Fish oil linked to increased risk of colon cancer in mice

[gymgreg]

That is going to be interesting.

Here is an article :

http://www.labspaces.net/106821/Fish_oil_linked_to_increased_risk_of_colon_cancer_in_mice

And here is the abstract of the study:

http://cancerres.aacrjournals.org/content/early/2010/08/25/0008-5472.CAN-10-1396.abstract

and a link to the researcher:

http://fshn.msu.edu/directory/facultyFenton.html

[Nicholas Sortino]

I couldn't get the article to load, but i read the abstract. Unless I misunderstood, the only source of fat they received was from one of those 3 oils. The rest of their diets was not elucidated. I see two glaring problems right there. Without knowing the rest of the diet, it is hard to determine whether or not that would be a contributing factor. Also, fish oil alone seems a very poor source of complete fatty acids, since it is very much primarily a PUFA oil, which humans (I cannot speak for mice) only need small amounts of.

It also seems these oils were a very small part of the diet. It says, "(doses ranging from 0.75-6.00%)." Can someone clarify what this means to me, as I don't have a lot of experience reading science literature. I am taking this to mean that is the percentage of their diet it is. If that is the case, that seems to be a very deficient amount of calories coming from fatty acids. Otherwise the only thing I could infer was that it meant that was the percentage of DHA in the oil.

Without reading the whole text, I also cannot see how the other mice fared in comparison. Did the IBS have similiar results in the other mice who were fed other oils?

Finally, I do not like studies that compare other animals to humans. While it may be useful as a starting point, I think it is silly to assume, "oh well it happened to this animal, so it is probably ther case for us as well." Humans are not mice, rats, pigs or any other animals. Until a study links things to humans, I will only but limited amounts of faith in it.

As a side note though, I've always felt that there was an upper limit to how much fish oil one should take in regards to the rest of their diet, and if you are eating a healthy diet with a good Omega 6:3 ratio already it is unnecessary to supplement with more Omegas. After your body gets the amount it needs for proper, they are pretty useless as an energy source compared to monounsaturated and especially saturated fatty acids.

[Ryan Libke]

What I note is that this study was focused on the localized effect of what it called DFO, or oil enhanced with DHA, on the intestinal tract, as opposed to considering how fish oil, when consummed as part of larger diet, can benefit the organism as a whole. That is, the usual prescribtion for fish oil is not for intestinal health, but for the health of the arteries, body-wide inflammation, and generally balancing out the intake of Omega 6 fatty acids.

I agree that studies of mice do not necessarily carry over to the understanding of how humans react to foods, but the study does raise a concern that should be explored. While I generally think that fish oil supplementation is warranted for most of us, given the prevalence of Omega 6 acids, and the shortage of Omega 3 acids, I am doubtful that taking any more than the body needs will have any beneficial effects. Generally speaking, the body wants balance, and too much of anything, including necessary and helpful nutrients, can cause more harm than good.

I am also curious about the DFO oil that they used; I am somewhat skeptical of manufactured or altered oils.

[Ryan Libke]

I am also curious is the effect the oil had on the local inflammation. That is, inflammation is a necessary function of the body. It becomes problematic when there is too much of it over a course of time. If the inflammatory process was impaired, that is, restricted to a certain level below normal, would that not render the tissue vulnerable to a foreign threat? In the study, the mice given the DFO had a reduced ability to combat the pathogen, which led to colitis, which is a risk for cancer. Could this be because of an impaired inflammatory process? I have no idea, I only read the abstract, and don't really have an understanding of these things, but it is interesting stuff.

[Joshua Naterman]

Good thinking, Wolf! One thing to keep in mind is that the reason mice are used for human comparison is that they have a similar digestive tract to ours. Similar enough for a fair amount of correlation. There are other animals that share the similar digestive tract but they aren't as easy to work with. To me, the biggest problem is the size of the mouse. Scaling by size and a percentile scale is not always accurate because there is more to systems than that, but still... interesting research. I haven't read it yet, but this definitely caught my attention.

[Kyle Courville]

It's a good thing I'm not a mouse. :wink:

[Jay Guindon]

http://www.zimbio.com/Essential+fatty+a ... lon+polyps

http://cancerres.aacrjournals.org/conte ... f_ipsecsha

http://jn.nutrition.org/cgi/content/abs ... f_ipsecsha

http://carcin.oxfordjournals.org/conten ... f_ipsecsha

[Graham Smith]

And here I thought that being a laboratory mouse was the chief cause of cancer in mice.

[Nicholas Sortino]

And here I thought that being a laboratory mouse was the chief cause of cancer in mice.

lol, I may have to quote that sometime