What actually is the recommended salt intake, and is it related to high blood pressure?
Despite widespread claims to the contrary, both a very high and a very low salt diet appear to increase one’s chances of cardiovascular related disease and mortality. It had previously been suggested that only a high salt diet led to such outcomes – recent research suggests the same is true of a low salt diet too. What is less clear is whether the same outcome is found in individuals with AND without hypertension (clinically high blood pressure). A recent meta-analysis (which studies lots of other studies & pools together all their findings) investigated whether a high or low salt diet was associated with cardiovascular disease and related death in people with and without high blood pressure, and provides a suggestion at what the recommended salt intake should be.
Unsurprisingly, a daily salt intake of above 7 g per day, or below 3 g per day were BOTH related with increased cardiovascular risk and related mortality in people with hypertension. Thus, a high or a low daily sodium intake had adverse health outcomes in people with high blood pressure. Check.
Surprisingly, however, and in people without hypertension, only a low daily sodium intake was associated with cardiovascular disease and related mortality; on the other hand, a high salt diet was NOT associated with adverse health outcomes. What?!!
Therefore, and in summary, compared with a ‘normal’ or moderate salt intake, high sodium consumption is associated with an increased risk of cardiovascular disorder and related mortality in people already diagnosed with high blood pressure/hypertension, but not in those without. On the hand other, a low daily sodium intake was negative for BOTH populations i.e. those with or without high blood pressure.
Recommended salt intake
What do the results of this study actually mean?
It means that lowering one’s intake of sodium is most likely NOT needed by most people!! Despite ubiquitous claims to the contrary, most people do not need to be cutting back on their salt intake!! In fact, in otherwise healthy populations currently without hypertension, a significant reduction in salt intake is most likely DETRIMENTAL to health, and not beneficial. In people who do have high blood pressure, neither an extremely high nor low sodium intake should be targeted; simply a moderate salt intake appears optimal. The recommended salt intake would therefore appear to be 4 – 5 g per day, and this appears true in both individuals with, and without, high blood pressure.
Why is this not necessarily a surprising finding?
Salt, or sodium, is essential to life. It helps to regulate fluid balance, and is critical to the action of cells in the body, and the firing of messages between cells. In addition, sodium balance is under tight regulation, and overall fluid balance is not just affected by sodium, but by many other important minerals. Lastly, and a quote from the paper:
emerging evidence suggests that inflammatory responses with infections involve mobilising high concentrations of sodium to the local tissues that are involved, and this ability might be part of an essential defence mechanism to external infections
So sodium appears to also have anti-bacterial properties in the body, which help to fight infection.
So how do I actually know how much I’m currently consuming, and how do I know how much I should consume?
Rather than trying to answer that question, I think a better message would be:
Consider reducing the amount of pre-packaged, refined/processed food you consume, then salt your food to taste
Generally speaking, it would be hard to add large quantities of salt – which would otherwise be detrimental to health – if you were consuming fresh, natural, whole foods most of the time. Added salt tends to come from packaged food/fried food/frozen food. Where you manage to eliminate or reduce your consumption of food from these sources, it’s very likely that you can simply ‘salt’ your food without having to worry about how much you’re actually consuming.
In summary: generalised advice for people to consume less salt is at best misleading and at worse detrimental. Instead, advice to reduce salt consumption targeted at people with high blood pressure is most certainly warranted. A better message in general would be for people to reduce the consumption of pre-packaged foods where salt has already been ‘added’. Minimising refined/fast/fried or packaged food will indirectly reduce your sodium intake to moderate (optimal) levels. Recommended salt intake would be between 4 – 5 g per day, which can be achieved indirectly through a diet composing of fruits & vegetables, meat, fish, dairy, eggs, as well as nuts, beans and grains.