The invention is a method for reducing the viral and microbial content of biological extracts which contain solids. The method comprises the steps of, (1), providing a biological extract which contains solids that comprise a biologically active substance, selected from enzymes, proteins and peptides, or a mixture of such substances; and (2) subjecting the biological extract to a high-pressure treatment; wherein the biological activity of the biological extract after the high-pressure treatment is at least 50% of the biological activity of the biological extract before the high-pressure treatment.