6 ms·

Fish oil supplements linked to prostate cancer (2013)

111 points by leib 8y ago

sigmaprimus 8y ago
Kind of an old article, here is a link to an article written around the same time that was updated last summer. https://www.health.harvard.edu/blog/fish-oil-friend-or-foe-201307126467 https://www.health.harvard.edu/blog/fish-oil-friend-or-foe-2...
- kensai 8y ago
  At a certain point it says: "Evidence linking fish oil and cancer has been all over the map. Some research suggests diets high in fatty fish or fish oil supplements might reduce the risk of certain cancers, including prostate cancer. Other research shows just the opposite, a link between eating a lot of oily fish or taking potent fish oil supplements and a 43% increased risk for prostate cancer overall, and a 71% increased risk for aggressive prostate cancer." Go figure! I guess, inconclusive at best.
  - pmoriarty 8y ago
    What dose of fish oil does one need to consume in order for the diet to be considered "high in fish oil"? Also, I've read in the past that it's important to balance omega-3's with omega-6. I wonder if any of this research takes that balance in to account.
  - ionwake 8y ago
    I wonder if anyone has compared cancer rates with those who eat euryhaline fish ( less sea toxins )
anaphor 8y ago
Keep in mind that this does not mean you have a 70% chance of getting prostate cancer if you take fish oil supplements. Based on this[0], it's roughly an increase from about 0.02% chance to about 0.034% chance (given no other information to base your risk on) [0]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2706483/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2706483/
- insertnickname 8y ago
  And this: >This was a large, well designed study that supports previous research linking high blood levels of omega-3 fatty acids with prostate cancer risk. However, it cannot show that fish oil supplements cause prostate cancer and it is possible that other confounders affected men’s risk (although the researchers tried to take these into account). Their conclusion contradicts their own headline.
  - deleted 8y ago
    [deleted]
  - shishy 8y ago
    It does not contradict their headline. Headline says there is some correlation between the two but they are careful to explain later that this does not necessarily imply causation and that further research is required.
    - insertnickname 8y ago
      The correlation they have found is between high levels of fish oil in blood tests and prostate cancer. They do not know whether those high levels are the result of supplementation or merely of eating fish. At least that's how I understood the article.
      - shishy 8y ago
        Fair but the article does address this albeit briefly: "Still, it is unlikely that the high levels of these fatty acids found in the highest quartile would be the result of diet alone. Adults are advised to eat two portions of fish a week, one of them oily, as part of a healthy balanced diet." You are right that the study doesn't explicitly say fish oil supplements directly caused the high levels of fish oil which were observed in these patients with prostate cancer. Dailymail at it again :).
        insertnickname 8y ago
vfc1 8y ago
The article does not talk about alternatives. A great alternative for Omega-3s are ground flax seeds, one tablespoon a day mixed for example in your oatmeal is enough - https://nutritionfacts.org/topics/omega-3-fatty-acids https://nutritionfacts.org/topics/omega-3-fatty-acids Also for the derived DHA/EPA, there are pollutant-free alternatives based on algae oil.
- aszantu 8y ago
  just eat fish, shellfish, etc?
  - massivecali 8y ago
    I think the part about pollutant free shouldn't be overlooked. Some labels claim they have removed harmful things like mercury from their fishoil supplements. Eating fish and shellfish in large quantities eould certainly increase your exposure to that and other contaminants.
    - darksaints 8y ago
      Smaller fish have negligible quantities of mercury and other pollutants, due to their short lifespan not allowing for bioaccumulation, as well as being much lower on the food chain. Herring, Anchovies, Smelt, Sardines, and even Mackerel or Trout, are all are excellent sources of EPA/DHA, and without any of the risks of larger fish.
      - pmoriarty 8y ago
        Another option is krill oil, which contains large amounts of omega-3's and is low in mercury because krill (tiny shrimp-like creatures) are at the bottom of the food chain and eat only algae, unlike large fish which eat other fish and thereby concentrate mercury in their flesh.[1][2] Incidentally, it's also possible to get DHA supplements sourced completely from algae. [1] - https://www.drnewtons.com/blog/avoid-dangers-mercury-pure-krill-oil/ https://www.drnewtons.com/blog/avoid-dangers-mercury-pure-kr... [2] - http://krill-oil.wellwise.org/krill-oil-side-effects/krill-oil-dangers http://krill-oil.wellwise.org/krill-oil-side-effects/krill-o...
newnewpdro 8y ago
I prefer eating quality canned sardines regularly instead of taking these supplements which can be viewed as a heavily processed industrial food derived from sources of unknown provenance. They have plenty of omega-3s and are very low on the food chain.
- thefounder 8y ago
  A good meal is definitely better than a dozen of pills.
- deleted 8y ago
  [deleted]
raverbashing 8y ago
> It is worth bearing in mind that this study did not assess participants’ diet and use of supplements. Researchers measured blood levels of fatty acids and analysed the association with prostate cancer risk. However, it is likely that the very high levels of fatty acids found in some participants’ blood came from supplements. Important point 2nd point to consider: is this for all types of cancer? More, less aggressive? Benign enlargement of prostate? In the article (comparison of the lowest Om3 quartile with the highest Om3 quartile): > 44% increased risk of low grade prostate cancer (HR (hazard ratio) = 1.44, 95% CI (confidence interval) = 1.08 to 1.93) > 71% increased risk of high grade prostate cancer (HR = 1.71, 95% CI = 1.00 to 2.94) > 43% increased risk of total prostate cancer (HR = 1.43, 95% CI = 1.09 to 1.88) 3rd point: could this be associated with something else (for example: heavy metals in fish) As most guidance by the NHS, this is very well explained and de-sensationalized > However, it cannot show that fish oil supplements cause prostate cancer and it is possible that other confounders affected men’s risk (although the researchers tried to take these into account)
