Therefore, it remains unclear whether resveratrol supplementation would benefit humans although its toxicity appears low. Other putative energy restriction mimetics, for example, metformin and rapamycin are used as pharmaceutical drugs but rapamycin in particular can cause severe side effects such as immunosuppression and thus is not suitable for supplementation in healthy humans. So far, interesting energy restriction mimetic candidate substances have been identified and it is feasible that there are more bioactives with such properties to be found in different diets which merit further research.