Margarine causes divorce!

My last post was about how easy it is to become confused about nutrition.  In that post, I cautioned that we have to careful about believing headlines, and also to be careful when an article says something is associated with something else.  I thought I would delve into that content a bit deeper.  See the headline above (the title of this post.)  Certainly sounds crazy and hard to believe, but follow along and see how reporting on a study, not unlike the typical reporting on the latest nutrition-related study, can be misleading.

Margarine Linked to Divorce, recent study reveals

Researchers at Big University of Maine (BUM) were out to discover the reason for the 18% decline in divorce rate that has occurred over the past 10 years and made a startling discovery.  Trying to find any cause for this decline, they turned to dietary habits and examined USDA data on per capita margarine consumption in the United States.  What they found was a strong association between the use of margarine and the divorce rate in Maine. The decline in margarine consumption they found correlated very strongly with the decline in divorce.
When asked about their groundbreaking research the authors of the study commented; "This study appears indicate that if we limit our consumption of margarine it will lead to better marital relationships and thus a reduction in the divorce rate."  If these findings prove to be correct, it indeed seems possible to reduce divorce.  Speculating on the reason for this relationship the authors say they believe it has something to do with the reduction in fat consumption that leads to better overall health and a corresponding improvement in marital relations. "We think this is a big step in reducing the divorce rate.  If people will limit their fat intake, we can see divorce rates continue to decline.  There's no reason this couldn't be applied across the whole country."

This is a real association using actual data.  I got it from a great web site titled "Spurious Correlations."  The creator of the site, Tyler Vigen, emphasizes that these correlations are not meant to imply causation.  The difference is key to understanding reporting on any research, but particularly nutrition research.

If there is a correlation between two things, it means that as one changes, the other changes.  In other words, if A and B are correlated, then as A goes up, B tends to go up, or as A goes up, B tends to go down.  (One of these is a positive correlation, the other is a negative correlation.) Notice that I didn't say that A causes B.  Correlation does not mean that something causes something else, it just means that when one changes, the other one seems to change.  They are probably related in some way, but you cannot conclude that one of them causes the other.

So for the example with divorce rates and consumption of margarine, you can see by the graph that they really are correlated.  They are strongly correlated.  Over the 10 years of data provided, as one changes the other changes in step.  But you should never conclude from this that margarine consumption causes divorce, or even that divorce causes margarine consumption.  So when you read a story or hear about something being correlated with (or associated with) something else, DO NOT THINK THAT ONE CAUSES THE OTHER.

So why would margarine consumption be correlated to divorce rates?  Maybe both of them are related to something else.  One possibility might be that over those 10 years the income increased or declined influencing both the chances of divorce as well as the food choices that people buy.

There is value to studies that look at correlation using existing data.  They are great clues to what may be going on.  For example, let's think about the relationship between cholesterol and heart disease.  Early in the study of heart disease it was observed in people with atherosclerosis (where plaque builds up in people's arteries) that where this exists, there is a lot of cholesterol there.  So that's a great observation that there is something going on between the disease and cholesterol.  That does not mean that cholesterol causes atherosclerosis. Maybe it means that atherosclerosis causes the cholesterol to be there!

An excellent analogy for this that I've heard is that if we wanted to prevent fires we could go to a bunch of fires and make observations to see what else is there and try to figure out how to prevent them.  What we likely would find is that there is a very strong correlation between house fires and the existence of fire trucks.  We could conclude that fire trucks cause fires.  A better conclusion though would be that fires bring fire trucks.  The same is probably more true about Cholesterol.

Be very wary when you hear about studies citing one thing is correlated with (or associated with) another.  Don't believe it when it is then claimed that to prevent some disease, that the correlation means you should reduce (or increase) the consumption of something else.

How I got here, pt. 1

where this started

My story starts back in the mid-90s.  This was a time when you learned things from things called books that were made out of paper.  (Strange concept these days.)  The Internet was getting started, but was not yet the go-to place where people got information.  That meant that: 1. Information was harder to come by. 2. It was difficult to get a broad range of views on topics.

