Cause and Effect: Salt, ball games & heart risk

Years ago, I began to hear warnings about salt consumption. Salt is known to cause high blood pressure, and high blood pressure is a risk for heart disease or at least undesirable heart events.

This puzzled me, because we had known both of these things for decades, but—somehow—I felt unsure that the two facts were transitive. That is,

If A leads to B and if B leads to C
does A necessarily lead to C?

I was also puzzled, because my mother used to give me salt pills on very hot days, whenever I was drenched in sweat after physical activity. Salt pills help retain fluids and they also re-establish electrolytes, along with plenty of water, of course. Was my mother ignorant of the dangers of salt? Why didn’t she realize that it leads to heart disease?

Later, as the salt scare reached a crescendo, I was seeing a cardiologist every 6 months. I visited him for my regular checkups, accessing his services as if he were an internist. But he wasn’t an internist. His other patients were referred to him as a high-value specialist. And he wasn’t just any cardiologist. He was a heart surgeon affiliated with the famous Framingham Heart Study. He was a pioneer in health research and respected as a teacher.

Relax. It’s not cocaine! It’s just salt.

Relax. It’s not cocaine! It’s just salt.

I asked this cardiologist about salt. First, he explained that his opinion was in the minority (i.e. I should take it with a grain of salt! — pun intended). He said that there was no merit to the popular fear about salt consumption. He felt strongly that, someday, the salt bogeyman would be de-mythed.

While he agreed that blood pressure is an indicator of cardiovascular health (because blocked arteries cause an increase in pressure), an increase caused by a temporary stimulant, such as salt, caffeine or exercise, was not cause for alarm. He believed it to be a risk only for individuals with long term hypertension due to an existing, systemic condition.

The experience taught be to be vigilant for the very common error of overlooking cause and effect. This can be tricky to unwind, because the nature of our language makes it subtle and because we all tend to make this mistake. And so, I prefer the following ‘Ball Game’ example. It is not part of my cardiologist’s explanation, but he agrees that it perfectly illustrates the point:

In the 1960s, a historical study of several thousand middle age males in the Chicago area found a high correlation between those who attend 2 more professional sporting events each week and a reduced incidence of heart attack. Although the study was not a double-blind, clinical trial (it was conducted by survey), the controls were rigorous. It included verification of facts, re-interview, and a statistical analysis to ensure that selection and participation represented a random cross section of the population.

The study concludes that men who frequently attend ball games have fewer heart attacks and live longer. But wait!… That’s not how the results were reported. Or at least, it’s not what people remember after hearing of the results.

What most people chose to hear was this:

       “If you go to two or more ball games each week, you will live longer”
—OR—
       “If you go to two or more ball games each week, you will live longer—even if you hate professional sports”

David Wells

Former Yankees pitcher, David Wells, loves baseball

Of course, neither statement is true. Not even the first one. The first words, “If you”, distort the conclusion. In fact, they suggest the opposite result! The report said “People who”, not “If you”

To say that ball games improve or prolong life is to confuse cause and effect. Although the study didn’t isolate cause and effect, a bit of reflection suggests that perhaps the reason people who regularly attend ball games live longer is because they…

  • are doing something that they love
  • have the luxury of spending weekdays away from work
  • have more money and less stress than individuals of average means
  • have partners who allow time for their favorite leisure activity

Now, suppose you don’t care at all for professional sports. If you twist the conclusion and assume that ball games cause health or wealth (rather than the other way around), then giving up your job and forcing yourself to attend sporting events will probably lead to marital problems, stress, poverty and premature death. In fact, this contradicts the conclusion of a good study.

So what about salt?

Today, the Wall Street Journal published a very short article at the bottom of page A7. Although it is called out as a feature story, I think that it is getting far too little attention. Low-Salt Benefits Questioned. It ends with these words:

“The chairman of the committee that wrote the report said [that it] fo-
cuses
on actual health outcomes rather than just high blood pressure.”

In the mid 1980s, perhaps my cardiologist was ahead of his time. Or, perhaps salt will be implicated again, when new studies control for cause and effect. But my point was not about salt or ball games. My point was to illustrate a famous statement that is alternatively attributed to Mark Twain and to British Prime Minister Benjamin Disraeli:

“There are three kinds of lies: lies, damned lies, and statistics.”

Learning to recognize that a conclusion has made an assumption of cause and effect (or more likely, that ‘cause’ was attributed by someone rephrasing the conclusion of a study) goes a long way to restoring the validity and value of an accurate statistic.

Ellery is neither a linguist nor philosopher. But he is troubled
that cause-and-effect are so often confused or overlooked.

