• Assessment
    Is there a dose response relationship of the soy protein and/or isoflavone effects on cholesterol levels?
    • Conclusion

      A significant dose response relationship has not been established between level of soy protein and/or isoflavones in the diet needed to achieve significant decreases in total and LDL cholesterol.

    • Grade: III
      • Grade I means there is Good/Strong evidence supporting the statement;
      • Grade II is Fair;
      • Grade III is Limited/Weak;
      • Grade IV is Expert Opinion Only;
      • Grade V is Not Assignable.
      • High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
      • Moderate (B) means we are moderately confident in the effect estimate;
      • Low (C) means our confidence in the effect estimate is limited;
      • Very Low (D) means we have very little confidence in the effect estimate.
      • Ungraded means a grade is not assignable.
    What daily amounts of soy protein (as supplement) are well tolerated?
    • Conclusion

      Diets containing up to 30 grams of soy protein (as supplements) per day were well tolerated.

    • Grade: II
      • Grade I means there is Good/Strong evidence supporting the statement;
      • Grade II is Fair;
      • Grade III is Limited/Weak;
      • Grade IV is Expert Opinion Only;
      • Grade V is Not Assignable.
      • High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
      • Moderate (B) means we are moderately confident in the effect estimate;
      • Low (C) means our confidence in the effect estimate is limited;
      • Very Low (D) means we have very little confidence in the effect estimate.
      • Ungraded means a grade is not assignable.
  • Intervention
    Does a person's initial cholesterol levels affect the impact of soy protein and/or isoflavones?
    • Conclusion

      Effect of soy protein and/or isoflavones may vary based on initial cholesterol levels

    • Grade: III
      • Grade I means there is Good/Strong evidence supporting the statement;
      • Grade II is Fair;
      • Grade III is Limited/Weak;
      • Grade IV is Expert Opinion Only;
      • Grade V is Not Assignable.
      • High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
      • Moderate (B) means we are moderately confident in the effect estimate;
      • Low (C) means our confidence in the effect estimate is limited;
      • Very Low (D) means we have very little confidence in the effect estimate.
      • Ungraded means a grade is not assignable.
    What does the evidence indicate is the relationship between intake of soy protein and serum total cholesterol, LDL-cholesterol, and triglycerides levels?
    • Conclusion

      Studies varied greatly in their estimation of the effect of diets low in saturated fat and cholesterol containing ~26-50 g of soy protein either as food or as a soy supplement, with 0-165 mg of isoflavones. Studies of individuals with normal and elevated cholesterol (total cholesterol >200mg/dL) and individuals with diabetes varied showing:

      • no effect on total cholesterol up to 20% lower serum total cholesterol
      • no effect on TG up to 22% lower
      • small effect (4%) up to 24% lower LDL-cholesterol.
    • Grade: II
      • Grade I means there is Good/Strong evidence supporting the statement;
      • Grade II is Fair;
      • Grade III is Limited/Weak;
      • Grade IV is Expert Opinion Only;
      • Grade V is Not Assignable.
      • High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
      • Moderate (B) means we are moderately confident in the effect estimate;
      • Low (C) means our confidence in the effect estimate is limited;
      • Very Low (D) means we have very little confidence in the effect estimate.
      • Ungraded means a grade is not assignable.