Study links diet to longevity, but with confusing findings

By Jennifer LaRue Huget

(File photo)

What you eat might well determine how long you live.

But it's not exactly clear what the optimal diet should be.

In a study published in the January 2011 edition of theJournal of the American Dietetic Association, researchers found that among 2,500 adults ages 70 to 79, those who maintained a diet consisting largely of foods deemed "healthy" were less likely to die and more likely to remain healthy than those whose diets included more of less-healthful foods during the 10-year period examined.

Researchers divvied the study subjects into six groups according to their predominant food choices among 108 food items tallied. Here's how the clusters fell out:

• "Healthy foods" (374 participants)
• "High-fat dairy products" (332)
• "Meat, fried foods, and alcohol" (693)
• "Breakfast cereal" (386)
• "Refined grains" (458)
• "Sweets and desserts" (339)

That "healthy foods" category was defined by relatively higher consumption of low-fat dairy, fruit, whole grains, poultry, fish and vegetables and lower intake of meat, fried foods, sweets, high-calorie beverages and added fat.

After all kinds of controls were applied to rule out the effects of gender, age, physical activity, smoking, race, total calorie intake and other variables, the numbers showed that the "high-fat dairy products" group had a 40 percent higher risk of mortality than the "health foods" group and that the "sweets and desserts" group had a 37 percent higher risk than the "healthy foods" group.

The study concludes:

A dietary pattern consistent with current guidelines to consume relatively high amounts of vegetables, fruit, whole grains, poultry, fish and low-fat dairy products may be associated with superior nutritional status, quality of life and survival in older adults.

But what to make of that "meat, fried foods and alcohol" group -- the one that you might notice is nearly twice the size of the "healthy foods" group? That group's not even mentioned in the news release (the study is not yet posted online) -- despite the fact that, when the numbers were crunched, that group's mortality risk was about the same as that of the healthy-eating group.

The study notes:

Unexpectedly, in this and several other studies, a pattern higher in red meat was not significantly associated with increased risk of mortality when controlled for relevant confounding factors. One suggested explanation is that plant-based diets may lower health risk because plant foods are protective, whereas diets high in animal foods may be more likely to increase risk only if the animal foods displace protective plant foods in the diet.

The study's lead author, Amy Anderson of the University of Maryland department of nutrition and food science, was good enough to make herself available to talk on the phone over the holiday weekend and tried to help me sort things out. I couldn't understand why the meat/fried food/alcohol group's relative good health wasn't singled out as helping keep folks alive longer, leaving all the credit to the "healthy foods" group.

Anderson followed up with an e-mail reviewing what she'd told me on the phone:

As mentioned on the phone, while we can't give definite reasons for our results, Table 1 in the paper [which shows percentage of total energy intake from selected food groups each cluster's diet] may provide some ideas for why the "meat, fried foods and alcohol" group didn't have a statistically significantly higher risk of mortality than the "healthy foods" group after controlling for many variables including education, physical activity, and smoking -- in other words, these other variables being equal. As Table 1 shows, the name of the "meat, fried foods and alcohol" group may be a bit misleading, because this group had a more similar diet to the "healthy foods" group than some of the others. We named the groups according to foods that people ate relatively more of in comparison to the other groups. The "meat, fried foods and alcohol" group ate on average about 4 percent of calories from meat, while the "healthy foods" group ate on average about 2.8 percent of calories from meat. The differences in fried food and alcohol intake between the "meat, fried foods and alcohol" group and the "healthy foods" group were also about 1 to 3 percent. In contrast, the "sweets and desserts" group ate on average about 25.8 percent of calories from sweets, while the "healthy foods" group ate on average about 6 percent of calories from sweets -- a difference of almost 20 percent in this food group. The "high-fat dairy products" group ate about 17.1 percent of calories from high fat dairy products, while the "healthy foods" group ate about 3.4 percent of calories from high fat dairy products -- a difference of almost 14 percent in this food group. In other words, it is not as though the "meat, fried foods and alcohol" group within this study population of 70-79 year-olds ate enormous quantities of these foods, just slightly more on average than the other groups. The "sweets and desserts" and "high-fat dairy products" groups, on the other hand, showed some more stark differences from the "healthy foods" group in their diets.

