Abstract The composition of pork loin can be modified by nutritional means to improve the nutritional quality of its fatty acid composition. The effects of a modified diet – enriched mainly in n-3 fatty acids – on fat composition in several anatomical locations in the loin is described here. Saturated fatty acid content was reduced to less than one third of total fatty acids. n-6/n-3 ratio was reduced from about 17 to less than 5. Polyunsaturated fatty acids were reduced to less than 30% of total fat. The effects of several variables such as sex, weight, individual and IGF2 and RYR1 genotypes on loin composition are studied. In an effort to establish a labelling strategy that emphasizes the healthy nutritional properties of pork meat, a statistical model that makes it possible to estimate fat composition and quantity is presented.