10/01/2019
Aaron CarrollI’m sure you’ve seen that everyone is screaming about red meat again. I’m going to save myself some time and point you to this Twitter thread I posted. Go read some stuff!
THREAD ON MEAT.
I'm sure you've heard by now that a bunch of studies was published last night on red meat. Their conclusion – the evidence for health risks is small and of low certainty. https://t.co/MefbjqsiyO (1/6)
— Aaron E. Carroll (@aaronecarroll) October 1, 2019
09/27/2018 Aaron CarrollWe’re once again talking about Brian Wasink, the Cornell Food and Brand Lab. They were in the news last year over a retracted study, and he’s back again with six more studies retracted. Nutrition research is hard. This is also not great for the public’s perception of science.
05/03/2018 Aaron CarrollThere was a big study on alcohol and life expectancy that was all over the news recently. It was pretty scary, and seemed to conclude that any alcohol use can shorten your life. Well, that study had a lot of problems. Let’s talk about it.
12/13/2017 Aaron CarrollNutrition research can be difficult, especially when kids, and Elmo, and careless research techniques ruin the outcome of the study. A study on kids’ nutritional choices was recently retracted because there were problems with the data collection. This happens a lot, and it isn’t doing science any favors.
11/28/2017 Aaron CarrollThe following originally appeared on The Upshot (copyright 2017, The New York Times Company) last week. I didn’t get it up because of Thanksgiving. Enjoy it now. You might also like my new book, The Bad Food Bible: How and Why to Eat Sinfully, which is available in stores!
In our house, there are no pictures of my wife and me that are more than a few years old.
When I was a medical resident, nearly two decades ago, I didn’t take very good care of myself. I was a pediatrician, and I counseled patients and parents all the time about how to eat right and get enough exercise. But I couldn’t seem to figure that out for myself. I gained a lot of weight, and so did my wife, Aimee.
After our second child was born, Aimee decided she needed to make a change. She told me she was going to try Weight Watchers. Since it seemed silly for us to prepare two meals at a time, I decided to join her.
It worked. Weight Watchers then was mostly focused on fat reduction, calorie counting and increased fiber. We both lost weight. I didn’t lose all that I wanted to, but it was certainly an improvement. Unfortunately, it was hard to keep sticking to the program. There were too many days I was hungry. I became too obsessed with “low fat,” as fat seemed to be how “points” were calculated. (Today, Weight Watchers points focus on calories, sugar, fat and protein.)
Years later, when I decided to try to lose weight again, I focused on exercise. I made it through the torments of P90X, P90X3 and Insanity. Each workout regimen had its own diet plan, with a list of foods to avoid. I stuck to none of them for more than four or five months. They were too hard, and after initial success, my weight loss stalled.
Most recently, I tried to go “low-carb.” I became convinced, by reading books and studies, that carbohydrates were the true danger, not fats. I eliminated sugar from my diet almost completely. Once again, my weight dropped, but it eventually stopped falling.
My experience is not abnormal. Studies of diets show that many of them succeed at first. But results slow, and often reverse over time. No one diet substantially outperforms another. The evidence does not favor any one greatly over any other.
That has not slowed experts from declaring otherwise. Doctors, weight-loss gurus, personal trainers and bloggers all push radically different opinions about what we should be eating, and why. We should eat the way cave men did. We should avoid gluten completely. We should eat only organic. No dairy. No fats. No meat. These different waves of advice push us in one direction, then another. More often than not, we end up right where we started, but with thinner wallets and thicker waistlines.
I’m a physician and researcher with a particular interest in analyzing dietary health research, and even I get dizzy with the different perspectives on something as seemingly simple as the benefits of brown rice or the dangers of red meat. This is one reason I’ve decided to focus much of my writing on dietary health. I want to be able to advise my patients about what healthful eating looks like, and eat that way myself.
