Fish Oil Side Effects & Potential Benefits Of Supplementing*
What to know about fish oil.
The reason people pop gelcaps filled with fish oil: The stuff, which comes from fatty fish like anchovies, sardines, mackerel, salmon, and tuna, is loaded with healthy fats called omega-3s, explains dietitian Lauren Kelly, R.D., head of community and nutrition for Sound. In addition to supporting your whole-body antioxidant status, plus cardiovascular and immune systems, omega-3s' anti-inflammatory properties also support your brain, eyes, and more—and since the body can't produce these healthy fats on its own, it's essential that you get them from food or a high-quality omega-3 supplement, she says.*
Another reason the omega-3s found in fish oil are so important, especially these days, is that the average American diet is (too) high in omega-6 fats, which have inflammatory properties. While omega-6s are found in healthy foods like pumpkin seeds, sunflower seeds, and walnuts, they're also found in high amounts in vegetable oils (aka soybean, corn, canola, etc.) and processed foods, Kelly explains. And when people eat lots of processed, vegetable-oil-containing foods, they consume too many omega-6s compared to omega-3s, which creates an omega fats imbalance and is counterproductive for omega-3s' anti-inflammatory actions.* For these reasons (among others) a quality fish oil supplement can be incredibly helpful—especially if you don't eat fatty fish like salmon or tuna at least two to three times a week, says Kelly.
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Can you take too much fish oil?
Just how many omega-3s you need—and thus how much fish oil would best support your health—depends on individual factors and health priorities. The Dietary Guidelines for Americans recommends adults get an average of 250 to 500 milligrams of EPA and DHA per day (that's about one to two servings of fish a week) for starters. The American Heart Association echoes this two-fish-serving baseline and then recommends a higher daily dose of these marine omega-3s—1,000 milligrams per day—for optimizing heart health.* Meanwhile, research indicates that pregnant women need 650 milligrams of omega-3s per day, with at least 300 milligrams of that coming from DHA (a must-have for baby's brain, eye, and neural development), specifically.* That said, clinical research indicates that up to 10,000 milligrams (aka a whopping 10 grams) of EPA and DHA can be taken safely without adverse effects. In fact, you're probably more likely to run into issues eating tons of fish than taking high amounts of fish oil, according to Andrea Paul, M.D. "The more likely negative health outcome is exposure to high levels of environmental toxins like mercury through very high levels of fish consumption," she says. Since quality supplement brands purify and test their products for contamination for things like heavy metals, you would actually face greater risk by eating lots of tuna than by taking a high-quality supplement for a concentrated dose of omega-3s.*
The potential side effects of too much fish oil.
That said, there are a few potential side effects that can come with consuming high amounts of fish oil, particularly if you have certain health considerations:
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1. Upset stomach
Though research suggests that a teeny-tiny proportion of people (just about 1%) experience digestive upset after taking fish oil, it is a potential side effect those with sensitive stomachs might notice. This could be simply because fish oil is fat, which some people have trouble digesting. "Fat may relax the lower esophageal sphincter [a set of muscles at the bottom of the esophagus, near the entrance to the stomach] and promote acid reflux or slow the flow of digestion," explains dietitian Isa Kujawski, MPH, RDN. But as Ashley Jordan Ferira, Ph.D., RDN, mbg's in-house nutrition scientist, warns: "A negative GI experience with an omega-3 supplement is more commonly tied to poor-quality ingredients, in other words, lower-quality fish oil or fish oil that's been allowed to oxidize and become rancid." So, it's of utmost importance to consider these "fishy" factors.
