SALT IN HEALTH AND PER­FOR­MANCE

Triathlon Magazine Canada - - T1 - BY PIP TAY­LOR

THE QUES­TION OF how much salt you need is both con­fus­ing and con­tentious. Salt is a prom­i­nent in­gre­di­ent in many sports nu­tri­tion prod­ucts and is con­sid­ered to be an im­por­tant fac­tor in nu­tri­tion guide­lines when it comes to hy­dra­tion and cramps. Adding to the con­fu­sion on what is ap­pro­pri­ate when it comes to salt in­take – and some­what at odds – is the decades-old mes­sage that salt is a prime cul­prit when it comes to high blood pres­sure and heart dis­ease. We’re of­ten told that we should put the shaker down. So what do we know about salt? And how much salt does an en­durance ath­lete re­ally need?

The shake down on salt

Salt is com­prised of 40 per cent sodium and 60 per cent chlo­ride. Sodium is a vi­tal nu­tri­ent: as a key com­po­nent of ex­tra­cel­lu­lar fluid, the elec­trolyte, along with potas­sium, mag­ne­sium and cal­cium, helps balance cell fluid lev­els and main­tain blood plasma vol­ume nec­es­sary for cel­lu­lar me­tab­o­lism and ab­sorp­tion. Sodium also helps reg­u­late heart con­trac­tion and func­tion. Both com­po­nents of salt – sodium and chlo­ride – are also im­por­tant when it comes to nerve sig­nalling and mus­cle con­trac­tion. The gen­eral think­ing went that if sodium in­take was high, blood pres­sure would soar, putting ex­tra strain on the car­dio­vas­cu­lar sys­tem. But over re­cent years, re­search has emerged quash­ing this ac­cepted wis­dom and re­veal­ing that, in fact, the link be­tween salt in­take and hy­per­ten­sion (high blood pres­sure) is over­stated.

Rec­om­men­da­tions still gen­er­ally ad­vise an in­take of be­low 1,500 mg of sodium per day, well be­low the av­er­age 3,400 mg in­take for most of us. But the truth is that, in healthy in­di­vid­u­als the kid­neys do a good job of reg­u­lat­ing lev­els of wa­ter and sodium (and other elec­trolytes) across a broad range of di­etary sodium in­takes. A sud­den in­crease in salt will cause a shift of fluid from in­tra- to ex­tra­cel­lu­lar fluid – help­ing to ex­plain that fluid re­ten­tion and swollen limbs we ex­pe­ri­ence after a Fri­day night feast of pizza and chips. But, over time, the kid­ney com­pen­sates and starts ex­cret­ing ex­tra sodium to match di­etary in­take. This is an im­por­tant con­cept to con­sider when talk­ing about ath­letes and so-called “salty sweaters” – the ones whose race suits and run clothes end up crusted with white salt.

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