The remarkable longevity of people in specific regions of Portugal, whose diets are based on whey cheese, has puzzled researchers for quite some time. Our data indicate that several oligopeptides are released from glycomacropeptide (originated in kappa-casein) and alpha-lactalbumin - and one surprisingly from beta-lactoglobulin, by plant proteases previously used in cheesemaking. A few of such peptides (e.g. DKVGINYW, KGYGGVSLPEW and DAQSAPLRVY) exhibit unusually strong antihypertensive roles in vitro, following generation in situ or synthesis de nova. The activities of the latter two are not significantly affected by simulated gastrointestinal digestion, despite undergoing partial hydrolysis. This piece of information is rather promising toward more comprehensive attempts to scientifically rationalise this Portuguese Paradox.