2. Blood thinning
If you have a bleeding disorder or take medications classified as blood thinners, out of an abundance of caution, Kelly recommends talking to your doctor about any supplements, including omega-3 fish oil supplements, you take (or are interested in taking), since they can have a blood-thinning effect at extremely high doses. Again, 10,000 milligrams of EPA plus DHA daily (that's 10 grams) has been shown to be safe according to research. The cautionary linking of fish oil to blood thinning started decades ago simply because of the way omega-3s interact with platelets, which are cell fragments in the blood that play an integral role in clotting, Kujawski says. Ferira says this potential side effect has been blown out of proportion. "Way too much of any good thing, even water, can have potentially negative effects on our health. But in this case, a textbook physiological mechanism, that omega-3s can impact platelets, has been used to broadly fearmonger against completely safe doses of omega-3s found in supplements." She goes on to say that, "In reality, the blood-thinning effect of fish oil actually occurs at absurdly high levels of EPA plus DHA, 10 grams plus, which by the way, no supplement even comes close to containing. Omega-3 supplements are playing in the 200- to 1,800-milligram range of EPA plus DHA 99% of the time." Ferira explains that the scientific case for omega-3s' safety is a strong one. "I'm talking about 80-plus research studies demonstrating the safety of low, medium, and high levels of daily EPA + DHA consumption. It's time somebody debunked this myth that is genuinely scaring people away from using a truly helpful tool fish oil supplementation) for whole-body health."*
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3. Blood sugar changes
There's conflicting science here, but some research does suggest that very high doses of omega-3 can affect blood sugar in some people, according to Kujawski. (Newer studies actively question this.) To be safe, she recommends checking in with your doctor if you have any blood sugar concerns. Ferira shares that, "to be clear, omega-3 supplementation research has been shown to be highly effective for promoting a healthy profile of lipids, with particular benefit to triglyceride levels. That same research has found a modest beneficial trend for glucose, insulin, and HbA1c measures of glucose control, while other studies have reached statistical significance, demonstrating omega-3s' ability to improve insulin sensitivity."* For most people, this means that omega-3s are actually helpful for your blood sugar balance, but Ferira explains, "For those with true hypoglycemia considerations, partner with your doctor to optimize your omega-3 supplement approach."
4. Too much vitamin A
Though not a concern with the large majority of fish oil options in gelcaps or softgels), "high doses of certain sources of omega-3s such as cod liver oil also contain high amounts of vitamin A," Kujawski explains. One teaspoon of cod liver oil, she says, contains 4,500 I.U. of vitamin A—so if you take multiple teaspoons per day (which some people might), you may exceed the recommended maximum tolerable upper intake level) of 10,000 I.U. for vitamin A. A few signs of too much vitamin A may include dizziness, queasiness, or even joint discomfort.
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5. Low blood pressure
While fish oil supplements' impact on blood pressure is exactly what makes them appealing to certain people, it may be a consideration for those who take blood pressure medications or who already have low blood pressure. So partner with a health care practitioner to be sure. Ferira shares that, "the fact that omega-3s have been shown in a large number of research studies to promote healthy blood pressure levels is compelling, so compelling that a couple of years ago, the FDA issued a claim for omega-3 food and supplement products containing at least 800 mg of EPA plus DHA per serving, saying those products may reduce blood pressure and the risk of hypertension, which is, in turn, a major risk factor for coronary heart disease."†
6. Trouble sleeping
Research is quite limited here, with just individual case studies one person) suggesting a link between taking high doses of omega-3s (specifically a very high-dose EPA supplement in this singular case) and trouble sleeping—so Kujawski says that more scientific investigation is needed to better understand any potential relationship between high amounts of omega-3s and sleep. Ferira concludes that "these case studies are informative, but n-of-1 reports are not something to base population info on. In fact, recent clinical trial research in healthy young adults found omega-3 supplements to be helpful for sleep architecture and efficiency."*
The positive effects of fish oil.
Of course, omega-3s (and the fish oil supplements that contain them) can benefit your health and well-being in a number of ways. Here is a bird's-eye view of some of the positive side effects of fish oil that experts and researchers have uncovered to date:
1. Immune support
Because omega-3s have been shown to have anti-inflammatory properties, combat oxidative stress, and directly support our immune response in the body, taking an omega-3-rich fish oil might be beneficial to the immune system.* All types of omega-3s help signal the immune system to activate our natural defense pathways.*
2. Cardiovascular wellness
One of the most well-known positives of omega-3s: cardiovascular health. In addition to promoting healthy blood circulation and pressure, these good-for-you fatty acids also support optimal levels of lipids, particularly triglycerides (a type of fat in the blood).* As Ferira alluded to before, the FDA believes the science collectively supports omega-3-rich supplements' ability at least 800 milligrams of EPA plus DHA per serving) to help reduce coronary heart disease risk.†
3. Bone & joint health
Because of their (lesser-known) role in helping to regulate calcium absorption, omega-3s support bone health, studies indicate. Those anti-inflammatory properties also come in handy for supporting joint function and comfort.* Ferira concludes, "If omega-3s were not top of mind for musculoskeletal health, they should be. The science is exciting and growing."*