dpatrick86 8y ago
This was based on the SELECT trial data, which means that it could just as easily be measuring the effects of a very large and prolonged dose of 400 IU of alpha-tocopherol as it is omega-3. Greater than 12x RDA. Moreover, it's been many years since this was published. If prostate cancer-promoting effects were so plainly an obvious effect of marine omega-3 supplementation, you'd expect to have seen it abundantly replicated by now.
- ip26 8y ago
  Maybe not, it's a very slow growing cancer, so they say.
nickpsecurity 8y ago
What about the packaging or matetial of the pill itself that contains the supplements? And any additives in the process? The processed stuff usually has higher risks. I wonder if any studies have been done on what contains the drugs which they also consume.
vibrato 8y ago
Let me give an alternative view of this epidemiological study. "Those more interested in their health (motivated to take supplements or eat a high omega-3 diet) more likely to be diagnosed by their doctor with common health issues"
- nraynaud 8y ago
  Participants were selected by having a cancer. Have you read the article? it's about growth rate.
  - pmoriarty 8y ago
    According to the article, "In this type of study, cases of people who have a particular outcome - in this case, prostate cancer - are matched against a random group of people who do not develop the condition." That sounds to me that in fact they were looking at cancer-free people as well.
  - vibrato 8y ago
    Right. My point is that less health conscious people would have un-diagnosed cancer. This would make it appear that more health conscious people (higher omega-3) have higher rates of cancer than baseline.
golemotron 8y ago
I don't like the reflexive notion that high levels of X in one's diet necessarily translate into high levels of X in one's blood chemistry. There should be a name for that nutritional fallacy.
internet_user 8y ago
tocopherols have been shown to have negative effects, including increased mortality, in other studies too. Nothing new here.
- tth3uoku 8y ago
  Most research has focused on α-tocopherol, which is thought to displace γ-Tocopherol. In a 2000 study of the relationship between α-tocopherol, γ-tocopherol, selenium, and prostate cancer, men in the highest fifth of the distribution for γ-tocopherol were five time less likely to develop prostate cancer than men in the lowest fifth. [1] "Recent epidemiological and preclinical studies have indicated that γ- and δ-tocopherols may be more effective because they are more efficient traps for reactive oxygen and nitrogen species." [2] 1. https://academic.oup.com/jnci/article/92/24/2018/2633585 https://academic.oup.com/jnci/article/92/24/2018/2633585 2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337152/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337152/
rossdavidh 8y ago
There is, I am starting to believe (regardless of whether or not this particular finding holds up), an ongoing problem with our approach to nutrition. The anti-pattern goes like this: 1) people who eat/drink X have health benefits 2) it seems to be related to X having Y in it 3) let's sell Y as a pill 4) dang, no health benefits, how did that happen? Now this could be for several reasons. Maybe eating/drinking X is a marker for a lifestyle that is healthy, or for coming from a background that includes beneficial genes of some sort. Maybe Y is not the only thing in X which matters, it's just the most obviously related thing, and you really need the whole package. Maybe the amount of Y you get from eating/drinking X is good, but in concentrated form at high levels there are drawbacks of some sort. But, however you look at it, putting Y into a pill (that can often be patented and sold as medicine) is not the same as eating/drinking X, and despite the financial incentives for claiming it is, we need to recognize that.
- noneeeed 8y ago
  It's like the whole thing with vitamin supplements. Unless you are actually deficient in one of them, taking them isn't going to do much for you, and in some cases might actually cause you harm. It's like fertiliser on a field, after a certain point the plants can't use any more and it just runs off to the rivers. Vitamin C is a good one for that, I seem to remember reading that at best taking large doses just means your piss contains a lot of it, and at worst, if you mega-dose for long periods, it raises your chance of getting some cancers. It reminds me of the adverts on the London Underground. Every time I travel through London to see my parents there will be adverts medicalising lack of sleep and exhaustion, flogging supplements and "remedies" for what is basically being tired, or "chronic tiredness syndrome" as one advert described it. I'm so glad I didn't choose that life.
  - ip26 8y ago
    Also risk of kidney stones.
    - noneeeed 8y ago
      Did not know about that one. Another reason not to waste my money :)
willart4food 8y ago
How about some "studies" to figure out the components of a well-balanced diet? * macros * what's out (well, this is easy actually) * what's in
vannevar 8y ago
The study in question does not link fish oil supplements to cancer. It correlates (with no clear evidence of causality) high blood levels of fatty acids with actual cases of prostate cancer. It is speculated that for at least some of the subjects, the high levels of fatty acids may have come from supplements. FTA: "It is worth bearing in mind that this study did not assess participants’ diet and use of supplements. Researchers measured blood levels of fatty acids and analysed the association with prostate cancer risk. However, it is likely that the very high levels of fatty acids found in some participants’ blood came from supplements."
aitchnyu 8y ago
NHS's Behind the Headlines is a welcome relief from pseudoscience. They apparently have a beef with The Mail Online. https://www.nhs.uk/news/ https://www.nhs.uk/news/

