Thread by @captainchloride

How much salt is not enough?

The most common dietary rec made by physicians is sodium restriction

But to what extent?

Is an overly sodium restricted diet harmful? Especially in HF?

🔥Grab a salted pretzel and read on
#medtweetorials #nephtwitter #cardiotwitter #MedTwitter

What degree of sodium restriction to you recommend to your heart failure patients?

🔥🧂 is important

💥🧂 conservation during human evolution from sea to land was vital

In the book From Fish to Philosopher, Homer Smith wrote “The tenacious conservation of salt is one of the most primitive - if not the most primitive - of functions in the vertebrate kidney"

Throughout history🧂has triggered wars and protests

💥Roman soldiers were paid in🧂(as were American soldiers in 1812)
💥Where we got the word “salary" 💰

💥Now? There is no shortage of 🧂

👉Dietary Na intake in US adults-3660mg
👉Dietary Na intake worldwide-3660-4000mg

Major societies differ regarding Na restriction recs

CDC: <2300mg
AHA: <1500mg
WHO: <2000mg

🔥We know ⬇️Na diets = clear benefit in HTN

🔥Cochrane review (185 studies)
💥⬇️ mean Na from a whopping 11.5g➡️3.8d =
💥⬇️SBP/DBP of 1/0 if normotensive and 5.5/2.9 if hypertensive

🔥Low Na DASH diet

💥Near linear BP improvement with low Na diet (1.1g) v intermediate (2.3g) and high (3.5g) Na diets

💥The effects of dietary sodium restriction on BP appear to be heterogenous with older, hypertensive and African American patients deriving the most benefit

How does this translate to actual CV outcomes?
🔥Data isn't as clear

💥One observational study in JAMA assessed effects of Na restriction and CV events in 2 cohorts at high risk of CV disease
👉jamanetwork.com/journals/jama/…

💥Found a J-shaped curve with <3g Na intake = ⬆️CV events

The PURE study, published in the NEJM found nearly identical results

👉pubmed.ncbi.nlm.nih.gov/25119607

🔥majority of participants with no CV disease
🔥also saw ⬆️ in CV events with a <3g sodium restricted diet

The problem?
💥Used AM urine collections to est. 24h Na excretion via the Kawasaki formula

Apparently validated here
👉pubmed.ncbi.nlm.nih.gov/8432042/

💥Important because >90% of dietary is Na excreted in urine

💥Shown in this systematic review
👉onlinelibrary.wiley.com/doi/epdf/10.11…

🔥The TOHP study, which utilized 24h urine collections for assessment of Na intake:

💥Did not see a J shaped curve
💥Instead found a significant ⬇️ in CV events ➡️ even at the lower end of Na intake

Read it here
👉ahajournals.org/doi/epub/10.11…

🔥Why would Na restriction cause problems?

💥The Cochrane study above showed ⬆️ neurohumoral activation with ⬇️🧂 intake

🔥But is this really harmful?
💥The Yanomami were shown to consume <1g (!) of Na in the INTERSALT study
💥have sky high aldo/renin levels
💥but no ⬆️ in CVD

🔥How about pts vulnerable to NH activation, i.e CHF pts?

Paterna et al randomized 232 pts w/HFrEF
💥30d post hosp. d/c
💥2.7g vs 1.8g Na diets
💥Both received diuretics +1L🥤restric + GDMT

🔥⬆️Na group had ⬇️BNP, hospital readmissions and mortality
👉pubmed.ncbi.nlm.nih.gov/19101237/

🔥Another RCT by Parrinello w/173 pts
💥compensated HFrEF
💥2.7g vs 1.8g Na diets
💥30d post hosp. d/c
💥Both groups 1L 🥤 restric.+diuretics+GDMT

🔥Pts in the 1.8g Na group had ⬆️renin, aldo, inflammatory cytokines and hospital readmissions

👉pubmed.ncbi.nlm.nih.gov/19944363/

🔥To be clear the above studies (and societal guidelines) discuss Na restriction
💥Na can be consumed in various forms BUT

👉study …-nih-gov.offcampus.lib.washington.edu/1910064/

💥showed that table salt (NaCl) provides 90% of dietary sodium

💥So we are really talking about both Na AND Cl-

🔥The HF studies above have issues
💥Same research group
💥? duplication of data between studies
💥Rigid diuretic protocol, i.e ⬇️ Na intake with same diuretic dose = ⬆️ r/o hypovolemia

🔥BUT theoretically possible that ⬇️🧂(to a degree) = ⬆️NH activation➡️bad outcomes in CHF

🔥⬆️Na clearly has detrimental effects
💥⬆️NOX-4 + VEGF
💥⬇️NO
💥⬆️myocardial hypertrophy and glomerular fibrosis

🔥But💡⬇️ Cl- is harmful in CHF pts. 👇 and the same principal may apply here!
💥Maybe ⬇️ Cl- by⬇️🧂= ⬆️ NH activation = bad outcomes

https://twitter.com/captainchloride/status/1297897935045181441?s=20

🔥While I’m not ready to advocate for my heart failure patients to liberally use their🧂shaker

It's at least food for thought...

Thanks to @christinelimont for help with this