6

votes

New study: Effects of n−6 PUFAs compared with SFAs

Answered on August 19, 2014
Created April 06, 2012 at 7:38 AM

Stephan Guyenet recently tweeted this study:

Effects of seed oil vs. butter on liver fat, inflammation and serum lipids over 10 weeks

I would love for this to be 'hacked' as it seems to fly in the face of paleo dogma.

E5c7f14800c5992831f5c70fa746dc5c

(12857)

on May 04, 2012
at 02:20 PM

thank you......

64433a05384cd9717c1aa6bf7e98b661

(15236)

on May 03, 2012
at 10:41 PM

cliff I tend to find you quite jarring in your responses on here, but I like your blog. You have a lot of good things to say and I like how it's organized in a concise and dense manner, and easy to read. good job

Be1dbd31e4a3fccd4394494aa5db256d

(17969)

on April 08, 2012
at 02:06 AM

Heh, perhaps...

Be1dbd31e4a3fccd4394494aa5db256d

(17969)

on April 07, 2012
at 07:23 PM

possibly........

Bfa1c9eacfc94a1b62f3a39b574480c6

(3700)

on April 07, 2012
at 07:38 AM

I have the paper in front of me. The diet was either heavy in linoleic acid, ie, "scones (baked-on sunflower oil), margarine, sunflower oil, and sunflower seeds, and the SFA group received "scones (baked-on butter) and butter."

74b00bbfe9ba0f647bb154ed5f923cb4

(156)

on April 07, 2012
at 04:05 AM

@Stabby: That looks like it should've been an answer, hehe. :-P

00c8eb3f6e6a1884216044ca29cf868a

on April 07, 2012
at 03:52 AM

As I mentioned above, the participants were instructed to "eat what you normally eat but try to eat more saturated fat/linoleic acid...and here's some buttered/margarined scones to help you along." In other words: we have no idea what they were eating.

00c8eb3f6e6a1884216044ca29cf868a

on April 07, 2012
at 03:40 AM

Also, you mentioned the difference in starting conditions. The group assigned to the SFA diet was, on average, OVER 11 POUNDS HEAVIER, almost two inches bigger in the waist, had 2.5 more pounds of visceral fat (the worst kind, usually indicative of existing metabolic issues) and 1.75 pounds more subcutaneous fat -- not to mention their fasting insulin was 8% higher. +++ Given that the absolute change in question is so small (the total variance was 2%), and the SFA group was in more than 2% worse physical shape to start, that could easily account for the entire difference by itself.

00c8eb3f6e6a1884216044ca29cf868a

on April 07, 2012
at 03:28 AM

Good analysis, and good catch of the myristic vs. palmitic. And that one dude who was measured at -0.8% of liver fat is really changing the slope of those lines. +++ Of course, the elephant in the room is that the actual dietary composition is completely unknown, because the participants were instructed to "eat what they normally ate but try to use more butter/sunflower oil/sunflower seeds" and given scones to eat. With < 30 subjects per group and so much overlap in the data, this is a major confounder.

00c8eb3f6e6a1884216044ca29cf868a

on April 07, 2012
at 03:12 AM

He deletes them sometimes, too...at least four that I know of are gone.

Be1dbd31e4a3fccd4394494aa5db256d

(17969)

on April 07, 2012
at 01:17 AM

http://www.westonaprice.org/know-your-fats/good-fats-bad-fats-separating-fact-from-fiction

Be1dbd31e4a3fccd4394494aa5db256d

(17969)

on April 07, 2012
at 01:17 AM

suppose. Metabolic syndrome changes so many things, it is hard to extrapolate to any of us. I'm keeping my omega-6 low, not extremely low, but probably half of what these guys have and all of my inflammatory markers are perfect, so I'm a bit biased. To this date there are no trials that examine a low omega-6 intake to my knowledge. There are some saying that 25g is no worse than 15g! Where are the ones pitting 6g against 15g? "omega-6 fine" is very premature. And there's the cancer and aging issue, Chris Masterjohn thinks that it takes years to see a real negative effect from omega-6...

