T Nation

Polyunsat. Fat Promotes Cancer?

On the heels of the megadosing fish oils thread:

http://www.T-Nation.com/readTopic.do?id=1510159

I went hunting around for info on fats. I found this alarming article which states that polyunsaturated fats (PUFs) promote (not cause) cancer. The main culprit appears to be the omega-6 linoleic acid, but all PUFs are bad in high dosages. This is the article:

http://www.second-opinions.co.uk/fats_and_cancer.html

How does this fit into the “omega-3s are great” and “PUFs are fantastic” type of publicity that most up-to-date nutritionists are espousing these days?

If PUFs are going to weaken my immune system (the main point I got from the article), I’d rather not be popping fish oil caps by the handful. Is this going to be another fad like the 80s’ no-fat craze? The problem is, if we’re wrong about PUFs, instead of a bunch of fat people (left over from the 80s), we’ll be left with a bunch of cancer patients.

What’s the opinion out there?

Admittedly I didn’t read the article but consider the very low cancer rate vs. high omega-3 intake among the japanese.

[quote]bdog527 wrote:
Admittedly I didn’t read the article but consider the very low cancer rate vs. high omega-3 intake among the japanese. [/quote]

Well, the author seems to implicate omega-6s as the main culprits.

The article you linked is pretty much common knowledge now.

Yes, those oils/fats that article is talking about are mainly soya/vegetable oils which spoil/become rancid with high heat and hydrogenation process. Avoiding trans fats (hydrogenation) has been common knowledge for quite some time.

That is why you should avoid all margarines, margarine spreads, vegetable cooking oils, crisco, etc.

I imagine if you cooked with fish oil or it became oxidized you could expect the same things and harmful effects.

Generally, the fish oil would be fine because the fish oil is kept refrigerated and away from light in dark bottles so it won’t become oxidized or rancid.

[quote]Miserere wrote:
On the heels of the megadosing fish oils thread:

http://www.T-Nation.com/readTopic.do?id=1510159

I went hunting around for info on fats. I found this alarming article which states that polyunsaturated fats (PUFs) promote (not cause) cancer. The main culprit appears to be the omega-6 linoleic acid, but all PUFs are bad in high dosages. This is the article:

http://www.second-opinions.co.uk/fats_and_cancer.html

How does this fit into the “omega-3s are great” and “PUFs are fantastic” type of publicity that most up-to-date nutritionists are espousing these days?

If PUFs are going to weaken my immune system (the main point I got from the article), I’d rather not be popping fish oil caps by the handful. Is this going to be another fad like the 80s’ no-fat craze? The problem is, if we’re wrong about PUFs, instead of a bunch of fat people (left over from the 80s), we’ll be left with a bunch of cancer patients.

What’s the opinion out there?[/quote]

[quote]Miserere wrote:
On the heels of the mega dosing fish oils thread:

http://www.T-Nation.com/readTopic.do?id=1510159

I went hunting around for info on fats. I found this alarming article which states that polyunsaturated fats (PUFs) promote (not cause) cancer. The main culprit appears to be the omega-6 linoleic acid, but all PUFs are bad in high dosages. This is the article:

http://www.second-opinions.co.uk/fats_and_cancer.html

How does this fit into the “omega-3s are great” and “PUFs are fantastic” type of publicity that most up-to-date nutritionists are espousing these days?

If PUFs are going to weaken my immune system (the main point I got from the article), I’d rather not be popping fish oil caps by the handful. Is this going to be another fad like the 80s’ no-fat craze? The problem is, if we’re wrong about PUFs, instead of a bunch of fat people (left over from the 80s), we’ll be left with a bunch of cancer patients.

What’s the opinion out there?[/quote]

Fish oil has been proven to weaken immune system in high doses, mainly EPA.

Fish oils and the immune system
OXFORD, UNITED KINGDOM. Animal studies have shown that an increase in fat intake can decrease the number of natural killer (NK) cells found in the blood and spleen. NK cells are an integral part of the natural immune response to virus infections and certain types of cancer. Researchers at Oxford University now report that fish oil significantly decreases NK cell activity in healthy human subjects.

Their clinical trial involved 48 men and women aged 55 to 75 years. The participants were randomized to receive one of six supplements for 12 weeks. The supplements were all provided in the form of capsules, three of which were to be taken with each meal. The nine capsules (daily intake) contained either a total of 2 g alpha-linolenic acid, 770 mg gamma-linolenic acid (from evening primrose oil), 680 mg arachidonic acid, 720 mg docosahexaenoic acid (DHA), 720 mg eicosapentaenoic acid (EPA)+ 280 mg DHA (fish oil) or a placebo (an 80:20 mix of palm and sunflower oils). All the participants had blood samples taken four weeks before start of supplementation, immediately before start of supplementation, and then every four weeks during the trial as well as after a four-week washout period. The researchers found no changes in killer cell activity except in the group taking fish oil. Here they observed an average decline of 20 per cent after 8 weeks and 48 per cent after 12 weeks. The decline was completely reversed after the washout period. The fact that no decline was observed with pure DHA strongly suggests that EPA was responsible. The researchers conclude that an excessive EPA intake could have adverse effects for people at risk of viral infections and some cancers. Editor’s Note: The British researchers’ speculation about fish oils perhaps affecting the effectiveness of NK cells in killing cancer cells is at odds with the results of many other studies. There are at least a dozen studies that show a clear protective effect of fish or fish oil against breast, colon, and prostate cancer. NOTE: This study was partly funded by Unilever. [54 references] Thies, Frank, et al. Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n-3 or n-6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 years. American Journal of Clinical Nutrition, Vol. 73, March 2001, pp. 539-48

