油总量，而不是 EPA＋DHA；看背面，一粒 1,000 毫克的胶囊可能只含 300 毫克 EPA＋DHA；有些产品检测低于标签：2015 年新西兰一项研究检测 32 款补充剂，平均只含标签 EPA＋DHA 的 68%（Sci Rep 2015）。
2. 新鲜度（氧化）：Omega-3 很脆弱，遇热、光和时间会氧化，可能出现鱼腥味；同一研究报告多数产品超过推荐的氧化上限；而行业主导的后续研究检测 47 款产品，结果更好：91% 符合标签、72% 符合更严格的 GOED 初级氧化上限（Sci Rep 2017）。两者的分歧本身就是教训：质量因产品而异，独立检测才能分辨。
3. 分子形态：鱼油有天然甘油三酯、浓缩乙酯和再酯化甘油三酯三种；一项对照比较中，以天然鱼油为 100%，再酯化甘油三酯的相对生物利用度为 124%，乙酯为 73%（2010）；任何形态与含脂肪的餐食同服都有助吸收。
4. 纯度和来源：凤尾鱼、沙丁鱼等体型小、寿命短的鱼，加上分子蒸馏，有助于把汞、多氯联苯和二噁英控制在低水平；可持续认证说明鱼是如何捕捞的。
Two certifications worth knowing
Health Canada Natural Product Number (NPN): an eight-digit number on the label showing the product is licensed for sale in Canada, with an approved formula, dose, quality standards and permitted claims. If a supplement sold in Canada has no NPN, that's a red flag.
NSF Certified: an independent organisation tests that the product contains what the label says, doesn't contain specified contaminants and is made under good manufacturing practices, with regular retesting and facility audits.
Other programs you may see on labels do similar independent testing (such as IFOS and USP), set industry quality limits (GOED) or certify sustainable fishing rather than purity (MSC, Friend of the Sea). A licence plus independent testing is a strong combination; when in doubt, ask the brand for a recent certificate of analysis.
值得了解的两项认证： Health Canada 天然产品编号（NPN）：标签上的八位数字，表示产品获准在加拿大销售，配方、剂量、质量标准和允许的宣称都经过批准；在加拿大销售的补充剂如果没有 NPN，就是一个警示信号。NSF 认证：由独立机构检测产品是否含有标签所列成分、是否不含特定污染物，以及是否按良好生产规范制造，并定期复检和审核工厂。标签上可能见到的其他标志，有的做类似的独立检测（如 IFOS、USP），有的制定行业质量上限（GOED），有的只认证可持续捕捞而非纯度（MSC、Friend of the Sea）。许可加上独立检测是很好的组合；有疑问时，向品牌索要近期的检验报告。
What about seal oil?
Seal oil, made mainly from harp seals in Canada and also produced in Norway, is sometimes promoted as superior to fish oil. Here's what's known:
It contains DPA, a third long-chain omega-3, at about 5% of the oil, far more than most fish oils, alongside EPA and DHA (DHA/EPA Omega-3 Institute).
Its omega-3s sit in a different position on the fat molecule, which some suggest may aid absorption, but whether that matters in practice isn't established.
Human outcome evidence is limited. DPA research is promising but mostly early, and there are no large trials showing seal oil works better than quality fish oil for the heart or brain.
It's legal in Canada, but not in the US or EU. Selling or importing seal products into the United States is prohibited under the Marine Mammal Protection Act, and the EU bans most commercial trade in seal products.
So seal oil is a reasonable option for some Canadians, for example people who want DPA or tolerate it better, but the evidence doesn't show it's "far better", and it typically costs more.
那海豹油呢？： 海豹油主要来自加拿大的竖琴海豹，挪威也有生产，常被宣传为优于鱼油。目前已知的是：它含有第三种长链 Omega-3——DPA，约占油的 5%，远高于大多数鱼油，同时含有 EPA 和 DHA；它的 Omega-3 在脂肪分子上的位置不同，有观点认为可能有助吸收，但实际意义尚未确定；人体结局证据有限，DPA 研究有前景但多处于早期，没有大型试验显示海豹油对心脏或大脑优于优质鱼油；它在加拿大合法，但在美国和欧盟不合法——美国《海洋哺乳动物保护法》禁止销售或进口海豹产品，欧盟也禁止大部分海豹产品的商业贸易。所以，对部分加拿大人来说（例如想补充 DPA 或对它耐受更好的人），海豹油是一个合理的选择，但证据并不支持它「大大优于」鱼油，而且价格通常更高。
How to judge value: cost per gram of EPA plus DHA
The price per bottle tells you little. Work out the cost per gram of EPA plus DHA:
(Price ÷ number of servings) ÷ grams of EPA + DHA per serving
For example, a $30 bottle of 120 capsules with 300 mg EPA plus DHA each provides 36 g in total, about $0.83 per gram. A $45 bottle of 60 capsules with 900 mg each provides 54 g, also about $0.83 per gram, with a third of the capsules to swallow. Add form and freshness to the comparison, and the "expensive" bottle can be the better value.