I appreciate Anderson's taking pains to help me with this. But the cynic in me has to wonder whether the finding that people who eat a bit more meat, fried food and alcohol manage to do all right, mortality-wise, may have been too out of whack with current dietary recommendations for comfort. Especially as the new Dietary Guidelines for Americans 2010, which are likely to promote consumption of whole grains and other plant-based foods, are about to be issued, I hope researchers will keep at it and tease this confusing situation out further.

Because if it really is okay to eat meat and fried food and enjoy alcohol after all, people should know about it.

Comments

The Longevity diet: The missing link is blood sugar. Blood sugar is the cause of aging,Diabetes,Obesity,Alzheimers..etc
(you do not have to be a diabetic to have this problem)

A popular diabetes diet in Europe was shown to reverse aging markers as the diabetes drug caused faster ageing and heart trouble. See herehttp://spirithappy.wordpress.com/2010/12/01/the-first-drug-they-give-you-to-heal-type-2-diabetes-hurts-your-cells/

Unfortunately billions of dollars are invested into diabetes and obesity drug makers so the public will never get this information

Posted by: healing1 | December 28, 2010 10:46 AM | Report abuse

It sounds to me as if the "cynic" in this article's author is looking for someone to give her the green light to consume as much meat, fried food and alcohol as she wants. I thought the study's lead author explained the findings quite well. It's basically "moderation in all things." Many studies show moderate consumption of alcohol can be a good thing. Same goes for meat, especially moderate consumption of lean meat and fish, and fried foods, as long as they are fried in good oils. I'm not aware of any scientist who claims consuming REAL servings of any of these things, while making whole grains, vegetables and fruit the bulk of your diet ever hurt anyone. The problems start when people super-size such foods to the exclusion of whole grains, fruit and veggies.

Posted by: lolly312 | December 28, 2010 1:17 PM | Report abuse

I'm going to use this study the next time I teach an advanced statistics course, as an example of 1) how to do things right, and 2) when you do things right, people who are not statistically literate (such as the writer here) will have a hard time, even when it is clearly explained (as it was -- to someone who knew statistics).

The basic methodology of the study was a clustering algorithm. That's a procedure which produces groupings based on minimizing differences within each group, and maximizing differences between groups. Clustering does not produce evenly spaced groups, because the world isn't evenly spaced; if you pulled a sample from Manhattan, Brooklyn, Philadelphia, San Francisco, and Tokyo, and grouped by physical location, two of the groups would be very close together, and a third one would not be far away from the two close ones. If you then tried to study weather with respect to physical location, you would discover that the close-together groupings didn't show much difference. That is what happened here. The meat/fried/alcohol group generally ate a healthy diet; they happened to indulge in some probably-not-healthy other stuff, but not very much of it. Differences were in the range of 1-3% (as differences between the location of Manhattan and Brooklyn are quite small plotted on the scale of the continent). Unsurprisingly, results in longevity were somewhere within the margin of error. (Just as the number of days it snows in Manhattan but not in Brooklyn are few and insignificant).

What the study says in terms of action is: eat a mostly healthy diet. There's not much difference between mostly healthy and perfectly healthy.

The writer was pushing for "so these other foods are okay." The study shows only that they don't seem to make a statistical difference in result, if the difference isn't very great in consumption. Apparently steak-and-eggs-with-a-beer consumers don't have that very often, and mostly eat like the healthy people, so it's not surprising they differ very little. Just as apparently, people who live on milkshakes really live on milkshakes, and pay the arterial consequences.

"Study shows two patterns of healthy eating and two patterns of unhealthy eating are common in general population" isn't much of a headline, but it's what this study shows. Period. Have a pork chop with your salad, and a glass of wine, now and then, if you like. This doesn't mean you can live on pork chops and wine.

And never talk to a reporter who has not, at least at one point in life, derived the Gaussian distribution from the limit of the binomial distribution.

