14 Little-Known Side Effects Of Fish Oil Supplements

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Fish oil supplements are popular as a source of heart-healthy omega-3 fatty acids. However, they may have some unpleasant side effects that you don't know about. Mild side effects include digestive problems, flu-like symptoms, and rashes. More severe symptoms are anxiety, insomnia, arrhythmia, allergic reactions and blood thinning. They may also cause inflammation, oxidative stress, cancer, and decreased immunity.

Fish oil supplements have one of the best reputations in the dietary and nutrition world. It’s full of omega 3-fats which are considered essential for brain development and is often prescribed as an effective way to reduce triglyceride levels, along with a healthy diet. However, is it really as good as it’s chalked up to be? Here are some little-known side effects of fish oil.

Mild Side Effects Of Fish Oil

1. Mild Skin Rash

Skin rash may be an allergic reaction to fish oil

Some people experience skin rashes when they start supplements of fish oil. If you do see a rash forming when taking fish oil, alert your doctor, because it may be part of an allergic reaction.

2. Back Pain

Back pain may occur when taking supplements

Doctors still aren’t quite sure why this happens but if you do experience back pain after starting the supplements, notify your doctor. It may be a sign of some underlying health condition that needs to be treated.

3. Unpleasant Taste

One may not like the fishy flavor of the supplements

People often complain of a fishy aftertaste when on these supplements which is extremely common. However, if a bottle of supplements smells particularly strong when you open it, it’s possible that the capsules may have gone rancid. Make sure to store them properly and throw them out when they cross their expiration date.

4. Upset Stomach

This is a common side effect of fish oil

One may experience nausea, vomiting, and diarrhea while on these supplements. Usually, these can be remedied by taking the capsules with a meal. It’s worth noting that you may experience vomiting and diarrhea if the capsules have gone rancid, so check the expiration date on your bottle.1

5. Frequent Belching

One may experience bloating from fish oil

One may feel more bloated and gassy than usual while on these supplements. Researchers aren’t sure why but it’s worth mentioning this to your doctor as well.2

6. Flu Symptoms

Fish oil may cause flu-like symptoms

Some people experience fevers, chills, colds, and sore throats while on this supplement. This is probably because your body is finding it difficult to tolerate the oil or you may have consumed a contaminated capsule.

Moderate To Serious Side Effects Of Fish Oil

1. Chest Pain And Uneven Heartbeat

Fish oil may cause chest pain.

In some people, fish oil supplements cause irregular heartbeats and chest pain. An irregular heartbeat can be extremely dangerous and lead to heart failure. If you experience chest pain after taking fish oil supplements, make sure to see your doctor as soon as possible.3

2. Allergic Reaction

Fish oil may cause allergic reactions.

People who are allergic to seafood and/or shellfish may want to stay away from fish oil capsules as they might trigger a reaction, which may include hives, difficulty breathing, or swelling of the face, lips, tongue, or throat. Check the ingredients as well to make sure there are no other components that you may be allergic to.

3. Increases Risk Of Bleeding Disorders

Taking fish oil may cause you to bruise easily

Bleeding disorders are conditions where the blood does not clot or ‘coagulate’ naturally. This may be an inherent condition or can be caused by certain medications which thin out the blood. Fish oil supplements are seen to increase this risk of bleeding without coagulation. This may also cause people to bruise more easily. People with bleeding disorders and those who take blood-thinning medication should talk to their physician before starting the supplement.4

4. Insomnia And Anxiety

Insomnia And Anxiety

While these are extremely rare, some people do experience an increase in symptoms of insomnia, anxiety, and overall agitation. These symptoms normally stop when the course of fish oil supplements is halted. 5

Possible Long-Term Side Effects Of Fish Oil

1. Increases Oxidative Damage

Fish oil may increase inflammation through oxidative damage.

Omega 3s are extremely vulnerable to oxidative damage. This means that they can spread this same effect to the rest of the body, increasing inflammation and therefore, the likelihood of developing chronic illnesses. Several studies have shown that consumption of fish oil supplements increases levels of oxidative stress and inflammation within just a short period of time.6 7

2. Increases LDL Levels And Insulin Resistance

Fish oil may increase LDL levels

Fish oil seems to cause an increase in the levels of LDL or ‘bad cholesterol’ in people with metabolic syndrome. People with metabolic syndrome are those who suffer from a number of conditions such as increased blood pressure, excess abdominal fat, increased blood sugar and cholesterol levels. They also showed increased insulin resistance as well.8 Some studies show that in people with high cholesterol, fish oil actually adversely affects the ratio of LDL to HDL and in some cases the triglyceride decrease is insignificant.9

3. Increases Risk Of Prostate Cancer

Fish oil may increase chances of prostate cancer

Some studies show that omega-3 fatty acids protect from prostate cancer, while other studies show the contrary. Researchers found that men with higher saturations of omega 3s in their blood were more likely to develop high-grade prostate cancer.10

4. Reduces Immunity

Fish oil may reduce immunity levels

In small amounts, omega 3 is an anti-inflammatory compound which prevents disease and deterioration. Some researchers have observed that high levels of omega 3 have an adverse effect on the immune system. It may lead to an abnormal immune response when fighting a bacterial or viral infection.11 This may make one more susceptible to sickness.

