I strongly disagree with the claim that sodium reduction does more good than harm; I think interventions to reduce sodium intake directly harm the people affected. This is true everywhere, but especially true in poorer countries with hot climates, where sodium-reduction programs have the greatest potential for harm.
(This is directly contrary to the position of the scientific establishment. I am well aware of this.)
The problem is that sodium is a necessary nutrient, but required intake varies significantly between people and between temperatures, because sweating costs 1g/L. That’s why people have a dedicated taste receptor for it, and why they sometimes crave it and at other times find it aversive.
If you sweat a lot and don’t consume salt, you will become lethargic; if you drink something with salt in it, you’ll immediately bounce back. If you’re a manual laborer, and someone sneakily removes some salt from your diet, you’ll either compensate by getting more salt elsewhere, or your productive capacity will drop.
If you look at the published studies on sodium through this lens, you will find that they are universally shoddy. Most are observational but measure sodium intake via urine, causing them to be confounded by exercise. Of those that have interventions, basically all of them start by removing people’s ability to self-regulate. I don’t think I’ve seen any that check for negative effects not related to hypertension, but I know the negative effects are there because I can remove the salt from my own diet and experience them.
Props for investigating and doing quantitative analysis. If you do proceed from this intermediate report to a deep-dive report or an intervention project, I hope you’ll consider the negatives that the academic research thus far has swept under the rug. I think a properly-conducted RCT, one that reduced sodium intake in a vulnerable population and then accurately reported the harms experienced, could have a significant positive impact.
That’s an interesting perspective! You’re right that the scientific experts would disagree strongly on this, and to cite one of them: “While there is some controversy over the idea of a U or J-shaped curve for salt intake and cardiovascular outcomes, the more robust studies show that these use faulty evidence.” Another expert adds to this, “In healthy adults, sodium is needed to sustain BP, but we don’t observe a J-curve normally: there is sodium in all food, and the kidney is a great engine at holding on to sodium in low sodium settings, such that lower BP is basically almost always better).”
I also don’t think it’s accurate to say that the evidence is observational. (a) Aburto et al’s (2013) meta-analysis of RCTs and prospective cohort studies shows that a reduction in sodium intake significantly reduced resting systolic blood pressure by 3.39 mm Hg; while Ettehad et al’s meta-analysis entirely of RCTs shows that every 10 mm Hg reduction in systolic blood pressure significantly reduced the risk of major cardiovascular disease events (relative risk: 0.8), coronary heart disease (relative risk: 0.83), stroke (relative risk: 0.73) and heart failure (relative risk: 0.73), leading to a significant 13% reduction in all-cause mortality). (b) Then there is the Strazzullo et al meta-analysis of both RCTs and population studies, showing that additional sodium consumption of 1880 mg/day leads to greater risk of CVD (relative risk: 1.14).
On the sweating issue (and hence the associated concerns about exercise and whether people in hot climates will be hurt) - I don’t think this is an unreasonable fear a prior, but the Lucko et al meta-analysis of RCTs suggests that 93% of dietary sodium is excreted via urine, so basically that should anchor our expectations that this isn’t going to be a significant way in which sodium is lost (let alone to such an extent that it has bad health consequences).
The existence of these meta-analyses is much less convincing than you think. One, because a study of the effect of sodium reduction on blood sugar combined with a study of the effect of antihypertensive medications don’t combine to make a valid estimate of the effect of sodium reduction on a mostly-normotensive population.
But second, because the meta-analyses are themselves mixed. A 2016 meta-meta-analysis of supposedly systematic meta-analyses of sodium reduction found 5 in favor, 3 against, and 6 inconclusive, and found evidence of biased selective citation.
I strongly disagree with the claim that sodium reduction does more good than harm; I think interventions to reduce sodium intake directly harm the people affected. This is true everywhere, but especially true in poorer countries with hot climates, where sodium-reduction programs have the greatest potential for harm.
(This is directly contrary to the position of the scientific establishment. I am well aware of this.)
The problem is that sodium is a necessary nutrient, but required intake varies significantly between people and between temperatures, because sweating costs 1g/L. That’s why people have a dedicated taste receptor for it, and why they sometimes crave it and at other times find it aversive.
If you sweat a lot and don’t consume salt, you will become lethargic; if you drink something with salt in it, you’ll immediately bounce back. If you’re a manual laborer, and someone sneakily removes some salt from your diet, you’ll either compensate by getting more salt elsewhere, or your productive capacity will drop.
If you look at the published studies on sodium through this lens, you will find that they are universally shoddy. Most are observational but measure sodium intake via urine, causing them to be confounded by exercise. Of those that have interventions, basically all of them start by removing people’s ability to self-regulate. I don’t think I’ve seen any that check for negative effects not related to hypertension, but I know the negative effects are there because I can remove the salt from my own diet and experience them.
Props for investigating and doing quantitative analysis. If you do proceed from this intermediate report to a deep-dive report or an intervention project, I hope you’ll consider the negatives that the academic research thus far has swept under the rug. I think a properly-conducted RCT, one that reduced sodium intake in a vulnerable population and then accurately reported the harms experienced, could have a significant positive impact.
That’s an interesting perspective! You’re right that the scientific experts would disagree strongly on this, and to cite one of them: “While there is some controversy over the idea of a U or J-shaped curve for salt intake and cardiovascular outcomes, the more robust studies show that these use faulty evidence.” Another expert adds to this, “In healthy adults, sodium is needed to sustain BP, but we don’t observe a J-curve normally: there is sodium in all food, and the kidney is a great engine at holding on to sodium in low sodium settings, such that lower BP is basically almost always better).”
I also don’t think it’s accurate to say that the evidence is observational. (a) Aburto et al’s (2013) meta-analysis of RCTs and prospective cohort studies shows that a reduction in sodium intake significantly reduced resting systolic blood pressure by 3.39 mm Hg; while Ettehad et al’s meta-analysis entirely of RCTs shows that every 10 mm Hg reduction in systolic blood pressure significantly reduced the risk of major cardiovascular disease events (relative risk: 0.8), coronary heart disease (relative risk: 0.83), stroke (relative risk: 0.73) and heart failure (relative risk: 0.73), leading to a significant 13% reduction in all-cause mortality). (b) Then there is the Strazzullo et al meta-analysis of both RCTs and population studies, showing that additional sodium consumption of 1880 mg/day leads to greater risk of CVD (relative risk: 1.14).
On the sweating issue (and hence the associated concerns about exercise and whether people in hot climates will be hurt) - I don’t think this is an unreasonable fear a prior, but the Lucko et al meta-analysis of RCTs suggests that 93% of dietary sodium is excreted via urine, so basically that should anchor our expectations that this isn’t going to be a significant way in which sodium is lost (let alone to such an extent that it has bad health consequences).
The existence of these meta-analyses is much less convincing than you think. One, because a study of the effect of sodium reduction on blood sugar combined with a study of the effect of antihypertensive medications don’t combine to make a valid estimate of the effect of sodium reduction on a mostly-normotensive population.
But second, because the meta-analyses are themselves mixed. A 2016 meta-meta-analysis of supposedly systematic meta-analyses of sodium reduction found 5 in favor, 3 against, and 6 inconclusive, and found evidence of biased selective citation.