如何判断性价比：每克 EPA＋DHA 的价格： 每瓶价格说明不了什么，请算每克 EPA＋DHA 的价格：（价格 ÷ 份数）÷ 每份 EPA＋DHA 克数。例如，一瓶 30 美元、120 粒、每粒含 300 毫克 EPA＋DHA，总共 36 克，约每克 0.83 美元；一瓶 45 美元、60 粒、每粒含 900 毫克，总共 54 克，同样约每克 0.83 美元，而要吞的胶囊只有三分之一。再把剂型和新鲜度加进比较，「贵」的那瓶反而可能更划算。
How Healos™ approaches omega-3
In the Healos™ Replenish stage, omega-3 is one of the nutrients used as complementary support, at an amount matched to your medication list and pharmacist-reviewed before your kit ships, including checks for blood thinners and heart rhythm considerations. Healos™ products are licensed by Health Canada (NPN). As with any brand, you're welcome to ask us for product details before you buy. The 91-Day Protocol moves through Detox, Replenish and Repair, with follow-ups at day 30 and day 60 (with a reminder to book your blood test) and a blood-test report review at day 90.
Healos™ 如何对待 Omega-3： 在 Healos™ 的补给阶段，Omega-3 是作为辅助支持的营养素之一，剂量与用药清单匹配，发货前经药剂师审核，包括抗凝药和心律方面的核查。Healos™ 产品获 Health Canada NPN 许可；和对待任何品牌一样，欢迎你在购买前向我们询问产品详情。91 天方案依次经过排毒、补给、修复，第 30 天跟进、第 60 天跟进并提醒验血、第 90 天验血报告解读。
The bottom line
Fish oils that look the same can differ in real EPA and DHA content, freshness, form and purity. Decide with your doctor whether you need one and at what dose; then check the back label for EPA plus DHA, look for an NPN and independent testing, prefer fresh, well-refined oil, compare cost per gram of EPA plus DHA and check it against your medicines, especially blood thinners.
结论： 看起来一样的鱼油，实际 EPA 和 DHA 含量、新鲜度、剂型和纯度都可能不同。先与医生决定你是否需要、剂量多少；然后看背面标签的 EPA＋DHA，认准 NPN 和独立检测，选择新鲜、精炼良好的鱼油，按每克 EPA＋DHA 比较价格，并与你的药物（尤其抗凝药）核对。
Frequently asked questions
How do I choose a good fish oil? Check the EPA plus DHA per serving on the back label, look for a Health Canada NPN and independent testing such as IFOS, USP or NSF, prefer fresh, well-refined oil and compare cost per gram of EPA plus DHA.
Is triglyceride fish oil better than ethyl ester? In one controlled comparison, re-esterified triglycerides showed 124% relative bioavailability versus natural fish oil, compared with 73% for ethyl esters. Taking any form with a fat-containing meal helps absorption.
Does fish oil go rancid? Yes, omega-3s oxidise with heat, light and time. Quality varies by product, so independent testing and good storage matter. A strong fishy smell or taste can be a sign of oxidation.
How much fish oil should I take after a heart attack? Ask your doctor. Large trials haven't shown that over-the-counter fish oil prevents heart attacks for most people, doses above 1 g a day have been linked to atrial fibrillation, and high doses can add bleeding risk with blood thinners.
常见问题：
鱼油怎么选？看背面每份 EPA＋DHA、认准 NPN 和 IFOS/USP/NSF 等独立检测、选新鲜精炼的、按每克 EPA＋DHA 比价。
甘油三酯型比乙酯型好吗？一项对照比较中再酯化甘油三酯相对生物利用度 124%，乙酯 73%，与含脂餐同服都有助吸收。
鱼油会变质吗？会，遇热光和时间会氧化，质量因产品而异，浓重鱼腥味可能是氧化信号。
心梗后吃多少？问医生，柜台鱼油在大型试验中未证明能预防多数人的心梗，每天超过 1 克与房颤相关，高剂量与抗凝药同用增加出血风险。
References
Albert BB, Derraik JGB, Cameron-Smith D, et al. Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n-3 PUFA. Scientific Reports. 2015;5:7928. doi:10.1038/srep07928.
Bannenberg G, et al. Omega-3 long-chain polyunsaturated fatty acid content and oxidation state of fish oil supplements in New Zealand. Scientific Reports. 2017;7:1488. doi:10.1038/s41598-017-01470-4.
Dyerberg J, Madsen P, Møller JM, et al. Bioavailability of marine n-3 fatty acid formulations. Prostaglandins, Leukotrienes and Essential Fatty Acids. 2010;83(3):137–141.
Gencer B, et al. Effect of long-term marine omega-3 fatty acids supplementation on the risk of atrial fibrillation in randomized controlled trials of cardiovascular outcomes. Circulation. 2021;144(25):1981–1990.
Skulas-Ray AC, Wilson PWF, Harris WS, et al. Omega-3 fatty acids for the management of hypertriglyceridemia: a science advisory from the American Heart Association. Circulation. 2019;140(12):e673–e691.
DHA/EPA Omega-3 Institute. What types of omega-3 fatty acids are in seal oil? (FAQ, dhaomega3.org).
US NOAA Fisheries. Marine Mammal Protection Act; Fisheries and Oceans Canada. Seal products and market.