4. Brain development & cognition.
The omega-3 DHA, in particular, is crucial for brain development, as well as for supporting cognition (including things like memory and mood) throughout your lifetime.* Ferira shares, "Indeed, these omega-3s are literally intrinsic to the cellular membranes of cells throughout our central nervous system, from our brain and retina to neurons throughout the body. They are ensuring healthy neuronal signaling via synaptic transmission, which translates practically into mental acuity, memory, vision, and more."* She caveats these potential benefits with an important message: "These central nervous system benefits are all predicated on the assumption that, of course, you are regularly consuming a meaningful amount of omega-3s EPA and DHA in the first place."*
5. Balanced mood
More recently, science has started digging more into another exciting perk of omega-3s: Their role in mental well-being. Researchers are still exploring exactly how EPA and DHA (the two omegas being touted for their mood benefits) have a positive impact here, but there is certainly evidence to suggest they have an important part to play in supporting a balanced mood.* "Given omega-3s' extensive neuroprotective roles in the body, it's not surprising that they have been linked to mood balance and health,"* concludes Ferira.
6. Healthy eyes & vision
In addition to brain development, DHA is also a must-have for eye development early on and function throughout life. It both works to ensure that the retina functions as it should and helps the eyes combat oxidative stress.* Explaining the science a bit more, Ferira shares that, "We know DHA supports functioning & regeneration of rhodopsin, a visual pigment that plays a critical role in the visual system that converts light into visual images. In other words, DHA helps you see, that's pretty important stuff!"*
The bottom line on fish oil and its effects.
Taking high-quality fish oil supplements that boast purity and potency, especially if you aren't much of a fish eater, can be a great move for everything from immune and cardiovascular health to cognition and joint health.* And though scientific evidence has shown that incredibly high amounts of fish oil can be tolerated, it's never a bad idea to check in with your doctor or nutritionist before making changes to your supplement routine, especially if you have certain health concerns or needs.
†Consuming EPA and DHA combined may reduce blood pressure and reduce the risk of hypertension, a risk factor for CHD (coronary heart disease). However, FDA has concluded that the evidence is inconsistent and inconclusive. One serving of omega-3 potency+ provides 1.5 grams of EPA and DHA.
If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.
Fish Oil: Health Benefits, Uses, & Safety
by Meenakshi Nagdeve last updated - Medically reviewed by Vanessa Voltolina (MS, RD) ✓ Evidence Based
Many of the health benefits of fish oil can be attributed to the presence of omega-3 essential fatty acids like docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), according to the USDA National Nutrient Database. Other useful essential fatty acids in fish oil include alpha-linolenic acid or ALA and gamma-linolenic acid or GLA. [1]
Here is a brief on omega-3 fatty acids: There are three types of omega-3 fatty acids, namely alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). All three are important for the body.
A few of these health benefits include its ability to aid in weight loss and improve the skin. It has also shown positive implications in reducing the risk of heart disease, high cholesterol, mental health disorders, and inflammation, as well as others.
There are various types of fish that are good sources of oil; they include mackerel, lake trout, herring, sardines, swordfish, oysters, albacore tuna, bluefin tuna, yellowfin tuna, turbot, pilchards, anchovies, and salmon. The quality of fish oil greatly depends on the type of fish from which the oil is retrieved.
Health Benefits of Fish Oil
Fish oil has a positive impact on most healthy adults, as it helps in weight loss, skincare, vision improvement, and other health issues.