These conflicting opinions about nutrition have one thing in common: the belief that some foods will kill you — or, at least, that those foods are why you’re not at the weight you’d like to be. This is an attitude about food that actually has its roots in an earlier and opposite idea — that some foods can keep us from dying (think of sailors avoiding scurvy by eating citrus). Indeed, some of the earliest “expert” advice about food was predicated on the notion that some foods can save us.
When many more Americans were malnourished than are today, making sure they got more of foods containing things like vitamin B and C made sense. Today, the vast majority of people in the United States are not suffering from vitamin or nutritional deficiencies. Advice is usually delivered in terms of deprivation, not supplementation.
Much of this advice comes in the form of moralizing. But by making so much of our focus on what we’re doing “wrong,” we’ve removed much of the joy from eating and cooking. I made sure to avoid negative tones a couple of years ago when I drew up a manifesto/road guide we called simple rules for healthy eating. They include the idea that you aren’t going to avoid all processed foods, but you might try to limit them. The one I felt most passionately about was No. 7 — “Eat with other people, especially people you care about, as often as possible.” But lately, I’ve been thinking that No. 2 — “Eat as much home-cooked food as possible” — may be the most important.
I’ve recently been learning more about cooking theory — not so much following recipes, but understanding why those recipes work. A favorite guide in this quest is “Salt, Fat, Acid, Heat” by Samin Nosrat. Right there in the title are two “forbidden” elements. They’re also some of the main reasons good food tastes good.
The home-cooked food rule probably did more than any other to help Aimee and me get down to reasonable weights. Today, we’re much happier with how we look and feel. There are pictures of us looking happy in recent years around the house. Thanksgiving has reclaimed its mantle as my favorite holiday, because it’s so centered on food and family.
And yet. While I’ve adopted a much healthier attitude toward food in general, I sometimes find myself slipping into old habits. These last few months, I’ve been trying to lose weight again. I’m not obese, and I’m healthy. But my weight and height place me in the “overweight” category, and I think I could be thinner. As before, I tried going low-carb. I lost weight initially, then hit a plateau. I’ve been getting frustrated.
I was complaining of this to Aimee last week when my oldest child, Jacob, asked me why I was dieting. He couldn’t understand the point. I had no answer. I don’t think it will make me healthier or make me live longer. It won’t improve my quality of life. I won’t be in better shape. My clothes would fit the same. I’m not even sure anyone would see a difference.
I’m still too liable to think that being thin is the same thing as being healthy. I’m still too inclined to think that dieting is the same as healthful eating. Neither are true. Too often I’m chasing some imagined ideal that has no real-world consequences. My other son, Noah, has my physique and may someday find it all too easy to put on pounds. What message am I sending to him when I obsess over the number on the scale?
Jacob’s wiser than me. I’m still learning. One theme of my Upshot articles is that we should weigh the benefits and the harms in any health decision. When it comes to food, too often we focus only on the latter. When my daughter, Sydney, made cupcakes last night and asked me to try one, I did. The joy it brought her, and me, was worth it.
11/12/2017 Aaron CarrollThe following originally appeared on The Upshot (copyright 2017, The New York Times Company). It was also adapted from my new book, The Bad Food Bible: How and Why to Eat Sinfully, which is now available in stores!
The headline had some of my friends in a panic.
Citing evidence, the American Society of Clinical Oncology warned that even light drinking could increase the risk of cancer.
Once again, we’ve been told that something we eat or drink is going to kill us. Once again, we’re provided an opportunity: A more nuanced discussion of risk — and how we communicate it — can leave us much happier, and perhaps healthier.
Let’s begin with the fact that it’s easy to use studies to talk about cancer. Nothing illustrates this better than the classic 2013 study that examined research on 40 common ingredients selected from an ordinary cookbook. Researchers found 264 different studies touching on at least one of those ingredients. Their conclusion? Depending where you look, you can find evidence that says that nearly everything we eat is both associated with higher rates of cancer and lower rates of cancer.
