Last update: December 26, 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.
By Derick Rodriguez, Associate Editor
Edited by Dr. Dimitar Marinov, MD, RDN, PhD
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?
Your body can produce the omega-3 fatty acids that it needs and are also found in fish oil, specifically EPA and DHA, on its own, but the process is highly effective and requires the consumption of a large amount of the essential omega-3 fatty acid called alpha-linoleic acid (ALA). Therefore it's considered much more efficient to consume the DHA and EPA that your body needs from food or supplements [2].
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:
- 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.
- Eicosapentaenoic acid (EPA): Derived from animal fats, EPA is crucial for neurological and cardiovascular health.
- 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?
- Omega-3 fatty acids are primarily ingested through fish oil supplements or dietary sources such as fatty fish.
- In the stomach, fish oil is mixed with gastric juices, initiating the breakdown process, though most digestion occurs in the small intestine.
- Pancreatic enzymes and bile salts are secreted into the small intestine to further emulsify and break down triglycerides into free fatty acids and monoglycerides.
- Free fatty acids and monoglycerides are absorbed by the enterocytes (cells lining the small intestine) through passive diffusion.
- Once inside the enterocytes, they are re-esterified into triglycerides and then packaged into chylomicrons, a type of lipoprotein.
- Chylomicrons enter the lymphatic system and eventually the bloodstream, which transports them throughout the body.
- Lipoprotein lipase, an enzyme on the walls of capillary blood vessels, breaks down the triglycerides in chylomicrons into free fatty acids and glycerol, which are then taken up by tissues.
- EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are incorporated into cell membranes, affecting cell membrane fluidity, flexibility, and various cell signaling pathways.
- These fatty acids also serve as precursors to eicosanoids (prostaglandins, thromboxanes, leukotrienes), which play critical roles in inflammation, immunity, and blood clotting.
- EPA and DHA can influence gene expression related to metabolism, including genes involved in fatty acid oxidation (for energy) and lipogenesis (fat creation).
- They reduce the expression of genes involved in inflammatory pathways, exerting anti-inflammatory effects.
- Excess fatty acids are stored in adipose tissue for energy reserves.
- Small amounts of unmetabolized fatty acids are excreted through the skin and kidneys.
- Metabolic products of omega-3 fatty acids, including those transformed into CO2 and water, can be excreted through the respiratory system and urine, respectively.
- The body efficiently uses most of the ingested omega-3 fatty acids, making the excretion of significant amounts uncommon.
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.
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].
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].
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].
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].
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.
- Salmon, Atlantic, farmed, cooked: DHA - 1.24 g, EPA - 0.59 g per 3 ounces
- Salmon, Atlantic, wild, cooked: DHA - 1.22 g, EPA - 0.35 g per 3 ounces
- Herring, Atlantic, cooked: DHA - 0.94 g, EPA - 0.77 g per 3 ounces
- Sardines, canned in tomato sauce, drained: DHA - 0.74 g, EPA - 0.45 g per 3 ounces
- Mackerel, Atlantic, cooked: DHA - 0.59 g, EPA - 0.43 g per 3 ounces
- Salmon, pink, canned, drained: ALA - 0.04 g, DHA - 0.63 g, EPA - 0.28 g per 3 ounces
- Trout, rainbow, wild, cooked: DHA - 0.44 g, EPA - 0.40 g per 3 ounces
- Sea bass, cooked: DHA - 0.47 g, EPA - 0.18 g per 3 ounces
- Oysters, eastern, wild, cooked: ALA - 0.14 g, DHA - 0.23 g, EPA - 0.30 g per 3 ounces
- Shrimp, cooked: DHA - 0.12 g, EPA - 0.12 g per 3 ounces
- Tuna, light, canned in water, drained: DHA - 0.17 g, EPA - 0.02 g per 3 ounces
- Tilapia, cooked: ALA - 0.04 g, DHA - 0.11 g, EPA - 0.00 g per 3 ounces
- Scallops, cooked: DHA - 0.09 g, EPA - 0.06 g per 3 ounces
- Cod, Pacific, cooked: DHA - 0.10 g, EPA - 0.04 g per 3 ounces
- Tuna, yellowfin, cooked: DHA - 0.09 g, EPA - 0.01 g per 3 ounces
- Lobster, cooked: ALA - 0.04 g, DHA - 0.07 g, EPA - 0.10 g per 3 ounces
- Ground beef, 85% lean, cooked: ALA - 0.04 g per 3 ounces
- Chicken, breast, roasted: DHA - 0.02 g, EPA - 0.01 g per 3 ounces
- Milk, low-fat (1%): ALA - 0.01 g per 1 cup
- Egg, cooked: ALA - 0.03 g per egg
- Edamame, frozen, prepared: ALA - 0.28 g per ½ cup
- Refried beans, canned, vegetarian: ALA - 0.21 g per ½ cup
- Kidney beans, canned: ALA - 0.10 g per ½ cup
- Baked beans, canned, vegetarian: ALA - 0.07 g per ½ cup
- Bread, whole wheat: ALA - 0.04 g per slice
- Canola oil: ALA - 1.28 g per 1 tbsp
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:
Soft gels are a type of capsule that contains a liquid form of the vitamin or supplement. They are easy to swallow and provide a pre-measured dose. Soft gels are known for their fast absorption rate, as the liquid content is quickly released and absorbed by the body.