Nutrition Facts Fish oil, herring Serving Size : 100 g 1 tbsp (13.6 g) 1 tsp (4.5 g) 1 cup (218 g) Nutrient Value Energy 902 Energy [kJ] 3774 Total lipid (fat) [g] 100 Fatty acids, total saturated [g] 21.29 12:0 [g] 0.16 14:0 [g] 7.19 16:0 [g] 11.7 18:0 [g] 0.82 Fatty acids, total monounsaturated [g] 56.56 16:1 [g] 9.64 18:1 [g] 11.96 20:1 [g] 13.63 22:1 [g] 20.61 Fatty acids, total polyunsaturated [g] 15.6 18:2 [g] 1.15 18:3 [g] 0.76 18:4 [g] 2.31 20:4 [g] 0.29 20:5 n-3 (EPA) [g] 6.27 22:5 n-3 (DPA) [g] 0.62 22:6 n-3 (DHA) [g] 4.21 Cholesterol [mg] 766 Sources include : USDA [2]
Boosts Heart Health
According to the American Heart Association (AHA), clinical trials have shown that foods containing omega-3s are effective in reducing the incidence of cardiovascular diseases (CVD). Fish oil is a great source of omega-3 and therefore, may help individuals reduce the risk of heart diseases and heart arrhythmias. It also contributes to lowering elevated levels of LDL cholesterol (bad) and increases the level of HDL cholesterol (good). Omega 3 containing fish oil helps prevent the accumulation of triglycerides and also reduces the level of excess triglycerides. Preliminary research has shown that fish oil’s healthy components can be used to reduce the risk of atherosclerosis in coronary patients. Thus, regular usage of this oil may help avoid sudden cardiac death. As per the American Heart Association, these preliminary findings still need to be confirmed by further detailed research. [3]
Weight Loss
Anti-obesity research conducted by the University of South Australia has shown that combining fish oil with exercise is more beneficial in reducing obesity than either one alone. Volunteers who were given fish oil in their diet and exercised showed greater weight loss as compared to those who did not regularly consume it and exercised. Fish oil contains omega-3 fatty acids, which help to promote weight loss, so a combination of physical workout and intake of this oil helps in reducing body fat significantly faster.
Improves Immunity
It is thought that regular consumption of fish oil may aid in boosting your immune system, thereby enabling you to resist the occurrence of common ailments, such as cold, cough, and flu. The omega-3 fatty acids present in fish oil are thought to bolster the immune system by affecting the activity and amount of cytokines and eicosanoids present in our body. Some preliminary researchers published in the journal Animal Science have also studied the effect of bovine consuming fish and fish oil on their immune systems. They found that fish oil aided in the growth of the animals. Similar research conducted on mice at Taichung Veterans General Hospital in Taiwan also showed positive results. [4] [5]
Reduces Inflammation
Fish oil may be an effective method in helping to reduce inflammation in the blood and tissues. Ideally, it is best to consume actual omega-3 containing fish products to reap all of the beneficial nutrient interactions. Fish oil is thought by some suffering from gastrointestinal disorders–such as Celiac disease, short bowel syndrome, and inflammatory bowel disease (IBD) including Crohn’s Disease and ulcerative colitis–to be effective in reducing inflammation.
Other inflammatory states including arthritis, rheumatism, Raynaud’s symptoms, may also benefit from this oil. It may help in reducing the need for large dosages of NSAIDs (non-steroidal anti-inflammatory drugs). The Royal Adelaide Hospital and the University of Newcastle, located in Australia, have reported that fish oil has shown positive effects in treating the symptoms of arthritis. [6] [7]
While some research shows that regular consumption of fish oil supplements, tablets, pills, and capsules may be helpful to those who suffer from chronic inflammatory diseases, the jury is still out and more research is needed to confirm the benefits. [8]
May Relieve Depression & Anxiety
Due to the presence of omega-3 fatty acids, fish oil has been promoted for relieving depression, sadness, anxiety, restlessness, mental fatigue, stress, and low libido. Countries where fish is frequently eaten, have a lower incidence of depression. Multiple preliminary studies have shown Omega-3s as a promising natural solution for mood disorders; however, more research is underway to confirm these beneficial effects.
