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