The gist of the oncology society announcement is that there is a reasonable amount of evidence finding an association between some cancers (specifically oropharyngeal and larynx cancer, esophageal cancer, hepatocellular carcinoma, breast cancer and colon cancer) and alcohol. It acknowledges that the greatest risks are with those who drink heavily, but it cautions that even modest drinking may increase the risk of cancer. In the United States, the announcement also notes, 3.5 percent of cancer deaths are attributable to alcohol.
Of course, this means that 96.5 percent of cancer deaths are not attributable to alcohol. If we eliminate heavy drinking, which no one endorses as healthy and where the association is surest, that number climbs. If we also eliminate those who smoke — smoking is believed to intensify the relationship between alcohol and cancer — the number of cancer deaths not attributable to alcohol approaches 100 percent.
Let’s stipulate that there may be a correlation between light or moderate drinking and some cancers. We still don’t know if the relationship is causal, but let’s accept that there’s at least an association. For breast cancer — which is the cancer that seems to be garnering the most headlines — light drinking was associated with a relative risk of 1.04 in the announcement. Relative risk refers to the percentage change in one’s absolute (overall) risk as a result of some change in behavior. (And 1.04 is a 4 percent change from 1.0, which represents a baseline of no difference in risk between an experimental group and a control group.)
A 40-year-old woman has an absolute risk of 1.45 percent of developing breast cancer in the next 10 years. This announcement would argue that if she’s a light drinker, that risk would become 1.51 percent. This is an absolute risk increase of 0.06 percent. Using what’s known as the Number Needed to Harm, this could be interpreted such that if 1,667 40-year-old women became light drinkers, one additional person might develop breast cancer. The other 1,666 would see no difference.
Of course, moderate or heavy drinking might increase the risks further. The absolute risks for that 40-year-old would go to 1.78 percent from 1.45 percent for the moderate drinker, and to 2.33 percent for the heavy drinker. Those numbers are still not that scary.
But maybe any increase in risk is too much for you. That’s fine. If you’re one of those people, though, you have to acknowledge that you can’t look at any one cancer in a vacuum. A person can get almost any cancer.
The large meta-analysis upon which this announcement was based looked at 23 types of cancer with respect to alcohol consumption. It found a harmful relationship between three of them and light drinking. But it also found protective relationships — meaning a decreased risk of cancer — between six of them and light drinking.
I’m not arguing that you should engage in light drinking to avoid those six cancers. I’m merely pointing out that cherry-picking allows you to come to different conclusions. With respect to moderate drinking, there were harmful relationships with seven cancers and protective relationships with three. The announcement focused on the former, not the latter.
A 2013 meta-analysis in the Annals of Oncology that looked at all cancers found that, over all, light drinking was protective; moderate drinking had no effect; and heavy drinking was detrimental.
It’s even cherry-picking to focus only on cancer, though. A person can get any number of diseases, and this fact makes the dangers of light and moderate drinking even muddier.
If you accept the methodology of case-control and cohort studies, from which many of the links between alcohol and cancer arise, you have to accept the results of similar studies of other diseases. For instance, a cohort study of about 6,000 people found that those who drank at least once a week had better cognitive function in middle age than those who didn’t. A 2004 systematic review found that moderate drinkers had lower rates of diabetes (up to 56 percent lower, although that’s a relative risk reduction).
Randomized controlled trials of alcohol (they do exist) show that light to moderate drinking can lead to a reduction in risk factors for heart disease, diabetes and stroke. These protective factors may be greater than all the other negative risk factors (even cancer) that might be associated with light or moderate drinking. More women die in the United States of heart disease than cancer. So do more men.
Moreover, dire warnings have consequences. I know far too many people who now throw up their hands at every news story because it seems as if “everything” causes cancer. These stories rarely acknowledge an alternative point of view. The absolute risks of light and moderate drinking are small, while many people derive pleasure from the occasional cocktail or glass of wine. It’s perfectly reasonable even if a risk exists — and the overall risk is debatable — to decide that the quality of life gained from that drink is greater than the potential harms it entails.
This is true for many, many foods, not just alcohol.