This delivery method is particularly beneficial for individuals who have difficulty absorbing nutrients from traditional pills. Soft gels are also easy to digest and gentle on the stomach, making them a good choice for those with sensitive digestive systems. However, it's important to store soft gels properly, as they are more susceptible to degradation from heat and light compared to other delivery methods.
Chewable supplements are a convenient and enjoyable delivery method, particularly for those who have difficulty swallowing pills. They come in various flavors, making them more palatable and easier to consume. Chewables are often formulated to provide a pre-measured dose, ensuring consistent intake.
Chewable supplements are a good option for children or adults who prefer a tasty alternative to traditional pills. However, some chewable supplements may contain added sugars or artificial flavors, so it's essential to read the ingredient list carefully and choose a reputable brand.
Liquid extracts are a concentrated form of a supplement that offer fast absorption and flexible dosing. The liquid form allows for quick absorption into the bloodstream, potentially leading to faster effects compared to capsules or tablets. The dropper enables precise dosage adjustments, making it easier to tailor the amount consumed to individual needs or as directed by a healthcare professional.
Liquid extracts may also provide enhanced bioavailability, as some may contain additional compounds or solvents that improve the absorption and utilization of the active ingredients in the body. However, they may have a strong taste that some individuals find unpleasant, and they require careful attention to dosage to avoid consuming too much of the supplement.
Proper storage is essential to maintain the quality and potency of liquid extracts, as exposure to light, heat, or air can degrade the active ingredients over time.
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.
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.
Do’s
Take fish oil supplements with a fat-containing meal for better absorption.
Swallow the capsules without chewing to get the most benefits and avoid a fishy taste later.
Talk to your healthcare provider to ensure it's safe and won't cause any issues.
Don’ts
Avoid taking fish oil on an empty stomach to avoid digestive issues.
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.
- People with Cardiovascular Issues: Fish oil may have promising effects on heart health, making it beneficial for people with cardiovascular risk factors [4].
- People with Arthritis: Research suggests that fish oil may help manage symptoms of arthritis, providing relief for joint pain and stiffness [7].
- People Aiming to Lower Blood Pressure: If you're looking to maintain or reduce blood pressure, fish oil may serve as a natural supplement to support this goal.
- People Wanting Cognitive Support: Omega-3s, particularly DHA, play a crucial role in brain health, making fish oil a potential support for cognitive well-being [5].
- People at Risk of Eye Diseases: Fish oil is linked to reduced risks of age-related macular degeneration, making it beneficial for older adults concerned about eye health [6].
- Have Fish or Shellfish Allergies: People allergic to seafood might experience adverse reactions to fish oil supplements. It's essential for them to consult healthcare providers before considering fish oil.
- Experience Bleeding Disorders: Fish oil, with its potential to lengthen bleeding time, may not be advisable for people with bleeding disorders.
- Take Blood-Thinning Medications: Since fish oil has anti-inflammatory properties, it may interact with anticoagulants and affect blood clotting. It's advisable for people on blood thinners to seek medical advice before using fish oil.
- Are Pregnant or Nursing: While fish oil can be beneficial, pregnant or nursing people should first consult healthcare providers to determine safety and dosage.
- Those with Low Blood Pressure: Fish oil can lower blood pressure, so people with already low blood pressure should use it cautiously.
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
Infants
- Birth to 6 months: 0.5 g/day
- 7–12 months: 0.5 g/day
- The maximum dosage for infants has not been established, but it's important to consult a healthcare provider for appropriate supplementation.
