Pretty much whenever a study is titled,
“Does X food cause Y problem(s)”
I click the study and use the browser’s search function for “BMI”.
I’m not even going to read a study like that if it didn’t control for something such as obesity.
–
Suppose you want to see if drinking soda negatively impacts health. Anybody not in the dementia ward can tell you a lot of soda drinkers are obese. The fact drinking soda can lead to obesity, while relevant, is often not the question being asked. Obviously, if soda can lead to obesity, and obesity can lead to innumerable health consequences, then soda can lead to innumerable health consequences.
-> We call this the transitive property. Which is not always so straightforward. Check out non-transitive dice if you enjoy laboring in confusion.
We also know many soda drinkers are poor. Obviously, being poor causes health problems. (It’s about the worst thing you can do, or have done, to your body.) While soda may not cause being poor, if they’re associated, that adds to your quandary.
The question is, all else being equal, does drinking soda harm your health?
You know, you’re a well to-do person, who likes to drink one or two cokes a day; some orange juice at breakfast once in a while, should you be concerned relative to your dopplerganger, who drinks nothing so sugary?
–Association of Sugary Beverage Consumption With Mortality Risk in US Adults
What the study did
- Enrolled over 13,000 people. Over 1,000 of them died during the 6 year follow up (sad! but helpful)
- As I will always belabor this point, when we do exercise science research, we’re supposed to be happy with 30-40
male college studentssubjects studied for 8 weeks. When we do cardiovascular research, we get over 10,000 people for 6 years. Yet somehow the exercise science people have “adequately powered” their studies. Hey, whatever helps you sleep at night.- The authors actually cite the “short” follow-up and “small” number of deaths as limitations of this study!
- As I will always belabor this point, when we do exercise science research, we’re supposed to be happy with 30-40
- Looked at all your typical sugary beverages. You know, soda and fruit juices. 100% fruit juice was included.
- Parents may be more interested now
- Looked at people 45 years and up i.e. people more likely to die
- Took a whole bunch of measures to properly control the study
- Tried to screen out anybody taking preventative dietary measures e.g. you already know you have heart issues so you make changes
- They used 4 different models
- 1: unadjusted
- 2: controlled for demographic characteristics and high-risk practices (race, age at baseline, sex, education, smoking, and alcohol consumption)
- 3: also body mass index
- 4: also dietary factors (saturated fat and fiber consumption) and physical activity
- Used a questionnaire for drink consumption
- We were doing great until now. This sucks. Asking people to tell you what they’ve eaten is clearly not ideal. But, I will say, when it comes to asking people what they drink, in particular with sugary drinks, I’m not as concerned as asking people to remember foods. We tend to consume what we drink fairly regularly, and not lie about it much, I think.
- Used drink consumption as a percentage of total calorie energy intake, which was also assessed with a questionnaire
- We’ve gone from sucks some to sucks fully. In order to get the percentage, we’re basing it off of people’s answers of their total energy intake. Asking people what they drink? Not terrible. Asking what they eat? Awful. You automatically have to take any results of a such a study with a HUGE grain of salt.
- The authors were well aware of this. All researchers are. All human beings are. Yet the researchers keep doing it.
- This can (probably) be mitigated (somewhat) by adjusting for BMI(?)
- Not to mention, people were also asked, say, “how active are you?” to adjust for physical activity
- Honestly, I tend to not even read studies that do self-reported questionnaires anymore either. If you stop reading here and start playing video games, you’re probably smarter than me.
- We’ve gone from sucks some to sucks fully. In order to get the percentage, we’re basing it off of people’s answers of their total energy intake. Asking people what they drink? Not terrible. Asking what they eat? Awful. You automatically have to take any results of a such a study with a HUGE grain of salt.
- The primary question was how much is sugary drink consumption, as a percentage of total energy intake, associated with coronary heart disease or all cause mortality
- We will focus on all-cause mortality. Basically how much is drinking sugar associated with killing you?
Here is more about the subjects
What the study found
This is of course going to be the headlines, and the study’s conclusion,
So drinking more sugar gives a greater risk of dying. Don’t think anybody is surprised by that general takeaway.