Be1dbd31e4a3fccd4394494aa5db256d

(17969)

on April 07, 2012
at 01:13 AM

are notoriously inaccurate, and I have seen Swedish Meal Time and the junk oils that Swedes get exposed to in processed foods. There is no way to account for that, so it is probably even more. Compound that with a caloric intake very high considering their lean mass and you have one heck of an omega-6 load as baseline. The authors would have us believe that their omega-3 intake was decent at baseline but I can't verify that. And if they have metabolic syndrome then it will be more likely to be damaged within the body and useless to allow saturated fats to function properly...or omega-6 I...

Be1dbd31e4a3fccd4394494aa5db256d

(17969)

on April 07, 2012
at 01:11 AM

amongst other things. I don't actually think that omega-6 is this linear toxin and the more we consume the worse it is...as least with regards to short term biomarkers. But after a point of consumption, that all of these men were past at baseline and probably still past regardless of which group they were in, and at that point the membrane phospholipids are already full and the damage of excess omega-6 has reached a point where it isn't any worse with regards to inflammation and metabolic functioning. The authors said that they all had 4% calories of omega-6 as baseline, but food surveys...

Be1dbd31e4a3fccd4394494aa5db256d

(17969)

on April 07, 2012
at 01:08 AM

It is a long and complex explanation, I'm sure someone will do it eventually. But I don't think that in people without metabolic syndrome we would see the same thing because of how saturated fats vs. polyunsaturated fats get metabolized when we're out of metabolic homeostasis. I have no reservations in saying that I think that saturated fats can be a bad thing in the short term if the endocrine system isn't working properly, but this doesn't apply to healthy people eating a mixed diet or people who are on a low carb diet to lose weight. Now how to get healthy...stop eating so damn much omega-6

A2c38be4c54c91a15071f82f14cac0b3

(12682)

on April 06, 2012
at 10:00 PM

@Melissa-They used sunflower oil.

9d43f6873107e17ca4d1a5055aa7a2ad

on April 06, 2012
at 07:07 PM

Which PUFA oils were they using? I think it matters a great deal because the phytochemicals in various oils give some very different properties in terms of oxidation resistance,etc.

9d43f6873107e17ca4d1a5055aa7a2ad

on April 06, 2012
at 07:06 PM

He puts addendums on old posts that he no longer agrees with.

0d0842381492a41b2173a04014aae810

(4875)

on April 06, 2012
at 06:40 PM

Agreed - I think butter seems like a poor choice of SFAs here. I'd be curious to see results of coconut oil or pastured tallow.

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on April 06, 2012
at 06:30 PM

Yes! Stephan doesn't defend his previous hypotheses; he critiques them.

4781cf8ae1bfcb558dfb056af17bea94

(4359)

on April 06, 2012
at 01:19 PM

Science si self-correcting and he is a... scientist. You should be happy he posts studies that potentially contradict his previous writings.

F3fc2e0a9577e7e481a387d917904d1e

(1070)

on April 06, 2012
at 12:41 PM

J. Stanton - here you go: http://bit.ly/HWmuum

F3fc2e0a9577e7e481a387d917904d1e

(1070)

on April 06, 2012
at 12:39 PM

J. Stanton -- What's your email? I have access to the paper.

00c8eb3f6e6a1884216044ca29cf868a

on April 06, 2012
at 08:25 AM

I'd love to look at it -- but fulltext isn't available and the abstract doesn't give details. Therefore, we don't know what was actually in the diets, and it's impossible to draw any conclusions.

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11 Answers

6
Medium avatar

on April 06, 2012
at 06:22 PM

There's a much stronger correlation between serum myristic acid and liver fat than with serum palmitic acid. In the same way that I've observed that a heavy butter, but not a heavy beef fat intake, shoots my cholesterol levels to the moon, it seems that this evolutionarily novel fat also has a different effect on liver fat levels. This is a mark against butter, not saturated fat.

I don't see this being an argument for increased linoleic acid intake at all.

0d0842381492a41b2173a04014aae810

(4875)

on April 06, 2012
at 06:40 PM

Agreed - I think butter seems like a poor choice of SFAs here. I'd be curious to see results of coconut oil or pastured tallow.

