Plant sterols naturally exist in plants but are destroyed when food is processed. Lestrin contains two of these important, naturally occurring plant sterols; Beta-sitosterol and Beta-sitostanol. Plant sterols may play a role in helping to maintain normal cholesterol levels as part of a healthy diet and lifestyle. Plant sterols naturally exist in plants but are destroyed when food is processed. Lestrin contains two of these important, naturally occurring plant sterols; Beta-sitosterol and Beta-sitostanol. Plant sterols may play a role in helping to maintain normal cholesterol levels as part of a healthy diet and lifestyle.