Question: why do people become sad for no reason?

Tatiana Trantidou answered on 24 Jun 2015:

There is a specific chemical produced in our brains, called serotonin. Serotonin is mainly responsible for the level of our happiness. If there is not enough serotonin produced in our brain, we feel sad. The production of serotonin is closely linked to the availability of vitamin B6 (found in meat, fish, poultry, cereals and legumes) and the amino acid tryptophan. So, if our diet is poor in vitamins and proteins, our body cannot produce enough serotonin. On the other hand, if we eat a meal packed with protein, the levels of serotonin will also drop. This happens because when we eat a high-protein meal, our blood is flooded with both tryptophan and its competing amino acids. They are all fighting for entry into the brain. This means that only a small amount of tryptophan gets through and as a result not enough serotonin will be produced.