Potassium

The VerdictMODERATE CONVICTIONWorth-It: Situational ROI (66/100)

Potassium lowers blood pressure and prevents strokes — but only if you get the dose right, and OTC supplements can't.

Switch your cooking salt. Swap regular table salt (100% sodium chloride) for a potassium-enriched version — LoSalt or NoSalt are 75% NaCl / 25% KCl. This single change is backed by a 20,000-person trial showing 14% fewer strokes and 12% fewer deaths. It costs about £3–5 per month and requires zero pills. If you take ACE inhibitors, ARBs, or water tablets — get a blood test first.

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The Plain English Version

Potassium genuinely lowers blood pressure and prevents strokes — but only if you get the dose right, and OTC supplements can't deliver it.

Potassium is an essential mineral your body uses to balance every cell — found naturally in bananas, potatoes, avocados, and most vegetables. Think of it as a counterweight to sodium: when you eat too much salt, your body holds onto fluid and your blood vessels tighten. Potassium tells the kidneys to flush sodium out and helps the blood vessel walls relax. The key insight from the last decade of research is that it's not about hitting a specific potassium number — it's about fixing the ratio of sodium to potassium in your diet. And the most effective way to do that isn't a capsule — it's changing what salt you cook with.

1 The verdict: Potassium genuinely reduces blood pressure and cuts cardiovascular risk — a 20,000-person trial over five years found that switching to potassium-enriched salt reduced strokes by 14% and deaths by 12%.
2 What most people get wrong: OTC potassium capsules at pharmacies are legally capped at 99mg per serving — less than 3% of the therapeutic dose — because high-dose solid tablets caused small-bowel injuries in the 1960s. These pills cannot produce the effects the trials showed.
3 Start here: Replace regular table salt with a potassium-enriched cooking salt (75% sodium chloride / 25% potassium chloride) for all home cooking. That's one swap, costs about £3–5 per month, and is the exact intervention in the landmark trial.

Best for

Adults with high blood pressure eating a high-sodium Western diet; anyone wanting to reduce cardiovascular risk; recurrent kidney stone formers (potassium citrate, separately).

Skip if

You have CKD, take ACE inhibitors, ARBs, or spironolactone — get medical clearance first. Healthy adults already eating plenty of vegetables and minimal processed food likely don't need to do anything extra.

Want the full evidence? Keep scrolling. ⌄

What to actually take

The Protocol

Dosing by Population

Population	Approach	Daily Target	Form	Source
General adults (cardiovascular protection)	Switch table salt → potassium-enriched salt (75% NaCl / 25% KCl)	3,400–3,500 mg/day (men); 2,600–3,500 mg/day (women)	LoSalt / NoSalt / potassium-enriched cooking salt	NASEM 2019; SSaSS 2021
Adults with hypertension	Salt substitution + high-vegetable diet	>3,500 mg/day total; ~1,170 mg supplemental above baseline	Potassium-enriched salt, dietary increase	EFSA 2016; Poorolajal 2017
Recurrent kidney stone formers (calcium oxalate)	Prescription K-citrate — requires urologist assessment	30–60 mEq/day (1,170–2,340 mg K)	Potassium citrate (prescription)	Soygur 2002; AUA guidelines
Keto / very-low-carb dieters	Daily supplemental replacement (insulin-driven renal losses)	2,000–3,000 mg/day supplemental	Potassium bicarbonate or citrate powder	Metabolic ward studies

Forms Comparison

Form	Bioavailability	GI Tolerance	Best For	Notes
Potassium-enriched salt (KCl + NaCl blend)	~94%	Excellent (via food)	Cardiovascular protection, BP management	Highest-evidence intervention; replaces table salt directly
Potassium citrate	~94%	Moderate	Kidney stone prevention, bone health, alkaline load	Alkalinises urine; reduces urinary calcium; prescription at therapeutic doses
Potassium bicarbonate	~94%	Moderate	Bone health, reducing urinary calcium, keto	Provides alkaline anion; dissolves easily in water
Potassium gluconate	~94%	Good	General supplementation	Gentler on the stomach than KCl; lower K density per gram
OTC potassium capsules (99mg)	~94%	Excellent	Clinically: nothing meaningful	FDA cap = <3% of therapeutic dose per serving; cannot produce BP effects
Food (potato, banana, avocado)	~94%	Excellent	All populations; DASH-pattern eating	Comes with fibre, Mg, Ca matrix — superior to isolated K supplements

Absorption tips

Bioavailability is not the problem — potassium absorbs at ~94% from all forms. The limiting factor is dose, not absorption.
The co-anion determines the additional benefit: KCl is best for BP and hypokalemia correction. K-citrate and K-bicarbonate add alkalinising effects — better for bone health and kidney stones.
Fix magnesium first if supplementation isn't working. Mg deficiency leaves the renal ROMK channel open, causing continuous K+ wasting in urine. Potassium supplementation without adequate Mg is largely futile in Mg-deficient states.
Spread doses across meals to minimise GI side effects at higher intakes.
Avoid solid high-dose KCl tablets — historical association with small-bowel ulceration. Powder, liquid, or food-form is safer.