111 points by leib 8y ago

Kind of an old article, here is a link to an article written around the same time that was updated last summer. https://www.health.harvard.edu/blog/fish-oil-friend-or-foe-201307126467 https://www.health.harvard.edu/blog/fish-oil-friend-or-foe-2...

kensai 8y ago
At a certain point it says: "Evidence linking fish oil and cancer has been all over the map. Some research suggests diets high in fatty fish or fish oil supplements might reduce the risk of certain cancers, including prostate cancer. Other research shows just the opposite, a link between eating a lot of oily fish or taking potent fish oil supplements and a 43% increased risk for prostate cancer overall, and a 71% increased risk for aggressive prostate cancer." Go figure! I guess, inconclusive at best.
- pmoriarty 8y ago
  What dose of fish oil does one need to consume in order for the diet to be considered "high in fish oil"? Also, I've read in the past that it's important to balance omega-3's with omega-6. I wonder if any of this research takes that balance in to account.
- ionwake 8y ago
  I wonder if anyone has compared cancer rates with those who eat euryhaline fish ( less sea toxins )

anaphor 8y ago

Keep in mind that this does not mean you have a 70% chance of getting prostate cancer if you take fish oil supplements. Based on this[0], it's roughly an increase from about 0.02% chance to about 0.034% chance (given no other information to base your risk on) [0]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2706483/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2706483/

insertnickname 8y ago
And this: >This was a large, well designed study that supports previous research linking high blood levels of omega-3 fatty acids with prostate cancer risk. However, it cannot show that fish oil supplements cause prostate cancer and it is possible that other confounders affected men’s risk (although the researchers tried to take these into account). Their conclusion contradicts their own headline.
- deleted 8y ago
  [deleted]
- shishy 8y ago
  It does not contradict their headline. Headline says there is some correlation between the two but they are careful to explain later that this does not necessarily imply causation and that further research is required.
  - insertnickname 8y ago
    The correlation they have found is between high levels of fish oil in blood tests and prostate cancer. They do not know whether those high levels are the result of supplementation or merely of eating fish. At least that's how I understood the article.
    - shishy 8y ago
      Fair but the article does address this albeit briefly: "Still, it is unlikely that the high levels of these fatty acids found in the highest quartile would be the result of diet alone. Adults are advised to eat two portions of fish a week, one of them oily, as part of a healthy balanced diet." You are right that the study doesn't explicitly say fish oil supplements directly caused the high levels of fish oil which were observed in these patients with prostate cancer. Dailymail at it again :).
      - insertnickname 8y ago

