The concentration of micronutrients in foods has decreased by 30% over the last 50 years. Micronutrition will be one of the next important topics in the Bloooness guide.
4 coffees a day = ½ teaspoon of salt lost in urine. 1 hour of sport = ½ teaspoon of salt lost. In this case, you'd need 1 teaspoon full of salt just to recover the lost salt.