Safety first

Safety & Interactions

⚠ Critical Interaction Warning

If you take ACE inhibitors (lisinopril, ramipril), ARBs (losartan, valsartan), potassium-sparing diuretics (spironolactone, amiloride), or have chronic kidney disease — do NOT increase potassium intake without a blood test first. These conditions impair your kidneys' ability to excrete potassium, making hyperkalemia (dangerously high blood potassium) a real risk. Severe hyperkalemia can cause fatal cardiac arrhythmias.

Drug Interactions

Medication	What Happens	Severity	Action
ACE inhibitors (lisinopril, ramipril)	Suppresses aldosterone → reduces renal K+ excretion → hyperkalemia risk	Severe	Monitor serum K+ if switching to potassium-enriched salt; avoid high-dose K+ supplements
ARBs (losartan, valsartan)	Blocks angiotensin II → aldosterone suppression → K+ retention	Severe	Same as ACE inhibitors — medical supervision required
K-sparing diuretics (spironolactone, amiloride)	Blocks epithelial Na channels or aldosterone receptors — profound hyperkalemia risk	Potentially Fatal	Potassium supplements and potassium-enriched salt are CONTRAINDICATED
NSAIDs (ibuprofen, naproxen)	Reduces GFR, impairs K+ elimination; triples hyperkalemia risk when combined with RAAS drugs or CKD	Severe	Avoid potassium loading with chronic NSAID use; especially dangerous with spironolactone
Digoxin	K+ and digoxin compete for Na+/K+-ATPase. Hypokalemia → fatal digoxin toxicity. Hyperkalemia → digoxin inefficacy.	Severe (both directions)	Maintain serum K+ strictly at 3.6–5.0 mmol/L; no unsupervised supplementation
Loop diuretics (furosemide)	Causes continuous K+ wasting (hypokalemia) — opposite direction	Moderate	Supplementation may be required — but only under medical supervision
Magnesium (deficiency)	Mg required to block ROMK channel — deficiency causes refractory K+ wasting in urine	Moderate	Correct Mg deficiency first; K+ supplementation without Mg will fail in Mg-deficient states

Contraindicated Populations

CKD Stage 3–5: Impaired glomerular filtration severely limits potassium excretion — even dietary increases can be risky
Potassium-sparing diuretic users (spironolactone, amiloride, triamterene): Aldosterone blockade + K loading = potentially fatal hyperkalemia
Type 4 renal tubular acidosis / hyporeninemic hypoaldosteronism: Impaired K handling regardless of GFR
Uncontrolled diabetes with renal involvement: High risk of hyperkalemia with any additional potassium load

Upper Limit

No tolerable upper intake level (UL) has been established by NASEM or EFSA for dietary potassium in healthy adults — normal kidneys efficiently excrete excess. The concern is entirely with supplemental forms in people with impaired renal excretion.

Clinical hyperkalemia threshold: serum K+ >5.0 mmol/L. Life-threatening: >6.0 mmol/L (cardiac arrest risk).

How confident are we?

MODERATE

The evidence for blood pressure and cardiovascular effects is HIGH — but only via dietary potassium and salt substitutes. OTC supplement pills (99mg) cannot deliver the therapeutic dose. Overall conviction is capped at MODERATE because the delivery mechanism consumers typically choose is ineffective.

BP reduction
(hypertensives)

HIGH

CVD events
(salt substitute)

HIGH

Kidney stones
(K-citrate)

HIGH

BP prevention
(normotensives)

MODERATE

OTC pills
(99mg)

LOW

What would change this verdict

To upgrade OTC supplementation from LOW to HIGH: a 5-year multi-centre RCT (N>10,000) comparing dietary salt substitution vs. high-dose oral potassium powder (not the capped 99mg tablets) showing equivalent MACE and stroke reduction. This would establish isolated oral supplementation as a viable alternative to salt substitution — a question the current trial base hasn't answered.

Supplement spending

Worth Your Money?

Weekly cost £0.75–1.25/week for potassium-enriched salt (replaces your regular table salt — same usage, slightly higher cost). OTC capsules: £2–3/week for a clinically irrelevant dose.

Worth it if You eat a high-sodium diet, have high blood pressure, or want to meaningfully reduce cardiovascular risk. The evidence here is about as strong as supplement research gets — a 20,000-person trial with hard clinical endpoints (stroke, death).

Lower priority if Your diet is already rich in vegetables, legumes, and minimal processed food — you're likely getting adequate potassium. Spending money on OTC capsules is a lower priority than any dietary change that increases fruit and vegetable intake.