Children
- 1–3 years: 0.7 g/day
- 4–8 years: 0.9 g/day
- 9–13 years (boys): 1.2 g/day
- 9–13 years (girls): 1.0 g/day
Teens
- 14–18 years (boys): 1.6 g/day
- 14–18 years (girls): 1.1 g/day
Adults
- 19 years and older (men): 1.6 g/day
- 19 years and older (women): 1.1 g/day
- Pregnant teens: 1.4 g/day
- Breastfeeding teens: 1.3 g/day
- Pregnant women: 1.4 g/day
- Breastfeeding women: 1.3 g/day
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.
Fish oil isn’t a good fit for vegetarians or vegans as it comes from fatty fish. Plant-based alternatives like algal oil, flaxseeds, chia seeds, and walnuts offer omega-3 fatty acids for people following a vegetarian or vegan diet.
Taking fish oil every day is generally safe and can be beneficial when following recommended dosages. People with specific health conditions or on medications should consult with a healthcare provider before adding it to their daily routine.
There is no definitive answer. Fish oil may help weight loss by supporting metabolic health and reducing inflammation. But it's not a standalone solution, and combining it with a balanced diet and regular exercise is key for effective weight management.
Fish oil is a type of food, similar to olive oil, seafood, or milk. It does have a set expiration date, and it can go bad if it's exposed to air, bright light, or heat.
You can take fish oil either in the morning or at night, based on personal preference. Some people find it easier on the stomach when taken with a meal, while others may prefer it on an empty stomach.
Store fish oil in a cool, dark place, away from heat and direct sunlight, to prevent oxidation and maintain its freshness. Keeping it in the refrigerator can extend its shelf life even more, and always make sure the container is tightly sealed to prevent exposure to air.
There is no definitive answer. While fish oil isn’t a direct sleep aid, the omega-3 fatty acids it contains may contribute to better sleep by promoting overall health and reducing inflammation.
Yes, fish oil can be taken on an empty stomach. It's generally well-tolerated, and taking it with or without food is a matter of personal preference.
Fish oil used to be applied on the skin before, but it’s not the best way to get omega-3s. It's best to take omega-3s orally.
Fish oil isn’t a good fit for vegetarians or vegans as it comes from fatty fish. Plant-based alternatives like algal oil, flaxseeds, chia seeds, and walnuts offer omega-3 fatty acids for people following a vegetarian or vegan diet.
Store fish oil in a cool, dark place, away from heat and direct sunlight, to prevent oxidation and maintain its freshness. Keeping it in the refrigerator can extend its shelf life even more, and always make sure the container is tightly sealed to prevent exposure to air.
Taking fish oil every day is generally safe and can be beneficial when following recommended dosages. People with specific health conditions or on medications should consult with a healthcare provider before adding it to their daily routine.
There is no definitive answer. While fish oil isn’t a direct sleep aid, the omega-3 fatty acids it contains may contribute to better sleep by promoting overall health and reducing inflammation.
There is no definitive answer. Fish oil may help weight loss by supporting metabolic health and reducing inflammation. But it's not a standalone solution, and combining it with a balanced diet and regular exercise is key for effective weight management.
Yes, fish oil can be taken on an empty stomach. It's generally well-tolerated, and taking it with or without food is a matter of personal preference.
Fish oil is a type of food, similar to olive oil, seafood, or milk. It does have a set expiration date, and it can go bad if it's exposed to air, bright light, or heat.
Fish oil used to be applied on the skin before, but it’s not the best way to get omega-3s. It's best to take omega-3s orally.
You can take fish oil either in the morning or at night, based on personal preference. Some people find it easier on the stomach when taken with a meal, while others may prefer it on an empty stomach.
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
- Omega-3 Fatty Acids - StatPearls - NCBI Bookshelf
- Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements
- Omega-3 Fatty Acids - Consumer
- The Effects of Fish Oil on Cardiovascular Diseases: Systematical Evaluation and Recent Advance - PMC
- Effects of Omega-3 Polyunsaturated Fatty Acids on Brain Functions: A Systematic Review - PMC
- Omega-3 Fatty Acids and Eye Health: Opinions and Self-Reported Practice Behaviors of Optometrists in Australia and New Zealand
- Omega-3 Fatty Acids for the Management of Osteoarthritis: A Narrative Review - PMC
- Omega 3 Fatty Acid and Skin Diseases - PMC
Editor
Derick Rodriguez
Derick Rodriguez focuses on editing health and wellness-related content. With over half a decade of experience in the digital realm, Derick has developed a unique skill set that bridges the gap between complex health concepts and accessible, user-friendly communication. His approach is deeply rooted in leveraging personal experiences and insights to illuminate the nuances of health and wellness topics, making them more approachable and empowering readers with knowledge and confidence.
Fact checker
Dr. Dimitar Marinov
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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