Kamis, 15 Mei 2014

Nutrition Confusion!

by Nina and Brad
Still Life with Apples, Meat and a Roll by Vincent van Gogh
One of the most important decisions we make each day to foster healthy aging is deciding what to eat. But what if our ideas about which foods are healthy (and which are not) are misguided? What if some of the advice we’ve been receiving from our doctors for the last 50 years is actually wrong?

I’ve already written a post for this blog Healthy Diets for Healthy Aging, in which I discussed why the field of nutrition is so confusing. But a few days ago Brad read me an article from the Wall Street Journal The Questionable Link Between Saturated Fat and Heart Disease that kind of blew my mind. In this article, Nina Teicholz, who has been researching dietary fat and disease for nearly a decade (and whose book The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet will be published by Simon & Schuster on May 13) claimed that the "very cornerstone of dietary advice for generations has been that the saturated fats in butter, cheese and red meat should be avoided because they clog our arteries" was based on theory that has never actually been proven. She wrote:

“The fact is, there has never been solid evidence for the idea that these fats cause disease. We only believe this to be the case because nutrition policy has been derailed over the past half-century by a mixture of personal ambition, bad science, politics and bias.”

She says that our distrust of saturated fat can be traced back to the 1950s to the work of  scientist named Ancel Benjamin Keys, whose research was flawed but who relentlessly (and successfully) championed the idea that saturated fats raise cholesterol and, as a result, cause heart attacks. She concludes by saying,  “More than a billion dollars have been spent trying to prove Ancel Keys's hypothesis, but evidence of its benefits has never been produced. It is time to put the saturated-fat hypothesis to bed and to move on to test other possible culprits for our nation's health woes.”

She goes on to speculate that our increased intake of carbohydrates (even fruit!) as well as food fried in vegetable oil could be the real villains, leading to increased obesity rates and other health problems. While I’ve spent some time explaining why we’re not going to be giving dietary advice on this blog (see Healthy Diets for Healthy Aging), I decided to ask Brad to comment on this article in case some of you out there had read it (or related articles) and were feeling as confused as I am.

NINA: You read this article to me, so what do you make of it? 

BRAD: Of course, we couldn’t help but notice that the author of the article has a forthcoming book. So, as with most authors on these topics, some bias is almost certain to exist to make the story more sensational, so one always has to keep that in mind. That said, the article was fascinating in its take on saturated fats and heart disease.  It made me consider why I generally push to the side of the plate some of the fat on a side of pork belly—the very few times I even eat it at all anymore. Or the guilty pleasure at eating bacon, knowing it’s “bad for me” but that it tastes so good. Or looking for the low-fat milk for on cereal (I won’t go near non-fat milk as it simply tastes awful).  However, I have pretty much forgone eating muffins, scones and donuts—which still appear to be villains in this new take on healthy and unhealthy foods.  As a scientist, I, of course, love to see doctrine upturned, especially when it's based on a lot of poorly constructed experiments with too many underlying assumptions, which both appear to have been in full play in the nutritional epidemiology studies such as the ones described in this article.

NINA: What do you think we should make of this analysis?  And how should we incorporate it into our thinking about a healthy diet?

BRAD: The question is: is this analysis to be believed, or somehow put in the space with all those other studies that seem to pop up with greater regularity—such as too much protein in your diet can cause cancer? That also reminds me that the author did not really consider cancer, neurodegeneration,  gastrointestinal diseases, and other things that are associated with aging in her analysis. I guess it confirms what I suspected all along, that we know surprisingly little about how diet really effects our health, particularly when our basic nutritional needs are being met. So, when I next confront a hamburger on my plate, do I take off the bun, eat the patty only, leave off the cheese, or add extra raw (or grilled) onions? Or do I just eat it with all the trimmings (and medium rare—the way I like it), and remind myself that I probably shouldn’t be eating mammals all that often (you know, for all the obvious and very real ethical and environmental concerns), and make sure my next meal is mostly vegetables (and not deep fried)...

NINA: Ack!


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