vfc1 8y ago

The article does not talk about alternatives. A great alternative for Omega-3s are ground flax seeds, one tablespoon a day mixed for example in your oatmeal is enough - https://nutritionfacts.org/topics/omega-3-fatty-acids https://nutritionfacts.org/topics/omega-3-fatty-acids Also for the derived DHA/EPA, there are pollutant-free alternatives based on algae oil.

aszantu 8y ago
just eat fish, shellfish, etc?
- massivecali 8y ago
  I think the part about pollutant free shouldn't be overlooked. Some labels claim they have removed harmful things like mercury from their fishoil supplements. Eating fish and shellfish in large quantities eould certainly increase your exposure to that and other contaminants.
  - darksaints 8y ago
    Smaller fish have negligible quantities of mercury and other pollutants, due to their short lifespan not allowing for bioaccumulation, as well as being much lower on the food chain. Herring, Anchovies, Smelt, Sardines, and even Mackerel or Trout, are all are excellent sources of EPA/DHA, and without any of the risks of larger fish.
    - pmoriarty 8y ago
      Another option is krill oil, which contains large amounts of omega-3's and is low in mercury because krill (tiny shrimp-like creatures) are at the bottom of the food chain and eat only algae, unlike large fish which eat other fish and thereby concentrate mercury in their flesh.[1][2] Incidentally, it's also possible to get DHA supplements sourced completely from algae. [1] - https://www.drnewtons.com/blog/avoid-dangers-mercury-pure-krill-oil/ https://www.drnewtons.com/blog/avoid-dangers-mercury-pure-kr... [2] - http://krill-oil.wellwise.org/krill-oil-side-effects/krill-oil-dangers http://krill-oil.wellwise.org/krill-oil-side-effects/krill-o...

newnewpdro 8y ago

I prefer eating quality canned sardines regularly instead of taking these supplements which can be viewed as a heavily processed industrial food derived from sources of unknown provenance. They have plenty of omega-3s and are very low on the food chain.

thefounder 8y ago
A good meal is definitely better than a dozen of pills.
deleted 8y ago
[deleted]

raverbashing 8y ago

> It is worth bearing in mind that this study did not assess participants’ diet and use of supplements. Researchers measured blood levels of fatty acids and analysed the association with prostate cancer risk. However, it is likely that the very high levels of fatty acids found in some participants’ blood came from supplements. Important point 2nd point to consider: is this for all types of cancer? More, less aggressive? Benign enlargement of prostate? In the article (comparison of the lowest Om3 quartile with the highest Om3 quartile): > 44% increased risk of low grade prostate cancer (HR (hazard ratio) = 1.44, 95% CI (confidence interval) = 1.08 to 1.93) > 71% increased risk of high grade prostate cancer (HR = 1.71, 95% CI = 1.00 to 2.94) > 43% increased risk of total prostate cancer (HR = 1.43, 95% CI = 1.09 to 1.88) 3rd point: could this be associated with something else (for example: heavy metals in fish) As most guidance by the NHS, this is very well explained and de-sensationalized > However, it cannot show that fish oil supplements cause prostate cancer and it is possible that other confounders affected men’s risk (although the researchers tried to take these into account)

dpatrick86 8y ago

This was based on the SELECT trial data, which means that it could just as easily be measuring the effects of a very large and prolonged dose of 400 IU of alpha-tocopherol as it is omega-3. Greater than 12x RDA. Moreover, it's been many years since this was published. If prostate cancer-promoting effects were so plainly an obvious effect of marine omega-3 supplementation, you'd expect to have seen it abundantly replicated by now.

ip26 8y ago
Maybe not, it's a very slow growing cancer, so they say.

nickpsecurity 8y ago

What about the packaging or matetial of the pill itself that contains the supplements? And any additives in the process? The processed stuff usually has higher risks. I wonder if any studies have been done on what contains the drugs which they also consume.