What can we do about this? We could make simple changes to have a better understanding of risk so that each new proclamation doesn’t send us into a tizzy:
1) Consider the absolute risks. A 30 percent increase in risk sounds scary, but an increase from 1 percent to 1.3 percent absolute risk does not, though these are the same things. Likewise, we should be more concerned about a 5 percent risk increase to 21 percent from 20 percent than about a 30 percent increase to 1.3 percent from 1 percent.
2) Don’t give too much weight to observational data. This is especially true when causal data are available.
3) Don’t focus on any one disease while ignoring others. Something may be harmful regarding one disease while beneficial regarding another.
4) Don’t cherry-pick. That is, don’t focus only on some studies, or only on some results. Review all the evidence for the most holistic picture possible.
5) Acknowledge the harms, as well as the benefits, of recommendations. Consider both cost and joy.
These rules may not make for exciting headlines. They may, however, lead to happier, and perhaps healthier, lives.
11/09/2017 Aaron CarrollThere’s a lot of news this week touting a study that suggests exercise is the key to maintaining a weight loss. Welp. Guess what? It wasn’t a great study. There were 14 participants, all of whom appeared on the TV reality show The Biggest Loser. We’ve talked before about the weight loss practices on that show, and how they aren’t really reproducible in real life. Here we go again.
Want better balanced information about nutrition? Go buy my book!!!!
10/31/2017 Aaron CarrollI’m trying to keep the number of posts I write about this to a minimum, but the publication date for my new book is a week away. The Bad Food Bible: How and Why to Eat Sinfully will be released on November 7. It grew out of some of my columns over at the Upshot about food (which also happen to be some of my most popular).
Preorders matter because they all count towards first week sales, and I’m told that’s important. So if you’re considering picking up a copy (and why wouldn’t you?), please consider buying one now from any of these sellers:
Thanks!
10/25/2017 Aaron CarrollThe following originally appeared on The Upshot (copyright 2017, The New York Times Company).
Changing your diet is hard. So is helping our children make healthy choices. When a solution comes along that seems simple and gets everyone to eat better, we all want to believe it works.
That’s one reason a study by Cornell researchers got a lot of attention in 2012. It reported that you could induce more 8-to-11-year-olds to choose an apple over cookies if you just put a sticker of a popular character on it. That and similar work helped burnish the career of the lead author, Brian Wansink, director of the Cornell Food and Brand Lab.
Unfortunately, we now know the 2012 study actually underscores a maxim: Nutrition research is rarely simple.
Last week the study, which was published in a prestigious medical journal, JAMA Pediatrics, was formally retracted, and doubts have been cast about other papers involving Mr. Wansink.
When first published, the study seemed like an enticing example of behavioral economics, nudging children to make better choices.
Before the study period, about 20 percent of the children chose an apple, and 80 percent the cookie. But when researchers put an Elmo sticker on the apple, more than a third chose it. That’s a significant result, and from a cheap, easily replicated intervention.
While the intervention seems simple, any study like this is anything but. For many reasons, doing research in nutrition is very, very hard.
First, the researchers have to fund their work, which can take years. Then the work has to be vetted and approved by an Institutional Review Board, which safeguards subjects from potential harm. I.R.B.s are especially vigilant when studies involve children, a vulnerable group. Even if the research is of minimal risk, this process can take months.
Then there’s getting permission from schools to do the work. As you can imagine, many are resistant to allowing research on their premises. Often, protocols and rules require getting permission from parents to allow their children to be part of studies. If parents (understandably) refuse, figuring out how to do the work without involving some children can be tricky.
Finally, many methodological decisions come into play. Let’s imagine that we want to do a simple test of cookies versus apples, plus or minus stickers — as this study did. It’s possible that children eat different things on different days, so we need to make sure that we test them on multiple days of the week. It’s possible that they might change their behavior once, but then go back to their old ways, so we need to test responses over time.
It’s possible that handing out the cookie or apple personally might change behavior more than just leaving the choices out for display. If that’s the case, we need to stay hidden and observe unobtrusively. This matters because in the real world it’s probably not feasible to have someone handing out these foods in schools, and we need the methods to mirror what will most likely happen later. It’s also possible that the choices might differ based on whether children can take both the apple and the cookie (in which case they could get the sticker and the treat) or whether they had to choose one.