Similarly, research conducted on prisoners has shown that when prisoners were given seafood containing a higher amount of omega-3 fatty acids, there was a significant drop in the homicide rate and the frequency of violence. Findings of another research study suggest that fish consumption may be beneficial for women’s mental health and reduces the risk of developing depression in women. While a clear link can’t yet be established given the multiple compounds in fish, it is a good basis for suggesting that increasing omega-3 content may be beneficial for this population. [9] [10]
May Reduce Risk & Progression of Neurodegenerative Disease
Research conducted at Louisiana State University has shown that fatty acids are connected to reducing the risk and slowing the progression of Alzheimer’s disease. Since fish oil is one of the best sources of essential fatty acids, including EPA and DHA, these may be a boon to those suffering. More research conducted at the University of California in Los Angeles validates the usefulness of fish oil as a possible remedy for the disease. The Alzheimer’s Association recommends consuming fish containing a higher content of omega-3 fatty acids to patients, as it may act as a defense against Alzheimer’s disease and dementia. [11] [12]
Reduction in ADHD Symptoms
Fish oil may have the potential to reduce the symptoms of Attention Deficit Hyperactivity Disorder (ADHD) due to its high concentration of fatty acids. For children suffering from hyperactivity, dyslexia, short attention span, low concentration, or learning disorders, fish oil may be a part of the solution.
Preliminary research conducted at the University of South Australia and CSIRO has shown that when children suffering from ADHD were given doses of fish oil and evening primrose capsules for 15 weeks, they showed significant improvements in their behavior. More research is in the works to look more closely at these potential benefits. [13]
Furthermore, it is believed that fish oil is useful in the normal development of the brain, along with helping your child concentrate on their studies. It has also been found that when pregnant women are given regular doses of fish oil, their toddlers display enhanced hand-eye coordination. [14]
Skin Care
Fish oil is great for improving the condition of dry skin by making it look shiny and vibrant. It has been found by some to be useful in treating various skin problems such as eczema, psoriasis, itching, skin redness, and rashes. In terms of psoriasis, the EPA present in fish oil restricts the growth of pro-inflammatory agents by producing arachidonic acid.
Fish oil can also be applied topically to get relief from psoriasis; however, many find that it has a limited positive effect. Intravenous administration of fish oil, however, has been shown more effective. It is also claimed by some people that the oil helps in preventing sunburn but the research behind that claim is not verified.
Treats Acne
Fish oil is thought to be a topical acne treatment. EPA present in the oil is known to inhibit androgen formation, which can affect the formation of sebum in the hair follicles, leading to acne. [15]
Prevents Ulcers
The presence of EPA and DHA in fish oil may have some benefit in the case of ulcers caused by Nonsteroidal anti-inflammatory drugs (NSAIDs). [16]
Supports Healthy Pregnancy
Fish oil is beneficial for pregnant women as the DHA present in it helps in the development of the eyes and brain of the baby. Lack of seafood – and thus omega-3s were linked with premature births, low birth weight, and miscarriages. Research conducted in Denmark, which involved 8,729 pregnant women, concluded that a diet with low amounts of fish resulted in a higher risk of premature or preterm babies. [17]
It is also believed that women who do not have a sufficient intake of EPA and DHA in their diet suffer from depression after childbirth. Thus, it may be beneficial to consume fish oil either by consuming fish or taking fish oil supplements, tablets, capsules, or pills during pregnancy for the overall development of the child and the well-being of the mother. However, fish oil obtained from the liver of the fish, for example – cod liver oil – should not be consumed during pregnancy as cod liver oil is high in retinol and vitamin A, which are usually known to cause birth defects. If you are pregnant or trying to become pregnant, be sure to discuss options for getting fish oil with your OBGYN or primary doctor.
Improves Fertility
Fish oils rich in omega 3 fatty acids may help improve fertility and cell division in sperm. Preliminary research conducted on animals has shown that when males are fed a diet containing fish oil, the quality of the sperm is enhanced. After ejaculation, the sperm has increased survival against lipid peroxidative attacks in the female genital tract, thereby increasing the chances of conception. On the other hand, similar animal studies have shown inhibition in the synthesis of prostaglandin E and prostaglandin F, which are produced in large quantities by human seminal vesicles. The research, however, found no impact on the count and mobility of sperm. More research is needed to clarify these results; however, given its slew of other positive benefits, it is still a benefit to consuming by most people. [18] [19]
Hair Care
Fish oil is thought to help maintain good hair shine and luster because omega-3 has growth stimulating properties and provides nourishment to the follicles. A good supply of protein is also necessary for hair growth, and since most fish varieties are rich in protein, eating fish provides both of these hair health benefits.
