Daily Fish Oil Consumption May Reduce Lifespan

In many areas of biological science and medicine, uncertainty and even controversy remains.

It has practically become common knowledge that taking fish oil is “good for you.” Many studies have confirmed diets high in omega-3 polyunsaturated fatty acids reduce risk of cardiovascular events and lower triglyceride levels. There are reports that fish oil reduces inflammation in the body and lowers the risk of many related disease such as even Alzheimer’s.

A new study in mice however leads to the surprising conclusion that regular fish oil consumption actually may reduce lifespan.

The researchers fed a special genetic variety of mice diets that either included 5% daily fish oil + 5% safflower oil or instead 10% daily safflower oil. The mice used were SAMP8 mutants that were bred to have accelerated aging and shortened lifespans. These mice are often used in longevity experiments because their average lifespans are only typically one year. They were fed these diets from 12 weeks of age on.

The researchers hypothesized since fish oil is so easily oxidized it may lead to greater oxidative stress within cells and thus actually accelerate aging, a process believed in part due to accumulative damage from oxidative stress. Safflower oil is an omega-6 fatty acid and is not readily oxidized – it could have beneficial effects without causing oxidative stress.

Sure enough, the study showed that the mice fed fish oil lived an average of 48.4 weeks while the mice fed pure safflower oil lived an average of 56.3 weeks, with all other conditions kept equal between the groups.

It was also shown that there were higher levels of oxidative stress in the fish-oil fed animals. The authors noted these levels of fish oil is equivalent to what people would be exposed to taking daily fish oil supplements, or eating a lot of fish, and caution their findings may extrapolate to humans.

The scientists conclude:

These findings suggest that intake of fish oil increases oxidative stress, decreases cellular function, and causes organ dysfunction in SAMP8 mice, thereby promoting aging and shortening the lifespan of the mice.

Nutrition 27 (2011) 334–337

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19 Responses to “Daily Fish Oil Consumption May Reduce Lifespan”

  1. Ilya Beraha says:

    I’ll be pretty brief. Mice are herbi and granivore, they DO NOT display a phenotype resp. genetic background suitable or even close to cold-acclimated humans to investigate and compare with HUMAN LIPID and PURINE NUCLEOTIDE Metabolism (the latter is different for rodents and humans) so such studies are NOT worth the paper they are written on. It is ingenuine (DISINGENUOUS) that to be the effect of omega3 PUFAs as they incorporate in the mitochondria and attenuate mito respiration resp. oxidative stress. TL;DR DON’T FEED SALMON to the MONKEYS!!! Take it as you wish. Sincerely.

    • Lyle J. Dennis, M.D. says:

      Good thoughts IIya
      It is for these reasons and many others hard to extrapolate rodent studies to humans. It is of course hard to do longevity studies on humans because they would take too long.
      Interpret and use these findings at your discretion

    • paul says:

      Yes, feeding fish oil to mice will have different effects. Some people do well on fish, others on meat, others on vegetables. Norweigans will eat more fish than someone living in a New York ghetto. All they eat is soda pop and kraft dinner. Try feeding the mice that diet.

  2. Steve Fowkes says:

    This study is not particularly well designed, but the results are probably right on target. There are other data that support this finding. I’ve been warning people about the dark side of fish oil for 20 years. One of them informed me about this post.

    There are many dietary components that are likely to be found to reduce maximum lifespan in a comparable way. L-cysteine, N-acetyl-L-cysteine (NAC), L-tryptophan, high-dose bioflavonoids, raw mushrooms, comfrey herb, w6-PUFAs, alfalfa sprouts, just to pick some highlights (and incite some controversy).

    Hormone replacement therapies with progesterone, testosterone, thyroid hormone and cortisol are also likely candidates. But before everybody panics, I’d like to point out that there is probably a mandatory trade-off between maximum lifespan and survivability, or metabolic robustness if you prefer. Or quality of life. The more you try to cultivate maximum lifespan, the more likely you are to die from accidents and tribulations. So a shortened maximum lifespan is not a bad thing if you gain a fully functional life in the bargain.

    Fish oil is a “cure of the decade” and harder to distinguish as a fad than cures of the year or cures of the month. Fish oil not only sabotages mitochondrial function, it undermines the foundations of the antioxidant defense system in the bargain. Plus, who wants increased skin wrinkles in our beauty-obsessed culture. These are not trivial side effects.

    Although this study may not be ideally designed, it may serve the beneficial function of helping people question the unquestionable myths surrounding fish oil. Until you ask a question, you cannot answer it.

    Thanks for the post.

  3. Bjarni says:

    Isn’t the conclusion a bit off? As I see it you can conclude 10% of your daily intake is better with 10% safflower oil than 5% fish oil and 5% safflower oil. Not that fish oil is better than no fish oil.
    In addition: Who recommends 10% oil intake anyway? To have a usefull study it should be done with a more normal dossage and with a control group that just lives with normal food and exercise.