5
A2c38be4c54c91a15071f82f14cac0b3

(12682)

on April 06, 2012
at 11:47 PM

Interesting study, I'll be examining it for the next few days but here's some points I noticed:

Most biochemical markers of health were about the same in both groups at baseline (triglycerides, alanine aminotransferase, etc.) but some weren't. Weight was higher in the SFA group (and subsequently so was BMI, waste circumference, visceral fat, and total fat mass). Still, this difference was small, but it's an worth noting. As calculated using a homeostasis model assessment-estimate for insulin resistance (HOMA-IR), the SFA group was higher than the PUFA group (2.0 vs. 2.6) and the SFA group was right on the line for what is often considered the clinical cutoff for insulin resistance. So, this might suggest that the butter group had a slightly less healthy lifestyle.

Plasma levels of high molecular weight adiponectin were quite different in the PUFA vs. SFA groups (2.62 vs. 3.56). Many people might consider this in the favor of the SFA group and I'm not honestly sure but I think more context is needed to explain that variance.

As Travis pointed, this study used butter as the saturated fat source, which is important because it contains higher levels of the saturated fat myristic acid. Myristic acid may have unique effects on health compared to the other saturated fatty acids and the study even had graphs which seemed to support this:

1:

The graphs illustrate the correlation the researchers found between liver fat and dietary changes in myristic acid (14:0 on the left) and palmitic (16:0) on the right. The correlation is much stronger with myristic and fairly weak (especially after removing outliers) for palmitic.

As someone else noted in their answer, the study was quite independent and doesn't note what food was being consumed (beyond sunflower oil in the PUFA group, butter in the SFA group, and scones in both). As Christopher Gagnon stated in his answer "Not many people put butter on salad". The study doesn't examine whether the PUFA group may have consumed healthier foods which could have affected the results.

Finally, sunflower oil and butter have differences beyond just their fatty acid compositions. Sunflower oil is rich in vitamin E (does Vit E improve symptoms of fatty liver disease? Some studies suggest it might). And, perhaps components in butter (like progesterone and IGF-1) negatively affected liver fat levels. I don't know, but you I'm suspicious that you can extrapolate the effects to just the fatty acids.

Edit:

I wonder how choline may have played into the results of this study. Chris Masterjohn has written a bit about choline, including this awesome post on how choline deficiency is probably the main driver of a fatty liver. Choline deficiency could have significantly influenced the results and we don't even know what the choline intake in either group was (choline receives no mention in this study). Masterjohn also points out in his article that "saturated fats increase the choline requirement a bit more than PUFAs do", citing this study. Finally, in this related post, CMast talks about how choline need is dependent on folate, b6, b12, and betaine intake (all of which lower choline need). In the SFA group, a lower intake of choline (and/or those choline sparing nutrients) and a greater need due to greater sat fat intake likely could have been responsible for greater liver fat accumulation.

00c8eb3f6e6a1884216044ca29cf868a

on April 07, 2012
at 03:28 AM

Good analysis, and good catch of the myristic vs. palmitic. And that one dude who was measured at -0.8% of liver fat is really changing the slope of those lines. +++ Of course, the elephant in the room is that the actual dietary composition is completely unknown, because the participants were instructed to "eat what they normally ate but try to use more butter/sunflower oil/sunflower seeds" and given scones to eat. With < 30 subjects per group and so much overlap in the data, this is a major confounder.

00c8eb3f6e6a1884216044ca29cf868a

on April 07, 2012
at 03:40 AM

Also, you mentioned the difference in starting conditions. The group assigned to the SFA diet was, on average, OVER 11 POUNDS HEAVIER, almost two inches bigger in the waist, had 2.5 more pounds of visceral fat (the worst kind, usually indicative of existing metabolic issues) and 1.75 pounds more subcutaneous fat -- not to mention their fasting insulin was 8% higher. +++ Given that the absolute change in question is so small (the total variance was 2%), and the SFA group was in more than 2% worse physical shape to start, that could easily account for the entire difference by itself.

3
E1c41fc9d29cec2c3066e000c9562d92

on April 07, 2012
at 03:28 AM

I think the Vitamin E component of this study explains the differences :).