Many people also like to feed fish oil to their pets, especially dogs and cats, as it promotes shiny and smooth hair.
Fish Oil and Lou Gehrig’s Disease
Fish oil is rich in omega-3 fatty acids, as mentioned. Recent research suggests that intake of a diet rich in omega-3 fatty acids may reduce or delay the onset of Amyotrophic lateral sclerosis (ALS) also known as Lou Gehrig’s disease. [20]
Fish Oil Side Effects
Even though fish oil has many benefits, excessive intake may cause allergy and side-effects. People who are allergic to seafood or fish, in particular, will experience effects like hives and swelling of face, lips, tongue, or throat. Consuming seafood or fish is not advised if you have a known allergy.
In the case of excess intake, one may also experience bad breath, stomach upset, loose stools, belching, nausea, or even more serious effects. Avoid consumption if allergic to fish. The American Heart Association recommends at least two servings of fatty fish weekly. [21]
Let us look at some of the side-effects in detail:
Children: Excessive intake of fish oil by children may lead to allergic reactions like itchiness, sneezing, or a dry cough.
Excessive intake of fish oil by children may lead to allergic reactions like itchiness, sneezing, or a dry cough. Pregnant Women: Even though fish oil has many benefits for pregnant women, the mercury content found in certain seafood can be harmful to the memory, hearing abilities, cognitive skills, and vision of the baby.
Caution on Fish Oil Amount
An excessive dosage of fish oil can have adverse allergies and side effects on the body. Furthermore, fish oil can be problematic if you have certain conditions, so it is necessary to check with your doctor before consuming fish oil supplements. While consuming fish oil directly from fish is one thing, taking it in the form of concentrated dietary supplements like liquid, tablet, capsule, pill, or soft gels may pose an issue. Dietary supplements in the United States are not regulated by the government, so choosing a safe option is important.
Should We Replace Vegetable Oils with Fish Oil?
The short answer: not necessarily. There are many websites which advise people to stop eating vegetable oils and switch to fish oil to increase their intake of omega-3 fatty acids. Fish oil is a good source of omega-3 essential fatty acids and should be consumed, but that doesn’t necessarily mean that one should completely replace vegetable oils with fish oil.
Vegetable sources, including flaxseed oil, soybean oil, hemp oil, canola oil, walnut oil, rapeseed, perilla, chia, and tofu are rich in ALA. The human body can convert ALA to DHA and EPA, though there are certain limitations to this conversion. Additionally, eating a varied, healthy diet full of many different foods is most beneficial for health, as different foods provide robust nutrition that the body needs to function optimally.
How much fish oil is safe to consume?
Fish oil can be consumed in various ways such as capsules or can be included in daily meals. Research suggests that the dosage should not exceed three fish oil capsules per day. 1000mg of fish oil contains approximately 300mg omega-3 fatty acids. A daily intake of 3000mg or less is commonly thought of as being safe for the general population. Pregnant and lactating women can consume approximately 3200 mg per day. [22] [23]
Fish Oil Purity
When purchasing fish oil, pay attention to quality. It is obtained from almost all fishes including – freshwater, farmed, ocean, deep sea, and shallow sea fish. All of these fish can be contaminated with toxic compounds such as mercury, arsenic, lead, forms of calcium, furans, dioxins, PCBs, and methylmercury, and can negatively affect the human body. Therefore, the fish oil used must be pure. Many companies sell ultra refined or distilled fish oil, but you should always check if the standards have been followed and research on the company or the product before adding it to your diet.
While fish oil has plenty of beneficial qualities, there is a lot of hype around its possible applications, and not all of them are accurate, so be wary when reading literature on this useful oil. Fish oil manufacturers have attempted to market it as a remedy for almost anything. We suggest that readers educate themselves fully before making an informed decision, rather than getting affected by both negative and positive propaganda about the beneficial applications of fish oil.
Fish Oil and Vitamins
Vitamin A and Vitamin D: Fish oil, especially the types obtained from fish livers like cod liver oil is a rich source of vitamin A and vitamin D. However, excessive dosage of cod liver oil can lead to vitamin toxicity, the accumulation of excessive vitamins in the body, which can cause serious side effects.
