Salt: More confirmation bias for your preferred narrative - 0 views
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When it comes to health, it’s the hard outcomes we care about. We pay attention to measures like high blood pressure (hypertension) because of the relationship between hypertension and events like heart attacks and strokes. The higher the blood pressure, the greater the risk of these events. The relationship between the two is well established. So when it comes to preventive health, we want to lower blood pressure to reduce the risk of subsequent effects. Weight loss, diet, and exercise are usually prescribed (though often insufficient) to reduce blood pressure. For many, drug treatment is still required.
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There is reasonable population-level data linking higher levels of salt consumption with higher blood pressure.
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From a population perspective, interventions that dramatically lower salt intake result in lower blood pressure.
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When it comes to clinical practice guidelines, low salt diets are the mainstays of pretty much every set of guidelines on the management of high blood pressure.
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The evidence supporting the relationship with hard outcomes is robust, but not rock-solid. We don’t have causal data, but we do have considerable epidemiologic evidence to suggest that reducing dietary salt consumption is likely to offer net benefits in the management of hypertension.
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The vast majority of the salt we eat (75%) is from processed foods. Restaurants are a large source, too.
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Few foods in their original state are naturally high in salt, and in general, we don’t add that much at the table.
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Seven studies made up this meta-analysis, including 6,489 patients in total. Three studies looked at those with normal blood pressure, two included patients with high blood pressure, and one was a mixed population, including patients with heart failure. The overall effect? Interventions had small effects on sodium consumption, which led to small effects on blood pressure. There was insufficient information to analyze the effects on cardiovascular disease endpoints.
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The authors go on to make the following point, which was ignored in the media coverage: Our findings are consistent with the belief that salt reduction is beneficial in normotensive and hypertensive people. However, the methods of achieving salt reduction in the trials included in our review, and other systematic reviews, were relatively modest in their impact on sodium excretion and on blood pressure levels, generally required considerable efforts to implement and would not be expected to have major impacts on the burden of CVD.
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Despite the modest and equivocal results, the authors seem to have lost the narrative on their own research findings: Professor Rod Taylor, the lead researcher of the review, is ‘completely dismayed’ at the headlines that distort the message of his research published today. Having spoken to BBC Scotland, and to CASH, he clarified that the review looked at studies where people were advised to reduce salt intake compared to those who were not and found no differences, this is not because reduced salt doesn’t have an effect but because it’s hard to reduce salt intake for a long time. He stated that people should continue to strive to reduce their salt intake to reduce their blood pressure, but that dietary advice alone is not enough, calling for further government and industry action.
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The true finding from the Cochrane review is that dietary interventions to reduce salt intake are largely ineffective at reducing salt consumption.
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Until the data are more clear, you can find the data to support whatever narrative you believe. If you want to demonize salt and ignore other factors that contribute to poor cardiovascular outcomes, you can do that. And if you believe that interventions to reduce salt consumption are misguided and unwarranted, and symptomatic of an overreaching nanny state, then you can find data to support that position, too.