Fish oil - here's what you need to know

Jacob Strøm

Jacob Strøm

Performance specialist. Cand.scient. Sports Science. 25+ certificates from EXOS, Barca Innovation Hub etc.

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Fish oil or omega 3 is a super popular dietary supplement, and for good reason, but few people know why and how much they actually need to get the best results. In this post I will explain what omega 3 is, what to look for when buying it, how and how much to take, as well as get into a few benefits of taking omega 3, as a supplement.
Fish oil - football performance

What is fish oil?

Fish oil is the common term for two different forms of omega 3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

These omega 3 fatty acids are largely found in fish, and it is this amount you should look for when buying fish oil, as it is these that have the greatest effect on our health.

Many fish oil supplements contain other omega 3 fatty acids that are not EPA or DHA, but could in many cases contain DPA, or other fatty acids that are not omega 3.

In general, there are many benefits to taking fish oil, especially since our diet today contains high amounts of omega 6 (red meat, eggs, etc.). For many, the ratio of omega 6 to omega 3 is; 15-20 to 1, and should be closer to 3 to 1! (1,2,3,4)

#1 - Fish oil can boost your weight loss

Much of the research there is on fish oil shows the positive effects fish oil has by reducing inflammation and lowering blood pressure, but recent studies suggest fish oil and so play a crucial role in weight loss.

As always, many studies are conducted on animals and it was also observations in animals that first showed a link between fish oil intake and weight loss. Previous research has also shown that fish oil can minimise the risk of increasing fat mass, despite a calorie surplus (5,6).

Based on these observations, it is suggested that supplementing with fish oil could somehow improve the body's ability to burn fat rather than store it.

Fortunately, these observations led to similar studies in humans! 🙂

In a study with 6 healthy adults, the researchers controlled their diet for 6 weeks, during the last 3 weeks they received fish oil as a supplement. Energy intake, resting metabolic rate, substrate (fat/carbohydrate) oxidation and body composition were measured before and after and before fish oil supplementation.

They found that fat loss was significantly greater with fish oil intake, as was an increase in muscle mass. Very surprisingly and interestingly, the group was able to lose fat and build muscle mass without exercising... (7)

This is unlikely to be true over a long period, nor is there any doubt that training is a necessity for best results, but it does say something about the potential of fish oil.

Also, the researchers measured that during the period of fish oil intake, they burned more fat as energy, which may be part of the explanation for the results.

#2 - Fish oil can improve your circulation

Cardiovascular disease is affecting more and more people and is one of the biggest killers in most modern societies...

Therefore, this is also one of the most researched areas, also when it comes to fish oil as a supplement. Exercise, fat loss and a healthy diet are as always key, but some supplements can be beneficial to improve circulation.

Previous observational studies found that men who consumed fish on a weekly basis had a lower mortality rate from cardiovascular disease compared to those who did not consume fish (8).

Another study also found that the level of fish intake had a significant impact on the risk of heart disease (9).

A controlled randomised trial analysed men over 2 years and found a 29% decrease in mortality in those taking fish oil as a supplement (10).

To further prove the important role of fish oil, one research group took it to a whole new level and included 11,324 patients with cardiovascular disease in their trial. They gave them either fish oil and vitamin E or an empty pill.

After almost 4 years, researchers find a 20% decrease in mortality in the group receiving fish oil and vitamin E (11)

One of the benefits of taking fish oil is that it can lower cholesterol levels, blood pressure and improve fat content in the blood.

A meta-analysis found an association between fish oil and a decrease in blood pressure, which has been confirmed again and again, and it has been concluded that fish oil may be effective against high blood pressure (12,13).

omega3 sources football performance

Example of different fish oil food sources (Photo: Christian Strøm)

#3 - Fish oil reduces inflammation

Inflammation is one of the overriding causes of a number of the most common diseases. In the past, inflammation was thought to be caused by obesity, but recent research suggests that inflammation can also lead to obesity.

High levels of inflammation can increase the risk of some types of cancer, reduced gut health and, as mentioned, can lead to obesity.

A supplement of fish oil can lower blood lipids, which is important for the regulation of inflammation in the body. Fish oil has also been shown to lower IL-6 and CRP, which are two important markers indicating the level of inflammation (14).

