Add spaces: Thehighertheamountofbeta-caroteneinthebeginningperiodsofthevariousstudies,thelowerthefrequencyofcancerlateron.Laboratoryandanimalstudieshaveshownthiseffecttobeduetobeta-carotene'sabilitytoinhibittumourcellgrowthandcancerdevelopment(1),(14),and(15).
The higher the amount of beta-carotene in the beginning periods of the various studies, the lower the frequency of cancer later on. Laboratory and animal studies have shown this effect to be due to beta-carotene's ability to inhibit tumour cell growth and cancer development (1), (14), and (15).