“保护效应”常见的英文表达是 “protective effect” 。
例如：
Studies have shown that this drug has a protective effect on the liver.（研究表明，这种药物对肝脏有保护效应。）
Regular exercise is believed to have a protective effect against cardiovascular diseases.（人们认为规律锻炼对心血管疾病有保护效应。）