  4. Bernie Kitts says:

    Who funded this study?

  5. John Monagin says:

    Important details of this study were not provided, such as how many mice were in each group, which profoundly effects statistical power. Quantity of anti-oxidants in the diets was not given. Theoretically, adequate anti-oxidants could minimize the free radical damage to the omega-3s (EPA and DHA) in the fish oil, reducing the main drawback of those fatty acids. This could be the focus of the next study. The comments of Steve Fowkes need some references, and generally have little credibility. E.g. I have prescribed fish oil for dozens of persons displeased by their skin wrinkles, and most have improved on that supplement. Lack of anti-oxidants, excessive tanning, and smoking (exposing the smoker to huge amounts of free radicals) do cause excessive wrinkling. Hypothyroidism is becoming more prevalent in recent decades, probably due to thyrotoxins in the environment (in many plastic products e.g.), and avoidance of pig thyroid or synthetic thyroid would likely shorten the lifespan in many of these patients, with the condition beginning commonly in middle age and slowly worsening each passing year. Lastly, living a healthy lifestyle and living a long life do not increase accidents per se, as safe exercise and vitamin D3 (from sunlight or supplementation) and certain anti-oxidants known to delay or prevent dementia actually keep individuals stronger and less likely to fall or by seriously injured in activities of daily living. Fish oil and anti-oxidants can delay or prevent macular degeneration in the elderly, allowing them to continue to drive safely. Steve, I’m glad you’re not in the healthcare business. Consider submitting your ideas to a science fiction site.

    • Darian Smith says:

      I’m interested in John Monagin regarding thyroid hormones. From what I understand Ames like mutations in humans which result in low TSH, and low thyroid hormones(among other hormones), results in lifespan extension of non-hormone supplemented humans.

      Species like the naked mole rat which has extraordinary longevity also shows low thyroid.

      Though non ames-like humans who have low thyroid hormones, tend to have high TSH which can result in edema complications. Is this the only ‘real’ problem? The reduced metabolic rate would increase likelyhood of obesity and associated risks, but this could be easily dealt with dietary intervention.

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  7. niner says:

    Ilya’s (quite correct) comments notwithstanding, the only thing I would take from this study is that fish oil megadosing is a bad idea. Given a 2000 Calorie diet, 5% is 100 Calories, which is 11 grams of fish oil. There are people who take that much fish oil, usually as an antidepressant or nootropic. That isn’t something I’d recommend.

  8. Daniel Horowitz says:

    Anecdotally, it seems dose/effect is non linear in humans, so large doses may be necessary for some people. I think what’s important with fish oil is rebalancing our Omega fatty acids ratio. Some people may not need any, and the supplement causes an imbalance, some people may need a significant dose because of the high Omega 6′s (/9) in their diet and lack of Omega 3′s. Hard to read too much into this, we are all different, and will react and benefit differently.

  9. cb says:

    I’m not completely convinced that this was result was actually due to oxidized fish oil in the body. The oceans are horribly contaminated nowadays and the researchers did not note in the paper that they were using a particularly refined fish oil. There was just one line indicating the sourcing: Fish oil and safflower oil were kind gifts from Nippon Oil and Fats, Co.

    For all we know, it could have been horribly contaminated with PCBs, Mercury, Dioxins. Contaminants could completely account for the decrease in lifespan and increase in oxidative stress. This might just be confirmation of the idea that people need to be more concerned about fish oil purity.

  10. [...] Question Biochemistry: Biochemistry: Why are omega-3 fatty acids so easily oxidized?http://extremelongevity.net/2011…Post   Add AnswerBIU     @    UpdateLink to [...]

  11. Rob says:

    Well, it certainly reduced the lifespan of the fish.

  12. Steve says:

    PUFAs and omega-3′s in particular oxidize because the conjugated double bonds make the molecule vulnerable to free-radical attack (the resulting radical in the FA chain is stabalized by being able to delocalize the radical electron. That’s all related to to why linseed is a “drying” oil (it’s acctually not drying in paints, but polymerizing in a free radical reaction) and why thinners with linseed oxidize so fast that they can heat and catch fire in hours, if a rag provides surface area.

    Feeding animals high omega-3 diets without enough vitamin E to counteract the free radical damage is problematic, and this study should really have had a control getting a LOT of vitamin E.

    The other problem with mice is they don’t get atherosclerosis, which is the biggest killer of humans. Omega 3′s decrease triglycerides and atherogenic high-density-LDL (the “bad LDL”) while fructose (in all that corn sweetener in your diet since 1980) increases both of these. That’s a battle you can’t see fought out, in some rapid-aging mutant mice.

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