|I have to admit: Whether a conclusion as general at this is warranted based on the data from a recent study is questionable.|
Ah, come on! That's so mainstream it must be propaganda from the "pharmaceutical enteprise/ cholesterol lowering drug entreprise" [sic!], right?
Well, I am just looking at the acknowledgements of the study the press release refers. Let's see: "None of the authors have any conflicts of interest to disclose" and "This study was funded by the Swedish Research Council (project K2012-55X-22081-01-3)." No, I wouldn't say this sounds like there had been a "pharmaceutical enteprise/ cholesterol lowering drug entreprise" funding the study
Just as an aside: Discarding the results, because the results are not inline with your own indoctrictinat like the guys who sponsored it, is pretty pathetic. If you want to argue that the results Fredrik Rosqvist and his colleagues from the Uppsala University, and the Center for Clinical Research Dalarna are b*s*, you better take a look at the study design to identify flaws and shortcomings - and guess what?! That's what we are about to do now.Now that we have all calmed down a bit, let's see what exactly we could freak out about - or, to put it differently, let's take a closer look at the study design, the results, and their interpretation.
I - The Research Question
I know that many of you don't care about questions. That's a mistake. In science, questions are everything. Answers are secondary. The motto of a true researcher is thus - just as the Greek philosopher Euripides had it - "Question everything. Learn something. Answer nothing." In the end, we've already made a very good start by questioning the scientists' conclusion that
"[...] overeating SFA promotes hepatic and visceral fat storage whereas excess energy from PUFA may instead promote lean tissue in healthy humans." (Rosqvist. 2014)What we are interested in part I of our analysis are not our questions, though. What we want to look at now, is the question that worried the researchers, the questions, whether ...
"[...]liver fat accumulation during moderate weight gain could be counteracted if the excess energy originate mainly from PUFA rather than from SFA." (Rosquist. 2014)This question, as logical as it may seem for the average individual who has been sucking up the "good fat (PUFA) vs. bad fat (SFA)" mantra with his PUFA-enriched formula ever since he was born, is obvious a reason to freak out for the meanwhile almost as average black-and-white thinking inhabitant of the blogosphere.
|Don't interpret this article as incentive to follow all dietary recommendations to the "T" before you've read my 2012 article on the effects of an allegedly heart healthy low fat diet on the LDL particle profile of healthy volunteers | read more|
In view of the fact that the alleged improvements (in many cases the values simply worsened less) of the blood lipids, glucose and insulin levels, the hypothesis that "liver fat accumulation during moderate weight gain could be counteracted if the excess energy originate mainly from PUFA rather than from SFA" (Rosquist. 2014) is legitimate, but probably optimistic.
II - Study Design
So, if the underlying hypothesis is valid, the next thing we could target to debunk the claim that saturated fats are more fattening / unhealthier than unsaturated fats would be to have a closer look at the design of the LIPOGAIN study:
Figure 1: Rel. changes in liver, visceral and subcutaneous fat in subjects over-consuming a high vs. low (white) saturated fat diet.
- the scientists made sure that the subjects gained weight at identical rates (3%) (the amount of muffins consumed per day was individually adjusted weekly, i.e. altered by +/- 1 muffin/day depending on the rate of weight gain of the individual)
- the dietary intervention was based on highly standardized food items
- muffins containing sunflower oil (high in the major dietary PUFA, linoleic acid, 18:2 n-6) or
- muffins containing palm oil (high in the major SFA, palmitic acid, 16:0).
- the muffing were baked in large batches under standardized conditions in a metabolic
kitchen at Uppsala University
- except for the type of fat, the muffins were identical with regard to energy, fat (51%), protein (5%), carbohydrate (44%; sugar to starch ratio 55:45), and cholesterol content, as well as taste and structure.
|Figure 2: Relative contribution of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids to the total energy intake of the subject before and after the study (Rosquist. 2014)|
- Bjermo, Helena, et al. "Effects of n− 6 PUFAs compared with SFAs on liver fat, lipoproteins, and inflammation in abdominal obesity: a randomized controlled trial." The American journal of clinical nutrition 95.5 (2012): 1003-1012.
- Rosqvist, Fredrik, et al. "Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans." Diabetes (2014): DB_131622.