The amaranth grain storage proteins contain a series of encrypted amino acid sequences that exhibit different physiological activities when they are released. These include antihypertensive, antithrombotic, and antioxidant activities. Different researchers have focused their interest in these activities. In this chapter, the main results achieved will be discussed. Amaranth peptides are able to inhibit angiotensin converting enzyme (ACE) and renin enzymes, main regulators of the renin-angiotensin-aldosterone system (RAAS), and affect the local RAAS. These effects induce a significant reduction in systolic blood pressure in hypertensive animal systems. Amaranth peptides obtained by simulated gastrointestinal digestion have the ability to inhibit in vitro blood clot formation, exerting their action over thrombin enzyme or fibrinogen polymerization. Studies carried out with rats fed with amaranth protein isolate showed a decrease in the coagulation parameters, indicating that the digestion of amaranth proteins releases peptides with antithrombotic effect in the bloodstream. Moreover, gastrointestinal digests and peptide fractions are able to inhibit or retard in vitro Cu⁺²/H₂O₂-induced low-density lipoprotein oxidation, this oxidation being the initial cause of the formation of in vivo atheromas. When amaranth is consumed by Wistar rats, some improvements in the oxidative status of the liver are registered.