Do You Really Need Them?

Now eggs come fortified with Omega-3

Fish oil supplements are often cited as one of the best ways to maintain and improve heart health but studies show that it does not really have a major effect in individuals who actually have risk factors associated with heart disease.12 Many speculate that the benefits of fish oil supplements were over-exaggerated in earl studies.

If your doctor has prescribed for you to take these supplements to reduce your triglyceride levels, by all means, continue taking them at the recommended dose, but the major danger with these supplements is getting an overdose of omega-3 when you may not really need it. Nowadays, foods like eggs, milk, and other dairy products are often fortified with omega-3. If you take supplements along with these foods, you’re getting an overdose of omega-3 without even realizing it.

Where To Get Your Omega 3

Here are some foods that are high in Omega-3

If you’re still considering taking the supplements, first try getting your omega-3 from foods in which they naturally occur. The American Heart Health Association recommends two servings of fish a week as part of a healthy diet, to maintain heart health. Salmon, mackerel, and light tuna are great options. If you’re not a fan of fish, try flax seed, flax seed oil, chia seeds, walnuts, pumpkin seeds, soy, and canola oil. These foods also contain other essential vitamins and minerals which support absorption and general functioning. This is much better nutritional value than the capsules One or two servings of these foods a day should cover your nutritional need.

References   [ + ]

1.Omega-3 fatty acids. University Of Maryland Medical Center
2.Omega-3 fatty acids. University Of Maryland Medical Center
3. Raitt, Merritt H., William E. Connor, Cynthia Morris, Jack Kron, Blair Halperin, Sumeet S. Chugh, James McClelland et al. “Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial.” Jama 293, no. 23 (2005): 2884-2891.
4.Fish oil may increase bruising. University Of Florida Health Communications.
5.Blanchard, Lauren B., and Gordon C. McCarter. “Insomnia and exacerbation of anxiety associated with high-EPA fish oil supplements after successful treatment of depression.” Oxford medical case reports 2015, no. 3 (2015): 244-245.
6.Mata, P., R. Alonso, A. Lopez-Farre, J. M. Ordovas, C. Lahoz, C. Garces, C. Caramelo, R. Codoceo, E. Blazquez, and M. De Oya. “Effect of dietary fat saturation on LDL oxidation and monocyte adhesion to human endothelial cells in vitro.” Arteriosclerosis, thrombosis, and vascular biology 16, no. 11 (1996): 1347-1355.
7.Saito, Morio, and Kazuhiro Kubo. “Relationship between tissue lipid peroxidation and peroxidizability index after α-linolenic, eicosapentaenoic, or docosahexaenoic acid intake in rats.” British journal of nutrition 89, no. 1 (2003): 19-28.
8.Godeny, Paula, Marcell Alysson Batisti Lozovoy, Jane Bandeira Dichi, and Isaias Dichi. “Effect of n-3 fatty acids in glycemic and lipid profiles, oxidative stress and total antioxidant capacity in patients with the metabolic syndrome.” Arquivos Brasileiros de Endocrinologia & Metabologia 54, no. 5 (2010): 463-469.
9.Demke, Donald M., Gary R. Peters, Otto I. Linet, Carl M. Metzler, and Karen A. Klott. “Effects of a fish oil concentrate in patients with hypercholesterolemia.” Atherosclerosis 70, no. 1-2 (1988): 73-80.
10.Brasky, Theodore M., Amy K. Darke, Xiaoling Song, Catherine M. Tangen, Phyllis J. Goodman, Ian M. Thompson, Frank L. Meyskens Jr et al. “Plasma phospholipid fatty acids and prostate cancer risk in the SELECT trial.” Journal of the National Cancer Institute 105, no. 15 (2013): 1132-1141.
11.Excess omega-3 fatty acids could lead to negative health effects. Oregon State University.
12.Risk, The, and Prevention Study Collaborative Group. “n-3 Fatty Acids in Patients with Multiple Cardiovascular Risk Factors.” Journal of Vascular Surgery 58, no. 3 (2013): 843-844.

Disclaimer: The content is purely informative and educational in nature and should not be construed as medical advice. Please use the content only in consultation with an appropriate certified medical or healthcare professional.

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