Besides the infallibility attached to the Pope's pronouncements taught with the fullness of his supreme
authority (the «extraordinary magisterium»), the «ordinary magisterium» can also be a source of infallible teaching, when it
concerns de fide doctrine (
concerning faith and morals), when it is marked by unity and unanimity, and when it is proposed to be definitive and
absolute teaching.
If «a
concerned mom» decides to believe all that Harvard says as
absolute authority, then she should also read their reports on how saturated fats do not cause high cholesterol and how cholesterol does not cause heart disease.