Conditional Value

References

Sources

Neal B et al. (2021). Effect of Salt Substitution on Cardiovascular Events and Death. N Engl J Med. N=20,995. SSaSS trial: 14% stroke reduction, 12% mortality reduction with 75% NaCl/25% KCl vs 100% NaCl over 4.74 years.
Wu Y et al. (2024). Salt Substitute and Incident Hypertension in Normotensive Older Adults. J Am Coll Cardiol. N=609, 2yr follow-up. 40% reduction in new-onset hypertension (HR 0.60, 95% CI 0.39–0.92).
Poorolajal J et al. (2017). Oral Potassium Supplementation for Management of Primary Hypertension. Int J Prev Med. Meta-analysis of 23 RCTs, N=1,213. SBP: -4.25 mmHg (95% CI -5.96 to -2.53); DBP: -2.53 mmHg (95% CI -4.05 to -1.02).
O'Donnell M et al. (2014). Sodium-to-Potassium Ratio and Blood Pressure, Hypertension, and Related Factors. Adv Nutr. Na:K urinary ratio superior to either mineral alone for blood pressure prediction in hypertensive populations.
He FJ et al. (2010). Potassium Chloride and Potassium Bicarbonate — Effect on Endothelial Function, Cardiovascular Risk Factors, and Bone Turnover. Hypertension. N=42. Crossover trial: KCl reduced albuminuria; K-bicarbonate reduced urinary calcium and bone resorption markers.
Soygur T et al. (2002). Potassium Citrate Treatment in Calcium Oxalate Stone Formers. J Endourol. N=90. 0% stone recurrence with 60 mEq/day K-citrate vs 28.5% control at 12 months post-SWL.
NASEM (2019). Dietary Reference Intakes for Sodium and Potassium. Adequate Intake: 3,400 mg/day (men 19+), 2,600 mg/day (women 19+). No UL established.
EFSA Panel (2016). Dietary Reference Values for Potassium. EFSA Journal. Adequate Intake: 3,500 mg/day for adults. Consistent with NASEM. No tolerable upper intake level established for dietary potassium.

Action ROI

Is this worth your time, money, effort, risk, and trust for this goal? Different from Verdict Score (evidence strength) and Leverage Map (relative importance) — Action ROI is the worth-it call once friction is priced in.

Action ROI score

66/100 Situational ROI Trust grade B

Yes, but as a salt swap, not a pill. Switching to potassium-enriched salt has strong evidence; the 99mg capsules sold for blood pressure are too weak to do anything.

Time

Low

Money

Low

Effort

Low

Risk

Medium

Why this score

Trust is high for the salt-substitute route (grade B): the SSaSS trial (Neal 2021, N=20,995, about 5 years) and a 23-RCT meta-analysis (Poorolajal 2017, N=1,213) are strong, but the strongest outcomes come from the dietary swap, not from the supplement most people buy.
Benefit is meaningful where it applies: minus 4.25 mmHg systolic and minus 2.53 mmHg diastolic in hypertensives (Poorolajal 2017), and 14 percent fewer strokes, 12 percent fewer deaths via salt substitution (Neal 2021).
Time and effort are minimal: swap one salt for another in cooking, no pills, no daily timing.
Money is low: a potassium-enriched salt runs roughly $4 to $8 a month and replaces the salt you already buy, so the net cost is near zero.
Risk is medium and the gating factor: in people on ACE inhibitors, ARBs, potassium-sparing diuretics, or with CKD, potassium loading can cause life-threatening hyperkalemia, so a blood test comes first for those groups.

Why it didn’t score higher

The supplement form people actually reach for (99mg OTC capsules) is clinically futile for blood pressure because the FDA caps the dose; the win requires a different action than most expect.
The medication and kidney interactions are serious enough that this is not a blanket-safe recommendation; a meaningful slice of hypertensives are on exactly the drugs that make it risky.
Effect size, while real, is modest (a few mmHg) and works best stacked with overall sodium reduction, not alone.

Best for

Adults with essential hypertension on a typical Western (high-sodium) diet who can switch to potassium-enriched salt
Recurrent calcium oxalate kidney stone formers (potassium citrate is first-line, 0 percent vs 28.5 percent recurrence at 12 months, Soygur 2002, N=90, prescription)
Normotensive older adults wanting prevention (salt substitution cut new-onset hypertension 40 percent, Wu 2024, N=609)

Lower ROI if

You are on an ACE inhibitor, ARB, or potassium-sparing diuretic (spironolactone, amiloride) without medical clearance
You have CKD stage 3 to 5 or undiagnosed kidney impairment
You rely on 99mg OTC capsules and expect a blood pressure effect
Your magnesium is low and uncorrected, which makes the kidneys waste supplemented potassium

Minimum effective dose

Replace table and cooking salt with a potassium-enriched salt (75 percent sodium chloride, 25 percent potassium chloride, e.g. LoSalt, NoSalt); no specific milligram target needed. For kidney stones, potassium citrate 30 to 60 mEq/day by prescription. OTC 99mg capsules do not reach a therapeutic blood pressure dose.

Track this

Home blood pressure over 4 to 8 weeks after switching salt
For anyone on RAAS drugs or with kidney concerns: a serum potassium check before and after starting

Potassium lowers blood pressure and prevents strokes — but only if you get the dose right, and OTC supplements can't.

The Protocol

Dosing by Population

Forms Comparison

Absorption tips

Safety & Interactions

⚠ Critical Interaction Warning

Drug Interactions

Contraindicated Populations

Upper Limit

Worth Your Money?

Every week, one supplement. The real evidence.

Sources

Action ROI

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