Prof. Marcos received her PhD from the School of Pharmacy at the Complutense University in Madrid, Spain (UCM) in 1982 and Master in Clinical Analysis by UCM in 1986 and received a grant from the Spanish National Research Council (CSIC). She was the Head of the Institute of Nutrition and Food Technology at the Mixed Center CSIC-UCM (1998-2002). She is the leader of the Immunonutrition Research Group at the Department of Metabolism and Nutrition at CSIC since 1987.

Prof. Marcos achieved the highest category at CSIC as a Research Professor in 2006 and her scientific consolidation has been recognized for 5 six-year terms since 1985.

She is a pioneer in the field of Immunonutrition in Spain, Founder and President of the International Forum of Immunonutrition for Education and Research (i-FINER) since 2007. In 2014 the i-FINER group has developed the International Society for Immunonutrition (ISIN), Dr. Marcos being also the President.

Positions performed by Prof. Marcos in Nutrition Societies:
• Spanish Nutrition Society (SEÑ): Treasurer (2010-2012), Vice-president (2007-2010), President (2003-2007), Vice-president (2001-2003), Member of the Board (1999-2003), Secretary (1997-1999);
• Federation of European Nutrition Societies (FENS): Vice-President (2015–2019), President (2011-2015), Treasurer (2007-2011);
• Federation of Spanish Societies of Nutrition, Food and Dietetics (FESNAD): President (2015-2020), Member of the Board (2003-2005),
• Spanish Society of Probiotics and Prebiotics (SEPyP): Vice-president (2009-2017)

Her research has been focused on different aspects of Immunonutrition: 1) immunomodulation properties of nutrients, bioactive compounds and functional foods, 2) evaluation of the nutritional status of healthy groups of population (especially adolescents, pregnant women, infants, children and elderly) and patients suffering from nutrition-immunity related diseases (eating disorders, overweight, obesity, celiac disease, intolerances, drug-addicts).

She has been participating in 83 research projects (66 as a leader) and 473 publications.

Since 1999 Prof. Marcos has been coordinating several multi-centre Spanish projects related to adolescent nutrition, eating disorders and obesity, funded by the Foundation for Health Research (FIS), Institute of Health Carlos III, Ministry of Health and Consumption as well as the Ministry of Education and Science or the Ministry of Science and Innovation.

The main awards and honours received by Prof. Marcos are as follows:
• The International Prize for her “Contribution to the study on nutrition and immunology” given by the Nutritional Immunology International Group in 1997.
• Since 2004 Prof. Marcos is Guest Lecturer ad-honorem at the Buenos Aires University (Chair of Nutrition. Department of Health, Nutrition, Food Technology and Toxicology. Faculty of Pharmacy and Biochemistry).
• Honorary Member of the Royal Academy of Pharmacy from Cataluña since 2011 and of the National Royal Academy of Pharmacy since January-2015
• Fellow of the International Union of Nutritional Sciences (IUNS) since 2013.
• Danone Institute Award Dr. Carles Martí Hennenberg for her Scientific Biography. December-2014.
• Honorary Member of the National Royal Academy of Pharmacy since January-2015.