Food Reward Friday

This week's lucky "winner"... Oreo cookies!!!

It's been hard to find time for Food Reward Friday lately, but this week I'm bringing it back with a vengeance.  Oreos have been one of America's favorite cookies since their introduction in 1912 by Nabisco.  They boast a tempting combination of crunchy chocolate cookie and soft, sweet filling.  From a food reward perspective, the combination of concentrated sugar, starch and fat make them a winner.  From a nutritional perspective, these same factors make them a loser. 

Although most adults can think of other desserts we'd rather eat, I think many of us can remember a time when Oreos were just about the pinnacle of deliciousness.  More than tasty enough to throw a tantrum for.  It also helps that Oreos lend themselves to playing with your food.

Interestingly, Oreos were the subject of a recent study on food reward in rats (1) that WHS reader Chris Cappuccio passed on to me.  This study, presented at the 2013 Neuroscience conference, got a lot of media attention, both positive and negative.  What did it find?

Food reward is the process by which behaviors are reinforced by food, and a "rewarding" food is one that makes you more motivated to obtain it once you've eaten it a few times.  In the current study, researchers used a measure of reward called conditioned place preference.  Basically, they repeatedly gave rats Oreos in a particular location, and then measured how much time the rats subsequently spent hanging around in that location hoping for Oreos*, even when the Oreos were omitted.  Crucially, the Oreos were pitted against healthy bland rodent chow, not against an absence of food. 

They found exactly what has been shown many times before: rats LOVE human junk food.  The rats trained with Oreos preferred to hang around the Oreo-associated location even when no Oreos were there, demonstrating that the Oreos are highly rewarding (i.e. Oreo consumption increased the likelihood of Oreo-seeking behavior).  Oreos are also highly rewarding in humans, otherwise they would not have sustained human Oreo-purchasing behaviors over the last century.

What comes next is the experiment that made this study so controversial: they compared the reward value of Oreos to the reward value of cocaine and heroin in their experimental model.  Intravenous cocaine or heroin was paired with a specific location, pitted against intravenous saline at another location, and the researchers subsequently measured how much time the rats spent hanging around the side paired with drug even when no drug was administered.

As expected, rats like cocaine and heroin, and they spent more time hanging around the drug-associated location hoping for a hit.  Here's the critical finding: in this experiment, the reward value of heroin and cocaine was not significantly different from the reward value of Oreos.  Also, all three conditions caused similar effects on neuron activity in the key reward-related brain region the nucleus accumbens.  The authors end the abstract with this:

These findings suggest that high fat/sugar foods and drugs of abuse trigger brain addictive processes to the same degree and lend support to the hypothesis that maladaptive eating behaviors contributing to obesity can be compared to drug addiction

This is what triggered the avalanche of positive and negative media coverage.  The negative coverage was mostly from people who are tired of hearing the argument that reward and addiction are the same thing, or that activation of brain regions involved in reward means something is addictive.  These people have a point, but there's a baby in the bathwater that we shouldn't discard.

Drug addiction is basically a very strong motivation to obtain the drug, as a result of the drug's high reward value (due to direct actions on brain reward circuits).  A person is so motivated to obtain a drug that she has a hard time controlling drug-seeking and drug use behaviors, and these behaviors supersede constructive behaviors like maintaining relationships and being financially responsible.

Similarly, people can be highly motivated to obtain certain foods (ice cream, pizza, potato chips, Oreos) due to the high reward value of those foods.  Although calling this 'addiction' is controversial, it does lead to the consumption of unhealthy calories in excess, superseding constructive behaviors like eating an appropriate quantity of healthy food. 

The word 'addiction' triggers strong emotional reactions and quickly leads to unproductive debate in the popular media.  I think the best way to think about this study is to discard the word 'addiction' and simply think about reward.  Oreos, cocaine, and heroin all had a powerful ability to motivate behavior in rats.  Even though we can't do this study in humans, and I doubt humans would find Oreos as rewarding as heroin, it is nevertheless clear that Oreos and other similar foods are highly rewarding in humans and can lead to behaviors that undermine health and other positive life outcomes.  This study is a good reminder of that.


* In a manner of speaking.  We can't read their minds to see if it truly contains hope.  See comments below by Aaron Blaisdell.

Beans, Lentils, and the Paleo Diet

As we continue to explore the foods our ancestors relied on during our evolutionary history, and what foods work best for us today, we come to legumes such as beans and lentils. These are controversial foods within the Paleolithic diet community, while the broader nutrition community tends to view legumes as healthy.