The study requested that the participants intake 15% of their energy as linoleic acid using the given food items. This is about 33 grams of fat. Per 100g of sunflower products, there is approximately 20 iu's of vitamin E. Enough to meet the RDA. The four main things this study found are the following:

  1. Decrease in liver fat.
    • Vitamin E will do this, but seemingly only in the short term. Looking at this study, refer to figure 2. The effect of Vitamin E on all of this seems to be largely transient. Note how the ALT levels drop quickly in the Vitamin E group, and then level out. At the end of 96 weeks the Vitamin E did nothing. If this would of been a 10 week trial, the vitamin E would of been "effective."
  2. Lowered cholesterol.
    • Vitamin E has not been shown to do this, but I'm pretty sure linoleic acid does actually do this. I don't think any of us really care here, as super low cholesterol isn't on our agenda, and I didn't even bother to look up a study. Just not interested in this part, haha.
  3. Fasted insulin "tended" to be higher in SFA group rather than PUFA.
    • Vitamin E will help restore insulin sensitivity, or at least its been found in high-dose situations. Admittedly the dose in this study would of been 1/40 of the dose in this study, but given the overwhelming small decrease in fasted insulin in the PUFA diet, I don't think its a long shot that it was the Vitamin E's doing. In the compliant subjects data, its a mere fraction of a decrease, and as Mscott points out, it appears the SFA group was more insulin resistant from the get go.
    • Vitamin E helps insulin sensitivity in fructose-fed rats. Not exactly the best study to quote, but this seems rarely researched.
    • Here is another look in humans.
    • Note that the effect on insulin sensitivity seems mostly transient as well. This was only a 10 week study after all.
  4. Plasma IL-1RA and TNF-R2 were lower during the PUFA diet than during the SFA diet.

I think if this study would of gone on for another 10 or 20 weeks, there probably would not have been very many differences. If anything, I think we can learn from this study that whole foods or oils extracted merely through crushing like sunflower, coconut, olive, rather than some artificial chemically derived canola, corn, or soybean oil, still has better effects on the body.

I don't have much to back up this last statement, but I don't think the whole PUFA vs SFA thing is that big of a deal honestly. Or is omega-6/omega-3 ratios. I think as time goes on, we'll find that those foods which present us with a "damaging omega-6 ratio" are packaged together with things like Vitamin E and other anti-inflammatory agents that make up the difference.

3
A7768b6c6be7f5d6acc76e5efa66464c

on April 06, 2012
at 02:18 PM

I commented on a link to this study in another thread, but am glad you posted it as a question of its own, since it deserves further scrutiny.

I wouldn't make much of it without seeing more information about the diet of study participants. I'm not qualified to "debunk" a study, but I can come up with a couple questions:

  1. The abstract says macronutrient ratios didn't change, but it didn't stipulate the actual ratios, nor if all participants had the same ratio.

  2. They only studied "abdominally obese" people, 15% of whom had diabetes. Could metabolic derangement influence results--particulalry if they didn't control food choice? Did the group consuming SFA also include the diabetics? Alternatively, did the PUFA group include the diabetics, but they happened to be properly managing their conditions--including avoiding lots of refined carbs?

  3. What did they eat? These studies rarely tell us what study participants actually consumed. The abstract mentions only butter. Everyone knows certain foods go well together, and to me it seems plainly obvious that the choice of a fat can naturally influence one to eat certain foods. I would think one less likely to spread olive oil on toast or pancakes. Not many people put butter on salad.

If they told participants who likely eat a SAD to limit their fat to SFA, it seems pretty likely to me that many would consume it with lots of refined and/or sugary carbs, so elevated lipids wouldn't surprise me.

Bfa1c9eacfc94a1b62f3a39b574480c6

(3700)

on April 07, 2012
at 07:38 AM

I have the paper in front of me. The diet was either heavy in linoleic acid, ie, "scones (baked-on sunflower oil), margarine, sunflower oil, and sunflower seeds, and the SFA group received "scones (baked-on butter) and butter."

00c8eb3f6e6a1884216044ca29cf868a

on April 07, 2012
at 03:52 AM

As I mentioned above, the participants were instructed to "eat what you normally eat but try to eat more saturated fat/linoleic acid...and here's some buttered/margarined scones to help you along." In other words: we have no idea what they were eating.

2
Ca1150430b1904659742ce2cad621c7d

(12540)

on April 08, 2012
at 11:56 AM

My philosophy:

Numbers can say anything we want them to say. In the end, we STILL don't really know what they MEAN. Is "fatty liver" bad? Is it transient? Did the butter cause inflammation, or was it something else in the person's life -- or is diabetes actually an inflammatory process in and of itself? In light of everything we DON'T know, I'm still leaning towards the following few basic rules.