Main stream medicine does not promote high dose fish oil unless indication based on heart disease. The main problem in society is that the percentage of “good” and “bad” is way off in diets. The real recommendation for society is to add a variety of fish low in heavy metals, and olive oil into diet several times a week, and cut back on the bad fat to get ratio inline.

You should know by now that everything you do is good and bad. Yes it does suck. I take a lot of fish oil and buy it at discount club. I should pay the extra $ and buy Flameout to get more DHA. If enough studies come out to make me change my mind I may cut back.

The root cause of serious chronic diseases such as heart disease, Alzheimer’s disease, cancer, arthritis, and asthma has been identified as chronic inflammation. Fish oil seems to be about the best thing out there for decreasing inflammation. Curcumin is another interesting supplement.

Like I said, you just can not win. If you want to play it safe I think the recommended dose from Flameout has it right for health benefits. Most supplements in very high doses tend to act like drugs, and tend to have strong influences on certain pathways in the bodies. Most, if not all drugs have both positive and negative effects on the body. We can not expect supplements to be different, especially in high doses. It seems that many things that suppress inflammation also decrease the immune system, such as fish oil and curcumin. The very same things that help us the most, may also hurt us in too high of doses.

It seems like a case of “everything in moderation”. It seems to me that 30 grams of fish oil and/or flaxseed oil a day isn’t that bad, as long as you are getting your mono and saturated fats in equal proportions.

The article, while having some interesting and valid points, misses the boat in some areas.

He makes no mention of the doses of fish oil that are administered to the patients in order for them to develop cancer. It is also somewhat bogus to make the lung cancer comparisons he does, since typically lung cancer develops AFTER smoking for some time. High rates of lung cancer should have correlated with people who had been smoking for a long time, not with the rate of current smokers.

Finally, it is also possibly an invalid comparison to compare percentage of people with cancer, since people live to be older now, and there is a correlation between age and cancer.

To me, that parts of the article that we should hang on to are

  • that an imbalance of fat intake should be avoided

  • most margarines are not healthy

  • polyunsaturated fats oxidize easily, and oxidation leads to free radicals, which can lead to cancer. This means, don’t cook with your polyunsaturated fats. Cook on low and medium heat with monounsaturated or saturated (think coconut oil) fats, and for high heat, use only saturated oil, since it is the most stable.

Thanks for the input, guys. Like icecold said, it’s a case of “you can’t win”.

Fish oils reducing inflammation but weakening the immune system seems to make sense, as inflammation is the body’s way of reacting to physical stresses it sees as dangerous, right?

I wonder what Poliquin thinks about this, in view of his megadosing fish oil recommendations.

Very interesting, im also curious about his opinion.

omega 6 is a PUF
omega 3 is a PUF

ancient man probably ate a 1:1 ratio of omega 6:3

the typical american diet is 15-25:1

we know excess omega 6 becomes pro-inflammatory, and causes increases in things like IL-6, TNFa, etc (these are bad in excess - basically an over-inflammatory response)

why is there so much lower incidence of cardiovascular disease, cancer, etc in Japan than the USA? one reason is probably the omega 6: omega 3 ratio, which is ~2-5:1 in Japan. much closer to the ideal 1:1 ratio.

maybe having a reverse ratio of omega-6 to omega-3, like 1:2 can be bad too as evidenced by the post by a previous poster. but its not a problem we see in society today since omega-6 is so much more ubiquitous, in things like corn oil which is in every american food.

omega-6 isnt bad - its an EFA and your body does need it. but too much omega 6 is bad. and i would imagine too much omega 3 is bad too. just keep a good ratio and you’ll be fine.

I can’t speak for poliquin but i think the type of people he is applying his advice to is important.

He works with very large, very hard working athletes. With metabolisms like humming birds on crystal. Their joints take a pounding, despite his directions they may party pretty hard, etc… they arnt 155 pound young men who lift half-heartedly 3-4 times a week.

so maybe his recommendations should be taken with a grain of salt?

[quote]Beatnik wrote:
I can’t speak for poliquin but i think the type of people he is applying his advice to is important.

He works with very large, very hard working athletes. […]

so maybe his recommendations should be taken with a grain of salt?[/quote]

I’ll have to reread his article, but the idea I got was that everyone was deficient and would benefit from upping their doses.

Of course, you’re quite right that a pro/semi-pro athlete is going to be placing a greater demand on his joints than I am, and would need more fish oil.

But this is something to discuss in the megadosing thread; in this one I’m interested in talking about PUFs promoting cancer.