I point out all these things to reinforce that this type of research isn’t as simple as many might initially think. Without addressing these questions, and more, the work may be flawed or not easily generalized.
These difficulties are some of the reasons so much research on food and nutrition is done with animals, like mice. We don’t need to worry as much about I.R.B.s or getting a school on board. We don’t have to worry about mice noticing who’s recording data. And we can control what they’re offered to eat, every meal of every day. But the same things that make animal studies so much easier to perform also make them much less meaningful. Human eating and nutrition are typically more complex than anything a mouse would encounter.
Overcoming these problems and proving spectacular results in preteens are some of the reasons this study on cookies and apples, and others like it, are so compelling. The authors have transformed this work into popular appearances, books and publicity for the Food and Brand Lab.
But cracks began to appear in Mr. Wansink’s and the Food and Brand Lab’s work not long ago, when other researchers noted discrepancies in some of his studies. The numbers didn’t add up; odd things appeared in the data, including the study on apples and cookies. The issues were significant enough that JAMA Pediatrics retracted the original article, and the researchers posted a replacement.
The problems didn’t end there. As Stephanie Lee at BuzzFeed recently reported, it appears that the study wasn’t conducted on 8-to-11-year-olds as published. It was done on 3-to-5-year-olds.
Just as mice can’t be easily extrapolated to humans, research done on 3-to-5-year-olds doesn’t necessarily generalize to 8-to-11-year-olds. Putting an Elmo sticker on an apple for a small child might matter, but that doesn’t mean it will for a fifth grader. On Friday, the study was fully retracted.
Making things worse, this may have happened in other publications. Ms. Lee has also reported on a study published in Preventive Medicine in 2012 that claimed that children are more likely to eat vegetables if you give them a “cool” name, like “X-ray Vision Carrots.” That study, too, may be retracted or corrected, along with a host of others.
As a researcher, and one who works with children, I find it hard to understand how you could do a study of 3-to-5-year-olds, analyze the data, write it up and then somehow forget and imagine it happened with 8-to-11-year-olds. The grant application would have required detail on the study subjects, as well as justification for the age ranges. The I.R.B. would require researchers to be specific about the ages of the children studied.
I reached out to the authors of the study to ask how this could have happened, and Mr. Wansink replied: “The explanation for mislabeling of the age groups in the study is both simple and embarrassing. I was not present for the 2008 data collection, and when I later wrote the paper I wrongly inferred that these children must have been the typical age range of elementary students we usually study. Instead, I discovered that while the data was indeed collected in elementary schools, it was actually collected at Head Start day cares that happened to meet in those elementary schools.”
This is a level of disconnect that many scientists would find inconceivable, and I do not mean to suggest that this is the norm for nutrition research. It does, however, illustrate how an inattention to detail can derail what might be promising work. The difficulties of research in this area are already significant. Distrust makes things worse. The social sciences are already suffering from a replication problem; when work that makes a big splash fails to hold up, it hurts science in general.
We want to believe there are easy fixes to the obesity epidemic and nutrition in general. We want to believe there are simple actions we can take, like putting labels on menus, or stickers on food, or jazzing up the names of vegetables. Sadly, all of that may not work, regardless of what advocates say. When nutrition solutions sound too good to be true, there’s a good chance they are.
10/03/2017 Aaron CarrollSome of our most popular HCT episodes have been about food. Or, rather, they’ve been about the science and research behind food, and the recommendations groups make about what you should, or shouldn’t eat. Good news! I’ve got a book on that topic coming out November 7. It’s called The Bad Food Bible: How and Why to Eat Sinfully. You can preorder it right now, and it’s also the topic of this week’s Healthcare Triage.
You can preorder the book at any of the below:
It goes without saying that I would love for you to buy it. Preorder it so you are assured to have it on the day of publication!
