The natural isomers of resveratrol, cis‐ and trans‐resveratrol, are natural phenolic substances synthetized via the shikimate pathway and found in many sources, including grapes, peanuts, blackberries, pistachios, cacao, cranberries, and jackfruits. They have functional and pharmacological properties such as anticarcinogenic, antidiabetic, anti‐inflammatory, and cardioprotective activities. The aim of this article is to review the data published on resveratrol and its isomers, and their biosynthesis in plants, food sources, health and toxic effects, and the excretion of their metabolites. Due to its contribution to the promotion of human health, it is convenient to gather more knowledge about its functional properties, food sources, and the interactions with the human body during the processes of eating, digestion, absorption, biotransformation, and excretion, to combine this information to improve the understanding of these substances. Resveratrol is a natural substance found in many plant species. Its main function is to protect these plants against infections and harmful stimuli. To humans, it represents an essential nutrient, as it can only be obtained through eating and digestion. The aim of this review is to study its pathways of synthesis in plants and its dietary sources, and to consider the biochemical processes and transformations during digestion, focusing on the pharmacologic effects of its two isomers: cis‐ and trans‐resveratrol.