Vitamin E: Fish oil undergoes oxidation and can become rancid, leading to the formation of free radicals. The addition of antioxidants such as vitamin E to the oil can help prevent the formation of these free radicals. [24]
An excessive dosage of fish oil is thought to lead to decreased levels of vitamin E in the human body. This is another reason why adequate intake–but not excess–should be achieved.
What are the benefits of fish oil?
There are many benefits of fish oil and you can take it in capsule form if you follow a plant-based diet and struggle to get your dosage of omega-3. Or, if you’re just not a fan of fish, the best fish oil supplements make a great alternative.
According to the National Center for Complementary and Integrative Health (opens in new tab) , nearly 8% of adults in the US take a fish oil supplement. Researchers have found omega-3s, especially the types found in seafood (fish and shellfish) and fish oil supplements, support your brain, eyes, and heart and fight inflammation in your body. You need to add omega-3 to your diet via food or supplements, as your body cannot make it like it can create vitamin D, for example.
The Dietary Guidelines for Americans (opens in new tab) recommend that adults eat eight or more ounces of a variety of seafood (fish or shellfish) per week for the nutrients seafood provides.
7 benefits of fish oil
1. Good for heart health
Fish oil has been shown (opens in new tab) to help increase HDL cholesterol (sometimes called “good” cholesterol), lower blood fats, reduce blood pressure, helping prevent the hardening of the arteries. A 2019 meta-analysis (opens in new tab) concluded that marine-derived omega-3 could lower the risk of heart attack and heart disease deaths.
People from countries with diets rich in omega-3 foods including fish and seafood - such as Japan and Greenland - show a lower risk of heart disease than Western countries such as the US and the UK where less is typically eaten (opens in new tab). What's more, the UK NHS acknowledges the beneficial effect of the long chain omega 3 fats (EPA and DHA) on maintaining a healthy heart (opens in new tab).
But what about fish oil supplements? A series of recent studies have called into question their heart-protecting qualities, including a major review (opens in new tab) of randomized studies in 2018 which showed omega 3 supplements had little or no effect on the risks of experiencing heart disease, stroke or death.
But the story doesn’t end there. In 2019, another large study was published showing that taking a high dose supplement of pure EPA could reduce heart attacks, strokes and cardiac deaths in a high-risk population by over 25%. So where does that leave us? Dr Alex Richardson (opens in new tab), a passionate advocate of the benefits of fish oil for health, says: “There is solid scientific evidence that the omega 3 from fish oils - DHA and EPA, and especially EPA - is beneficial for a healthy heart.
“The reason you get so many seemingly conflicting results with nutritional studies can be to do with the limitations of those studies - often reflecting budgets, practicalities or the ethics of trials on humans - but also because clinical trials vary so much in the populations studied - formulations and dosages used, outcome measures and compliance.
“Whenever possible, it's always best to get nutrients from real food, rather than supplements. But for those who can't or won't eat fish and seafood at least twice a week or more, supplements can help to increase blood and tissue levels of these omega 3. International scientific experts recommend (opens in new tab) at least 500mg/day of EPA and DHA for general heart health in the general population.”
2. Helps brain function
Research (opens in new tab) has found that omega-3 is essential for typical brain function. In one study (opens in new tab), fish oil improved cognitive performance in healthy adults between the ages of 51 and 72 in just five weeks, compared with the effects of a placebo. Studies (opens in new tab) have also connected higher blood levels of omega-3s with a lower risk of depression and anxiety. When used in conjunction with standard antidepressant therapies, fish oil supplementation has been beneficial in treating depression compared to a placebo.
3. Improves bone density
In the typical American diet, it's common to consume far more omega-6 fatty acids—which are found in plant oils, like corn and sunflower oils—than omega-3 fatty acids. Scientists (opens in new tab) think this imbalance may cause low bone density in both men and women. Older adults with higher omega-3 intakes have been shown (opens in new tab) to maintain greater bone density, making fish oil a possible way to tackle the issue of age-related bone loss.
