Each year, World Salt Awareness Week returns with a message that sounds settled, almost beyond debate: reduce salt intake for better health. It is often presented as one of the clearer areas of nutrition science, where the evidence is consistent and the guidance is straightforward.

But nutrition has a long history of mistaking confidence for certainty.

At The Noakes Foundation, much of our work has been grounded in the observation that widely accepted ideas are not always the most rigorously examined, and that meaningful progress in metabolic health often requires a willingness to revisit and interrogate long-standing assumptions. Salt is a clear example of this. While efforts to reduce hypertension and cardiovascular disease risk have shaped current guidance on sodium (based on early observations linking salt intake with blood pressure and subsequent research attempting to characterise this relationship (Dahl, 1960; INTERSALT Cooperative Research Group, 1988) these findings are often taken to imply a simple, consistent cause-and-effect relationship that the evidence does not uniformly support. What emerges instead is a far more variable and context-dependent biology than current messaging tends to reflect.

The origins of the salt-hypertension hypothesis can be traced back to early work such as that of Dahl, who observed associations between salt intake and blood pressure across populations, alongside experimental findings showing that very high salt intakes could induce increases in blood pressure in animal models (Dahl, 1960). These findings were important in establishing a plausible biological link, but they were never designed to capture the complexity of human dietary patterns or long-term health outcomes.

This line of thinking was later reinforced by large-scale observational work, most notably the INTERSALT study, which examined sodium excretion and blood pressure across multiple countries (INTERSALT Cooperative Research Group, 1988). While often cited as evidence of a global relationship between sodium intake and hypertension, closer analysis revealed that much of the association was driven by a small number of very low-sodium, non-industrialised populations, with relatively weak relationships observed within most other groups. This nuance, however, is rarely reflected in how the findings are communicated (sound familiar?)…

More recent analyses have added another layer to this picture by suggesting that the relationship between sodium intake and cardiovascular outcomes may be J-shaped, with potential risks associated with both very high and very low intakes (Mente et al., 2016; Robinson, 2019). This challenges the assumption that lower intake is always better and instead points towards a more nuanced understanding of optimal intake ranges.

From a physiological perspective, this complexity is not surprising. Sodium is not simply a dietary exposure; it is part of a tightly regulated system. When intake is reduced, the body activates compensatory mechanisms, including increases in renin, aldosterone, and sympathetic nervous system activity (Graudal et al., 2014). The European Society of Cardiology has similarly acknowledged that the relationship between salt and hypertension is influenced by individual variability and broader dietary and physiological factors, rather than a uniform effect across populations (ESC, 2023).

Perhaps more importantly, sodium does not act independently of the metabolic context in which it is consumed. Insulin plays a direct role in renal sodium handling, promoting sodium reabsorption, and in states of insulin resistance, this effect is amplified (DeFronzo, 1981). Within this environment, sodium becomes part of a broader metabolic disturbance rather than the primary driver of disease.

When that metabolic context shifts, the role of sodium shifts with it. In the setting of carbohydrate restriction, reductions in insulin lead to increased sodium excretion through the kidneys, a phenomenon that has been consistently observed in both fasting and low-carbohydrate states (Hallberg et al., 2018). Individuals adopting these approaches often experience a loss of sodium and fluid during the initial stages of adaptation, which can present as fatigue, dizziness, or reduced exercise tolerance. These effects are frequently attributed to the diet itself, when they are more accurately understood as a reflection of altered electrolyte balance. In this context, increasing sodium intake is not only appropriate but often necessary.

This is where current public health messaging begins to diverge most clearly from physiology. A universal recommendation to reduce salt intake does not account for individuals who are actively improving their metabolic health, lowering insulin levels, and consequently increasing sodium loss. For these individuals, strict sodium restriction may undermine, rather than support, their progress.

The source of sodium also warrants consideration. Diets high in ultra-processed foods are typically high in sodium, but they are also characterised by refined carbohydrates, low micronutrient density, and poor overall dietary quality. It is within this context that higher sodium intake is most consistently associated with adverse outcomes. However, attributing these outcomes solely to sodium risks oversimplifies a far more complex dietary pattern.

