Procedure for obtaining fatty acids of pharmacological and nutritional interest comprising the steps of: a) feeding a gas or mixture of gases comprising CO 2 into a reactor containing a culture that comprises at least one species of microalgae capable of photosynthesis; b) photosynthesis by the species of microalgae using the CO 2 supplied, producing a biomass containing the general formula compound: wherein: A and X are equal or different independently and are selected from alkyl C 3 -C 10, alkenyl C 1 -C 10, cycloalkyl C 1 -C 7 or any substituted or unsubstituted aryl group; n is an integer from 1 to 10; R is selected from H, a hydroxyl group, alkyl C 1 -C 4, alkenyl C 1 -C 3, cycloalkyl C 3 -C 7 or any substituted or unsubstituted aryl group; W is selected from the group consisting of a hydroxyl group, a glycerol molecule bound to an additional general formula compound forming a diglyceride, or a glycerol molecule bound to two additional general formula compounds forming a triglyceride; and their salts, and solvates; c) extraction of the general formula compound from the biomass obtained in step b); and d) concentration and/or purification of the general formula compound from the extract obtained in step c); characterised in that, after the photosynthesis step, between 5 and 100% of the culture is removed from the reactor, which is then separated in a solid fraction that contains biomass, which biomass subsequently undergoes the step of extracting the general formula compound and a liquid phase fraction that contains carbonates and/or bicarbonates, which are separated from the liquid fraction, after which the liquid fraction substantially free of carbonates and/or bicarbonates is then returned at least partially to the reactor. a) feeding a gas or mixture of gases comprising CO 2 into a reactor containing a culture that comprises at least one species of microalgae capable of photosynthesis; b) photosynthesis by the species of microalgae using the CO 2 supplied, producing a biomass containing the general formula compound: wherein: A and X are equal or different independently and are selected from alkyl C 3 -C 10, alkenyl C 1 -C 10, cycloalkyl C 1 -C 7 or any substituted or unsubstituted aryl group; n is an integer from 1 to 10; R is selected from H, a hydroxyl group, alkyl C 1 -C 4, alkenyl C 1 -C 3, cycloalkyl C 3 -C 7 or any substituted or unsubstituted aryl group; W is selected from the group consisting of a hydroxyl group, a glycerol molecule bound to an additional general formula compound forming a diglyceride, or a glycerol molecule bound to two additional general formula compounds forming a triglyceride; and their salts, and solvates; A and X are equal or different independently and are selected from alkyl C 3 -C 10, alkenyl C 1 -C 10, cycloalkyl C 1 -C 7 or any substituted or unsubstituted aryl group; n is an integer from 1 to 10; R is selected from H, a hydroxyl group, alkyl C 1 -C 4, alkenyl C 1 -C 3, cycloalkyl C 3 -C 7 or any substituted or unsubstituted aryl group; W is selected from the group consisting of a hydroxyl group, a glycerol molecule bound to an additional general formula compound forming a diglyceride, or a glycerol molecule bound to two additional general formula compounds forming a triglyceride; and their salts, and solvates; c) extraction of the general formula compound from the biomass obtained in step b); and d) concentration and/or purification of the general formula compound from the extract obtained in step c);