Dietary guidelines emphasizes the importance of a varied diet to provide an adequate nutrient intake. However, the aging is often associated with consumption of monotonous diets that can be nutritionally inadequate, increasing the risk for the development or progression of diet-related chronic diseases such as the metabolic syndrome (MetS). To assess the relationship between dietary diversity (DD) and nutrient adequacy and to identify associated demographic variables related with DD. We analysed cross-sectional baseline data from the PREDIMED-Plus study: 6587 Spanish adults, aged 55–75 years, with overweight/obesity and MetS. Using a 143-item validated semi-quantitative food frequency questionnaire (FFQ), we calculated an energy-adjusted score of DD (DDS). Nutrient inadequacy was defined as an intake below 2/3 of the recommended dietary intake at least of ≥4 of 17 nutrients. Logistic regression models were used to evaluate the relationship between nutritional inadequate intakes and DDS. In the higher DDS quartile there were more women and less current smokers. Compared with subjects in the highest DDS quartile, those in the lowest DDS quartile had a higher risk of inadequate nutrient intake OR=28.56 (95% C.I. 20.80-39.21). When we estimated diversity for each one of the food groups, participants in the first quartile of diversity had a higher risk of nutrient deficiency: for vegetables, OR= 14.03 (IC 95% 10.55-18.65), fruits OR=11.62 (IC 95% 6.81-19.81), dairy products OR= 6.54 (IC 95% 4.64-9.22) and protein foods OR=6.60 (IC 95% 1.96-22.24). As DDS decreases, the risk of inadequate nutrients intake rises. Given the impact of nutrient intake adequacy on the prevention of non-communicable diseases, health policies should focus on the promotion of a healthy varied diet, specifically promoting the intake of vegetables and fruit among population groups with lower DDS such as men, smokers or widow people.