Last update: June 11, 2024

Fish Oil: The Complete Guide

Explore everything about fish oil with our in-depth guide, covering dosage, benefits, and potential side effects. Discover the key insights into omega-3 fatty acids, heart health, and more for holistic well-being.

Stephanie Wright

By Stephanie Wright, RN, BSN

Edited by Dr. Dimitar Marinov, MD, MBA, PhD

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Key takeaways

  • Fish oil is a nutrient-rich substance full of omega-3 fatty acids
  • Omega-3s contribute to heart health, brain function, and more
  • Different types of Omega-3 fatty acids, including Alpha-linolenic acid (ALA), Eicosapentaenoic acid (EPA), and Docosahexaenoic acid (DHA).
  • A lack of omega-3 fatty acids can lead to dry skin, joint pain, and increased inflammation
  • You can meet your recommended dosage through food sources or supplement

    What is fish oil?

    Fish oil is a nutrient-rich substance that comes from oily fish like anchovies, salmon, sardines, and trout. Typically taken in supplement form, fish oil gives you an easy way to add essential omega-3s to your diet. It's full of omega-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are good for your heart and may help with inflammation [1]. It also has important nutrients like vitamins A, D, and E.

    Your body needs omega-3 fatty acids. Omega-3 fatty acids, particularly EPA and DHA, play crucial roles in the body and can fully satisfy the needs of the body for omega-3 fats. Thus, getting enough is important for many functions, including maintaining the health of the brain, heart, and other parts of the body [1].

    Can your body produce omega-3s?

    Omega-3 fatty acids are essential nutrients. That means your body cannot make it alone. Instead, you must get EPA and DHA from food sources or supplements.

    Vikings and the Ancient Power of Cod Liver Oil

    Vikings were pioneers in using cod liver oil as a supplement, crucial in their diet during the harsh winter months. They would boil water in a large pan, place birch branches over it, and set the liver atop to steam. The oil collected was so revered that it was dubbed the "Gold of the Ocean" [9].

    Different types of omega-3s

    There are three types of omega-3 fatty acids:

    1. Alpha-linolenic acid (ALA): Found primarily in plant oils like flaxseed and soybeans, ALA is essential and must be obtained through our diet as our bodies can't produce it.
    2. Eicosapentaenoic acid (EPA): Derived from animal fats, EPA is crucial for neurological and cardiovascular health.
    3. Docosahexaenoic acid (DHA): The longest of the three omega-3 acids, DHA is sourced from animal fats and is vital for brain, heart, and fetal development.

    How does fish oil work in your body?

    What are some benefits of fish oil?

    The omega-3s found in fish oils are essential for maintaining good health. Here are a few benefits of adding fish oil to your diet.

    1. Supports heart health

      Fish oil's omega-3 fatty acids, particularly EPA and DHA, are known for their role in heart health. They help in maintaining healthy blood lipid levels, including triglycerides, which are crucial for cardiovascular wellness. Additionally, omega-3s can support normal blood pressure, a key factor in heart health [4].

    2. Contributes to healthy brain function

      DHA, a major component of brain tissue, is vital for normal brain function. This includes supporting cognitive health, such as memory and learning capabilities. Omega-3 fatty acids, especially EPA, have also supported mood balance. The neuroprotective properties of omega-3s help in maintaining the structural integrity of brain cells, which is crucial for long-term brain health [5].

    3. Helps eye health

      DHA is also crucial for eye health, particularly for the retina. It plays a key role in maintaining normal vision. This is especially important during the visual development of infants both during pregnancy and in early childhood [6].

    4. Boosts joint health

      Omega-3 fatty acids influence the body’s response to inflammation, which can support joint comfort and reduce discomfort associated with physical activity. They contribute to maintaining joint flexibility, essential for overall mobility and daily activities. Omega-3s may also support the health of joint cartilage, which cushions and protects the bones, thereby enhancing joint function [7].

    5. Promotes healthy skin

      In skin health, omega-3 fatty acids help maintain the skin’s barrier function, which is essential for keeping the skin hydrated and protected from external irritants. They can contribute to the maintenance of normal skin appearance, promoting skin elasticity and potentially reducing visible signs of aging [8].

    What are some signs of omega-3 deficiency?

