Salt in the athlete’s diet – the whole truth
[Aticle translated by Google – Google Translate]
Sodium is an essential element and in the right amount is crucial for the maintenance of water and electrolyte homeostasis. It is the main cation of extracellular fluid. Its primary function is to maintain fluid balance in the body and provide transport for many key substances. The salt consists of about 40% sodium, 60% chloride and possible trace elements. It is commonly accepted that salt retains water in the body. It could also be common answer – in the right amount the salt reduces the water retention, and does not cause it – an explanation later in the article. The diet of the typical “Janusz” consists of an excess of salt, which results in an increased risk of hypertension, cardiovascular diseases, and autoimmune diseases caused by osmotic stress. (1, 2) The physical activity of the average “Kowalski” is negligible. A typical “western diet” consists of highly processed, pro-inflammatory products, it is often deficient in potassium, so salt intake is not the only risk factor for these diseases. Current guidelines to limit sodium intake to below 2,300 mg per day can potentially lead to side effects caused by deficiency of this element. (3)
The demand of athletes is a completely different story (4) During trainings there is a significant loss of water and electrolytes (5), which drastically raises the bar of demand for individual mineral components. The loss of sodium during training reaches even more than 1500 mg per liter of sweat. (6) Sodium is necessary for the proper functioning of the sodium-potassium pump. The difference in sodium and potassium concentrations on both sides of the cell membrane allows the potential of the membrane to arise, resulting in functions such as the transmission of nerve impulses and the contraction and relaxation of muscle cells. Sodium deficiency can cause muscle cramps, as does the lack of other electrolytes. (7, 8) The demand will vary depending on many external factors. (9) In the case of athletes, sodium is particularly important – it is necessary in the rehydration process. Already 2% dehydration results in deterioration of the athlete’s exercise parameters (10)
Loss of water and electrolytes during physical activity can be compounded by high ambient temperature. (11) Consuming significant amounts of low mineralized water results in a rapid reduction in serum sodium, which leads to a reduction in vasopressin release and an increase in urine volume over a short period of time. This is the reason why the strategies of “water loading” are an effective method of rapid weight loss, (12) and we owe this to the densities of aquaporin channels in the cell membrane of the renal tubular epithelium even after the increase in vasopor- itin after cessation of fluid intake. Long-term, low sodium supply will have the opposite effect – activates the renin-angiotensin-aldosterone system. Decreasing sodium concentration will increase water retention too much by increasing aldosterone levels. Lots of players reduce their intake of salt long before weighing, and then wonder why they can not dehydrate effectively … A gradual increase in aldosterone levels occurs only after 24 hours after discontinuation of sodium (13), therefore, using strategies to keep the sodium supply high we are able to effectively keep the levels of aldosterone low and make our dehydration more effective.
Strong activation of the RAA system adversely affects insulin sensitivity. (14, 15) Angiotensin II and aldosterone activate nicotinamide dinucleotide phosphate (NADPH) dinucleotide oxidase to produce reactive oxygen species. Activation of redox-sensitive serine kinases, such as JNK and ERK-1 kinases, leads to phosphorylation of serine in the IRS-1 receptor substrate and decreased interaction with phosphatidylinositol 3-kinase (PI3K). This in turn leads to the reduction of protein kinase B (Akt) and PKC activity, reduction of GLUT4 translocation to the membrane and reduction of glucose transport, therefore maintaining the appropriate concentration of individual electrolytes affects the proper glucose metabolism. Effective loading of carbohydrates and recuperation of the player after weighing is therefore dependent on the appropriate rehydration and supplementation of electrolytes. The digestive system of a dehydrated athlete is unable to properly secrete digestive enzymes. An inseparable element of recuperation should be an individually prepared hydration plan by using products with the right amount of minerals and appropriate osmolality. The balance of individual electrolytes during recuperation should depend on the diet for the period of loading and on the intake of possible intravenous infusions. Only properly hydrated body will be able to effectively metabolize glucose, thanks to the efficiency of sodium-dependent glucose transporters – SGLT. (16)
It really does not really matter what kind of salt you will use … I recommend using high quality natural rock salt, for example, Kłodawa or Himalayan, due to the content of trace elements and the lack of anti-caking agents. The difference is however marginal, so not everyone has to overpay. Taking into account standards for the Polish population and recommendations from the USA, the basic demand for sodium for the average “Smith” is 1500-2300 mg (1 mg sodium = about 2.5 mg salt). During the effort, the athlete loses significant amounts of sodium with sweat and there are large discrepancies here. The 2017 study showed that sodium loss among team sports riders ranges from 400 mg to 2000 mg per liter of sweat. (6) In another NFL experiment, the concentration of sodium loss was 642 mg – 6.7 g / an hour which is a huge difference between individuals. (17) First of all, the competitor should estimate the amount of sodium lost with sweat based on his own observations, external factors such as ambient temperature. Then, estimate the amount of sweat lost during physical activity. In order to estimate sweat loss, the formula -> Sweat loss (ml) = weight loss during training (g) + amount of water consumed during training (ml) – amount of urine expelled (g) can be used. I suggest you follow the basic recommendations for the general population and add to this the estimated loss of sodium during training. When designing a diet that meets the demand for sodium, it is worth paying attention to the high sodium content in processed foods.
Sources: (1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4105387/ (2) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4034518/ (3) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4188229/ (4) https://www.ncbi.nlm.nih.gov/pubmed/17617999 (5) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2902030/ (6) https://jissn.biomedcentral.com/articles/10.1186/s12970-017-0197-4 (7) https://www.ncbi.nlm.nih.gov/pubmed/17465610 (8) https://www.ncbi.nlm.nih.gov/pubmed/16521848 (9) http://journals.lww.com/acsm-csmr/Fulltext/2014/07000/The_Salt_Paradox_for_Athletes.2.aspx (10) https://www.ncbi.nlm.nih.gov/pubmed/22808714 (11) https://www.ncbi.nlm.nih.gov/pubmed/12801207 (12) https://www.ncbi.nlm.nih.gov/pubmed/29182412 (13) http://hyper.ahajournals.org/content/hypertensionaha/15/4/376.full.pdf (14) https://www.ncbi.nlm.nih.gov/pubmed/21880378 (15) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3551270/ (16) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3935955/ (17) https://www.ncbi.nlm.nih.gov/pubmed/20617911