(Image credit: Getty Images)
4. May reduce inflammation
Inflammation is your immune system’s way of fighting infection and treating injuries. However, chronic inflammation is associated (opens in new tab) with health conditions such as kidney disease, diabetes, and heart disease. Reducing inflammation may help treat symptoms of these diseases. Scientists believe (opens in new tab) that because fish oil has anti-inflammatory properties, it may help treat chronic inflammation conditions. Additionally, fish oil supplements can significantly reduce joint pain (opens in new tab) and stiffness in people with rheumatoid arthritis, which causes pain in the joints. This is why many of the best supplements for joints contain fish oil.
5. May improve asthma symptoms
Several studies (opens in new tab) show that fish oil may reduce asthma symptoms, particularly in children. The supplements may also be helpful in pregnancy. In a review (opens in new tab) of nearly 100,000 people, a mother’s fish or omega-3 intake was found to reduce the risk of asthma in children by 24–29%. Furthermore, taking fish oil supplements during pregnancy may reduce (opens in new tab) the risk of allergies in babies.
6. Can help with weight management
Some research (opens in new tab) has linked omega-3 to fat loss. And supplementing your diet with fish oil has also been shown (opens in new tab) to slow the normal decline in muscle mass and function in older adults. Other research has demonstrated that fish oil may also indirectly affect weight management (opens in new tab) by stimulating areas in the brain that control food intake.
7. Protects eye health
Some evidence suggests that getting an adequate intake of omega-3 may help protect eye health. Optometrists often recommend (opens in new tab) taking supplements containing omega-3 to support eye health, even though scientific evidence does not always support their use for this purpose. In some cases, eating a diet rich in fruit and vegetables may be as beneficial as supplements. For example, in 2019, scientists who looked at the data (opens in new tab) of 4,202 people in Holland found that those who consumed fresh fruits and vegetables and two weekly servings of fish were less likely to develop age-related macular degeneration than those who did not.
Is fish oil good for pregnancy?
The NHS recommends pregnant and breastfeeding women eat at least one portion of oily fish a week as omega 3 fatty acids EPA and DHA help a baby’s nervous system to develop (opens in new tab). (Although note they set an upper limit of two portions of oily fish and recommend certain fish to avoid.) But what if you don’t eat fish?
Dr Richardson says: “In 2018, a systematic review of randomised clinical trials (opens in new tab) showed that supplementation with omega-3 EPA and DHA during pregnancy reduces premature births and low birth weight. Prematurity and low birth weight raise the risk of physical and mental health disorders across a child’s life so pregnant women (and those of child bearing age) would do well to ensure they eat at least two portions of fish a week - one of which should be oily - or take an omega 3 supplement containing EPA and DHA omega-3s.”
If choosing a supplement, she advises looking for one that provides at least 250-300mg DHA and to ensure it states it is safe for use in pregnancy. “Some supplements, such as cod liver oil, can contain high doses of vitamin A and D which can be harmful in excess."
How much fish oil should you take?
In most cases, the best way to consume nutrients is through food, unless a doctor or nutritionist recommends you take supplements.
The American Heart Association recommends (opens in new tab) eating two servings of fish (particularly fatty fish) per week. A serving is 3 ounces cooked or about ¾ cup of flaked fish. Fatty fish like anchovies, herring, mackerel, black cod, salmon, sardines, bluefin tuna, whitefish, striped bass, and cobia are high in omega-3 fatty acids.
Researchers have found it challenging to define an optimal amount of omega-3 fatty acids per day. The American Heart Association (AHA) recommends adults take between 500–1,000 milligrams (opens in new tab) of omega-3 per day. However, other countries and organizations recommend different doses. It may also be necessary to increase the dosage if you are pregnant, nursing, or at risk of heart disease.
You can take fish oil capsules with water during a meal. However, if you do not typically eat much fat at breakfast, you may wish to wait until lunch or their evening meal before taking it.
Some people experience gastrointestinal side effects when taking fish oil. If you experience this side effect, you may find it helpful to split your fish oil into two doses (opens in new tab) and take them at different times of the day.
Fish oil has a blood-thinning effect, so too much can increase bleeding risk, especially when combined with other blood thinners, like aspirin. Fish oil can also interact with some prescription medications, so discuss it with your doctor before you start taking the supplement.
