The hormone system works like a wireless transmission system whose messenger substances are the hormones. Hormones control many processes in our organism (e.g. the metabolism of muscles, bones and tissues during the growth phase, reproductive processes and the mineral and nutrient balance). Hormones work in very small doses and even small fluctuations in concentration can have widespread effects. Plants form and provide us humans with many nutrients that we cannot form ourselves: plants also contain so-called secondary plant substances. These can only be formed in plants. They can play a crucial role in maintaining an intact hormone balance. The collective term "secondary plant substances" covers more than 30,000 different substances. Among the most important representatives we count the flavonoids, the isoflavonoids, the carotenoids, the saponins and the lignans. Secondary plant substances perform a variety of protective functions in the human body. Secondary plant substances can strengthen the immune system, protect the body from free radicals and regulate the hormone balance. The more extensively we supply our body (through fruit, vegetables, salads and food supplements) with secondary plant substances, the more resistant and vital it is, the better our quality of life.