Compound in Apple Peels Found to Add Fat; Don’t Worry, it’s the Brown Kind

Back when I was much more lazy about writing on this blog than I am now, I usually maintained a rather large queue of research articles to write about. One day, I became incredibly depressed by just how many were being put on hold. So, as an answer, I started what I called, “Fast Friday Four.” I basically gave a short synopsis of four research papers based completely on their press releases.

It was crap.

But in one of those Friday editions, I covered research from the University of Iowa that indicated a chemical called ursolic acid – particularly concentrated in apple peels – seemed to encourage muscle growth, stop muscles from atrophying, and reduce blood sugar levels, cholesterol, and triglycerides.

Now, there’s even more news. The substance also appears to raise the amount of brown fat found in the mice who consume it.

So why would anyone ever want to take the peel off to eat an apple?

The only reason I know anything about brown fat is because a friend of mine currently is finishing up his Ph.D. on the subject at the University of Washington. The short of it is that besides the usual type of blubber found in the recesses of Burger King fanatics, there is a second type of fat that clings in small amounts to skeletal muscles. And rather than resulting in the consumption of too many calories, this brown fat actually burns calories. Thus, there’s a big push in the scientific community to figure out how to have more of the stuff – or turn more of it on – in adults.

In the new study that followed up the one mentioned previously on Fast Friday Four, Christopher Adams of the University of Iowa fed mice a lot of fat and a lot of ursolic acid. Besides backing up their previous results, the researchers found that reduced obesity, pre-diabetes and fatty liver disease. And one of the ways that it did this was by increasing the amount of brown fat found in the mice.

“Our study suggests that ursolic acid increases skeletal muscle and brown fat leading to increased calorie burning, which in turn protects against diet-induced obesity, pre-diabetes and fatty liver disease,” Adams says. “Brown fat is beneficial and people are trying to figure out ways to increase it. At this point, we don’t know how ursolic acid increases brown fat, or if it increases brown fat in healthy mice. And, most importantly, we don’t know if ursolic acid will benefit people. Our next step is to determine if ursolic acid can help patients.”

Inspired by this awesome scientist who accepts questions and ballparks answers to things like, “How fast would I have to throw a burrito to light it on fire?”, let’s take a look at just how much ursolic acid we’re talking about.

Assuming a person eats about two kilograms of food per day (4.4 pounds), he or she would have to eat 2.8 grams of ursolic acid to reach the 0.14% level described in the paper. Now, let’s that an apple’s peel is five percent of its total mass, and that ursolic acid makes up five percent of the composition of an apple peel. (Note that both of these estimates are probably high.) Adding up all the numbers, and taking an average apple to be 100 grams, one would have to eat 11 apples a day to hit that mark.

Let’s hope that they come out with a pill form.