vibrato 8y ago

Let me give an alternative view of this epidemiological study. "Those more interested in their health (motivated to take supplements or eat a high omega-3 diet) more likely to be diagnosed by their doctor with common health issues"

nraynaud 8y ago
Participants were selected by having a cancer. Have you read the article? it's about growth rate.
- pmoriarty 8y ago
  According to the article, "In this type of study, cases of people who have a particular outcome - in this case, prostate cancer - are matched against a random group of people who do not develop the condition." That sounds to me that in fact they were looking at cancer-free people as well.
- vibrato 8y ago
  Right. My point is that less health conscious people would have un-diagnosed cancer. This would make it appear that more health conscious people (higher omega-3) have higher rates of cancer than baseline.

golemotron 8y ago

I don't like the reflexive notion that high levels of X in one's diet necessarily translate into high levels of X in one's blood chemistry. There should be a name for that nutritional fallacy.

internet_user 8y ago

tocopherols have been shown to have negative effects, including increased mortality, in other studies too. Nothing new here.

tth3uoku 8y ago
Most research has focused on α-tocopherol, which is thought to displace γ-Tocopherol. In a 2000 study of the relationship between α-tocopherol, γ-tocopherol, selenium, and prostate cancer, men in the highest fifth of the distribution for γ-tocopherol were five time less likely to develop prostate cancer than men in the lowest fifth. [1] "Recent epidemiological and preclinical studies have indicated that γ- and δ-tocopherols may be more effective because they are more efficient traps for reactive oxygen and nitrogen species." [2] 1. https://academic.oup.com/jnci/article/92/24/2018/2633585 https://academic.oup.com/jnci/article/92/24/2018/2633585 2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337152/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337152/

rossdavidh 8y ago

There is, I am starting to believe (regardless of whether or not this particular finding holds up), an ongoing problem with our approach to nutrition. The anti-pattern goes like this: 1) people who eat/drink X have health benefits 2) it seems to be related to X having Y in it 3) let's sell Y as a pill 4) dang, no health benefits, how did that happen? Now this could be for several reasons. Maybe eating/drinking X is a marker for a lifestyle that is healthy, or for coming from a background that includes beneficial genes of some sort. Maybe Y is not the only thing in X which matters, it's just the most obviously related thing, and you really need the whole package. Maybe the amount of Y you get from eating/drinking X is good, but in concentrated form at high levels there are drawbacks of some sort. But, however you look at it, putting Y into a pill (that can often be patented and sold as medicine) is not the same as eating/drinking X, and despite the financial incentives for claiming it is, we need to recognize that.

noneeeed 8y ago
It's like the whole thing with vitamin supplements. Unless you are actually deficient in one of them, taking them isn't going to do much for you, and in some cases might actually cause you harm. It's like fertiliser on a field, after a certain point the plants can't use any more and it just runs off to the rivers. Vitamin C is a good one for that, I seem to remember reading that at best taking large doses just means your piss contains a lot of it, and at worst, if you mega-dose for long periods, it raises your chance of getting some cancers. It reminds me of the adverts on the London Underground. Every time I travel through London to see my parents there will be adverts medicalising lack of sleep and exhaustion, flogging supplements and "remedies" for what is basically being tired, or "chronic tiredness syndrome" as one advert described it. I'm so glad I didn't choose that life.
- ip26 8y ago
  Also risk of kidney stones.
  - noneeeed 8y ago
    Did not know about that one. Another reason not to waste my money :)

willart4food 8y ago

How about some "studies" to figure out the components of a well-balanced diet? * macros * what's out (well, this is easy actually) * what's in

vannevar 8y ago

The study in question does not link fish oil supplements to cancer. It correlates (with no clear evidence of causality) high blood levels of fatty acids with actual cases of prostate cancer. It is speculated that for at least some of the subjects, the high levels of fatty acids may have come from supplements. FTA: "It is worth bearing in mind that this study did not assess participants’ diet and use of supplements. Researchers measured blood levels of fatty acids and analysed the association with prostate cancer risk. However, it is likely that the very high levels of fatty acids found in some participants’ blood came from supplements."

aitchnyu 8y ago

NHS's Behind the Headlines is a welcome relief from pseudoscience. They apparently have a beef with The Mail Online. https://www.nhs.uk/news/ https://www.nhs.uk/news/