The invention provides compositions and methods for radio protection and chemo prevention using therapeutic and prophylactics methods of using (S,S)-SDG (R,R)- SDG, (S,R)-SDG (R,S)-SDG, SDG, SECO, EL, ED, analogs thereof, stereoisomers thereof and other related molecules. In one aspect, the invention relates to a method for protecting a biomolecule(such as genetic material like a nucleic acid, a protein or a lipid), a cell, or a tissue, from radiation damage in a subject in need thereof, the method comprising administering to said subject an effective amount of flax seed, its bioactive ingredient, degradant or a metabolite thereof.
