Can fish oil lower blood lipids? Many people may be eating it wrong...

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“Can taking fish oil lower blood lipids?”

Many advertisements claim that "taking fish oil can lower blood lipids and remove waste from blood vessels", making blood vessels healthier.

Rumor Analysis

This statement is not rigorous enough.

"Blood lipids" is not a single indicator. The four general blood lipids include total cholesterol, high-density lipoprotein, low-density lipoprotein and triglycerides. Omega-3 fatty acids in fish oil cannot reduce cholesterol and low-density lipoprotein, but can only deal with triglycerides.

Some studies have shown that consuming DHA and EPA is beneficial to cardiovascular health. However, the content of DHA and EPA in different fish oil products varies greatly, so it is recommended to take it under the guidance of a doctor or nutritionist and reduce the intake of other oils accordingly. In daily life, it is recommended to give priority to eating fish to supplement nutrition, but be careful to avoid frying.

Many advertisements claim that "eating fish oil can lower blood lipids", but can fish oil really be taken by everyone and is it suitable for all symptoms of high blood lipids? Be careful not to take it right, or it will add fuel to the fire.

What is "fish oil"?

First of all, we need to distinguish "cod liver oil" which is only one letter different from "fish oil". Cod liver oil is oil extracted from the liver of fish, and its main active ingredients are vitamin A and vitamin D. If you come here for blood lipids, exclude this wrong option first. Fish oil is lipid extracted from the fat of deep-sea fish.

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The main ingredient in fish oil that is useful to us is Omega-3 fatty acids. Omega-3 fatty acids are a type of polyunsaturated fatty acid that is essential to the human body but cannot be synthesized by the body. One of its ingredients is DHA (docosahexaenoic acid), which is often seen in advertisements for infant formula and other maternal and child products. It plays an important role in the vision and intellectual development of infants and young children. The other ingredient is EPA (eicosapentaenoic acid). Many studies have shown that Omega-3 fatty acids are beneficial to cardiovascular and heart health [1].

“Fish oil lowers blood lipids”

Which one is higher?

Have to eat enough

Blood lipids are not a single indicator. The four general blood lipids include total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides. Except for the high-density lipoprotein cholesterol, the others are "bad" blood lipids that we need to lower. The omega-3 fatty acids in fish oil cannot lower cholesterol and low-density lipoprotein, it can only deal with triglycerides.

Mild triglyceride elevation can usually be restored to normal by controlling diet. If the level is still high despite dietary control, fibrates can be taken, and fish oil can also be used in combination. In the event of drug side effects, or after excluding other causes and receiving statins and other drug treatment, severe patients with triglycerides ≥ 5.6 mmol/L (500 mg/dL) or even 11.3 mmol/L (1000 mg/dL) should be given omega-3 fatty acids to lower triglyceride levels [2].

Triglyceride levels

Solution

<1.7mmol/L

No intervention required

1.7～5.6mmol/L

Diet control + fibrates

(Can also be taken with fish oil)

≥5.6mmol/L

Pharmaceutical + Prescription Grade Fish Oil

EPA and DHA in omega-3 fatty acids both have the effect of lowering triglycerides and triglyceride-rich lipoprotein cholesterol in a dose-dependent manner. That is to say, fish oil has a therapeutic effect only when the ratio of these two components is high. Generally speaking, fish oil with a purity of more than 90% can be called prescription fish oil. The purity of fish oil on the market ranges from 30% to 97%. If you take a 30% pure fish oil, you will also take in 70% of other fats. Therefore, if you take it wrong, it is really possible to make your blood lipids "add oil to oil".

In addition to purity, we also need to look at the DHA+EPA content in the ingredient list. The amount recommended in the Chinese Blood Lipid Management Guidelines is 1 to 4 grams per day [3], which means that the amount recommended in the instructions for use must be at least 1 gram per day.

In general, for healthy people , fish oil, a common health supplement, has limited lipid-lowering effects due to insufficient dosage, and is not necessary as a magical supplement for preventing or treating cardiovascular disease. For people with high blood lipids, high-purity fish oil can be used as an auxiliary treatment , but fish oil cannot replace statins for cholesterol management. It is recommended to first conduct lifestyle interventions when blood lipids are abnormal, and then consider fish oil supplements if the effect is insufficient, but be sure to pay attention to the need to be under the guidance of a doctor .

Looking in the mirror of rumors

In the process of selling health products, exaggerating the functions of products and deliberately confusing them with drugs are the most common rumors. We should develop a correct understanding of health products: health products cannot replace a balanced diet and a healthy lifestyle, let alone medicines. They are a supplement to daily life, not a substitute.

References

[1] Saini RK, Keum YS. Omega-3 and omega-6 polyunsaturated fatty acids: Dietary sources, metabolism, and significance — A review[J]. Life Sciences, 2018, 203:255-267.

[2] National Cardiovascular Disease Expert Committee, Cardiovascular Metabolic Medicine Committee, Li Jianjun, Dou Kefei. Chinese expert consensus on the role of omega-3 fatty acids in the prevention and treatment of cardiovascular diseases[J]. Chinese Journal of Circulation, 2023, 38(2):116-130.

[3] Joint Expert Committee on the Revision of the Chinese Guidelines for Blood Lipid Management, Wang Zengwu, Li Jianjun, et al. Chinese Guidelines for Blood Lipid Management (Basic Edition 2024)[J]. Chinese Journal of Circulation, 2024, 39(4):313-321.

Planning and production

Author: Xu Ke, attending physician of the Department of Endocrinology, the First Affiliated Hospital of Wenzhou Medical University

Reviewer: Ma Fangfang, Associate Chief Physician and Associate Professor, Department of Cardiology, First Hospital of Hebei Medical University

Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center