Saturday, November 19, 2011

This Just In: The Infamous Lard-Based High-Fat Rodent Diet Is Twice as High in PUFA as Previously Reported

by Chris Masterjohn

Hi folks!

It's certainly been a while.  Up until this past weekend I was preparing for Wise Traditions, and this week I've been playing catch-up after taking a few days off from work for that conference.  It was a blast, and I'll write more about it soon.

One of the things I love about measuring glyoxalase activity is that although the assay takes all day, it has a lot of short incubation steps that leave me with a multitude of five-minute breaks.  If I'm not feeling too lazy, that can give me time to write a blog post or two, as long as they're short and not too data-heavy.  

So here's a short one.  

I got an email today from Dr. Matthew Ricci, the Vice-President and Research Director of Research Diets, the company that produces the infamous 60% fat, lard-based rodent diet D12492.  I've written about this diet before.  The company had previously been using the USDA database to determine the diet's fatty acid profile, but recently had it directly analyzed, knowing that the fatty acid profile of lard can vary according to what the pigs are fed.

It turns out that the diet obtains 32% of its fat from PUFA instead of the previously reported 17%.  The ratio of omega-6 linoleic acid to omega-3 linolenic acid had been previously reported as 7.8 but is actually 14.  

The diet also has half as much of the monounsaturated palmitoleic acid as previously reported.  Research Diets will soon be replacing the old fatty acid profile on their web site with a new one reflecting the direct analysis.

Dr. Ricci said that the company has not received many complaints about variability with their diet, so he thinks that although each new batch is likely to vary from the one before it to some degree, the new analysis probably reflects what the fatty acid profile has been for years better than the one that has actually been on the web site.  Stephan Guyenet informed me that one of his colleagues had once measured the fatty acids in this diet directly and came up with similar results, only the omega-6-to-omega-3 ratio was a whopping 16, supporting this view.

Kudos to Research Diets for their commitment to honesty and transparency.  They could have kept on using the USDA database, but didn't.  And they certainly didn't have to write me and tell me about it.  I had inquired about the fatty acid profile in the past, and they remembered!  A thoughtful bunch.

Research Diets estimates that 50,000 mice worldwide are getting chubby on this diet.  It turns out they're getting chubby on twice as much PUFA as we thought they were.

Read more about the author, Chris Masterjohn, PhD, here.


  1. Important tidbit, thanks for this. I never considered the high fat mouse-murder diet to be evidence that high fat diets were even necessarily bad for rodents because of the mitigating effect of long-chain omega-3 fats as seen here and elsewhere. I think that researchers need to look at long-chain PUFAs as important nutrients when using high fat diets, because there seems to be an interplay between them.


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  2. This makes me wonder which components were displaced by PUFAs in their profile(?)

  3. Hey Chris,

    It was great to meet you at Wise Traditions last weekend - both of your presentations were excellent.

    And thanks for sharing the info regarding the lard in D12492 - scary. It is scary to me because even with pastured pork, the HUGE percentage of a pig's diet is cereal grains.

  4. So do you suppose that this is true of average lard, or do they get their lard from some special source?

  5. That poses an interesting question about what is the "average" profile of lard out there, how does it vary with the animal's diet, and where on earth do we get reliable data for such information?

  6. It is these bits of information, basically the unstated assumptions that researchers make (e.g., i.e., accepting supplier's analysis of fatty acids profile), that seem to be the source of a lot bad research conclusions. One of the many great services you have been providing is pointing these things out. Thanks!

    I would guess that Research Diets uses the cheapest lard they can get, which would mean corn-fed factory farm lard. That might explain part of it. I'm sure the once or twice a year I eat locally sourced pork at a nice restaurant that I am getting something closer to the USDA analysis, probably better.

  7. Wow...that is HUGE. Double the badness, yet SFAs have been taking the blame. Thanks for posting!

  8. Of course if diet is not really controlled, the work is no longer science.

    It isn't just here. First, mice are herbivores. In a Mouse's natural environment they get very little fat and no refined sugars, Yet the "standard test diet" contains both in starkly unnatural quantities. Other mouse "high fat test diets" contain large amounts of trans fats.

    Conclusions reached by these and other studies are meaningless and a huge waste of resources. Real science is very hard to do. Sadly, the typical motions involved in keeping grant money flowing is not real science.

    How badly this taints a HUGE body of research is unknown.

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