Posted by: PasserThru | December 28, 2010 1:34 PM | Report abuse

Kind of hard to draw any conclusions from the study if the 'groupings' were not significantly different in their diets. To her credit, the scientist did explain that.

Unfortunately, these types of poorly constructed studies are often used by people and companies to push positions that the preponderance of science finds false. Confusion is the enemy of good advice, the friend of those who seek to deceive (or be deceived)

Posted by: mgferrebee | December 28, 2010 1:47 PM | Report abuse

The study author's explanation for the lack of a deleterious effect of eating meat is clearly and convincingly stated. It is very interesting that the meat group got only four percent of their calories from meat. I have contended for a long time that even meat eaters eat far more vegetables than even they realize. Now if they could just cut it all out . . .

Posted by: aspenhallinn | December 28, 2010 1:50 PM | Report abuse

Doesn't anyone ask about the quantities eaten? Not calories--quantity.

Posted by: joan10 | December 28, 2010 2:43 PM | Report abuse

Perhaps it's the writer's interpretation of this finding'...people who eat a bit more meat, fried food and alcohol manage to do all right, mortality-wise...'
that needs enlightenment.
A healthy lifestyle, with or without red meat, et al, means that you don't abuse any one food group.
If balance is the key to good living, surely a good steak, few glasses of wine and yummy desert every now and then won't hurt one's health as long as one has his/her health in sight at all times.
So have that juicy steak and enjoy
your workout the next day, too!

Posted by: writersMAMA | December 28, 2010 3:08 PM | Report abuse

Let me assure all readers, there is no confusion in this study!
My credits: Discoverer of the cause of obesity, the disease which leaves a trail of others in its wake. I condemned the pyramid food guide after one glance in 1992. Not a studied reaction but an instinctive,immediate revulsion predicting the epidemic obesity future.
I had survived 7 years, 1939-1946 (WWII)deprived of food, starvation, but escaped with a food regimen which has left me---I will be 86 on Jan. 7th--- in superior health.
I will not divulge the obesity code, I am waiting to sign a large organization to handle the recovery campaign.
That said---I will leave a hint; you are a misguided lot, greens and grains have promoted obesity ( I call it carbohydritis),you will be requested to abandon food guides and diets! You will become reacquainted with your inner ego, the gut. Needless to say, I have promoted red meat and saturated fat for ages. Why? It allows me to be well fed in small portions!
Send a BD card the address in hartsmartliving.com
Why am I so well? I have an attitude! Does it show?

------------Hart---------

Posted by: hart0007 | December 28, 2010 5:15 PM | Report abuse

The main problem I see is that the researchers went into the study with a deeply ingrained hypothesis on what "healthy" eating meant. They even named of one of the categories they were supposedly studying "healthy foods"! Then, when they found another category that showed similar results in health and longevity, they did not adjust their reporting accordingly.

The fact that one of their categories was named qualitatively (e.g. healthy) rather than descriptively (e.g. high-fat dairy) shows their pre-experimental bias, and they continued to report their findings within these preconceived expectations. They highlighted that the "healthy foods" consumers lived longer, but chose not to highlight that the "meat, fried foods, and alchohol" group ALSO lived longer, This displays the pre-analysis bias they began the study with and could not fully shake when publishing their findings.

Kudos to Jennifer LaRue Huget for calling them on this. Science is all about re-evaluating preconceived ideas when experimental data does not match the hypothesis. Without this, there would be no advance in scientific understanding. 

Posted by: kcastro22 | December 28, 2010 5:41 PM | Report abuse

And what about people who just plain don't tell the truth about what they "REALLY" eat anyway?? If some so called dietetic groupie stopped me and asked what I ate, I would be tempted to tell her only the healthy things eaten, and not mention the See's Truffles I just consumed..........just like when men are asked how often they do stuff, lol. And so it goes, nothing really is new, is it?? Yet reams are written to support a group's existance to get research grants.

Posted by: kuchen | December 28, 2010 9:26 PM | Report abuse

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