Body Fat Modulation with Corn Oil & L-Carnitine: What You Can Learn From Your Schnitzel

Its quite remarkable that, primates aside, swine are among the best models of human metabolism. So, even if you do not feel piggy at all, the fact that pigs just as humans are omnivores, makes them a much better model for metabolic disease than rodents. It is thus not too unrealistic to assume that we can learn something about ourselves from the results of a very recent study published in the Journal of Animal Science (Apple. 2011).

Figure 1: American Pork Cuts; quality is determined by corn-oil and carnitine intake of the swine.
What lessons can you learn from our pink relatives?

Investigating the effects of l-carnitine supplementation on the quality characteristics of fresh pork bellies from pigs fed three levels of corn oil, J.K. Apple and his co-workers observed a linear trend towards decreased belly-firmness with increasing amounts of corn oil (0, 2 or 4%) in the diet. If you look at the average American, his/her high corn oil consumption and their respective (pot-)bellies, this should not surprise you. All aesthetic considerations aside, those feisty pot-bellies are nothing but the outward sign of metabolic derangements that - without appropriate lifestyle interventions - have their owners suffer from diabetes, high blood pressure, chronic inflammation, and all the other players in the (eventually) deadly "game" of metabolic syndrome.

[...] belly firmness decreased linearly (P < 0.001) with increasing dietary OIL, but there was no (P ≥ 0.137) effect of CARN on any belly firmness measure.

Now, did the touted fat-burner l-carnitine prevent these effects? No, it didn't. Yet, what it did do is it increased the amount of saturated (SFA) and mono-unsaturated (MUFA) fatty acids and decreased the amount of polyunsaturated fatty acids (PUFA) in the belly tissue:

Dietary CARN increased (P < 0.05) the proportion of total SFA in the intermuscular fat layer, increased (P < 0.05) the proportion of total MUFA in the primary and secondary lean layers, and decreased (P < 0.05) the proportion of total PUFA in the intermuscular fat and secondary lean layers of pork bellies.

In view of the finding that increasing the amount of corn oil in the diet tended to increase the PUFA content of the belly tissue, while depositing the highly oxidative polyunsaturated fatty acids preferentially in fat and not lean layers, one must acknowledge that L-carnitine, despite not being able to prevent the outwardly visible (and touchable) negative effects of a diet high in omega-6 rich corn oil, was yet able to modulate the effects of excess PUFAs on intra-tissue body fat composition.

Against the background of the recent changes in the scientifically accepted perspective on the previously vilified saturated fatty acids and possible beneficial effects on cell stability and inflammation the significance of these results goes beyond profane insights into the management of pork quality and solidify the foundation of my previous recommendation to avoid omega-6 instead of increasing the overall PUFA load by additional omega-3 supplementation. What's new, however, is the role l-carnitine supplementation may play in your efforts to get rid of overly high tissue levels of omega-6, since the reduced storage in fat tissue and the increased storage in muscle could be able to (a) decrease inflammation of the fat tissue and, at the same time, (b) increase oxidation of PUFAs in exercised muscle tissue. Yet, without appropriate dietary changes and the incorporation of regular exercise sessions into your  new, healthier lifestyle all carnitine in the world won't help you, if you insist on eating too many breaded and fried schnitzel with French fries and a boatload of mayonnaise and ketchup.