My recent post on a local “holistic” doctor brought a number of considered and interesting comments (all of whom are quite polite and patient, even when I disagree with them).
Some of the issues deserve fleshing out.
Heart disease is a major killer. Hypertension is one of the strongest risk factors for heart disease. In some people, salt contributes to hypertension, and reduction of salt intake reduces bad outcomes. In people with congestive heart failure, salt-restriction is crucial.
The statement of this idea led to some interesting objections, with a good helping of goalpost-shifting.
The objections raise some important points, but also engage in some typical denialist tactics.
I’ve just been looking for basic information, and coming up empty-handed, so I hope you can understand my frustration. I’m not one to hold on to bad ideas in the face of evidence, but I’d like to see a prima facie case made first.
and
I’ve also seen a study in the news in the last few months that was reported to show a significant increase in mortality among high-risk patients over a 10-year period for those who maintained a high salt intake. That raises questions that weren’t answered in the news article, such as: How did the diets compare otherwise? It’s reasonable to assume that someone who reduces their salt intake because of blood pressure is going to make other dietary changes as well, and vice versa. If other variables were controlled, then by what mechanism does salt increase mortality? What do those results mean for individuals with normal blood pressure?
and
The correlation between sodium intake and heart disease doesn’t prove anything. This is a classic example of correlation not equalling (sic) causation. Processed and fast food, the biggest sodium offenders, also tend to be loaded with saturated fat and cholesterol. Could these not also be the cause of the artery disease, and the salt just be a relatively innocent bystander?
I am not saying that there is no place for a low-sodium diet, I’m just saying that I’ve yet to see any evidence for one in general. (emphasis mine –PalMD)
This is simply an argumentum ad ignorantiam. The fact that the commenter doesn’t know the answers does not affect the validity of the conclusions stated. Does he think that researchers have never asked these questions?
How about a plausible method by which salt causes ateriosclerosis?
and
We have no convincing evidence that blood pressure increases resulting from salt intake contribute substantially to heart disease or stroke. You, and the medical profession in general, are taking a giant illogical leap.
Actually, I gave references. If he can’t be bothered to check them, it’s hardly my fault, or the fault of the medical profession.
High salt intake may raise blood pressure in some groups, but it does not necessarily lead to chronic or dangerous hypertension. And chronic hypertension might be an effect, rather than cause, in many cases. We don’t really know.
I already said that there is great variability to patients’ susceptibility to salt, so objection noted. Actually, we do know that hypertension is a cause rather than an effect of heart disease.
We do know that the major causes of artery disease leading to heart attacks and strokes are cigarette smoking and type 2 diabetes. So we do not have any clear connection between a high salt diet and artery disease. And you have admitted that.
In addition to cigs and diabetes is hypertension. As cited, in many patients, high salt intake leads to hypertension. Hypertension leads to heart disease. To require the most proximate cause is an absurd argument. Medical science looks for correlations, and tries to explain them. Much of the time we understand the specific mechanisms involved. To ask for more and more detailed explanations is simply moving the goalposts—if you don’t like the answer, just ask more detailed questions until everyone is tired of answering you.
Unfortunately, I am not a member of the AMA, so I don’t have access to that article. I did want to read it given the alarmist wording of the headline, but it wasn’t $15 of want, especially since I’d need to pay for the references, ad infinitum….
If the commenter is unwilling to accept my expert status, that is quite reasonable. But then to be unwilling to dig up the data himself, well, that’s just silly. To gain information, you can either listen to an expert or try to interpret the data yourself. To be unwilling to do either is simply intentional ignorance. To then expect others to buy that as a legitimate argument is not just unfair, it’s asinine.
The point here is not about individual commenters—it’s about strategy and errors in thinking. For complex information, we trust in experts—we have no choice. If we are curious about going deeper, we look up the primary sources.
Salt may or may not be an important cause of heart disease, although evidence favors the connection; there are certainly more important causes. But in some people, salt very directly causes increased blood pressure, and high blood pressure most certainly does lead to heart disease. That fact does not negate other causative factors (which is another non sequitur brought up in some comments).
Denialism involves, well, denial. If you don’t like a fact, then just keep looking for ways around the truth. Or plug your ears and go, “la la la la la.” Either has the same effect.
Leave a Reply