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Chicken, Egg, and Taste Buds

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A new study published online in the journal Archives of Disease in Childhood indicates that obese children and adolescents, as compared to their lean counterparts, have less sensitive taste buds. The researchers suggest that this difference in taste sensitivity may be an explanation for the development of obesity.

That may be true, but the study in question can't say for sure because it was cross-sectional, meaning it examined weight and taste sensitivity (in slightly fewer than 200 children, age 6 to 18, half of them obese) at the same time. Cross-sectional studies can show that both A and B happen in the same people, but they can't reliably say anything about cause and effect, because they provide no view of what happens over time. In other words, we don't know from this study which came first: a taste for Southern-fried chicken, or taking on the shape of an egg.

In more politically correct terms, the study can't determine if obesity is the result of innately less sensitive taste buds, or if the foods that fuel obesity deaden taste buds by bathing them all day long in sugar, salt, and food chemicals such as monosodium glutamate. While I think there could well be some of both going on, I confidently would put most of my own eggs in that second basket, with bad food choices causing obesity, and beating taste buds all but senseless.

My impression is, of course, informed by relevant science, and professional experience. I will lay out my case.

First, rates of childhood obesity are very high, and still rising. Recent reports, such as the just-issued "F as in Fat: How Obesity Threatens America's Future 2012" from the Robert Wood Johnson Foundation and the Trust for America's Health, show us a possible future in which virtually every child in the U.S. today grows up to be an overweight or obese adult. While it's possible that variation in taste sensitivity is making some of us -- adults and children alike -- more vulnerable to obesity than others, clearly the vulnerability is all but universal. So the obesity threat is, in a word, bigger than variation in taste sensitivity can explain.

Second, there has long been evidence that taste perception is influenced by food intake, just as there is some evidence that food intake may be influenced by taste sensitivity. Reports from the Iowa Women's Health Study, for instance, which has been run since the mid-1980s, showed that women who transitioned to a plant-based, lower-fat diet actually acquired, over a span of months, aversions to many of the processed and fast foods they liked at the start.

Over 20 years of clinical care, I have been through such transitions innumerable times with patients. One of the most straightforward involves milk. People who drink whole milk inevitably find that skim milk tastes a bit like dishwater. But if, in an effort to reduce intake of saturated fat, such people stick with skim milk for not more than two weeks, their taste adjusts to it.

In as little as a week, and almost never more than two, people habituate to skim milk. If they stick with it a bit longer, and then retry whole milk, suddenly whole milk feels like drinking wallpaper paste. There may be rare exceptions, but I have been through this with many patients -- both adults and children -- and the results are impressively consistent.

The same basic principle pertains to others foods. Familiarity is a potent driver of dietary preference; we tend to like what we're used to. We see this at the level of culture, where babies in Mexico learn to like spicy food, and Inuit babies learn to like seal. Genetically, we are all much more alike than different -- but culture changes what we find familiar.

In our own culture, we have simply grown familiar with ever more-processed, ever sweeter, ever saltier foods. I've had many personal encounters with this, but one anecdote stands out.

I had given a talk at a conference in California, and my wife and I were flying back home to Connecticut. We found ourselves at one of the hub airports in the middle of the country, hungry, and with the contents of our snack pack depleted. Looking for an option that satisfied our nutrition standards, we found a smoothie bar featuring images of fresh fruit, and with banner ads all about health. It looked perfect.

Catherine and I each ordered a smoothie, emphasizing the fresh fruits we wanted. We were handed two big cups, we each took one sip -- and then looked for a place to spit it out. It was sickeningly sweet. We literally couldn't swallow it, and each wound up throwing our smoothie away and staying hungry.

Now, I'm a bit of a nutrition fanatic -- so this anecdote could be all about that. But my wife is not. She eats well, too, of course, but is -- if anything -- a foodie, not the food police. If she could have stomached that smoothie, she sure would have done so. But it really was too sweet to swallow.

But only for us! Clearly, others could swallow it -- or that smoothie bar would long since have gone out of business. So, my wife and I were different. How?

It wasn't about being more virtuous. It wasn't about having more willpower. It was, clearly, about having taste buds that registered what most American taste buds did not -- a huge excess of sugar.

Now, the odds that my wife and I (I'm of Northern European stock, born in California; she's of Spanish ancestry, born in Algeria and raised in Southern France) both happen to have a genetic predisposition for highly sensitive taste buds are very long indeed! Far more likely is that our taste buds, exposed routinely to only moderate amounts of sugar in our healthful diets, remained sensitive to sugar. In contrast, most clients of that smoothie bar, eating a typical American diet, had apparently beaten their taste buds into something like a coma.

That, I believe, is what the new study is really about. Bathe taste buds all day long in sugar, salt, and chemicals -- and they become insensitive to them. Eat pasta sauces more concentrated in added sugar than ice cream topping (yes, really!), and lose your sensitivity to sugar. Eat breakfast cereals more concentrated in added sodium than potato chips or pretzels (yes, really!), lose your sensitivity to salt.

The good news is, this process can be fully reverse engineered. We could look at this study as an indication that innate taste preferences make obesity more or less likely. But we might instead choose to see the opportunity to make better food choices that help us stay lean, and like the taste of doing so.

Taste buds can be rehabilitated. The rehab isn't even all that difficult. You can, in fact, cut down on your sugar intake by choosing better pasta sauce and salad dressing. You can reduce your salt intake by choosing better breakfast cereal. The rest will follow. And overall, the potential health and weight benefits from trading up to more nutritious foods are nothing short of incredible.

Shifting steadily to more wholesome foods inevitably means reducing the time taste buds spend each day bathing in sugar, salt, and food chemicals. As a result, it almost certainly means greater taste sensitivity. When you become more sensitive to salt, you actually prefer less. The same is true for sugar. When you prefer food that is better for you, eating well is not a chore -- it's a preference.

I believe we can all get there from here.

Taste buds are, perhaps, easily led astray. But they are also resilient little fellas, and when they can't be with the foods they once loved, they pretty readily learn to love the foods they're with. So put yours in the company of foods that are better for you, and let your taste buds learn to love the foods that love you back.

-fin

Dr. David L. Katz; www.davidkatzmd.com
www.turnthetidefoundation.org

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