AGING?F***THAT!
16 OCTOBER 2026 · LEE C. STONEHOUSE
Sodium and potassium ions moving through channels in a cell membrane

Healthspan depends less on salt alone than on the sodium-to-potassium ratio in the diet.

The Sodium-to-Potassium Ratio: The Number That Decides What Salt Actually Does to You

If you remember a single number from this article, remember the pair that decides most of it: roughly 1,600 mg of sodium and 4,700 mg of potassium a day. That balance point sits at the centre of the evidence, and it is close to the exact opposite of what the average over-40 plate delivers.

Salt has spent decades as public enemy number one, and the story was never that simple. Sodium is an essential electrolyte; without it you cannot hold fluid balance, conduct a nerve impulse or contract a muscle. What modern diets get wrong is not the salt cellar on the table. It is the ratio between sodium and its quieter partner, potassium, that flips almost completely in industrialised eating patterns.

That is why Lee C. Stonehouse's AGING?F***THAT! framework treats the sodium-to-potassium ratio as one number worth knowing, not two ingredients worth fearing. For adults over 40 working on healthspan, it is one of the few electrolyte facts that changes shopping behaviour the very next day.

THE ANCESTRAL INVERSION

Human physiology was built in a kitchen very different from ours. Pre-agricultural diets drew almost all of their sodium from the food itself and their potassium from plants: leaves, tubers, fruit and root vegetables. When researchers reconstructed those eating patterns, they estimated a sodium-to-potassium ratio of roughly 1:10 or better. Today's western diet runs close to 1:0.5, meaning more sodium than potassium, an inversion of more than twenty-fold (Cordain et al., American Journal of Clinical Nutrition, 2005).

The body still carries the machinery tuned for the old world. Hormones, kidney handling and vascular smooth-muscle behaviour all evolved under conditions where potassium was abundant and sodium was scarce. A diet that keeps the ancestral arrangement gives those systems the environment they were designed to work in.

WHY THE RATIO BEATS SALT ALONE

Blood-pressure research has quietly shifted from "salt bad" to "the balance matters". The PURE study followed more than 100,000 adults across 18 countries and found that very high sodium intake raised cardiovascular risk, but so did very low intake: the relationship was J-shaped, with the lowest risk in the middle of the range. Potassium, by contrast, showed a simple linear benefit: more potassium, lower blood pressure, fewer events (Mente et al., The Lancet, 2018).

Work on the ratio itself makes the point sharper. In a long-term study of adults in a Scottish cohort, higher sodium-to-potassium ratios predicted increased cardiovascular risk, and the ratio performed better than sodium alone as a predictor (Cook et al., Archives of Internal Medicine, 2009). A meta-analysis of randomised trials and cohorts reached the same conclusion from the other direction: increasing potassium lowered blood pressure, and the effect was strongest in the people eating the most sodium (Aburto et al., BMJ, 2013).

Put together, the picture is consistent. The ratio predicts cardiovascular outcomes better than either mineral on its own, because the two elements interact at the level of the kidney and the blood-vessel wall. Potassium encourages the kidney to excrete sodium and helps vascular endothelium relax. Sodium and potassium are not two separate risks; they are one dial.

WHAT THE ADRENAL CONNECTION MEANS AFTER 40

There is a deeper, less-discussed layer: the hormone aldosterone, which governs sodium retention, and cortisol's broader influence on electrolyte handling. Chronic stress shifts fluid and mineral balance in ways that make a bad dietary ratio worse, and midlife is precisely when stress load, blood pressure and vascular stiffness begin to compound. This is why the sodium-potassium conversation sits inside the wider stress-management and sleep tenets rather than in nutrition alone.

It is also why a single lab snapshot can mislead. Electrolytes measured in a blood panel reflect what the kidney is holding that day, not what the diet delivers over months. That is one reason the biological age results approach used in the AGING?F***THAT! system reads biomarkers as a pattern, with repeat testing under consistent conditions, rather than as isolated numbers to panic about.

THE THREE FIXES

#1 Do not chase zero salt. Cutting sodium to the bone is not the win it appears to be. The PURE data put the low-risk zone at moderate intake, and very low sodium carries its own risks. Salting food to taste is compatible with the evidence. The excess hides in packaged and restaurant food, where a single ready meal can carry more than half a day's sodium.

#2 Chase potassium instead. Beans, lentils, potatoes, avocados, bananas, leafy greens and yoghurt are all strong sources, and most adults take in roughly half the recommended amount. Every one of those foods pushes the ratio in the ancestral direction. Anyone with kidney disease, or on blood-pressure or potassium-sparing medication, should speak to a GP before pushing potassium hard, because in that group the dial works differently.

#3 Eat like the ratio matters, because it does. A plate built around whole foods, with plants doing most of the volume and processing kept low, moves the ratio without a single gram of counting. The 4,700 mg potassium target lands almost automatically when vegetables and pulses carry the meal, the same pattern that fibre-first eating rewards, which is why the two habits travel together.

MEASURE · INTERVENE · TRACK · REPEAT

Electrolytes are one of the panels tracked alongside the wider biomarker set that feeds the biological age model. The point is not to memorise mineral tables. It is to measure the pattern, intervene on the plate, and track whether the numbers move.

FREQUENTLY ASKED QUESTIONS

What is the ideal sodium-to-potassium ratio?

The evidence points to an intake pattern near 1,600 mg sodium and 4,700 mg potassium daily, close to 1:3. Ancestral diets ran nearer 1:10. The practical goal is simple: potassium-rich plants dominating the plate, sodium mostly from added salt rather than packaged food.

Is salt actually bad for you after 40?

Sodium is essential, and very low intakes carry their own risks. The PURE study found lowest cardiovascular risk at moderate sodium intake. The excess in western diets comes mainly from processed food, so the fix is pattern-level, not bans on the salt cellar.

What are the best potassium-rich foods?

Beans, lentils, potatoes, avocados, bananas, leafy greens, yoghurt and dried fruit lead the list. A single baked potato can carry around 900 mg. Most adults reach only about half the recommended 4,700 mg, so potassium is the side of the ratio worth building deliberately.

Can potassium lower blood pressure?

Meta-analyses of randomised trials show increasing potassium lowers blood pressure, with the strongest effect in people eating high sodium. It works partly by prompting the kidney to excrete sodium. Anyone with kidney disease or on relevant medication should seek clinical advice first.

How do you measure your sodium and potassium balance?

Blood panels capture the moment; 24-hour urine collections capture intake. The AGING?F***THAT! approach tracks electrolytes within a full biomarker pattern, repeated under consistent conditions, so trend beats snapshot.

DEEP DIVE: SOURCES