  1. Don't worry about numbers... weight on a scale, macronutrient/micronutrient ratios, cholesterol levels, etc.

  2. Eat food prepared from scratch. As much as possible, have it be food that makes your essence/spirit/being sing.

  3. Have that food come from ingredients you could make or grow at home, with the help of simple tools (yes, I actually have a hand-tool for obtaining nut and olive oils! You can find it here).

  4. Follow your appetite. If you're not hungry, don't eat.

  5. Make sure the plants and animals you eat grew in as close to THEIR natural state as is possible for you to afford.

  6. Make your body work hard at least a little while every day -- then let it rest as completely as possible a while every day, too.

  7. Let your mind be active, and challenge your beliefs at least once a day, then give yourself a break and just laugh over something completely senseless and silly, just because it feels good.

  8. Treat the people around you with dignity, regardless of their eating habits, size, shape, or politics -- and make sure you let the people you truly cherish know that they're in your thoughts every day.

If I don't live a long and healthy life doing that -- then I guess I was meant to die young and I guess I'm not willing to waste a whole lot of time over-analyzing it.

E5c7f14800c5992831f5c70fa746dc5c

(12857)

on May 04, 2012
at 02:20 PM

thank you......

64433a05384cd9717c1aa6bf7e98b661

(15236)

on May 03, 2012
at 10:41 PM

cliff I tend to find you quite jarring in your responses on here, but I like your blog. You have a lot of good things to say and I like how it's organized in a concise and dense manner, and easy to read. good job

1
C836b2644e7319bb957fbb794a97708e

on April 06, 2012
at 10:30 PM

I wonder what else they were eating. I am not an expert but I would guess that certain combinations are bad for health even if the food is individually neutral

1
4781cf8ae1bfcb558dfb056af17bea94

(4359)

on April 06, 2012
at 01:28 PM

Much has been written here before about the fact that we don't know understand the mechanisms by which excessive omega 6 consumption causes disease. That it does not have a simple relation to inflammation (i.e., more LA = more AA-derived eicosaoids) as had previously been thought, has now been known for a few years.

I think it would be unwise to exonerate excessive consumption of linoleic acid on the basis of a few studies finding no correlation with poorly understand surrogate markers of disease. Such consumption is unnatural (i.e., unpaleo). There is decent evidence from human and animal trials that such consumption causes diseases, like cancer and heart disease. There is also contradictory evidence from other trials-- but these generally appear to be less well conducted.

0
9b0a4701e373d4dd13831cfb9b13f42d

(1677)

on April 06, 2012
at 06:44 PM

This study doesn't mean anything to me, as I don't really eat butter, if it was coconut oil . vs. PUFA then Id take notice

0
4781cf8ae1bfcb558dfb056af17bea94

(4359)

on April 06, 2012
at 01:33 PM

Much has been written here before about the fact that we don't know understand the mechanisms by which excessive omega 6 consumption causes disease. That it does not have a simple relation to inflammation (i.e., more LA = more AA-derived eicosaoids) as had previously been thought, has now been known for a few years.

I think it would be unwise to exonerate excessive consumption of linoleic acid on the basis of a few studies finding no correlation with poorly understand surrogate markers of disease. Such consumption is unnatural (i.e., unpaleo). There is decent evidence from human and animal trials that such consumption causes diseases, like cancer and heart disease. There is also contradictory evidence from other trials-- but these generally appear to be less well conducted.

0
4e184df9c1ed38f61febc5d6cf031921

(5005)

on April 06, 2012
at 08:00 AM

It seems to be quite the opposite of what he writes here

http://wholehealthsource.blogspot.co.uk/2009/06/fatty-liver-reversal.html

Both cannot be right!

4781cf8ae1bfcb558dfb056af17bea94

(4359)

on April 06, 2012
at 01:19 PM

Science si self-correcting and he is a... scientist. You should be happy he posts studies that potentially contradict his previous writings.

00c8eb3f6e6a1884216044ca29cf868a

on April 07, 2012
at 03:12 AM

He deletes them sometimes, too...at least four that I know of are gone.

9d43f6873107e17ca4d1a5055aa7a2ad

on April 06, 2012
at 07:06 PM

He puts addendums on old posts that he no longer agrees with.

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on April 06, 2012
at 06:30 PM

Yes! Stephan doesn't defend his previous hypotheses; he critiques them.

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