All sauerkraut takes is shredded cabbage, salt and a container sealed from the air. Salt draws water out of the cabbage and holds back unwanted microbes, while lactic acid bacteria naturally present on the leaves turn its sugars into lactic acid. The acidity rises until it blocks most harmful germs. The same lacto-fermentation gives us Korean kimchi and some traditional pickles.
Chlorine on its own is fairly gentle. But when it combines with urine, sweat and other grime from swimmers, it forms chloramines, which cause stinging eyes and that classic 'chlorine smell'. A well-kept pool barely smells at all. Shower before you swim and never pee in the water.
Muscle mass slowly shrinks with age, putting independence at risk. But in 1990, a study had nursing home residents aged 86 to 96 train their legs for eight weeks: their strength more than doubled. Muscle responds to training at any age. Getting up from a chair without using your hands is already an exercise.