When individuals transition towards whole, minimally processed foods, the role of sodium often changes. Foods such as meat, eggs, vegetables, and natural fats are not engineered for hyper-palatability, and salt becomes a practical tool that enhances flavour and supports adherence. In this setting, sodium is not driving overconsumption but facilitating a dietary pattern that is more aligned with metabolic health and long-term sustainability.

None of this suggests that sodium intake is irrelevant or that individual variability should be ignored. There are clearly subgroups, including those with salt-sensitive hypertension, for whom moderation remains important. However, the prevailing emphasis on uniform reduction fails to reflect the diversity of physiological responses and the importance of metabolic context.

A more useful approach would move beyond reductionist messaging and instead consider the broader picture: dietary quality, insulin dynamics, individual variability, and the physiological state of the person. When viewed through this lens, sodium is neither inherently harmful nor universally beneficial, but rather a necessary nutrient whose effects depend entirely on the context in which it is consumed.

World Salt Awareness Week offers an opportunity not simply to repeat familiar advice, but to revisit the assumptions that underpin it. If we are willing to question the science, not to dismiss it, but to interrogate it more carefully, we may find that the story of salt is not one of simple harm, but one of balance, physiology, and context.

References

Dahl LK. Possible role of salt intake in the development of essential hypertension. 1960. Int J Epidemiol. 2005 Oct;34(5):967-72; discussion 972-4, 975-8. doi: 10.1093/ije/dyh317. Epub 2005 Sep 5. PMID: 16143660. 

DeFronzo RA. The effect of insulin on renal sodium metabolism. A review with clinical implications. Diabetologia. 1981 Sep;21(3):165-71. doi: 10.1007/BF00252649. PMID: 7028550. 

European Society of Cardiology. (2023). Salt and hypertension: Current views.
https://www.escardio.org/communities/councils/cardiology-practice/scientific-documents-and-publications/ejournal/volume-22/salt-and-hypertension-current-views/

Graudal N, Jürgens G, Baslund B, Alderman MH. Compared with usual sodium intake, low- and excessive-sodium diets are associated with increased mortality: a meta-analysis. Am J Hypertens. 2014 Sep;27(9):1129-37. doi: 10.1093/ajh/hpu028. Epub 2014 Mar 20. PMID: 24651634. 

Hallberg, S.J., McKenzie, A.L., Williams, P.T. et al. Effectiveness and Safety of a Novel Care Model for the Management of Type 2 Diabetes at 1 Year: An Open-Label, Non-Randomized, Controlled Study. Diabetes Ther 9, 583–612 (2018). https://doi.org/10.1007/s13300-018-0373-9 

Intersalt: an international study of electrolyte excretion and blood pressure. Results for 24 hour urinary sodium and potassium excretion. Intersalt Cooperative Research Group. BMJ. 1988 Jul 30;297(6644):319-28. doi: 10.1136/bmj.297.6644.319. PMID: 3416162; PMCID: PMC1834069. 

Mente A, O’Donnell M, Rangarajan S, Dagenais G, Lear S, McQueen M, Diaz R, Avezum A, Lopez-Jaramillo P, Lanas F, Li W, Lu Y, Yi S, Rensheng L, Iqbal R, Mony P, Yusuf R, Yusoff K, Szuba A, Oguz A, Rosengren A, Bahonar A, Yusufali A, Schutte AE, Chifamba J, Mann JF, Anand SS, Teo K, Yusuf S; PURE, EPIDREAM and ONTARGET/TRANSCEND Investigators. Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies. Lancet. 2016 Jul 30;388(10043):465-75. doi: 10.1016/S0140-6736(16)30467-6. Epub 2016 May 20. Erratum in: Lancet. 2021 Apr 10;397(10282):1350. doi: 10.1016/S0140-6736(21)00727-3. PMID: 27216139.

Robinson AT, Edwards DG, Farquhar WB. The Influence of Dietary Salt Beyond Blood Pressure. Curr Hypertens Rep. 2019 Apr 25;21(6):42. doi: 10.1007/s11906-019-0948-5. PMID: 31025198; PMCID: PMC7309298.