2 thoughts on “Cause and Effect: Salt, ball games & heart risk

  1. Ellery, The WSJ article is no longer accessible at the link posted in your Blog above. Here is the text of that article…
    _____________

    Low-Salt Benefits Questioned
    The Wall Street Journal, May 15, 2013
    —By Jennifer Corbett Dooren

    An influential government panel said there is no evidence that very low-salt diets prevent heart disease, calling into question current national dietary guidelines on sodium intake.

    The Institute of Medicine, in a report released Tuesday, said there isn’t sufficient evidence that cutting sodium intake below 2,300 milligrams per day cuts the risk of heart disease. The group of medical experts also said there is no evidence that people who already have heart disease or diabetes should cut their sodium intake even lower.

    Sodium, a key component of table salt, has been shown to raise blood pressure, which in turn raises the risk of heart disease, but studies have shown inconsistent results on whether high-sodium diets actually boost the risk of heart problems.

    Current U.S. dietary guidelines recommend that Americans limit their sodium intake to no more than 2,300 milligrams daily—or about a teaspoon of salt. For people who are 51 and older or African-American, or who have hypertension, diabetes or chronic kidney disease—groups that together represent half of the U.S. population—the guidelines call for no more than 1,500 milligrams a day. But the Institute of Medicine report said there isn’t enough evidence to support the 1,500-milligram threshold.

    Some groups, including the American Heart Association, set an even tougher standard and suggest all Americans consume no more than 1,500 milligrams of sodium. In a statement, the group said it wasn’t changing its advice and that it disagreed with many of the IOM’s conclusions.

    The group’s chief executive, Nancy Brown, said that “well-established evidence … links too much sodium to high blood pressure and heart disease.”

    Most Americans far exceed recommended sodium levels, consuming an average of 3,400 milligrams per day. Sodium is found in most processed and packaged foods. Doctors say it would be difficult for most people to keep from consuming more than a teaspoon a day of salt unless they eat mainly fresh food and avoid most restaurant food.

    The Institute of Medicine said those with very high sodium intake would benefit from reducing it, but the report didn’t recommend a specific healthy range for sodium consumption.

    A 2005 report by the institute found that 1,500 milligrams was the minimum amount needed for adequate nutrition and up to 2,300 milligrams could be consumed each day without raising blood pressure. Those ranges were then used to set U.S. dietary guidelines.

    Brian Strom, the chairman of the committee that wrote the report and a public health professor at the University of Pennsylvania, said the new report focuses on actual health outcomes rather than just high blood pressure.

    “The data show that lowering salt [consumption] is beneficial but it raises questions of harm from too little salt,” Dr. Strom said. “It’s a subtle message.”

    A separate report published Monday in JAMA Internal Medicine by researchers at Northwestern University and the Center for Science in the Public Interest looked at sodium levels in processed and restaurant foods from 2005 to 2011. On average, the report found that sodium levels in processed foods declined by 3.5% but rose by 2.6% at fast-food restaurants. The CSPI said voluntary efforts by food industry to cut sodium weren’t working and called on the Food and Drug Administration to mandate sodium reductions.

    FDA Commissioner Margaret Hamburg said the agency was working on setting new sodium guidelines but suggested the agency would phase in any cuts over several years. “It’s very hard to just abruptly, significantly lower salt in food,” she said in an interview.

    Dr. Hamburg said the agency would prefer to continue working with industry on a voluntary basis rather than mandating sodium levels.

  2. Yet another reason one should not be looking toward mainstream (commercial) media for advise and direction on health. I’m sure there was some commercial motive behind this scare – do you remember all the bad press about dairy fat and coconut oil!

    Now, the question you should ask yourself is this, are you consuming refined white salt or salt that is mineral rich.

    How do I keep my body in tune? At the very minimum I ensure that each day I consumer about 4 Tbls of good fat (Cod Liver Oil, Olive Oil, Coconut Oil or Sunflower seed – I use NO OTHER OILS), about 2 tbls of seeweed (soaked then rinsed), and with each meal I consume much more live vegetables than protein and I ensure that animal protein is never overcooked. Then – simple rule of thumb, consume nothing that has been laboratory modified, created, or bleached. (which by the way is getting harder and harder as companies like Monsanto work harder at keeping consumers in the dark.)

    Let thy food be thy medicine! (the problem with this is that because big pharma can’t corner the market on whole food (because farming is basically free trade – or is it), to better meet your dietary and environmental needs (so they claim), they are genetically modifying your food (and patenting it!) Yum! they’ve created corn with built in pesticides so they can apply less to the outside envelope. So, the headline here would read – GM Corn Reduces Pesticide Use! Sure! but now it’s on the wrapper your tossing, it’s in the corn that you’re eating! – Ah – wait! We’ve circled back to the issue Elery writes about!

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