Friday, February 3, 2012

SAD - Human Study Shows: Three Days on "High Fat" Standard American Diet Produce Heart Healthier LDL Particle Profile Than NCEP-Approved Low Fat Diet

Image 1: SAD or just mad? It does in fact look like you better stick to Royal TS, French fries & co instead of following a low fat diet according to the guidelines of the National Cholesterol Education Program if you care about your heart health.
In view of the fact that millions of lives depend on it (literally, not just figuratively!) it is actually quite surprising, some would probably say "scandalous" that the experimental evidence (and I am talking about controlled experiments on real, healthy human beings, not about epidemiological and thusly statistical) for the purported beneficial effects of a non-calorically restricted "healthy low fat diet" in the absence of additional exercise interventions is... scarce, to say the least. I was thusly positively surprised, when I hit on a study from a group of researchers from the Institute of Nutraceuticals and Functional Foods at the Laval University and the Lipid Research Center at the CHUL Research Center in Québec, Canada, the title of which suggested that it could provide exactly that - experimental evidence in support of the purportedly healthy low fat diet (Guay. 2012).

Scientists and their interpretation of a "high fat" diet...

I guess, those of you for whom this is not the first visit to the SuppVersity will be aware that I have made a habit of looking at the data first, to make up my mind, before I even take a closer look at the scientists interpretation of the latter (this is what is usually called the "conclusion"). And, geez! The "high-fat diet", the Valérie Guay and her colleagues advertise in the title of their paper turned out to be another case of the standard American diet, the relative fat content of which (32% of total calories) is not exactly, what's on my mind, when I think of a "high fat" diet.
Figure 1: Relative macronutrient composition of the baseline and the isocaloric test (high and low fat) diets (left); total fiber, cholesterol and phytosterol content, as well as polyunsaturated to saturated fatty acid (PUFA/SFA) ratio and total fat in % of total calories (right; data calculated based on Guay. 2012)
The fact that this paper still made into the news, although the researchers' interpretation of a "high fat" diet was designed to "reflected as closely as possible current North American men averages", does yet already tell you that the results were not that the "healthy low fat diet bet the crap out of the standard American one".

SAD! Standard American Diet beats the nasty small LDL particles out of a healthy low fat diet

In fact, a closer look at the somewhat cryptically presented study results revealed that, at least as far as the measured outcome variables of this particular study are concerned, the exact opposite was the case: It was not the purportedly healthy low-fat diet which was designed according to the recommendations of the National Cholesterol Education Program Adult Treatment Panel III (cf. JAMA. 2001) which induced favorable changes in the lipid profile of the twelve initially healthy normal-weight male volunteers (~27.1y; BMI 25.2kg/m²) who took part in this 3-day randomized, double-blind, crossover study, but the calorie-, fiber- and vegetable- and animal-protein-wise identical "high fat" diet, which had been designed in the image of the infamous "standard American diet" (SAD).
Figure 2: Lipid profile (left) and its relative changes (compared to baseline, right) in response to the 3-day dietary intervention (data calculated based on Guay. 2012)
If you look at the data in figure 2 through Pfizer-ish-blue glasses you will probably say: "Wait a minute! The cholesterol level did decrease in the low fat group! So this must be the better diet." And yes, this may actually be the case, if you define better according to the same fundamentally "cholesterol is bad for you"-paradigm which has been flushing billions of dollars (and of course Euros ;-) into the coffers of Pfizer & Co over the last decades. If you have yet been following the by no means "latest" scientific research on the correlation of cholesterol and heart disease, you will be aware that neither total cholesterol, nor total LDL levels, but rather the amount of highly oxidizable small LDL particles is a relatively reliable marker of the risk of heart disease (Lamarche. 1997)- and, fortunately, Guay et al. are aware of that, as well, and measured the characteristics of LDL particles by the means of electrophoresis.
Figure 3: Relative distribution of LDL particle sizes (left), cholesterol content (mmol/L) of LDL fractions (middle), and mean LDL particle size and LDL peak particle diameter (LDL-PPD; right); * indicates p < 0.05; ** indicates p < 0.001 (data adapted from Guay. 2012)
The results of the LDL-particle analysis shown in figure 3, show quite neatly, that the unquestionably unhealthy standard American diet (Attention: Do not misinterpret these study results as a carte blanche to stick to eating your regular crappy diet!) did not only result in more favorable triglyceride (1.48 vs 1.01mmol/L, p = 0.0003) and HDL levels (1.29 vs 1.41 mg/L, p = 0.05; cf. figure 2), than its allegedly "healthy" low fat counterpart, it was ...
[...] also associated with a significant increase in LDL particle size (255.0 vs 255.9Å; p = 0.01) and a significant decrease in the proportion of small LDL particle (<255.0 Å) (50.7% vs 44.6%, p = 0.01).
And although Guay et al. are quick to point out that "because the present study was only conducted in men, the results cannot be generalized to the whole population", I would say that these results should at least.make you reconsider if following a "healthy low fat diet" in accordance with the dietary guidelines of the National Cholesterol Education Program will help you lower your risk of heart disease... unless, of course, you have already popped so much Lipitor & co that the chronic lack of cholesterol is already hampering your cognitive abilities -.what? Ah, yes... of course, the favorable results occur only if you take you daily dose of statins with your low fat meals... right, how could I forget that ;-)