    Omega-3 fatty acid deficiency can manifest in several ways, often affecting various aspects of health and well-being. Some common signs of omega-3 deficiency include [3],[10]:

    • Dry, Rough, or 'Bumpy' Skin: Omega-3 fatty acids play a crucial role in maintaining the health of cell membranes, including those of skin cells. A deficiency can lead to changes in skin texture, making it dry, rough, or bumpy.
    • Skin, Hair, and Nails Issues: Low omega-3s can cause dry skin, brittle hair, and peeling or cracking nails; may also lead to skin rashes and dandruff.
    • Fatigue and Sleep Problems: Deficiency might contribute to difficulty sleeping and overall fatigue; improving omega-3 intake can enhance sleep quality and energy levels.
    • Concentration and Mood Challenges: Insufficient omega-3s can impair memory, focus, and lead to irritability and anxiety.
    • Joint Pain and Leg Cramps: Omega-3s have anti-inflammatory properties that help mitigate joint swelling and pain; also prevent potential joint damage.
    • Allergic Reactions: Symptoms like hives, asthma, and eczema can be signs of omega-3 deficiency.
    • Excessive Ear Wax: Increased omega-3 levels might reduce ear wax buildup and protect against hearing loss.
    • Cardiovascular Issues: Essential for heart health, omega-3s help prevent heart disease and manage cholesterol levels.
    • Menstrual Difficulties: Women with harsh menstrual cycles may find relief by boosting their omega-3 intake, easing symptoms like heavy flow and clotting.

    Never self-diagnose

    If you feel you may have a deficiency or are concerned or curious about taking this supplement, talk to a doctor or healthcare professional. They can accurately diagnose and recommend the appropriate treatment plan for your specific needs.

    Sources of fish oil

    Omega 3s can be obtained from various sources, primarily from foods but also from supplements when dietary intake is insufficient.

    Omega 3-rich foods

    Below is a categorization of various foods based on their omega-3 content, helping you to identify sources that can boost your dietary fish oil intake.

    Is food intake always the best?

    Obtaining omega-3s oil from food is generally recommended. However, in cases of significant deficiency, dietary restrictions, or certain health conditions, supplements may be necessary.

    Fish oil supplement formulations

    Forms of fish oil

    • Natural Triglyceride (TG) Form: Common form where EPA and DHA are present as triglyceride esters, similar to their natural state in fish. Typically offers up to 300 mg of EPA and DHA per 1,000 mg of oil.
    • Ethyl Ester (EE) Form: Created by replacing the glycerol backbone in TG fish oil with ethanol, allowing for higher concentrations of EPA and DHA. Often used in prescription omega-3 fatty acids.
    • Re-Esterified Triglyceride (rTG) Form: Produced by removing ethanol from EE and re-binding the fatty acids to a glycerol backbone. Retains the potency and ratios of EE.
    • Mixed Form: A combination of the natural TG form and the more potent EE form.

    Delivery methods

    Fish oil supplements come in various delivery methods, each offering its own set of benefits and ways of consumption. Here's a brief overview of the different delivery methods:

    Choose a method that fits your routine

    Do not overlook the delivery method. Fish oil supplements come in tablets, capsules, soft gel, chewable, powders, and liquid forms—choose the one that best fits your daily routine to stay consistent.

    What to look for in fish oil supplements

    When selecting a supplement, several key factors must be considered to ensure you choose a high-quality product that effectively supports your health goals and overall well-being.

    • Dosage and potency

      The dosage of fish oil in supplements varies, so it's important to choose one that aligns with your specific needs. This includes considering your age, gender, and health status, like pregnancy or existing deficiencies. The fish oil formulation can impact its potency and bioavailability, which affects how effectively your body can absorb and use it.

    • Quantity and delivery method

      The delivery method is crucial. Fish oil supplements come in various forms, including tablets, capsules, powders, chewables, and liquid forms. Your choice may depend on factors like ease of swallowing, convenience for traveling, or personal preference regarding taste and texture. Also, evaluate the quantity of fish oil to determine how long it will last based on your daily requirements.

