Fish oil supplements linked to prostate cancer (2013) | Hacker News Reader

Fish oil supplements linked to prostate cancer (2013)

nhs.uk

111 pointsleib65 comments

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.

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.

Also risk of kidney stones.

Did not know about that one. Another reason not to waste my money :)

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.

Maybe not, it's a very slow growing cancer, so they say.

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/

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.

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.

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.

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 :).

I suppose the NHS isn't to blame for what the Daily Mail wrote, but it's a bit confusing that they have a page on their website with the title "Fish oil supplements linked to prostate cancer". I now see that it's supposed to be part of a whole series ("Behind the Headlines") dissecting articles about health, so the headline is a quote or a restatement of what the Daily Mail wrote. It would be nice if they put it in quotemarks or otherwise indicated more clearly that they, the NHS, aren't making the claim (which clearly they aren't).

My understanding was that basically every man will, if they live long enough, have some cancerous cells in their prostate.

The main risk seems to be going from "so slow growing you die of old age first" to "fast enough growing it becomes a problem", unless I am horribly mistaken.

agreed, and the headline talks about "link" because such a refined thinking doesn't fit in a headline.

I worked in a lab that was studying prostate cancer for a summer internship, and most of our samples came from young men who died in motorcycle accidents. They found that a majority of the samples had some presence of benign tumors, but it only really becomes noticeable once malignant tumors develop.

I don't know how representative the samples were of the entire population - one theory was that our young motorcycle samples had significantly higher testosterone on average and were more likely to develop those tumors.

Young, and dead motorcyclists. Young male motorcyclist is the definition of testosterone-fueled lethality. (I grew out of sportbikes after two good friends died.)

The so called balls to brain ratio.

I ride bikes but am low T. For shame.

I'm sorry about your friends. My dad has lost at least one, been hit no fewer than 5 times (none his fault), and gone down one other time (lowsided at Deal's Gap). Miraculously he is still alive. This post probably makes him sound much more reckless than he really is. He is the most cautious person I know, probably due to these experiences.

This is how most doctors I know perceive it as well. I know quite a few doctors since I'm one myself.

One pathologist I happen to know, says the chances of finding cancer cells in your prostate is about the same as your age: 50 -> 50% chance, 60 -> 60%.

As I understand it, the fact that 1.00 is included in the range of CI indicates that the result in question could well be down to random chance/variation. i.e. because 1.00 is included, chance has not been eliminated.

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-2...

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.

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.

I wonder if anyone has compared cancer rates with those who eat euryhaline fish ( less sea toxins )

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

Also for the derived DHA/EPA, there are pollutant-free alternatives based on algae oil.

just eat fish, shellfish, etc?

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.

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.

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-kr...

[2] - http://krill-oil.wellwise.org/krill-oil-side-effects/krill-o...

Fish don’t make omega 3 oils, they ingest them from algae. So you can just cut out the middle fish and get them from algae yourself, in the form of algae oil supplements.

well the omega 3 to omega 6 ratio is the point of taking O6 How do you know how much O3 you need? So O6 is in plant-oils, how many O3 Capsules do you need to eat with your salad if you put olive Oil on it? Fish and shellfish already have the perfect ratio, unless you cook them in plant oils.

I prefer flax seed oil to ground flax seeds, due to cyanide being present in the shells.

Not to mention the constipation. Different fiber affects people differently I suppose, but for me, flax seed binds me up pretty bad.

And do you think shells aren't pressed when the flax seeds are for oil extraction?

Hydrogen cyanide is not fat soluble, so the levels are presumably much lower in the oil.

It's not a replacement.

https://www.health.harvard.edu/heart-health/why-not-flaxseed...

You should feel bad for promoting Michal Greger's bullshit.

https://www.humanewatch.org/hsus_doc_exposed_as_schlock/

https://www.thatnerdysciencegirl.com/2015/11/13/the-case-aga...

The article is realistic, there is no major issue in recommending flaxseed.

> Flaxseed oil will give your diet a nice little omega-3 boost in the form of alpha-linolenic acid. You might try adding some to your salad dressing. But it's a backup, not a substitute, for the omega-3s in fish and fish oil because of the conversion factor.

The real issue is: are you deficient in Omega-3 oils? Here's how much ALA you need (which is what Flaxseed has) https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/...

Flax seeds are a bad source of omega 3s, because the oil they have, ALA, isn't used in the body and the conversion into DHA/EPA (which are) is poor [0].

[0]: https://examine.com/nutrition/can-i-eat-flax-seeds-instead-o...

So what are vegetarians, or those with fish allergies, are supposed to be eating?

A well balanced diet without focusing on any particular food or supplement in the belief that it's some magic bullet for good health?

If one wanted omega-3s of the DHA/EPA variety, there's algae oil. It's commonly available as a supplement from many of the same companies that produce fish oil supplements.

What’s the mercury level

Zero.

...did you even read the article? The study found a link between blood concentration of omega-3 fatty acids and prostate cancer. The issue is with omega-3s in general, not that particular form of supplement.

The article also states that there is little evidence for any benefits from similar supplements.

I think that if the risks associated with pollutants in fish oil capsules were significant enough to affect the results, they would have been mentioned in the study.

The HN Guidelines ask:

"Please don't insinuate that someone hasn't read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that.""

https://news.ycombinator.com/newsguidelines.html

Alpha-linolenic acid (ALA), the main type of fat in flaxseed oil also seems to increase prostate cancer risk:

https://www.ncbi.nlm.nih.gov/pubmed/15051847

Just in case anyone else was confused by this, Alpha-lipoic acid is also abbreviated as ALA.

Alpha-lipoic acid is an antioxidant that helps the body turn glucose into energy, and is also a popular supplement.

> The article does not talk about alternatives.

Alternative for what?

You don't need an alternative for a food supplement with unproven benefits and potential risks. The alternative is to not take it.

I have abandoned flax seeds after finding out their impact on testosterone.

> 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)

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."

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.

A good meal is definitely better than a dozen of pills.

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.

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.

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/

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

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"

Participants were selected by having a cancer. Have you read the article? it's about growth rate.

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.

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.

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

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 2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337152/

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