I was reasonably healthy but high blood pressure was looming due to family history, I was starting to gain a bit of weight and didn't really have a ton of energy.  What I learned was that: 1. The key way to health and weight control was exercise -- aerobic, to build muscle which burns more calories even at rest than fat.  2. You have to avoid fat, eat lots of complex carbohydrates, vegetables and fruit.  3. You need to watch your calories and eat less than you burn through exercise, etc. if you want to lose weight.

Much of what I learned and believed can be summarized in a couple books that made perfect sense to me, particularly in the vacuum of other information sources.  They were "Fit or Fat" and "The Fit or Fat Target Diet." by Covert Bailey.


a long spiral down

This low fat, high exercise approach worked fairly well for me, on and off at least.  The "on" was when I was really regularly exercising.  The "off" was at all other times.  When I started that, I was getting into road cycling -- typically some pretty long rides like centuries or half-centuries.  Cycling is an excellent calorie burning activity.  For one thing, for me, it is an activity that I can do for extended periods of time because you are moving fast and able to avoid boredom.  Cycling burns a lot of energy.  An hour ride burns around 500 calories.  A half-century burns around 2000-3000 calories (almost double an average day) and a century burns around 4000-5000 calories.

For various reasons, I got out of cycling and then only the intermittent exercise I would do (stationary bike, treadmill, some weightlifting) would keep me at any level of fitness, and allow me to keep weight off.

Simultaneously, and not coincidentally, other health markers declined.  Most importantly,  my blood pressure gradually increased being "borderline high" for a number of years, despite avoiding sodium and largely following the low fat guidance, finally spiking at a somewhat "scary high" level, meaning that I now had to get on medication.  I was daily taking a combined beta blocker and diuretic.   It did indeed control my blood pressure.  Of course, as with most modern medications, it also brought side effects.  Initially I experienced some tiredness, but this wasn't bad, it was more a feeling of relaxation that eventually went away.  Worse though, after several years on the medication, I discovered that my potassium levels were seriously low.  So, I started taking a prescription potassium supplement, eventually taking a very large does just to keep my serum potassium levels reasonable.  I was getting regular heartburn which I thought was probably due to the potassium, but as you'll soon see had nothing to do with that.

Over the years, while my blood pressure stayed fairly stable, other, not-so-positive things were happening.  I was beginning to get arthritis symptoms, particularly in my hands.  The heartburn continued and gradually got more frequent.  (I was taking Prevacid almost daily and sometimes had to take courses of Prilosec.)  My doctor wasn't happy with my cholesterol numbers (he was of course focused on total and LDL cholesterol but my triglycerides were also above normal.)  I had started to take fish oil for a few years and that had helped my arthritis symptoms somewhat and actually brought my HDL numbers just into the normal range.  My blood glucose numbers were getting worse, to the point I was considered pre-diabetic.

Less quantitative, but easily important things were happening as well.  I was getting less and less able to even think about doing what I thought would make me healthier.  While I still tried to eat what I thought was healthy, I would give into temptation more and more when those cookies were sitting out at a business meeting, or having an evening snack that I knew I didn’t need. I would also think about exercising but seldom would I have the energy to start, or if I started would I have the energy to keep it up.  I got to the point that I was starting to resign myself that I was too old to really change my health or fitness level significantly, and figured I would continue to gain weight, would continue to take prescription medications the rest of my life (and add to those that I was already taking.)  I thought this was just an expected part of the aging process and without some super-human effort, which I didn’t feel I had in me, was impossible to change.

There was quite a bit of buzz about low carb several years back, even to the point that restaurants were offering lettuce-wraps etc, I never paid much attention or thought that these people were missing the point that the problem wasn’t the bun or the bread but the fat in the sandwich that was being lettuce-wrapped.

How things changed ...

I welcome your feedback!