BUT, what about our covariates? The variables we controlled for? BMI, physical activity?
“These results were attenuated with the stepwise addition of covariates”
As they went from model 1 to model 4, the death risk went down. As a reminder, our models,
- 1: unadjusted
- 2: controlled for demographic characteristics and high-risk practices (race, age at baseline, sex, education, smoking, and alcohol consumption)
- 3: also body mass index
- 4: also dietary factors (saturated fat and fiber consumption) and physical activity
Here’s how they phrase it,
“In the fully adjusted model 4, comparing high with low sugary beverage consumers, the adjusted HR of CHD-mortality was 1.44 and of all-cause mortality was 1.14”
HR = hazard ratio. Basically, if it’s above 1, you have a greater risk of death, as 1 is the reference group (essentially non-sugary drinkers). So HR = 2 would be you have twice the likelihood of death.
In chart form,
You see as they adjusted for more variables, the hazard ratios come down.
But wait a second. Why are there some numbers UNDER 1? Here:
That would mean once you adjust for demographics, never mind body size or physical activity, when people drank a moderate amount of sugary beverages, they had LESS risk of death than those drinking ~no sugar!
-> Note how adjusting for more than demographics had much less, if not zero, subsequent impact. You want to have the biggest impact on people’s health? Make poor people not poor.
For context, if you eat 2-3,000 calories a day, 5-10% of your diet would be a Coke or two a day.
The authors don’t mention this anywhere. They merely conclude,
“The findings of this study suggest that higher consumption of sugary beverages, including fruit juices, among older adults is associated with increased all-cause mortality.”
An awfully convenient, lazy, conclusion. They go through this diligent process of trying to control for everything they can think of, have access to 13,000 people enrolled for years, then say that.
What’s higher mean? For what people? Suddenly irrelevant in the conclusion. Which they know 99% of people will only ever read or discuss.
-> Yes, yes, I get it. Journalists want headlines. Researchers need exciting takeaways. I know. It’s not an easy balance. But this has to get better.
I mean, they clearly know it’s not that simple,
“Our finding showing an attenuation of the association with the addition of [total energy] consumption to the models suggests that the association of sugary beverage consumption with mortality that we observed may, at least in part, be because of an increase in [total energy] consumption when these beverages are consumed.”
In other words, they’re not even sure if it’s the sugary drink, or the extra calorie consumption!
Bolding mine,
“In conclusion, the results of this study suggest that higher consumption of sugary beverages, including sugar-sweetened sodas, soft drinks, and fruit drinks as well as naturally sweet fruit juices, is associated with increased all-cause mortality among older, LIKELY POOR, OUT OF SHAPE, OBESE, SMOKING, DRINKS MORE THAN THREE SUGARED DRINKS PER DAY, US adults.
IF YOU’RE WEALTHY AND HEALTHY, YOU MIGHT ACTUALLY LIVE LONGER BY DRINKING SOME SODA AND OR JUICE.
¯\_(ツ)_/¯”
–
This is a great illustration of not focusing on minutia with your health. Like if you’re obese and a smoker, should your primary care doctor really be focusing on whether you drink orange juice? 100% juice or not?
-> Let’s be real. The only question that matters is pulp (barbaric) or no pulp (you care about human decency).
Because we’ve gone through thousands of words, years of time, hundreds of thousands (if not millions) of dollars, to say being
- poor
- a smoker
- obese
- sedentary
- an alcoholic
- a consumer of more than 10% of your calories through sugared water
is bad.
While drinking a cup of sugared water, once or twice a day, is (based on a questionnaire study where we have no clue how much people actually consumed) little, if not nothing, to worry about.
Primarily because, for most people, drinking a little sugar will not lead to being poor, or smoking, etc. Conversely, going from a little sugar to no sugar, will not lead to being rich, not smoking, etc.
You probably already knew that. And if you were worried about one or two hundred calories of liquid sugar a day to begin with, it might be time to make life a little more exciting.
Posted on June 10, 2019