Beans and lentils have a lot going for them. They're one of the few foods that are simultaneously rich in protein and fiber, making them highly satiating and potentially good for the critters in our colon. They're also relatively nutritious, delivering a hefty dose of vitamins and minerals. The minerals are partially bound by the anti-nutrient phytic acid, but simply soaking and cooking beans and lentils typically degrades 30-70 percent of it, making the minerals more available for absorption (Food Phytates. Reddy and Sathe. 2002). Omitting the soaking step greatly reduces the degradation of phytic acid (Food Phytates. Reddy and Sathe. 2002).

The only tangible downside to beans I can think of, from a nutritional standpoint, is that some people have a hard time with the large quantity of fermentable fiber they provide, particularly people who are sensitive to FODMAPs. Thorough soaking prior to cooking can increase the digestibility of the "musical fruit" by activating the sprouting program and leaching out tannins and indigestible saccharides. I soak all beans and lentils for 12-24 hours.

The canonical Paleolithic diet approach excludes legumes because they were supposedly not part of our ancestral dietary pattern. I'm going to argue here that there is good evidence of widespread legume consumption by hunter-gatherers and archaic humans, and that beans and lentils are therefore an "ancestral" food that falls within the Paleo diet rubric. Many species of edible legumes are common around the globe, including in Africa, and the high calorie and protein content of legume seeds would have made them prime targets for exploitation by ancestral humans after the development of cooking. Below, I've compiled a few examples of legume consumption by hunter-gatherers and extinct archaic humans. I didn't have to look very hard to find these, and there are probably many other examples available. If you know of any, please share them in the comments.

To be clear, I would eat beans and lentils even if they weren't part of ancestral hunter-gatherer diets, because they're inexpensive, nutritious, I like the taste, and they were safely consumed by many traditional agricultural populations probably including my own ancestors.

Extensive "bean" consumption by the !Kung San of the Kalahari desert

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Recent and Upcoming Appearances

Smarter Science of Slim

Jonathan Bailor recently released an interview we did a few months ago on the neurobiology of body fat regulation, and the implications for fat loss.  It's a good overview of the regulation of food intake and body fatness by the brain.  You can listen to it here.

Super Human Radio

Carl Lanore interviewed me about my lab's work on hypothalamic inflammation and obesity.  I'm currently wrapping up a postdoctoral fellowship with Dr. Michael Schwartz at the University of Washington, and the interview touches on our recent review paper "Hypothalamic Inflammation: Marker or Mechanism of Obesity Pathogenesis?"  Dan Pardi and I are frequent guests on Carl's show and I'm always impressed by how well Carl prepares prior to the interview.  You can listen to the interview here.

The Reality Check podcast

Pat Roach of the Reality Check podcast interviewed me about the scientific validity of the "carbohydrate-insulin hypothesis" of obesity.  The Reality Check podcast "explores a wide range of controversies and curiosities using science and critical thinking", and a dash of humor.  This one should be very informative for people who aren't sure what to believe and want a deeper perspective on the science of insulin and body weight regulation.  You can listen to it here.

Obesity Society conference

Next Thursday 11/9, I'll be speaking at the 2013 Obesity Society conference in Atlanta.  My talk is titled "The Glial Response to Obesity is Reversible", and it will be about my work on the reversibility of obesity-associated hypothalamic neuropathology in mice.  My talk will be part of the session "Neuronal Control of Satiety" between 3:00 and 4:30, specific time pending.  See you there!

Buckwheat Crepes Revisited

One of my most popular posts of all time was a recipe I published in 2010 for sourdough buckwheat crepes (1). I developed this recipe to provide an easy, nutritious, and gluten-free alternative to flour-based crepes. It requires no equipment besides a blender. It's totally different from the traditional buckwheat crepes that are eaten in Brittany, in part because it's not really a crepe (I don't know what else to call it, maybe a savory pancake?). I find these very satisfying, and they're incredibly easy to make. They're especially delicious with fresh goat cheese, or scrambled eggs with vegetables, but they go with almost anything. Chris Kresser also developed his own version of the recipe, which is fluffier than mine, and more like a traditional pancake (2).

Buckwheat is an exceptionally nutritious pseudograin that's rich in complete protein and minerals. In contrast to most whole grains, which have low mineral availability due to phytic acid, buckwheat contains a high level of the phytic acid-degrading enzyme phytase. This makes buckwheat an excellent source of easily absorbed minerals, as long as you prepare it correctly! Phytase enzyme works best in an acidic environment, which may be part of the reason why so many cultures use sour fermentation to prepare grain foods. My original recipe included a sour fermentation step.

But there's a problem here. Buckwheat doesn't ferment very well. Whether it's because it doesn't contain the right carbohydrates, or the right bacteria, I don't know, but it spoils rapidly if you ferment it more than a little bit (using a strong sourdough starter helps though). Others have told me the same. So here's my confession: I stopped fermenting my buckwheat batter about a year ago. And it tastes better.

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