    • Quality and manufacturing

      Quality is paramount when selecting fish oil supplements. Look for products manufactured under strict quality control guidelines and those that have undergone third-party testing for purity and label accuracy. Certifications from recognized bodies can be a reliable indicator of a high-quality product. Additionally, consider the manufacturer's reputation and transparency in their production processes.


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    How and when should you take fish oil for maximum absorption?

    To get the most out of your fish oil supplement, it's crucial to consider the timing and method of consumption. The following dos and don'ts offer guidance on optimizing absorption, efficiently supporting your health and wellness, and minimizing potential discomfort.


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      Take fish oil supplements with a fat-containing meal for better absorption.

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      Swallow the capsules without chewing to get the most benefits and avoid a fishy taste later.

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      Talk to your healthcare provider to ensure it's safe and won't cause any issues.


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      Avoid taking fish oil on an empty stomach to avoid digestive issues.

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      Don't chew fish oil capsules.

    Who should take fish oil?

    Taking fish oil supplements has its potential benefits, but it may not be for everyone.

    Recommended dosage

    The numbers provided are recommended dosages of Fish Oil in your supplements but should also focus on the amount the omega 3's within that serving. For adults - 250 mg of combined EPA and DHA is the minimum dose that you should be in your fish oil supplements for general health. However, depending on the goal of supplementation higher values may be more appropriate. Your health care provider would be best to consult for specific amounts

    Side effects of excessive fish oil consumption

    While fish oil supplements are generally safe when taken within recommended limits, excessive intake can have adverse effects:

    • Unpleasant Taste and Bad Breath: Some people may encounter a fishy aftertaste or bad breath after taking fish oil.
    • Prolonged Bleeding: Due to its blood-thinning properties, fish oil may lead to cuts taking longer to stop bleeding.
    • Digestive Symptoms: Minor digestive issues like burping, diarrhea, or heartburn may happen.

    Always consult your doctor

    If you're experiencing side effects, consult your healthcare provider. They may recommend a different fish oil formulation or adjust your dosage. Balancing your fish oil needs with any discomfort is crucial and should not be overlooked.

    Health made easy: your go-to resource for essential vitamins and supplements

    Frequently asked questions about fish oil (FAQ)

    Our library of expert-authored articles covers just about every question you might have about vitamins, minerals, and supplements — along with some you might not have known you had.

    Final thoughts

    Fish oil is a helpful supplement that supports heart health, reduces inflammation, and boosts brain function. It might also help with arthritis and possibly improve sleep. Take it as part of a healthy lifestyle, either in the morning or at night, with or without food, but its effects vary from person to person.

    Sources and references

    1. Omega-3 Fatty Acids - StatPearls - NCBI Bookshelf
    2. Omega-3 Fatty Acids - Consumer
    3. Omega-3 Fatty Acids - StatPearls - NCBI Bookshelf
    4. The Effects of Fish Oil on Cardiovascular Diseases: Systematical Evaluation and Recent Advance - PMC
    5. Effects of Omega-3 Polyunsaturated Fatty Acids on Brain Functions: A Systematic Review - PMC
    6. Omega-3 Fatty Acids and Eye Health: Opinions and Self-Reported Practice Behaviors of Optometrists in Australia and New Zealand - PMC
    7. Omega-3 Fatty Acids for the Management of Osteoarthritis: A Narrative Review - PMC
    8. Omega 3 Fatty Acid and Skin Diseases - PMC
    9. The History of Fish Oil: A Viking-Laden Tale
    10. Omega-3 Deficiency Symptoms & How to Get Enough | Camas Swale


    Stephanie Wright avatar

    Stephanie brings over 13 years of diverse nursing experience to the table, having honed her expertise in critical care, mental health, and utilization management. Her journey as a registered nurse across these various healthcare sectors underscores her adaptability and deep commitment to patient care.

    Fact checker

    Dr. Dimitar Marinov avatar

    Dr. Marinov has years of experience in scientific research and preventive and clinical medicine. His publications in peer-reviewed journals are on nutritional status, physical activity, and musculoskeletal disorders among adolescents.

    At VitaRx, we're not just passionate about our work — we take immense pride in it. Our dedicated team of writers diligently follows strict editorial standards, ensuring that every piece of content we publish is accurate, current, and highly valuable. We don't just strive for quality; we aim for excellence.

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