How much should I take?

The amount depends largely on the goal, but equally important is the rest of the diet, since, as mentioned, the ratio of omega 3 to omega 6 also plays an important role.

As always, I would prefer real food over supplements, but it can be difficult to get enough omega 3 through regular diet, especially if you want the most optimal results.

Based on a number of studies, I would recommend taking between 2 and 6 g EPA and DPA (combined) per day. Important you are aware that it is 2 g EPA/DHA, not just 2 g fish oil.

The vast majority of 'known' brands have no more than 200mg EPA/DHA per 1000mg, which is relatively low and would mean you would need to take over 10 pills to get a real effect. Instead, choose a manufacturer with a minimum of 750 mg EPA/DHA per 1000 mg.

When should I take it?

The most important thing is that you take it - the second most important thing is when. If you have trouble remembering to take your supplements, I would do it first thing in the morning, or at the first meal.

If you take a larger quantity, I would divide it in two. If you are a little more advanced and good at taking your supplements, I would take omega 3 in my meal after exercise to help lower inflammation,.

Here's some ecstasy 🙂

Bonus info

  1. Memory and learning: the role of DHA in memory has been studied several times, and a higher serum concentration of DHA is correlated with better verbal skills in the elderly (15) and deficits of DHA may impair memory in rats.

    A study of healthy adolescents (18-25 years) found that after 6 months of 750 mg DHA and 930 mg EPA daily, their memory improved in a number of tests. (16) Similar results were found in adolescents with low fish intake who experienced improved memory and reaction time with 1160 mg DHA supplementation daily over 6 months (17).

  2. Stress: Fish oil supplementation in rats has been shown to normalize the stress response in a study testing long-term environmental stress (18). This has been replicated in a number of other studies, with animals and humans, where supplementation of 1.5 - 1.8 g DHA daily was shown to attenuate the adrenaline response to exposure to stress (19, 20). In longer term studies, students taking 20 exams were found to have a similar decrease in norepinephrine (-31%) with a 1.5 g DHA daily intake, while no change was found in cortisol (21).

  3. Insulin sensitivity: In healthy individuals, it is not certain that fish oil improves insulin sensitivity when the diet consists of 37% fat at a dose of 3.6 g EPA and DHA daily (22). In this study they found no significant improvement and the ratio of omega 6 to omega 3 was 6:3. Other studies have found similar results (23).

    Even when fish oil intake is combined with exercise, a similar study found no significant change in insulin sensitivity that could be due solely to omega 3 (24). They believe that fish oils have positive properties but do not act synergistically with exercise.

    However, other studies find an improvement in insulin sensitivity, in populations where the ratio is even worse. This could be in groups such as the elderly, metabolically unhealthy and obese (25,26,27,28).


