The effect of eliminating all animal (meat and fish) products except eggs and milk products from the current Spanish-Mediterranean diet was studied in 14 healthy subjects. This dietary manipulation decreased saturated and monounsaturated fat, protein, and cholesterol intakes. During the 2-month intervention period, a decrease in total plasma cholesterol concentrations (4.53+/-0.13 vs. 4.29+/-0.13 mmol/l, p <0.05) was observed, mostly as a result of decreased high-density lipoprotein cholesterol levels (1.66+/-0.08 vs. 1.47+/-0.08 mmol/l, p <0.05). The decrease in low-density lipoprotein cholesterol levels (2.51+/-0.15 vs. 2.43+/-0.13 mmol/l) did not reach statistical significance. Nevertheless, there was a significant association between the decrease in cholesterol intake and the decrease in low-density lipoprotein cholesterol levels (r=0.719, p <0.01). The decrease in protein intake was also correlated with the decrease in total cholesterol levels (r=0.629, p <0.05). Body weight and lean body mass were not modified during the study. Maximal aerobic power and maximal oxygen consumption were not significantly affected by the diet manipulation. In conclusion: a 2-month change from the current Spanish-Mediterranean diet to an ovolactovegetarian diet in young healthy persons Plasma lipids decreases total plasma cholesterol levels, but mainly due to a decrease in Physical exercise high-density lipoprotein cholesterol levels.