  1. Simopoulos AP. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med (Maywood)(2008).
  2. Simopoulos AP. New products from the agri-food industry: the return of n-3 fatty acids into the food supply. Lipids. (1999)
  3. Simopoulos AP. Omega-3 fatty acids in health and disease and in growth and development.Am J Clin Nutr(1991).
  4. Sanders TA. Polyunsaturated fatty acids in the food chain in Europe. Am J Clin Nutr(2000).
  5. Clouet, P., Niot, I., Gresti, J., Demarquoy, J., Boichot, J., Durand, G., & Bézard, J. (1995). Polyunsaturated n-3 and n-6 fatty acids at a low level in the diet alter mitochondrial outer membrane parameters in Wistar rat liver. The Journal of Nutritional Biochemistry, 6(11), 626-634.
  6. Cunnane, S. C., McAdoo, K. R., & Horrobin, D. F. (1986). n-3 Essential fatty acids decrease weight gain in genetically obese mice. British journal of nutrition, 56(01), 87-95.
  7. Couet, C., Delarue, J., Ritz, P., Antoine, J. M., & Lamisse, F. (1997). Effect of dietary fish oil on body fat mass and basal fat oxidation in healthy adults. International journal of obesity, 21(8), 637-643.
  8. Stone, N. J. (1996). Fish consumption, fish oil, lipids, and coronary heart disease. Circulation, 94(9), 2337-2340.
  9. Zhang, J., Sasaki, S., Amano, K., & Kesteloot, H. (1999). Fish consumption and mortality from all causes, ischemic heart disease, and stroke: an ecological study. Preventive medicine, 28(5), 520-529.
  10. Burr, M. L., Gilbert, J. F., Holliday, R. A., Elwood, P. C., Fehily, A. M., Rogers, S., ... & Deadman, N. M. (1989). Effects of changes in fat, fish, and fiber intakes on death and myocardial reinfarction: diet and reinfarction trial (DART). The Lancet, 334(8666), 757-761.
  11. GISSI-Prevenzione Investigators (1999). Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. The Lancet, 354(9177), 447-455.
  12. Harris, W. S. (1997). n-3 fatty acids and serum lipoproteins: human studies. The American journal of clinical nutrition, 65(5), 1645S-1654S.
  13. Appel, L. J., Miller, E. R., Seidler, A. J., & Whelton, P. K. (1993). Does Supplementation of Diet With 'Fish Oil'Reduce Blood Pressure? A Meta-analysis of Controlled Clinical Trials. Archives of internal medicine, 153(12), 1429-1438.
  14. Ellulu, M. S., Khaza'ai, H., Abed, Y., Rahmat, A., Ismail, P., & Ranneh, Y. (2015). Role of fish oil in human health and possible mechanism to reduce the inflammation. Inflammopharmacology, 23(2-3), 79-89.
  15.   Serum Phospholipid Docosahexaenonic Acid Is Associated with Cognitive Functioning during Middle Adulthood.
  16. Improved Working Memory but No Effect on Striatal Vesicular Monoamine Transporter Type 2 after Omega-3 Polyunsaturated Fatty Acid Supplementation.
  17. Stonehouse W, et al. DHA supplementation improved both memory and reaction time in healthy young adults: a randomized controlled trial. Am J Clin Nutr(2013).
  18. Eguchi R, et al.Fish oil consumption prevents glucose intolerance and hypercorticosteronemia in footshock-stressed rats. Lipids Health Dis.(2011)
  19. Hamazaki T, et al. Anti-stress effects of DHA. Biofactors(2000).
  20. Hamazaki T, et al. Administration of docosahexaenoic acid influences behavior and plasma catecholamine levels at times of psychological stress. Lipids. (1999)
  21. Sawazaki S, et al. The effect of docosahexaenoic acid on plasma catecholamine concentrations and glucose tolerance during long-lasting psychological stress: a double-blind placebo-controlled study. J Nutr Sci Vitaminol (Tokyo) (1999).
  22. Giacco R, et al. Fish oil, insulin sensitivity, insulin secretion and glucose tolerance in healthy people: is there any effect of fish oil supplementation in relation to the type of background diet and habitual dietary intake of n-6 and n-3 fatty acids. Nutr Metab Cardiovasc Dis.(2007)
  23. Egert S, et al. Effects of dietary alpha-linolenic acid, eicosapentaenoic acid or docosahexaenoic acid on parameters of glucose metabolism in healthy volunteers. Ann Nutr Metab(2008)
  24. Bortolotti M, Tappy L, Schneiter P. Fish oil supplementation does not alter energy efficiency in healthy males. Clin Nutr(2007).
  25. Tsitouras PD, et al. High omega-3 fat intake improves insulin sensitivity and reduces CRP and IL6, but does not affect other endocrine axes in healthy older adults. Horm Metab Res(2008)
  26. Maki KC, et al. Prescription omega-3-acid ethyl esters reduce fasting and postprandial triglycerides and modestly reduce pancreatic β-cell response in subjects with primary hypertriglyceridemia. prostaglandins leukot essence fatty acids(2011).
  27. Fedor D, Kelley DS. Prevention of insulin resistance by n-3 polyunsaturated fatty acids. Curr Opin Clin Nutr Metab Care. (2009)
  28. Ramel A, et al. Beneficial effects of long-chain n-3 fatty acids included in an energy-restricted diet on insulin resistance in overweight and obese European young adults. Diabetologia. (2008)

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